# Lotus Elon - Electric 1969 Lotus Elan S4



## 4Foxtrot (Apr 1, 2019)

OK .. Electric Lotus Elan.
I've been a lurker for some time - and want to extend a *HUGE thank you* for ALL the inspiration found on here 🙏

If it helps anyone else I used Instagram to log the conversion / build of a 50 yr old Lotus Elan: www.instagram.com/lotus_elon/ (or without Instagram: MAS Design Products Ltd. - Design Engineering Inventing ) notes are in posts (or hover over pictures for 2nd link)..

*Background:* recovering petrol head who LOVES the handling/steering/balance/lightweight of Lotus cars - especially 60's Elans (as fun at legal speeds as well as on track).

*Mission: *to keep same weight _*and*_ handling balance, similar or better performance as ICE but no noise/smells/hassles (achieved - now testing and tweaking ✌ )

FWIW although superlight, original Lotus Elan's dirty little secret is they are terribly inefficient - 23mpg! - which was annoying - it now runs for free, powered by the sun (via pv panels).

*Costs*: tatty elan (£23K) but with rebuilt twincam engine, new chassis and suspension. Sale of ICE parts £8.5K Cost of most EV and conversion parts £12K, total £26.5K PLUS about 500 hours, blood sweat and tears (as an engineer).

*Basic Spec:*

650Kg (1430lbs which is ~20kg lighter than before conversion)
Hyper9
5 x Telsa Model X P90D modules (3 in front 2 in rear) ~28kWh (same weight distribution so keeps lovely steering/ handling)
best/worst range 200/100 miles
6.6Kw Charger
simpBMS
Kept Gearbox, but not clutch - pulls from zero in top gear, crazy in 1st/2nd
*Controversial - *Some hatred from Lotus purists (even 1st owner who is in 70's .. "you did WHAT with MY car ? " !!). But, to be fair, a LOT of likes from more enlightened lotus folk.

Once again THANKs to all you generous folk who have inspired, freely shared information, links, and experiences of what works ( and what doesn't !!) 👍


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## 4Foxtrot (Apr 1, 2019)

Thanks for approving this post 😘


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## 4Foxtrot (Apr 1, 2019)

'Lotus Elon' Got the Collecting Cars Treatment - by the looks of the comments its a marmite car  There again many folk just dont like EV's 

*Lockdown Project - Lotus Elan EV*
*



 *

Just for balance here it was before the conversion - an improvement ??


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## MattsAwesomeStuff (Aug 10, 2017)

Really cool build. I've wanted to convert an Elise or an Exige for a while now, but, even a donor is prohibitively expensive.

Looks pretty slick


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## Greenbeast (Jun 23, 2009)

MattsAwesomeStuff said:


> Really cool build. I've wanted to convert an Elise or an Exige for a while now, but, even a donor is prohibitively expensive.
> 
> Looks pretty slick


I thought an Elise might not be crazy money now? Unless you exclusively mean a gen2 one


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## brian_ (Feb 7, 2017)

Greenbeast said:


> I thought an Elise might not be crazy money now? Unless you exclusively mean a gen2 one


An early Elise has gone from old enough to be cheaper than a new car to old enough to be collectible - they'll probably never be cheap.


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## Greenbeast (Jun 23, 2009)

brian_ said:


> An early Elise has gone from old enough to be cheaper than a new car to old enough to be collectible - they'll probably never be cheap.


Bugger, missed my opportunity I guess. I almost bought one once about 12 years ago, time flies!


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## Fightingtorque (Nov 30, 2020)

That's a lovely build. I am in a similar position, got some much loved petrol cars including a Lotus Esprit, but I want to build an EV, so I hunted round for a starting point and found this Excel for sale with the powertrain and many other bits already missing. I'd like to achieve similar goals to your Elon - good handling and matching the original performance at least within reasonable road speeds. I only need enough range for local use as I will keep my petrol cars for longer adventures.

Cost is an issue, but I'm hoping to make it a daily driver rather than a hobby toy, so that will help with the justification.


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## MattsAwesomeStuff (Aug 10, 2017)

Greenbeast said:


> I thought an Elise might not be crazy money now?


I saw an Exige locally for $18,000 (CAD, ~13,000 USD). And I thought "Okay, sounds pricey, I'll look around for them and pick up one for cheap".

Then I asked on the Lotus forums, and I think the cheapest anyone had seen one was one that was imported to Canada as parts-only racing car, never to be legal for road use, for $25,000. Otherwise north of $35,000.

"Cheap" to me is, like, I dunno, under 10-15k. Anything approaching a downpayment on a house, for a toy, makes me feel wastefully luxurious.


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## Greenbeast (Jun 23, 2009)

MattsAwesomeStuff said:


> I saw an Exige locally for $18,000 (CAD, ~13,000 USD). And I thought "Okay, sounds pricey, I'll look around for them and pick up one for cheap".
> 
> Then I asked on the Lotus forums, and I think the cheapest anyone had seen one was one that was imported to Canada as parts-only racing car, never to be legal for road use, for $25,000. Otherwise north of $35,000.
> 
> "Cheap" to me is, like, I dunno, under 10-15k. Anything approaching a downpayment on a house, for a toy, makes me feel wastefully luxurious.


Yeah my idea of cheap is not far off of yours.


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## Duncan (Dec 8, 2008)

4Foxtrot said:


> OK .. Electric Lotus Elan.
> I've been a lurker for some time - and want to extend a *HUGE thank you* for ALL the inspiration found on here 🙏
> 
> If it helps anyone else I used Instagram to log the conversion / build of a 50 yr old Lotus Elan: www.instagram.com/lotus_elon/ (or without Instagram: MAS Design Products Ltd. - Design Engineering Inventing ) notes are in posts (or hover over pictures for 2nd link)..
> ...


How do you get 100 - 200 miles range out of 28 kwh??


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## OR-Carl (Oct 6, 2018)

Great looking build! I must have missed it when you first posted, but I took a look at some the photos on that link you posted. You really did a good job on weight to get 28kwh of batteries into a car that only weighs 1400 lbs! I am looking for input from others who are running Tesla modules - specifically about charging voltages, LVC values and voltage sag. Would love to pick your brain if you have the time to answer some questions.


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## MattsAwesomeStuff (Aug 10, 2017)

Duncan said:


> How do you get 100 - 200 miles range out of 28 kwh??


Q: How do you make 5 lbs of fat look attractive?
A: Put a nipple on it.


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## brian_ (Feb 7, 2017)

Duncan said:


> How do you get 100 - 200 miles range out of 28 kwh??


That's 140 to 280 Wh/mile, or 87 to 175 Wh/km... that's 8.7 to 17.5 kWh/100 km (the units used by Natural Resources Canada in their 2020 Fuel Consumption Guide). The worst end is typical for the moderate-consumption current EVs in urban conditions; the best end is far better than even the best current EV in urban conditions.

My guess is a combination of

low mass (the Elan is small and basic by current standards, and was small and light even for its time),
reasonably low aero drag (for a convertible),
favourable test conditions (low and constant speed), and 
creative accounting.
But that's only a guess.


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## 4Foxtrot (Apr 1, 2019)

Duncan said:


> How do you get 100 - 200 miles range out of 28 kwh??


Hypermiling in top gear, under 50mph with a 650Kg TINY, 4 foot wide, slippery shape -- but admittedly apart from not slowing for any bends/roundabouts not as much FUN


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## 4Foxtrot (Apr 1, 2019)

OR-Carl said:


> Great looking build! I must have missed it when you first posted, but I took a look at some the photos on that link you posted. You really did a good job on weight to get 28kwh of batteries into a car that only weighs 1400 lbs! I am looking for input from others who are running Tesla modules - specifically about charging voltages, LVC values and voltage sag. Would love to pick your brain if you have the time to answer some questions.


I've just started a 'Hyper9' thread to discuss errr, hyper9's and also sag .. in Motors.. (just waiting for approval - please )
but here is what I found:









Otherwise TIPs
On tesla Modules - DONT ditch the control boards, and get a simpBMS from Tom De Bree (EVnut on socials) . Building on on work by EVTV, and a teensy - simpBMS works with the existing tesla boards, bleed resistors etc. and gives everything needed (temp, balance, charge control current display etc.) .

Use the built in battery cooling circuits - tesla are WAY ahead on thermal control for both heating AND cooling by a water circuit going right thro the pack. I pump battery water via a light radiator in the summer and an immersion heater in winter (to heat me too !!) .
I hope this helps - More pix on build 'thread' > Login • Instagram mas-design.com/lotus-elon/


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## brian_ (Feb 7, 2017)

In the steady-state high speed section of that chart the car is running about 170 amps at 110 volts for 18.7 kW; that's at 7500 RPM, but what is the road speed? If that's 50 mph, that's 374 Wh/mile, which is not good even for highway speed. At that rate, 28 kWh would be gone in 1.5 hours or 75 miles. I'm guessing that the car is driven at a very low average speed to get the 100 to 200 miles range out of 28 kWh.

But the chart does show the 17% voltage sag at 800 amps well.


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## brian_ (Feb 7, 2017)

4Foxtrot said:


> Use the built in battery cooling circuits - tesla are WAY ahead on thermal control for both heating AND cooling by a water circuit going right thro the pack.


I've alway liked this idea, although the LG Chem system in the Chevrolet Volt is a better implementation. GM found that this level of heat transfer is not necessary for a typical EV (rather than a plug-in hybrid with a relatively small battery compared to the motor power), and uses the less expensive cold-plate system for their BEVs.


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## 4Foxtrot (Apr 1, 2019)

brian_ said:


> In the steady-state high speed section of that chart the car is running about 170 amps at 110 volts for 18.7 kW; that's at 7500 RPM, but what is the road speed? If that's 50 mph, that's 374 Wh/mile, which is not good even for highway speed. At that rate, 28 kWh would be gone in 1.5 hours or 75 miles. I'm guessing that the car is driven at a very low average speed to get the 100 to 200 miles range out of 28 kWh.
> 
> But the chart does show the 17% voltage sag at 800 amps well.


The chart had nothing to do with range testing .. it was just a snippet of log files I found that nicely illustrated voltage sag. 

I'm waiting for a longer thread to be approved - on this and hyper9 generally in 'motors' section.


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## brian_ (Feb 7, 2017)

4Foxtrot said:


> The chart had nothing to do with range testing .. it was just a snippet of log files I found that nicely illustrated voltage sag.


Yes, I understand that, but by coincidence it includes a handy bit of steady-state data for a hint at the energy consumption situation.


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## 4Foxtrot (Apr 1, 2019)

brian_ said:


> Yes, I understand that, but by coincidence it includes a handy bit of steady-state data for a hint at the energy consumption situation.


Do I sense some doubts ? 🙏 the car has 4 gear ratios, is used in winter and summer, sometimes for fun, sometimes for cruising. One day I'll find a flat circuit and smash the 200mile range. Until then 100 miles of fun filled back roads will do .


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## brian_ (Feb 7, 2017)

4Foxtrot said:


> Do I sense some doubts ? the car has 4 gear ratios...


I'm just interested in the actual performance of the design, including the characteristics that might explain the surprising range as Duncan mentioned; I'm not questioning the range that has been reported.

To my list of post #14, I should add "gear ratio selection", since shifting can select the most efficient of four possible motor speeds for each road speed and load condition.


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## OR-Carl (Oct 6, 2018)

Anything over 100 miles in a DIY EV is impressive in my book. How/did you implement regen? I am planning on using the 1-pedal system for my build, but I am not sure if I am going to add multiple regen profiles. There seems to be a lot of pessimism about regen, but a 10% boost in range with no weight penalty seems like it is worth a little extra work.


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## brian_ (Feb 7, 2017)

OR-Carl said:


> There seems to be a lot of pessimism about regen, but a 10% boost in range with no weight penalty seems like it is worth a little extra work.


The data in post #16 (which I realize was not intended to illustrate regen) shows some substantial negative currents (that is, regenerative braking output) under deceleration. There certainly is some potential there.


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## 4Foxtrot (Apr 1, 2019)

OR-Carl said:


> Anything over 100 miles in a DIY EV is impressive in my book. How/did you implement regen? I am planning on using the 1-pedal system for my build, but I am not sure if I am going to add multiple regen profiles. There seems to be a lot of pessimism about regen, but a 10% boost in range with no weight penalty seems like it is worth a little extra work.


In the Tau / SME software which comes with the hyper9 there are 3 profiles, each configurable with a different regen %. These can be switched from the compact display 'ESH button as below..








The Tau software can control a huge number of settings - I'm still tweaking it.
.. for example I'm trying to work out how to switch regen profiles by switches rather than display (ideas ??) ... that's one of the Q's question posed on a new 'Hyper9 thread' waiting for approval in 'Motors' section where I am hoping _*all hyper9 tips, experiences etc independent of conversion, such as this, can be slotted*_. .. Once approved I'll link here.


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## OR-Carl (Oct 6, 2018)

Yeah, a thread for Hyper 9 questions is a good idea. I did not get the display, so I am hoping to get everything set up the way I want on a computer, and then hopefully not need to fuss with too much after that. I went back and looked, and there do seem to be wires in the main harness that handle regen profile selection. Main wiring diagram, page 6. k1-18 and k1-19 are switched to ground to select profiles 2 and 3 respectively.


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## 266917 (May 4, 2020)

These are such cool cars, and it's worth doing just for the pun.


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## 4Foxtrot (Apr 1, 2019)

OR-Carl said:


> Yeah, a thread for Hyper 9 questions is a good idea. I did not get the display, so I am hoping to get everything set up the way I want on a computer, and then hopefully not need to fuss with too much after that. I went back and looked, and there do seem to be wires in the main harness that handle regen profile selection. Main wiring diagram, page 6. k1-18 and k1-19 are switched to ground to select profiles 2 and 3 respectively.


You are absolutely right .. profile 1 can have no regen, and alternative regen %'s can be assigned to Profiles 2 & 3 ... and the on/off digital switch inputs can also be assigned. This mean's (I hope) I can use spare wire in the loom like to K1-7 ... I just never got round to properly checking it out (too much fun testing/driving )  









*Mods - PLEASE can you approve 'The Hyper9 thread' (I'm not fussed to be 1st author - its just needed - as there is all sorts of Hyper9 info dotted about the forum but not in one place) . Hyper9 is getting a very popular drop in system. *
I am still in awe of the Tau software. I wonder if Dana's other TM4 products use it eg their 150Kw motive motor/inverter ?? (but getting that into the non oem space may be the challenge )


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## MattsAwesomeStuff (Aug 10, 2017)

4Foxtrot said:


> *Mods - PLEASE*


*

I don't know if we even have moderators anymore. The overloards never pay attention to us. Volunteer mods don't get notifications anymore.

I think Duncan still has mod priviledges, but not announcements, so he has no idea what he has to do.*


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## 4Foxtrot (Apr 1, 2019)

Huge thanks to @OR-Carl for starting 'THE Hyper9 Thread' .. needs to be done to share experiences .. I've added a few (along with cock-ups  ).

Update on Lotus_Elon: we are locked down in UK atm with C19 so haven't been able to drive much, until recently wife now works at local mass vaccination centre and I have to take and pick her up - hilly twisty - tough route  even in 5degC temps its SO much more efficient than the Model3 on same route like uses 1/2 to 1/3 scarce winter PV KWh's.
It shows Colin Chapmans mantra of added lightness (and aero) works well for EV's.
So, musing a conversion of one of his lightest, most slippery (low Cd.A) .. a Lotus 23b Replica .. if I can find one : *Imagine:* 20-30KWh, + 90Kw hyper9 + <400Kg Performance AND efficiency.








Dream EV's and then make them real ...


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## 4Foxtrot (Apr 1, 2019)

Just did 41 miles using only 4.8KWh !
Like loads of people enjoying sun after 2+ months lockdown. Traffic flowed but at 40-50mph, it helped only having to push 650Kg / 4' wide / minimal CdA.
At that rate the potential range is 239 miles - maybe more if also hypermiling, but where's the fun in that


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## MattsAwesomeStuff (Aug 10, 2017)

4Foxtrot said:


> Just did 41 miles using only 4.8KWh !


Sweet.

100 watthours per mile at modest speeds? That's impressive.


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## G27e (May 8, 2021)

This thread is amazing. It's been done in such a professional and sympathetic way, very impressed. 

Is there somewhere where I can find more info?

Also, did you retain the clutch? Is the gearbox there to make the build easier AND to give higher performance / efficiency?


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## brian_ (Feb 7, 2017)

G27e said:


> Also, did you retain the clutch?


The very first post says "Kept Gearbox, but not clutch"


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## 4Foxtrot (Apr 1, 2019)

G27e said:


> This thread is amazing. It's been done in such a professional and sympathetic way, very impressed.
> 
> Is there somewhere where I can find more info?
> 
> Also, did you retain the clutch? Is the gearbox there to make the build easier AND to give higher performance / efficiency?


Thanks and Sure: Kept Gearbox, but not the heavy bellhousing/clutch/flywheel - I wasn't sure which ratio would be best - glad I did as there is now a choice 1st for max torque at wheels (hooligan mode) 4th for cruise / best efficiency - hyper9, unlike many electric motors, has best efficiency low down in its rev range (with enough torque to also set off from zero in 4th gear) - 3rd is an all round gear. 2nd v fast, but upto 50mph. 
Build logs: Login • Instagram or if not on insta: (scroll down and hover over pictures for information text) : MAS Design Products Ltd. - Design Engineering Inventing

Currently installing gear knob switch to turn off regen, to allow easier on-the-move gear changes (regen drops revs to zero without loads so must be off to change gear).


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## brian_ (Feb 7, 2017)

4Foxtrot said:


> Thanks and Sure: Kept Gearbox, but not the heavy bellhousing/clutch/flywheel
> ...
> Build logs: Login • Instagram or if not on insta: (scroll down and hover over pictures for information text) : MAS Design Products Ltd. - Design Engineering Inventing


I was surprised to see that the bellhousing had been omitted, because without it the input shaft would be too long. The solution turns out to be replacing the bellhousing with a custom conical housing which fits the transmission on the back end and the motor on the front end, so there is no separate adapter plate needed. It's lighter because the front face is only the size of the motor, instead of the larger flywheel size, and because it is aluminum (iron was stock for this transmission, but aluminum bellhousings are available aftermarket). Nice 









Most transmissions, especially newer ones, don't have a removable bellhousing so this would not be so easy... although of course an electric conversion can (and often does) including a change of transmission. The Elan used a Ford transmission, apparently a Type E, and specifically a 2000E (shared with the Ford Cortina) at least initially.


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## MattsAwesomeStuff (Aug 10, 2017)

Hurray, links that do not require an instagram account.

I liked your heating/cooling diagrams. This is one of those "I'll deal with that later" items I've been putting off even planning for a couple years until I get rolling.

Just overall your project is fantastic, thanks for documenting.


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## brian_ (Feb 7, 2017)

4Foxtrot said:


> Currently installing gear knob switch to turn off regen, to allow easier on-the-move gear changes (regen drops revs to zero without loads so must be off to change gear).


Upshifts should still be possible with regen on (because motor speed needs to drop anyway), but they would need to be fast (because motor speed will drop quickly). Turning off regen will make downshifts easier, but they would be even better if the controller were programmed to speed up to the synchronous speed of the input shaft for the next gear higher, rather than just coasting.

Perhaps a two-way rocker switch - one way to set only slight regen for upshifts, the other way to apply slight accelerating torque?


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## brian_ (Feb 7, 2017)

4Foxtrot said:


> ...hyper9, unlike many electric motors, has best efficiency low down in its rev range...


I don't think the HyPer 9 efficiency map is unusual - best efficiency is usually at moderate speed and relatively high load.


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## MoonUnit (Jun 29, 2019)

4Foxtrot said:


> *Basic Spec:*
> 
> 650Kg (1430lbs which is ~20kg lighter than before conversion)
> Hyper9
> ...


Hi, just read the full post, and looked at the pics on the website. Thanks for sharing it all, and congratulations on getting it running so nicely.

I have a similar setup but in a Beetle so I don't enjoy the same level of handling and finesse as you do ... and I am still range testing. I hope to be able to report more on that when I've gathered more data.

I wanted to ask about your charger - I have the same one - and I note it kicks out a lot of heat when charging at 6.6Kw. I have mine mounted in the front spare wheel well for now but it runs so hot I feel like I need to open the bonnet to get airflow. I see yours is in your boot, what do you do about ventilation, if anything?


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## 4Foxtrot (Apr 1, 2019)

MoonUnit said:


> I note it kicks out a lot of heat when charging at 6.6Kw. I have mine mounted in the front spare wheel well for now but it runs so hot I feel like I need to open the bonnet to get airflow. I see yours is in your boot, what do you do about ventilation, if anything?


Thanks  
The charger gets warm but not hot, even at 32A 7 KWh ... the boot is ventilated (into the cabin) - which helps a bit. 
But 90+% charging is at home, with boot open. This is where the charge controls are - simpBMS can control 2 rates: I tend to use mainly 11A as to get power directly from the PV panels on the roof. Direct conversion: Sun to Fun 

PS good handle 'MoonUnit'


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## 4Foxtrot (Apr 1, 2019)

Good Progress Today: Got brilliant #Hyper9 SME/ Tau software to simulate clutch with gear knob button (as below).








This is for on-the-move gear changes and now get 2 levels of regen: normal and e-brake. 
As the motor rotor weight (or rather rotational mass) is not too much higher than the clutch (gone), the button switches to profile 2 (no regen), which allows easy, clutch less gear changes, and brake signal to Profile 3 (higher regen).
I expected to have to set profile 2 to give a specific rpm for best but found this is not necessary as the software can control how fast the motor rev's drop so it behaves like an ICE engine and the gears sync nicely.
Chuffed, as I've been planning this for ages.


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## brian_ (Feb 7, 2017)

4Foxtrot said:


> Good Progress Today: Got brilliant #Hyper9 SME/ Tau software to simulate clutch with gear knob button (as below).


It doesn't really simulate a clutch, but it does simulate some throttle control to make shifting easier and is used when a clutch would used for shifting if there were one.



4Foxtrot said:


> As the motor rotor weight (or rather rotational mass) is not too much higher than the clutch (gone)


The clutch disk would be larger in diameter than the motor rotor, but the rotor is so much more massive than the clutch disk that the motor inertia is certainly higher than the clutch disk inertia. The motor inertia is clearly high enough to be an issue (it is for everyone with a clutchless system), but if it is now tolerable that's great. 



4Foxtrot said:


> ... the button switches to profile 2 (no regen), which allows easy, clutch less gear changes, and brake signal to Profile 3 (higher regen).
> I expected to have to set profile 2 to give a specific rpm for best but found this is not necessary as the software can control how fast the motor rev's drop so it behaves like an ICE engine and the gears sync nicely.
> Chuffed, as I've been planning this for ages.


For upshifts, that's all great - it's like upshifting with an engine while not using the clutch, which works fine if it is timed well. Success!
Downshifts should be much better without the regen, but the synchros still need to handle speeding up that motor interia; again, if the inertia is low enough to be tolerable that's good, although not as good as logic to power the motor to the higher shaft speed.


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## 4Foxtrot (Apr 1, 2019)

Oh Brian


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## MoonUnit (Jun 29, 2019)

4Foxtrot said:


> Thanks
> The charger gets warm but not hot, even at 32A 7 KWh ... the boot is ventilated (into the cabin) - which helps a bit.
> But 90+% charging is at home, with boot open. This is where the charge controls are - simpBMS can control 2 rates: I tend to use mainly 11A as to get power directly from the PV panels on the roof. Direct conversion: Sun to Fun
> 
> PS good handle 'MoonUnit'


Thx, the handle is a joke I share with my son. Probably could have picked a better one ... 

So mine does get quite hot at 6.6KW/h, and I know these chargers will run at about 60 deg C. So far no thermal cutout has been triggered but I have been at pains to open the front boot an inch or so to allow airflow. Right now in Merry England it's not very warm but come the summer I'm not confident it will run without cutting out. We shall see ...


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## MoonUnit (Jun 29, 2019)

4Foxtrot said:


> Good Progress Today: Got brilliant #Hyper9 SME/ Tau software to simulate clutch with gear knob button


Checking I understand you - the button engages (your) profile 2, which you have set up to have no regen? So when you press the button, the motor spools down by itself (assuming you are not pressing the throttle) and is not applying regen itself? 

And when you don't press the button, ie when driving normally, you are set up to have automatic off-throttle regen?

I do run a physical clutch in my conversion and the controller does not like downshifts when in an off-throttle regen profile. It's jerky, with regen kicking in and out, as if confused. A bit of throttle 'resets' it. But it's happier if the no-regen profile is engaged when down shifting.


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## 4Foxtrot (Apr 1, 2019)

MoonUnit said:


> Checking I understand you - the button engages (your) profile 2, which you have set up to have no regen? So when you press the button, the motor spools down by itself (assuming you are not pressing the throttle) and is not applying regen itself?
> 
> And when you don't press the button, ie when driving normally, you are set up to have automatic off-throttle regen?
> 
> I do run a physical clutch in my conversion and the controller does not like downshifts when in an off-throttle regen profile. It's jerky, with regen kicking in and out, as if confused. A bit of throttle 'resets' it. But it's happier if the no-regen profile is engaged when down shifting.


I hope your son was not christened 'MoonUnit' as some might have done  

And Yes exactly, 
Profile 1 (normal) is 30% regen 
Profile 2 (Activated by gear Knob button) is zero regen & a slow drop in revs
Profile 3 (activated by brake lights) is full regen, before mechanical brakes - I'm currently experimenting around 40 to 80% regen (brilliant software !!).


In Profile 2, clutchless gear changes work better than expected with 'Electric Clutch button' - as the revs of the motor drop gently, with easy gentle force of gear stick the syncro's dont have to do much and the gears slide in as revs approximately match, throttle is available to blip for down changes too .. its actually very easy and feels normal. 

FWIW here is the install of my charger: it hangs down (like a bat) in the boot area - mounted on brackets so there is about 1" air gap all round it.


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## MoonUnit (Jun 29, 2019)

4Foxtrot said:


> I hope your son was not christened 'MoonUnit' as some might have done


Ha - no, no danger of that.



> And Yes exactly,
> Profile 1 (normal) is 30% regen
> Profile 2 (Activated by gear Knob button) is zero regen & a slow drop in revs
> Profile 3 (activated by brake lights) is full regen, before mechanical brakes - I'm currently experimenting around 40 to 80% regen (brilliant software !!).


Understood, sounds like an interesting solution. I'm going to fit a brake pressure transducer because I find that with no regen, the brakes are so awful on the Beetle it feels a bit scary, and with 30% ish regen it's a bit stop/start (although good in traffic jams). I don't use the 3rd regen profile at the moment. I think with a transducer, I can have the no-regen-freewheeling but the regen will help when I hit the brakes.



> FWIW here is the install of my charger: it hangs down (like a bat) in the boot area - mounted on brackets so there is about 1" air gap all round it.


Noted. Mine's more enclosed. I have other components around it and they don't like the heat. I'm going to have to move it. Yawn.

I see you have a switch for the charge rate, does the SimpBMS not control that via handshaking with the off-board charge point?


View attachment 122736

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## vjoshi (Feb 23, 2021)

4Foxtrot said:


> OK .. Electric Lotus Elan.
> I've been a lurker for some time - and want to extend a *HUGE thank you* for ALL the inspiration found on here 🙏
> 
> If it helps anyone else I used Instagram to log the conversion / build of a 50 yr old Lotus Elan: www.instagram.com/lotus_elon/ (or without Instagram: MAS Design Products Ltd. - Design Engineering Inventing ) notes are in posts (or hover over pictures for 2nd link)..
> ...


As a long time Lotus fan and an environmentalist, you have nothing to apologize for!!! Lotus is known for its handling. Having an old and outdated engine to say "I have the original motor" I leave to the snob collectors. If you have better rubber for tires in 2021 verses what one had in 1970, you wouldn't think twice about changing tires. So, why fret over changing the engine to something that is truly awesome. I owned a lot of Lotus cars (1972 Elan, 1977 Esprit, 1985 Esprit, 1991 Elan and now a 1997 Elise). I am converting the Elise to electric at this very moment and using the Hyper 9HV motor with the X144 controller. I am truly grateful for your posts and your insights. I actually have other questions that you could help me with. I am wondering if there is a way to contact you directly.


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## 4Foxtrot (Apr 1, 2019)

vjoshi said:


> As a long time Lotus fan and an environmentalist, you have nothing to apologize for!!! Lotus is known for its handling. Having an old and outdated engine to say "I have the original motor" I leave to the snob collectors. If you have better rubber for tires in 2021 verses what one had in 1970, you wouldn't think twice about changing tires. So, why fret over changing the engine to something that is truly awesome. I owned a lot of Lotus cars (1972 Elan, 1977 Esprit, 1985 Esprit, 1991 Elan and now a 1997 Elise). I am converting the Elise to electric at this very moment and using the Hyper 9HV motor with the X144 controller. I am truly grateful for your posts and your insights. I actually have other questions that you could help me with. I am wondering if there is a way to contact you directly.
> View attachment 122748


Thanks - And yes an electric Elise is a fantastic EV candidate - especially if the weight and balance can be kept - the handling is just sublime !! Colin Chapmans 'Added lightness' for performance on the straights AND on corners is SO True. 
Tesla had to stick in a heaver battery into their 2008 roadster to calm the range critics, but now with more upto date energy dense battery tech from either Tesla MS or LG/ipace etc, you should get both performance and range.

If not t done already I'll DM you with contact details... happy to share experiences (aka mistakes to avoid  )


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## 4Foxtrot (Apr 1, 2019)

Published in Lotus Drivers Club 'Chicane' Magazine. Part 1 of 3 "From Elan to Elon .. a journey of adding lightness, quietness and efficiency" 
1. From the Steel age to the end of the ICE age (early personal journey to EV's) 
next
Part 2 (upcoming) Smart Thinking, Bad soldering, ‘Brave Little Toaster’ and marriage planning for Elon. 
Part 3 (upcoming) Making the ‘Electric Dream’ real, Elon is naughty, and other experiences of free, silent fun !


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## Yellow lotus (Oct 4, 2021)

Hi 4foxtrot,
Could you tell me how you coupled the hyper 9 to gearbox as I'm using near enough the same system on my 71 europa. A little bit heavier but looking at your setup should work with transaxle. Thks Paul.


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## 4Foxtrot (Apr 1, 2019)

Yellow lotus said:


> Hi 4foxtrot,
> Could you tell me how you coupled the hyper 9 to gearbox as I'm using near enough the same system on my 71 europa. A little bit heavier but looking at your setup should work with transaxle. Thks Paul.


Sure, I could have kept the bellhousing, but on the Elan its cast iron, big and heavy - if the Bellhousing was lighter Aluminium or Magnesium alloy I'd keep it. What is the Europa bellhousing made of ?

The coupling between the hyper9 and the gearbox used a dead clutch plate centre spline fixed with 6 (M8 cap heads iirc) to a standard motor coupler with a simple turned aluminium part that also held the 4 magnets for the tacho, rpm hall sensor.

BUT - Can you See the mistake ??? 









..... 4 magnets

BUT the ICE engine is .... 4 stroke

So how many magnets are needed to drive the tacho  ?


..................................................................................................................................TWO 😆😆😆
lesson learned !!

BTW - I'd love an E-Ropa  (it was a teenage bedroom pin-up, and later I got a Twinc, but was just too tall for it :-( )


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## 4Foxtrot (Apr 1, 2019)

To explain the regen / gearchange profiles on Hyper9 Tau software - there are 3 switchable regen and drive profiles, each are adjustable 0-100% I dont use a clutch, instead I switch off regen to change gear as the motor has low inertia and spins down gently with no regen.


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## remy_martian (Feb 4, 2019)

You CAN do clutchless up and downshifts using the throttle and by the sound/tach. Obviously on an electric, no engine sound to go by. Did that on the F-350 as I was losing the clutch slave cylinder on a cross country trip.

When shifting, unload the driveline by feathering the throttle which at that point makes a pull to neutral effortless, then adjust motor RPM close to what you need and lightly shift it into gear as you tweak the throttle. Not sure if regen on or off matters here...the diesel had it "on", so maybe mild regen vs none means better RPM control? You probably do not want 100% torque at button push. It's nice that you can easily play with these settings.

It's a slow shift, but with the massive rotor inertia (picking it up takes two arms) relative to a clutch disc (pick up with a finger), I think you'll smoke your synchros pretty quickly if you're using them to brake or speed up the rotor without RPM matching with the throttle pedal.

Sure, it works now with your diddle button, but in a few hundred shifts you may be pulling the trans out if you're braking or accelerating the rotor with the synchros.


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## 4Foxtrot (Apr 1, 2019)

Yes, I should have mentioned I DO match rev's and am gentle with the stick - its _*really*_ easy to do - the "diddle" button allows that (good name .. I'll take that  )
The 2000E box on the Elan is one of fords best . And trust me .... 'no harm was done to innocent synchro's' .. when filming this 😆


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## Yellow lotus (Oct 4, 2021)

4Foxtrot said:


> Yes, I should have mentioned I DO match rev's and am gentle with the stick - its _*really*_ easy to do - the "diddle" button allows that (good name .. I'll take that  )
> The 2000E box on the Elan is one of fords best . And trust me .... 'no harm was done to innocent synchro's' .. when filming this 😆


Hi 4foxtrot, 
How difficult was it too registar the Elon as an electric car with the dvlc.
I'm putting the hyper 9 to the renault gearbox for now to keep the alterations 
Very low to keep dvlc happy and then go to town when registered as ev.
Will limit torque as I don't think the 4 speed will last long.
Starting project in February. 
What problems did you have?
Rgds paul


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## 4Foxtrot (Apr 1, 2019)

Yellow lotus said:


> Hi 4foxtrot,
> How difficult was it too registar the Elon as an electric car with the dvlc.
> I'm putting the hyper 9 to the renault gearbox for now to keep the alterations
> Very low to keep dvlc happy and then go to town when registered as ev.
> ...


Hi Paul It was Dead easy ! - just sent a letter pictures which clearly showed the Motor / EV conversion (at a 1/2 way stage) 


















PLUS the registration number, plus on the V5 changed fuel to 'ELECTRICTY' (NOT electric !!!! ) that was all. The insurance wasn't effected C £140 pa with Footman James who i'd recommend (they can do track cover  ) As its classed as a 'major change' you have to get an annual MOT - which again is easy and a good opportunity to check bolt tightness - v important with the extra torque .. more info > on build log MAS Design Products Ltd. - Design Engineering Inventing hover over each picture for a description and scroll down for more: has the full story.


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## MoonUnit (Jun 29, 2019)

Yellow lotus said:


> Hi 4foxtrot,
> How difficult was it too registar the Elon as an electric car with the dvlc.
> I'm putting the hyper 9 to the renault gearbox for now to keep the alterations
> Very low to keep dvlc happy and then go to town when registered as ev.
> ...


I am having a completely different experience to 4Foxtrot with DVLA. I asked them what they wanted, they told me to send the V5 and evidence of the conversion. I asked them what they meant; they said they didn't want pictures, they wanted "documentary evidence", which they clarified as receipts for parts etc. I thus sent them the V5 and some meaty receipts, heard nothing for 6 weeks, chased them and was told they did in fact want pictures, and ones that included the number plate. I sent them pictures of the engine bay with a hyper9 in it and controller, with number plate in shot etc., heard nothing for 8 weeks. I chased them again and they said I had to get it inspected. They sent their own inspector, who agreed it was indeed electrically powered. That was two weeks ago and not heard anything since.

One thing that struck me was they seemed to be interested in how the battery boxes were installed, as in how they were attached to the car, as they had asked the inspector to check that. He made an off-the-cuff comment that 'clearly this isn't some funny hybrid', so that might have been a concern of theirs. It may be that 4Foxtrot's pics satisfied them because they could see the battery modules. My modules weren't visible in my pics. The other thing is that DVLA seem to be barely functioning in the best of times, and these are not the best of times, so it may just be my bad luck.


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## remy_martian (Feb 4, 2019)

Sounds like they may have come across tax evaders throwing batteries in the trunk/boot trying to loophole an ICE into a hybrid.


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## MoonUnit (Jun 29, 2019)

4Foxtrot said:


> To explain the regen / gearchange profiles on Hyper9 Tau software - there are 3 switchable regen and drive profiles, each are adjustable 0-100% I dont use a clutch, instead I switch off regen to change gear as the motor has low inertia and spins down gently with no regen.
> View attachment 126019


Question - your braking regen is binary, it's either on or off depending on the brake lights switch. It's not brake pressure dependent. Does this give you enough brake 'feel' or is it a bit 'grabby'? 

I am yet to plumb in a brake pressure transducer but I'm hoping that when I do it'll be a better solution than the one I currently have, which is either no regen, mild, or strong.


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## 4Foxtrot (Apr 1, 2019)

MoonUnit said:


> Question - your braking regen is binary, it's either on or off depending on the brake lights switch. It's not brake pressure dependent. Does this give you enough brake 'feel' or is it a bit 'grabby'?
> 
> I am yet to plumb in a brake pressure transducer but I'm hoping that when I do it'll be a better solution than the one I currently have, which is either no regen, mild, or strong.


Very good Question…
The Tau software brings in regen gradually, its never On/off.
How it works on my setup is: there is general regen - ie when foot is off accelerator pedal. This is both switchable (by a switch on the dash) AND adjustable (in the software).

When the brake is pressed, additional regen is added, again its not on/off it’s gentle, switchable and can be adjusted in the software.

It all works really smoothly (better than expected tbh). Having both Modes instantly switchable gives more control than my wife’s Tesla.

So I’m happy it didn’t go for the pressure switch - I planned to add one but found was not needed, and might have prevented getting the 3 regen options (off, ~30% on & ~50% braking).
But … Its not all rosy tho’ … for different reasons:

1. When the battery is near full, and especially when cold. Just like on the Tesla, Regen needs to turned down, or it tries to push the battery voltage too high. This is prevented by the software, but then throws an overvolt error. So I switch off both regens when I set off in this situation, and when I’ve forgotten to preheat the battery. Then as the battery warms, SOC goes below 90-95% and voltage is pulled down a bit, I switch back 1st general regen, and then braking regen.

2. Both regen % are fully adjustable in the software, but As I’ve got a gearbox, these need ideally to be optimised for each gear. I mostly use 3rd and 4th (and occasionally 2nd for a fast getaway ;-)) So 3rd has more overall regen than 4th. And 2nd even more. This is much more noticeable than the additional braking regen.

I think the Tau software options are many and brilliant. I hope this helps.
Cheers
Mark


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## MoonUnit (Jun 29, 2019)

4Foxtrot said:


> Very good Question…
> The Tau software brings in regen gradually, its never On/off.
> How it works on my setup is: there is general regen - ie when foot is off accelerator pedal. This is both switchable (by a switch on the dash) AND adjustable (in the software)


Thanks for the comprehensive answer. I might try the same setup and see how it goes.


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## VanDeGraaff (Oct 23, 2020)

4Foxtrot said:


> OK .. Electric Lotus Elan.
> I've been a lurker for some time - and want to extend a *HUGE thank you* for ALL the inspiration found on here 🙏
> 
> If it helps anyone else I used Instagram to log the conversion / build of a 50 yr old Lotus Elan: www.instagram.com/lotus_elon/ (or without Instagram: MAS Design Products Ltd. - Design Engineering Inventing ) notes are in posts (or hover over pictures for 2nd link)..
> ...


I had an Elan in the early 70s. I wish I still had it. Thanks for keeping this baby alive.


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## Plusjim (10 mo ago)

4Foxtrot said:


> OK .. Electric Lotus Elan.
> I've been a lurker for some time - and want to extend a *HUGE thank you* for ALL the inspiration found on here 🙏
> 
> If it helps anyone else I used Instagram to log the conversion / build of a 50 yr old Lotus Elan: www.instagram.com/lotus_elon/ (or without Instagram: MAS Design Products Ltd. - Design Engineering Inventing ) notes are in posts (or hover over pictures for 2nd link)..
> ...


Inspired by your built I started last year transforming my '69 Lotus Elan +2 that I own since '87. The Lotus is now on the road again as EV, registered as a +1 (the weight increased by 90 kg and now only one person is allowed on the back seats)
I used a 16Kw engine with 96v and 32 kwh Battery Pack. There is a little more space in the +2 where the petrol tank used to be. I kept the former boot space as the two chargers (400/220v) are situated under the floorpan where the spare sat. I used the 5 speed Ford Type9 gearbox with aluminium bellhousing that I had already installed earlier.
I'm very happy with the result and I like the amazing drive.
I have to thank you for giving me the idea to dive in this projet.
Cheers.
Jim.


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## 4Foxtrot (Apr 1, 2019)

Plusjim said:


> Inspired by your built I started last year transforming my '69 Lotus Elan +2 that I own since '87. The Lotus is now on the road again as EV, registered as a +1 (the weight increased by 90 kg and now only one person is allowed on the back seats)
> I used a 16Kw engine with 96v and 32 kwh Battery Pack. There is a little more space in the +2 where the petrol tank used to be. I kept the former boot space as the two chargers (400/220v) are situated under the floorpan where the spare sat. I used the 5 speed Ford Type9 gearbox with aluminium bellhousing that I had already installed earlier.
> I'm very happy with the result and I like the amazing drive.
> I have to thank you for giving me the idea to dive in this projet.
> ...


Awsome Jim … super neat 👍


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## bkwanab (Nov 5, 2021)

Duncan said:


> How do you get 100 - 200 miles range out of 28 kwh??


Simplicate and add lightness.


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## remy_martian (Feb 4, 2019)

Weight is everything. It's why I'm getting heartburn about my Silverado reservation...heavy pig based on Hummer.


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## 4Foxtrot (Apr 1, 2019)

Update:
I have had several enquiries for cad files/plans but sorry, I can’t supply specifics as my liability insurance wouldn’t cover - and the work is very experimental (ie doesn't always work).

I am now using Elon as a ‘daily’, eg 27mile commute etc and really enjoying this Elan more than all my previous 8 Elans. Along with total reliability - it just goes. The electric torque, even from zero in top gear [Daughter Setting off in Top Gear New video by Mark Sanders ] - allows undiluted fun in the handling dept. …. uninterrupted by gear changes…., but hey I know some would miss the noise. Elon (car AND person) is proper marmite : 50:50 love and hate 🤣

Below are a typical set of Q&A’s from another Elan owner thinking about a similar EV conversion.
Which might help others:

*1) *Did you say the battery packs were from a Type X Tesla? - what was the capacity of each pack was it 27kw total i.e. 5.5kw per pack* ?*
YES early Model s/x modules were 5kWh (s/x85 2013+ ) and over time they increased to 6+ kWh (s/x100 ) . 
I'd only trust modules I know the history of / matched, and ALL from the same car / known sources eg 2nd life batteries in Christchurch, UK zero-ev or ECC in wales.
BUT even 2012 modules work well with capacity levelling off well over 90% and some going back up !!

*2) *What was used to space the battery packs, enabling them to be stacked on top of each other* ?*
Space was tight vertically for the 3 modules in the front, so I stacked them on top of each other with special 4mm closed cell (wont wear) foam between modules. Adjustable structural spacers and tie rods between the module rail mounts.
Other EV converters would frown on this, especially in the EU, and use a metal box supporting the modules on rails but:
a) before conversion my carbs leaked petrol directly above the distributor
b) space and weight were at a premium
c) I sealed the modules in a plastic case from water ingress
d) i understand the risks 

*3)* Is the Hyper 9 connected directly to the gearbox output shaft, without the clutch plate etc, or is the clutch retained* ?*
Yes, I used a spare clutch plate inner to match the splines along with a standard adapter drive flange and an own design simple cnc'ed joiner between the standard parts (with magnets for the hall sensor>amp>tacho )

*4) *Where was the bell housing adaptor plate obtained from* ?*
Own design cnc'ed. BUT, although it will be v tight at the front of the motor to chassis, heavier and slightly more weight on front wheels, you could possibly keep the bell housing, clutch, lightened flywheel and design/make adapters:
a) motor shaft to Flywheel
b) Motor case to Bellhousing
c) front of bell housing to original engine mounts/rubber>Chassis mounts.

But my main aim was to keep the balance/weight distribution the same above all else (essence of elan handling is THE key for me).
And with same power, but much more torque from zero, a clutch would be more useful for faster down changes, possibly more fun ?? but otherwise adds weight, slip/reliability problems.
I also have size 11 shoes and long legs, so the clutch pedal space is welcome (the pedal is still there but tucked up out of the way.

*5)* Contacts for supply of various parts * ?*
I didn't use but - Second Life EV Batteries Ltd - Used electric car (EV) batteries- Tesla in christchurch, UK (also sell the simpBMS)
Zero EV - Electric Vehicle Conversions for wire etc, and now motor, cooler and controllers (I used ecc but they are now TV and own projects mainly)
AVC2 for public charger handshake (from ECC Welcome to Electric Classic Cars)
Home for charger (or from zero-ev.co.uk now)
ebay (with caution !!! ) for many misc parts eg water pump, vacuum pump, Non-return valves, vacuum sensor (for headlights) etc NB use over cable current sensors NOT inline shunts)
Own spares from various engineering projects eg valves, tubes wires, connectors etc (up-cycling)

Plus LOTS and lots of deep googling and learning from others projects.

*Dont *- (ie my mistakes)  ...
use 4 magnets for hall sensor (2 for 4 cycle engine equivalent ... durrrrr  )
use cheap crap voltage monitors relays or contactors .. or test fully, off the car

I Hope this helps - and do check out ALL the pictures and my descriptions descriptions on insta/web for more, warts and all - MAS Design Products Ltd. - Design Engineering Inventing
Cheers, Mark, Poole UK


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## brian_ (Feb 7, 2017)

4Foxtrot said:


> *1) *Did you say the battery packs were from a Type X Tesla? - what was the capacity of each pack was it 27kw total i.e. 5.5kw per pack* ?*
> YES early Model s/x modules were 5kWh (s/x85 2013+ ) and over time they increased to 6+ kWh (s/x100 ) . The s/x 70/75 modules are less desirable as smaller capacity and iirc less volts, but same profile...


No, they're not different in voltage. All S and X modules before the most recent redesign - the ones with 14 or 16 modules of this shape - are 6S in configuration. Their capacity varies due to different number of cells in parallel and different capacity cells (all of 18650 format), but their voltage is the same.


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## remy_martian (Feb 4, 2019)

Module voltages are the same.

The Tesla battery packs are indeed a different voltage. 14 module and 16 module.


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## 4Foxtrot (Apr 1, 2019)

remy_martian said:


> Module voltages are the same.
> 
> The Tesla battery packs are indeed a different voltage. 14 module and 16 module.


I knew there was something less desirable about the 75 Modules.. thanks for the correction guys 😆


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## floydr (Jun 21, 2021)

remy_martian said:


> Module voltages are the same.
> 
> The Tesla battery packs are indeed a different voltage. 14 module and 16 module.





4Foxtrot said:


> I knew there was something less desirable about the 75 Modules.. thanks for the correction guys 😆


It is the number of modules in a pack which is different. The modules all have 5.3kWh read remy last posts
75/14=5.35kWh per module 85/16=5.31kWh per module so if you used 75kWh modules you would get .04kWh more per module 
later floyd


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## remy_martian (Feb 4, 2019)

There are some modules, as Brian noted, with differing cell counts/capacities but they are all the same within a particular donor car. The ones you noted are most prolific.


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## brian_ (Feb 7, 2017)

4Foxtrot said:


> I knew there was something less desirable about the 75 Modules.. thanks for the correction guys 😆


Good - as long as you understand that all of these modules (which you were calling "packs" are the same roughly 22 V (nominal) voltage, and the difference is in energy (or amp-hour) capacity. "Pack" means all of the modules in one housing, and there is only one pack in any Tesla, so for them (and almost all EVs) "pack" means the same as "complete battery". Since you're not using a complete Tesla Model S or X battery, it doesn't matter whether it includes 14 or 16 modules; it is the specifications of a single module that matter to your choice.


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## 4Foxtrot (Apr 1, 2019)

To answer a couple a PM's: what to do differently with hindsight..

With my experience with Elon , using a Hyper9 motor, and if money was no object, I think I'd keep the 4 speed gearbox, possibly modified to just 2nd and 4th and also a lightened clutch with super lightweight flywheel plus magnesium bellhousing, for faster changes between gears - but this would be slightly heavier than my set up eg c 670-680kg.
..Or ..
Use a single overall gear ratio halfway between 3rd gear and 4th gear (based om 3.7 diff) - which would be a compromise between starting acceleration and top speed.

This is because the huge torque (230Nm) of the Hyper9 motor starts at zero and then tails off above 5000 rpm.
I could use a more powerful, 'torquey' and higher revving motor - but this would then put much more stress on all the other Elan parts than even a highly tuned twincam would do eg chassis, diff, drive shafts, hubs, etc etc), and such motors tend to be 400v rather than 120v, so would need more, but smaller batteries / complex BMS etc.

I love the size, steering and handling of Elans - all enjoyed at legal speeds.
Electric just adds quietness, and steering that isn't interrupted by gear changes - otherwise its pure Elan.
There are also other benefits which maybe only I (as a nerd ) appreciate:
Free to use (via PV panels), with free fill ups at Tesco's (imagine rolling upto a petrol station and filling for free)
Similar range (I got 23mpg before conversion) - but bladder range remains the same
I've done some longer trips with short 'top-ups' on route eg tescos, many charging places with food (and loo's) and mates places - it just takes planning stops where there are chargers, all part of the EV adventure.
AND .. No stinky exhaust, smells, oil burning/dripping, rough running, flat spots, overheating or stuttering in traffic.
(but I know from owning 8 Elans this can be part of the 'fun')


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## Plusjim (10 mo ago)

4Foxtrot said:


> To answer a couple a PM's: what to do differently with hindsight..
> 
> With my experience with Elon , using a Hyper9 motor, and if money was no object, I think I'd keep the 4 speed gearbox, possibly modified to just 2nd and 4th and also a lightened clutch with super lightweight flywheel plus magnesium bellhousing, for faster changes between gears - but this would be slightly heavier than my set up eg c 670-680kg.
> ..Or ..
> ...


Hi,
220NM is too much torque for the 4 speed. The 5speed T9 box (out of a Sierra) that I use is built for max 200NM.
That's why I had to use a smaller engine of 170NM max. This gives a little more torque than the original Elan ( I think is 152Nm) and doesn't stress the back axle too much. To cope with more NM I changed the donuts and the inner and outer axles to Tony Thompson race spec. Concerning the weight I have an alu bell housing and a new flywheel without the ring gear, but I use until now the original clutch. Will see how long it survives !
Will depend of my driving style. For a quick start I use 1st gear and change to 3rd for normal driving (especially efficient from 50 to 90 km/h) and 5th for cruising on motorways. 2nd and 4th rarely used.
Did now more than 2000 troublefree km without the same symptoms you mentionned (stinky etc)
It' happy motoring....


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## 4Foxtrot (Apr 1, 2019)

Great stuff ! Please share more about your set up eg motor, batteries, weights and of course PICTURES. ( or links in case I missed it) 

Yes I only release the full 230 Nm in top gear (straight thro) and rarely in lower gears (limited by wheel spin from standard tyres ) . All good in 3000 miles so far. For track - top gear only.

Putting wider/ stickier tyres on would be faster, but this would strain the whole drive train more. I prefer lower grip as more fun at sensible speeds


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## Plusjim (10 mo ago)

4Foxtrot said:


> Great stuff ! Please share more about your set up eg motor, batteries, weights and of course PICTURES. ( or links in case I missed it)
> 
> Yes I only release the full 230 Nm in top gear (straight thro) and rarely in lower gears (limited by wheel spin from standard tyres ) . All good in 3000 miles so far. For track - top gear only.
> 
> Putting wider/ stickier tyres on would be faster, but this would strain the whole drive train more. I prefer lower grip as more fun at sensible speeds


The battery pack is of 96v, 32kwh. I posted some photos march 23. The car had 885kg and has now 980kg, so still under 1 ton 😀. Engine 50kg, 8 batteries 200kg. Range: realistic 170 km (with 20% power left) tested on motorways.
Wider wheels = less km/kw😬


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## 4Foxtrot (Apr 1, 2019)

Plusjim said:


> The battery pack is of 96v, 32kwh. I posted some photos march 23. The car had 885kg and has now 980kg, so still under 1 ton 😀. Engine 50kg, 8 batteries 200kg. Range: realistic 170 km (with 20% power left) tested on motorways.
> Wider wheels = less km/kw😬


Sorry Jim, My bad - I didn't connect you with your earlier post about the Elan +2
NICE work !! I'm also loving the LED's and its good to know more about the spec's.
Fun yet Quiet with no smells makes a lotus better IMHO. .. but what has been the reaction to your conversion from the Lotus community ? (mine has been marmite 50:50 love and hate  )
All the best
Mark, Dorset UK


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## Plusjim (10 mo ago)

Went 1. of May to my british Sports cars owners Club annual ralley meeting..(70 cars)
..
Some were very interested, some even didn't. 
look at the car at all..most of Them talked about it but not to me ☹
I think we have to wait for some years and They all will talk about it 🤗
Was a Daily ride about 100 miles.
Did a short fill Up during mid break. Easy. Very easy..
Only disadvantage, the smell of the cars that I followed....😠


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## Kar0z (7 mo ago)

Hi Foxtrot,
That job is amazing !
Long time lurker here, I only created my account today : do you have news on your average Wh per km (or mile…) consumption ? Do you ever plan to bring it to a chassis dyno to get regulated measurements on reference cycles to compare ?


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## 4Foxtrot (Apr 1, 2019)

Kar0z said:


> Hi Foxtrot,
> That job is amazing !
> Long time lurker here, I only created my account today : do you have news on your average Wh per km (or mile…) consumption ? Do you ever plan to bring it to a chassis dyno to get regulated measurements on reference cycles to compare ?


Thanks  - long story short: it varies:

My regular commute its 54 miles round trip, with slower traffic it seems to use 7.1kWh, but when its clear that goes up to 9.2kWh (hilly, twisty Dorset roads aka FUN! ).
This is in 1:1, 4th gear (with overall gear ratio of 3.77:1 to 13" wheels).. 
I'm sure when really 'booting it' it would use more .. But never anything close to its 23mpg or worse when ICE. 
I've been meaning to do a proper, average 'economy run' eg using 55mph, flat, little wind (which seems to give Tesla's quoted ranges), but there always seems to be too many temptations  
I guess Colin Chapmans Mantra of simplify and add lightness, combined with a tiny frontal area really helps. 

Most lightweight small profile Lotus will make excellent EV's (but with only primary safety) - what are you planning ?


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## 4Foxtrot (Apr 1, 2019)

Plusjim said:


> Went 1. of May to my british Sports cars owners Club annual ralley meeting..(70 cars)
> ..
> Some were very interested, some even didn't.
> look at the car at all..most of Them talked about it but not to me ☹
> ...


 Much the same here .. I went to a recent Lotus Meet Up, for the 1st time.








Mainly modern cars, with just a few 60's Elans. Owners of the moderns were fascinated, and the discussion was all about which would be best to convert: Elise, Evora or VZ220 vs Tesla Roadster, the only barrier, generally was "missing the engine sounds". But I got 'cold shouldered' by the other immaculate Elan show cars' owners 😲 Even when I just tried to discuss common set ups (tyres, springs, shox etc.)


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## Kar0z (7 mo ago)

4Foxtrot said:


> what are you planning ?


I’d love to hyper9 a Corvair with a powerglide, knowing full well that :
1) I’m on the wrong side of the atlantic
2) French regulations regarding retrofits are terribly restrictive atm
3) Even converterless, the valve body operation would require some plumbing, oil pumps and relays for 0 rpm adaptation.

In the meantime I started developing some scripts to guesstimate consumptions on speed traces (in order to evaluate penalty on highway vs city, regen braking potential etc), so having real-world data to fit is always interesting ! Alas, I only know the weight of your car, Cd and frontal area are largely approximated at this point for your case…


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## bkwanab (Nov 5, 2021)

Duncan said:


> How do you get 100 - 200 miles range out of 28 kwh??


Keep the weight down. If you could make a Nissan Leaf weigh half as much it could go twice as far, in principle.


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## brian_ (Feb 7, 2017)

bkwanab said:


> Keep the weight down. If you could make a Nissan Leaf weigh half as much it could go twice as far, in principle.


Yes... if it also had half of the frontal area for aerodynamic drag.


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## Kar0z (7 mo ago)

bkwanab said:


> If you could make a Nissan Leaf weigh half as much it could go twice as far, in principle.


Well, at iso-Cd and Area in steady state conditions, no. But it's true, weight is directly linked to power necessary to a given acceleration rate, as well as rolling losses (but that's only relevant at low_-ish_ speeds, above which drag takes over).

But my guesstimate for the Elan is a <1.5m2 frontal area (really tiny) and a Cd around 0.38-0.40 given some sources (really OK for a convertible) => That's a main driver for consumption reduction.

Up to that point I may or may not have used my MATLAB license at work (according to my lawyer, I definitely didn't do it with work resources), so I don't have the initial numbers I computed at hand... But I'm in the process of importing them on GNU Octave at home to share here.

Generally I ran both steady speed computations of losses and peak power capabilities sorted by slope, as well as power/energy estimates on varied dynamic cycles (WLTC, some RDE traces, etc), but at this point I feel they are too highly reliant on Cd and Frontal Area.
Drivetrain mechanical efficiency is not a huge source of error I think, as these are usually not too variable as long as you don't add a torque converter somewhere in the middle : there's some literature on bearing efficiencies, and you always end up around 0.85 anyway you do it. As well, I took some liberties regarding electrical efficiency, as I think EVs have flat enough efficiency characteristics that in the end it's all fairly irrelevant if you're at 2k rpm or 5k rpm as long as you're not too high/too low, or at the bleeding edge of your power (extreme amperage should likely degrade efficiency, both on the battery and controller side).


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## MattsAwesomeStuff (Aug 10, 2017)

4Foxtrot said:


> I got 'cold shouldered' by the other immaculate Elan show cars' owners 😲 Even when I just tried to discuss common set ups (tyres, springs, shox etc.)


The insufferable elitism and gatekeeping is alive and well in almost every community around the world.

I got into it with one a few months ago. My argument was "It's okay for _you_ to have a strong opinion, but it doesn't make it 'the correct' opinion to have." This loser was trying to argue that cars have a certain character or spirit and that there are correct and incorrect things to do to them. He was arguing this as fact. I tried arguing that, no, again, you can look at a car and have an opinion about what you would like to do to it, or what you think others should do to it, but, that's all it is, an opinion, maybe even a popular opinion, and others will have other preferences. He was all "No, that RUINS the vehicle, and whether you want to admit it or not a car DOES have certain character and things that should or shouldn't be done to it."

The dumbass was a moderator, and after a few back and forths where I basically embarrassed him (or rather, he embarrassed himself and I was politely explaining why he was being nonsensical), he deleted the whole conversation to cover it up, because his own peers (I was very much an outsider) were liking my posts and not his. Unsuprising, a person that literally cannot understand the concept of his opinion not being fact, is also so egotistical that he's a crybaby about it, and, is also a powertripper. He later PM'd me and asked me to not reply to him in threads any more because I'm obviously just out to attack him constantly (in, umm, one thread total, ever). I literally had to look up the username to know who he was. Imagine the humiliation of losing a feud, with someone who's unaware they're even in one with you, or knows you exist.

I replied and told him that, despite him seeming embarrassed, it was a disservice to the community to have deleted that discussion because it's a common thread in many communities, and that the thought process of how and why to mind your own business and to be tolerant or even supportive of those with different opinions is beneficial to the community, as evidenced by the number of people who were liking posts and and involved in the discussion.

Anyway, rant over.



Kar0z said:


> Well, at iso-Cd and Area in steady state conditions, no. But it's true, weight is directly linked to power necessary to a given acceleration rate, as well as rolling losses (but that's only relevant at low_-ish_ speeds, above which drag takes over).


... but he wasn't making an argument about acceleration rate (where it's only semi-true). He was making an argument about range. So, that's definitely false. Brian's correction is spot on (or, some near-equivalent to where total resistance from air drag all combined is also cut in half, whatever path that takes).


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## Kar0z (7 mo ago)

MattsAwesomeStuff said:


> ... but he wasn't making an argument about acceleration rate (where it's only semi-true). He was making an argument about range. So, that's definitely false. Brian's correction is spot on (or, some near-equivalent to where total resistance from air drag all combined is also cut in half, whatever path that takes).


I was writing at the same time as Brian, and we definitely seem to be in agreement (see my mention of iso-Cd and Area) even though his statement may have been more direct.
The part about acceleration is just an added remark as to why you'd expect larger relative gains from a lower weight on a dynamic speed trace compared to a steady-speed exercise.
To rephrase this acceleration/consumption part and why I don't think it's only "semi-true" ^^ : accelerating a body is a matter of mass and resultant effort, ie if you're at a given speed with any vehicle, it is implied you're already developing the effort to overcome your roll and air resistance at this speed, and from that point the extra power consumption required for any given acceleration is purely governed by the mass, provided you have enough reserve tractive effort.


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## stevefed (Feb 23, 2015)

Plusjim said:


> Went 1. of May to my british Sports cars owners Club annual ralley meeting..(70 cars)
> ..
> Some were very interested, some even didn't.
> look at the car at all..most of Them talked about it but not to me ☹
> ...


Yea! Love the clean build. I get a lot of the same from the Porsche/VW 914 community, which is somewhat annoying since the 914 has always been a bastard child calling for modification. I'm neck deep in a DC to AC upgrade process, just hoping to finish before the school year starts back up, tick-toc Thanks for sharing, the struggle is real!


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## 4Foxtrot (Apr 1, 2019)

Update/Data points with some daily miles (and not much hypermiling  ) ... (cross posted from the Hyper9 thread)

" To add to data points with quite a few miles on the Hyper9 with standard Gearbox (3.77 diff and 13" tyres FWIW , but only 650kg / 1430lbs to pull).
I'm finding most of the time I'm in top gear 1:1.
The hyper 9 has enough torque to be able to pull away smoothly from zero in top gear... but I dont expect to win any drag races.
If I know I need a swift getaway, eg entering fast moving traffic etc I might select 3rd gear for a smooth fast getaway, or even 2nd for a very fast getaway - being careful to avoid wheel spinning (Colin Chapman did not like LSD's as he thought they spoil Lotus balance at speed). Never use 1st gear unless I want to leave a skid marks and smoke !!
In top gear, once the speed gets to 20-30mph there is little point in using 3rd or lower gears.
Top gear then benefits from the lovely fat Hyper9 torque band ~ 1000rpm tho to ~5000 rpm (or over 100mph)
3rd will rev to 8000 but the torque drops off at about 5000 - and top is faster due to staying in the torque band.

There are some lovely quiet country roads in Dorset on my commute - Top gear is just perfect for these - I get to concentrate on the steering and handling without the need to think about interupting this changing gears.

All this was learning for me as I assumed (wrongly) that the lower gearing in 3rd would give better acceleration in the 50+ mph region than higher geared 4th but turns out the *torque* advantage (as below) was more important and power misleading "
View attachment 132120


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## bkwanab (Nov 5, 2021)

Kar0z said:


> Well, at iso-Cd and Area in steady state conditions, no. But it's true, weight is directly linked to power necessary to a given acceleration rate, as well as rolling losses (but that's only relevant at low_-ish_ speeds, above which drag takes over).
> 
> But my guesstimate for the Elan is a <1.5m2 frontal area (really tiny) and a Cd around 0.38-0.40 given some sources (really OK for a convertible) => That's a main driver for consumption reduction.
> 
> ...


FYI, the frontal area of the S2 Elan is stated as 1.35m2 while the S2 Europa is stated as 1.48m2, not surprising as the Europa is around 10 " wider but 2" lower. The cd for the Europa, a hard top, is 0.29 and the Elan convertible 0.40 which seems a little high but is the best number I can find online. The Nissan Leaf is 2.276m2 with a cd of 0.32, So my unscientific calculations show that potentially my 1970 Europa equipped with a Leaf powertrain and 24kwh battery might be good for 150 miles, assuming the modified Europa EV weight can be kept the same as before at 1460 lbs (which I believe is possible).

Comments?


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## bkwanab (Nov 5, 2021)

bkwanab said:


> FYI, the frontal area of the S2 Elan is stated as 1.35m2 while the S2 Europa is stated as 1.48m2, not surprising as the Europa is around 10 " wider but 2" lower. The cd for the Europa, a hard top, is 0.29 and the Elan convertible 0.40 which seems a little high but is the best number I can find online. The Nissan Leaf is 2.276m2 with a cd of 0.32, So my unscientific calculations show that potentially my 1970 Europa equipped with a Leaf powertrain and 24kwh battery might be good for 150 miles, assuming the modified Europa EV weight can be kept the same as before at 1460 lbs (which I believe is possible).
> 
> Comments?


Oh, I should add an early Leaf weighs more than 3,500 lbs, i.e more than twice the estimated weight of a modified Europa. 180 - 200 miles possible with the modified Europa? Surely not.


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## 4Foxtrot (Apr 1, 2019)

Streaming Wet Thruxton, and did NOT get electrocuted in lotus Elon









Fun (and scary) keeping the tiny tyres, lightweight and massive torque on 'the lake'. 
70mph 'tank slapper' at Allard on the edge of the lake (and on the edge of fear/excitement/browntrousers







)


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## Woolf (Nov 4, 2019)

Fantasic photo!

Very nice job on Elon, I've enjoyed reading this thread


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## Winterhawk (9 mo ago)

Love your Elan! Having owned 4 S2's (sold last 6 years ago) I would have loved to do what you have to yours. My last one was powered by a non original twin cam, had a non original (Spyder) backbone chassis, etc, so converting that one wouldn't have bothered me at all. Great job!


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