# Thoughts on Overdrives...



## Duncan (Dec 8, 2008)

Hi Alec

First - don't worry too much about your diff
The thing that limits torque is tyre adhesion - and a diff is designed to take the loads when somebody drops the clutch in first gear

Motor revs - bit of a suck it and see unless you can find somebody who has some actual information


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## Own Little World (Sep 5, 2016)

Thanks for the response Duncan.

Yes, I would sorely love to have some dyno information for the motor controller pair. I think I have now read the entire internet and still drawn a blank.

I take into account your comments about tyre slip limiting the strain on the diff. The main reason for my concern is that the people at Spydercars, who build new chassis and running gear upgrades for Elans recommend replacing the diff when they stick a 2 litre Zetec engine in to replace the 1600 twin cam. They have a lot of experience with modifying Elans and seem to think the diff is a point for improvement.

Unfortunately the (new) chassis I have, as I have discovered, will not take the Sierra diff that is recommended and so I am left with a choice of either replacing the back end of a brand new chassis (not first choice) or somehow making sure the diff doesn't see any monstrous torques.

I think my scope for programming the Enova controller is extremely limited and therefore my looking into overdrives.

I generally like the suck it and see approach, however, with the news I have been kindly given here about increased levels of testing and certification for EV conversions in the UK, makes me think I have to try and get most of this stuff right first time.

Thanks again for your pointers. Good food for thought.

Alec


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## Duncan (Dec 8, 2008)

Hi Alec
Don't worry about "programming" the Enova
EV controllers basically give you current control - the software or whatever sets the max and your throttle position sets the percentage of the max

So half throttle gives you half current which is half torque!
The bogan torque limiting program is a block of wood under the throttle pedal!

the next level is to add a limit stop or resistor in the throttle

As far as the certification is concerned with the current state of the art you are not building a finished car - the Alec Mk1 will be replaced by the Mk2 and so on - BUT once it's certified you don't need to go back for every tiny tweak 
(like a new chassis, motor, body shell and batteries)


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## Own Little World (Sep 5, 2016)

Ha ha.

Thanks Duncan.


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## Karter2 (Nov 17, 2011)

Own Little World said:


> .....The main reason for my concern is that the people at Spydercars, who build new chassis and running gear upgrades for Elans recommend replacing the diff when they stick a 2 litre Zetec engine in to replace the 1600 twin cam. .......
> 
> Alec


..jeeez ! , are there really such heathen bastards around that would swap that loverly Lotus TC for a crummy Zetec !?
..it would make my eyes bleed to see that !


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## Duncan (Dec 8, 2008)

Hi Karter
Only somebody who has forgotten what those twin cams were actually like would say that!
That's a bit harsh - they were pretty good for the day - 
I'm not sure about the Zetec but my Fiat/Lancia twin cam was hugely monstrously better, stronger and better designed than the Lotus unit


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## Karter2 (Nov 17, 2011)

Sure, in stock Lotus / Ford factory tune they were not too impressive or reliable...( which matched the rest of the car !)
But, there were/are some tuners who could really turn them into 1.8 - 2.1 L reliable powerhouses.
...and of course the originality factor in a collectors car !
Lets face it, the MX5 has the Elan beat in every way, but i would still give my middle limb for a S3 drophead Elan !


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## Own Little World (Sep 5, 2016)

It seems that there might be a shortage of original of Twin Cams out there, which might be the reason for some conversions.

I suspect that the only reason I managed to find my project was that someone had harvested the engine and box out of it. Which for an EV converter was a dream come true.


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## hmincr (Jan 20, 2012)

Hi
Care to post more info regarding the Hyundai 90 KW motor ? Where are you located ?

Thanks


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## Own Little World (Sep 5, 2016)

Hi hmincr,

I would dearly love to be able to post more about them but to be honest I have found precious little myself.

I was kindly pointed in their direction by Tomdb on this site. Essentially they are complete sets of components from Hyundai/Enova that were taken from Smith Edison delivery vans in the UK and being sold as second hand but barely used.

I am not sure how many sets there are left but there is information on this site:

http://www.evpartssale.co.uk/ev_motors_and_controllers.html

25kW continuous and 90kW peak, max voltage 208V, max current 338A, max speed 9000 RPM.

Very good for the price.

Alec


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## hmincr (Jan 20, 2012)

Hmmm, a little too big physically for my limited space motorcycle build. 

Thanks Alec, Harold


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## tommypress (Jul 20, 2016)

Duncan said:


> Hi Alec
> 
> First - don't worry too much about your diff
> The thing that limits torque is tyre adhesion - and a diff is designed to take the loads when somebody drops the clutch in first gear
> ...


100% agreed!


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