# Planning of Electric Race Car



## kennybobby (Aug 10, 2012)

It sounds like a fun project.

What i've read about building a race car, the first item to select is the wheel size and tires. This sets the axle height and other geometric parameters of steering and ride height will be determined around that. 

Also the tire width or contact patch will determine the torque limits and power requirements, and the diameter will give you the revs per mile. 

From that you can calculate the motor and gearbox combination to make the torque and speed for the longest straight at the track venues. 

Now it gets to an iteration of solutions for weight and aerodynamic loads, how much battery (voltage and current) for the motor windings and gearing to make the required torque and RPM. You can push the envelope in whichever parameter will optimize your desired performance parameter (range, speed, torque, weight, cooling or not, etc).

Take a look and read thru Ripperton's electric track bike thread, it is one of the most viewed of any on this forum.


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## marcellatwin (May 7, 2015)

kennybobby said:


> It sounds like a fun project.
> What i've read about building a race car, the first item to select is the wheel size and tires. This sets the axle height and other geometric parameters of steering and ride height will be determined around that.
> 
> Also the tire width or contact patch will determine the torque limits and power requirements, and the diameter will give you the revs per mile.


Interesting, haven't thought of that too much. So I just looked up GTE Pro car specs from WEC and they use 18" as well as Honda Type R TCR (touring car) and they use 18". The Civic Si TC uses 17". So I would say my max is 18" and also probably one of the most popular so lots of cheaper spares possibly. But when I look up Spoon and other racing Honda EGs I see 15", 16", and some people run 17". So not really sure. It seems everyone suggests going with the smallest wheel possible for lighter weight and less rolling mass and inertia, as long as it clears the brakes. Good thing is I'll be moving the front brakes in-board and the rears can be on the smaller size. So maybe 16" or 17" since they seem more common than 15". Thoughts?

As for tire width I really wouldn't know. I don't know that much about setting up cars. I also think there is a limit depending on the class, but not sure. Any suggestions? I guess I can start to work on some basic Excel code to calculate numbers from the wheel to the motor with different variables to change like tire size, final drive ratio, top speed. The only issue is I don't know the total weight of the car to figure out the normal force and therefore the friction force on the tires. Guess I can work on an assumed weight range; best case, worst case.



kennybobby said:


> From that you can calculate the motor and gearbox combination to make the torque and speed for the longest straight at the track venues.


Yeah I've been thinking about that a lot lately, in terms of looking at top speeds of hatchbacks like Golf Rs in SCCA at the end of a straight to determine the gear ratio based on the torque curve of each motor. Most motors I've looked at have max torque from 0 to some RPM anywhere from 25% to 75% of max RPM depending on motor voltage. So thinking of picking a top speed and picking an RPM of 10-20% above the rpm where max torque starts to drop off. That will get my the diff ratio with a set tire diameter. So I still have a little power and top speed left even at the end of a straight rather than running out of steam before the end of the straight. But I'm not sure on how to select the tire wall size after I get the wheel diameter so I can get the tire diameter. Any thoughts on tire wall size and how selecting that can affect handling?



kennybobby said:


> Now it gets to an iteration of solutions for weight and aerodynamic loads, how much battery (voltage and current) for the motor windings and gearing to make the required torque and RPM. You can push the envelope in whichever parameter will optimize your desired performance parameter (range, speed, torque, weight, cooling or not, etc).


I've been avoiding it but I just might have to write an optimization program and figure out all the cost functions for each parameter. I've been avoiding this because I'm afraid the best solution will be the costliest, like running an 800+V system which I didn't want to for the first version. And as for aerodynamic loads, I have NO idea what a good goal is. I want to do just a simple flat floor, simple rear diffuser, rear wing (single, maybe double element), simple flat front splitter, and maybe canards. But don't know what kind of downforce numbers I should aim for.



kennybobby said:


> Take a look and read thru Ripperton's electric track bike thread, it is one of the most viewed of any on this forum.


I'll definitely have to check them out. I know bike racing is very different from cars when it comes to calculations, just cause they are soooo much more efficient, lighter weight, better cooling, etc. But maybe I can get some insights.

Thanks for your thoughts and help. It helps to talk to someone (type this out) and think out-loud, made me think about how to progress that I didn't think about before.


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## Duncan (Dec 8, 2008)

Hi
30 minutes is a very very long time
It will be incredibly difficult and expensive to have a competitive electric car for that period

You would be much better off concentrating on the time trials or sprints or hill climbs where a "run" is less than five minutes

Longer events mean a huge battery and an uncompetitive car 

It's fairly easy to build an EV with 500 hp - but that would be 400 kw and a 30 minute event would need 200 kwh - or well over a ton of batteries

The limitation is the batteries!

With a five minute event that drops to 30 kwh - and you save a huge amount of weight

I can do five short "runs" on a charge - not six! - about 8 minutes - but I only have 14 kwh and the events I enter are relatively low speed - the longest straight is 200 meters - I hit 100 mph - before having to brake savagely for the next chicane


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## marcellatwin (May 7, 2015)

Duncan said:


> Hi
> 30 minutes is a very very long time
> It will be incredibly difficult and expensive to have a competitive electric car for that period
> 
> ...


I have considered time trials and will probably do a few events as shakedown for when the car is running. Hill climb would be fun too. But my ultimate goal (Version 2 or 3) is endurance racing, with battery swapping.

I'm not sure your math works out though. While yes a 400 kW at 30 mins is 200 kWh. But that is assuming you are at full throttle, 400 kW for the entire race. If you look at the Italian Grand Prix circuit, F1 spends about 70% at full throttle, and that's nothing but straights and chicanes. But something like the Monaco circuit is only 34% of the time. So there is a lot of time off throttle and/or regenerating while braking.

I'll also be shooting for 150-250 kW for the motor. A video recently surfaced with a Tesla Model 3 Performance doing a track day for 30 mins solid and lost 250 miles of range. So a 4,000 lbs vehicle with 340 kW running continuously for 30 mins only used ~78% of its 75kWh pack. Also Formula E run 250 kW for 45-50 mins, albeit all on street circuits, weighting 1,800 lbs (so a little bit lighter), and only use 54 kWh batteries.

A guy made an open top prototype car running in SCCA on the East coast and he says he does 30 mins races with a bit to spare and is competitive. I don't know how big the pack is, or how much the car weights, but he is running 180 hp.

In summary, I'm pretty sure I can run for 30 mins with a pack less than 75 kWh. The trick will be balancing enough batteries so have the power and range, but not too much it weights too much.

Hope I didn't come across as mean, just checking the math out. Also it caused me to do more research and found out some more things I didn't know (like how little you are on throttle for a street circuit), so it still helped me, thanks.


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## brian_ (Feb 7, 2017)

While the energy requirement for anything more than a short sprint might be manageable, cooling (of both the battery and the motor) is potentially a problem as well. I'm not saying that it can't be done, just that you need to pay attention to this issue.

The experience of this race team should be interesting to you:
Tesla Powered Cobra Race Car
Modified Bolt Pack for Tesla Cobra EV Race Car


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## brian_ (Feb 7, 2017)

The race sanctioning body and class that you choose is extremely important. They all have extensive sets of rules, and most are based on the assumption that some variation of the stock engine will be used, so an electric conversion will usually be either illegal or impossible to assess against the rules. They also tend to have many rules about tires, so picking a size and designing around that could easily lead to an illegal vehicle if you don't consider the rules when making the choice.

This is all substantially easier (but still not trivial) if you target solo competition instead of fender-to-fender racing, because solo series tend to have a class to accommodate almost anything.


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## brian_ (Feb 7, 2017)

marcellatwin said:


> Running an axial flux type motor, or something similar, around 150-250 kW, through a quick change differential on the front axle (keep it simple for Version 1, maybe later go to rear wheel or all wheel drive). Quick change diff for several reasons. One, it would allow quick and easy changing of final drive ratios at a track. I found you can get ratios that range from 2 all the way up to 9. This also allows for a wide range of motor selection.


I like the idea of a quick-change final drive unit, but I don't understand why the plan is specifically for an axial-flux motor. In addition to being what seems like an unnecessary restriction, those motors tend to be short (axially) but large in diameter, which will place the bottom of the motor far below the axle line, to the point of potentially being a ground clearance concern.


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## brian_ (Feb 7, 2017)

marcellatwin said:


> Moving the front brakes inboard. This will lessen up unsprung weight and allow for hard brake lines throughout.


I suggest learning from the experience of generations of race car designers and racers over decades: no one uses inboard brakes because they are not worth the problems that they cause.



marcellatwin said:


> Same goes for suspension. Would like to do push or pull rod with heave dampening but not sure on doing this for Version 1. Depends on time and budget.


Pure race cars do routinely use inboard suspension units actuated by push or pull rods, but they do it to leave aerodynamic tunnels clear inboard of the wheels. The Civic will not have aerodynamic tunnels, so I see no point in the added complexity of an inboard suspension. Inboard suspensions in cars without the aerodynamics to need them are usually made visible, which is a hint that they are there to impress other people with the "race" tech in the vehicle, rather than for any functional purpose.


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## Duncan (Dec 8, 2008)

The energy requirements

F1 cars are not on "full throttle" for most of the time because they have oceans of power

With less power you will be on "full power" for longer! - so you may use less total energy than a more powerful car - but it will not be as much less as you think

If you have serious amounts of grip then you will use MORE energy on a lap than you will if you don't

The Tesla Model 3 may have used 60 kwh in a half hour of practise - but a car with similar weight and more grip will end up using MORE energy

Your lighter car but with tyres and suspension optimised for grip may well use MORE energy

I would also agree with Brian about push/pull rod suspension - the main advantages come from aerodynamic improvements and you do need to know what you are doing

I remember a friend bought a single seater with push rod suspension and it felt awful!
When I did a quick analysis it had been done as "monkey see monkey do" - it had FALLING rate suspension and bad geometry
We fixed it by moving a suspension pickup point and designing a new pivot lever


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## marcellatwin (May 7, 2015)

brian_ said:


> While the energy requirement for anything more than a short sprint might be manageable, cooling (of both the battery and the motor) is potentially a problem as well. I'm not saying that it can't be done, just that you need to pay attention to this issue.
> 
> The experience of this race team should be interesting to you:
> Tesla Powered Cobra Race Car
> Modified Bolt Pack for Tesla Cobra EV Race Car


Yes that is what I'm most worried about. That is why I'm looking at motors, motor controllers, and batteries with liquid cooling.

OMG thank you for those links. That is why I'm on this forum. Reading their posts, so detailed, really helped and gave me a lot of perspective and ideas. Like I said, I'm in the planning and design stage right now, never thought of the Bolt batteries. I thought about the Model S modules but was worried about the cooling. I would love to use the Model 3 modules but I don't think they will work size wise. They seem very long but haven't found too many people who have taken them apart and used them in other projects. I'm definitely going to try to reach out to them.



brian_ said:


> The race sanctioning body and class that you choose is extremely important. They all have extensive sets of rules, and most are based on the assumption that some variation of the stock engine will be used, so an electric conversion will usually be either illegal or impossible to assess against the rules. They also tend to have many rules about tires, so picking a size and designing around that could easily lead to an illegal vehicle if you don't consider the rules when making the choice.
> 
> This is all substantially easier (but still not trivial) if you target solo competition instead of fender-to-fender racing, because solo series tend to have a class to accommodate almost anything.


Yes I completely agree. That is why, as of today, I've reached out to both the SCCA and NASA to see what they may say about possible classes. Seeing how EVSR races in SCCA, I reached out to him today as well about what class he runs and what were some of the SCCA requirements. I hope that if I get an exception, it will be to put me in a class with similar HP rather than the open/unlimited classes that have much faster cars in them. Once I hear from them I can start working on with any tire, suspension, or aero limitations.

I will consider solo competition possibly as a testing area but the ultimate goal is fender to fender. I see enough examples of it that I know it's doable.



brian_ said:


> I like the idea of a quick-change final drive unit, but I don't understand why the plan is specifically for an axial-flux motor. In addition to being what seems like an unnecessary restriction, those motors tend to be short (axially) but large in diameter, which will place the bottom of the motor far below the axle line, to the point of potentially being a ground clearance concern.


Axial-flux mostly due to the amount of work and research I did on them for a school racing team I was a part of (electric land speed car). I have been thinking about the ground clearance. I thought I could maybe rotate the diff and motor assembly about the axle axis, essentially tilting the motor up to clear the bottom of the car. I'm sure that will make the subframe more "interesting" as the mounts are now at more of an angle. Any thoughts? I also like the efficiency and power density of those motors and from what I can tell they have better cooling designs (as well as less thermal mass).


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## Frank (Dec 6, 2008)

Which school and car? 

Sent from my SM-T380 using Tapatalk


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## marcellatwin (May 7, 2015)

brian_ said:


> I suggest learning from the experience of generations of race car designers and racers over decades: no one uses inboard brakes because they are not worth the problems that they cause.


So I'm curious about what kind of problems they cause. I know a lot of people don't do it mostly cause there is no room with an engine taking up most of the space. I've been reading about it and I know you have the half-shaft absorb some of the shock from braking , causing a slight delay in pedal feel. I figured that could be solved by using carbon fiber drive shafts, which I was considering anyway. I also know cooling can be a challenge but with regen braking the brakes wouldn't be as heavily used as well as I would make sure there are cooling duct for them. What other problems have people had??



brian_ said:


> Pure race cars do routinely use inboard suspension units actuated by push or pull rods, but they do it to leave aerodynamic tunnels clear inboard of the wheels. The Civic will not have aerodynamic tunnels, so I see no point in the added complexity of an inboard suspension. Inboard suspensions in cars without the aerodynamics to need them are usually made visible, which is a hint that they are there to impress other people with the "race" tech in the vehicle, rather than for any functional purpose.


Funny I actually thought of doing tunnels in the car like the Nismo LMP race car a couple of years ago. But I have a tendency to over think sometimes on the first iteration. A couple things I thought:
-I figured it would give me more control over angles and geometry
-More dampening options. I really like the idea of heave dampening, which I could still do with a pushrod attached to a conventional double A-arm suspension


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## marcellatwin (May 7, 2015)

Frank said:


> Which school and car?


Embry-Riddle Aeronautical University. Our project was called Eagle Work: Advanced Vehicle Lab. It's a student designed and built vehicle to break a record by going 250+ mph. It uses A123 26650 Lithium Iron Phosphate cells. For a few years I was the battery team lead. I helped design the battery pack. It's only 12.4 kWh but enough to run twice, required for official records. It uses two YASA motors driving the front wheels with two RMS PM150 motor controllers. They had a couple set backs so they probably won't run till next year. Here's a link to our website: http://www.eagleworksavl.com/


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## brian_ (Feb 7, 2017)

marcellatwin said:


> I would love to use the Model 3 modules but I don't think they will work size wise. They seem very long but haven't found too many people who have taken them apart and used them in other projects.


Like the earlier Model S and X, the Model 3 pack is as long as can be fit between the axles. The unique thing about this design is that there are only four modules (the largest modules of any production electric car) and they are all the full length of the pack (two longer modules in the middle and two shorter ones on the sides to fit as the pack curves around the wheel wells), and since the car is large the pack is long. I have seen a couple of teardown videos, but have not heard of anyone using these modules at all. There would be very few vehicles not designed to use these long modules which could accommodate them.



marcellatwin said:


> That is why, as of today, I've reached out to both the SCCA and NASA to see what they may say about possible classes. Seeing how EVSR races in SCCA, I reached out to him today as well about what class he runs and what were some of the SCCA requirements. I hope that if I get an exception, it will be to put me in a class with similar HP rather than the open/unlimited classes that have much faster cars in them. Once I hear from them I can start working on with any tire, suspension, or aero limitations.


The difficulty for the sanctioning bodies is that engine rules exist both to limit the cost of preparing a car, and to level out competition. It would be difficult to define limitations for an EV which would make it comparable to any specific engine type and size, and it would be reasonable for competitors in the class to be concerned that a well-funded team could beat them simply by paying a lot of money for a lot of power in an EV. This is the sort of issue which has been key to various non-conventional engine designs being banned from various types of competition.

Since it is routine in amateur racing for different classes of cars to run on the track at the same time, classification is mostly about fair competition rather than putting the closest competitors together on the track. Expect to run with much faster cars, whether or not your results are being compared. In our nearly stock Honda I experienced extreme BMWs and Corvettes blowing past me like I was in first gear on a freeway. 



marcellatwin said:


> I will consider solo competition possibly as a testing area but the ultimate goal is fender to fender. I see enough examples of it that I know it's doable.


I think that's an excellent idea. 



marcellatwin said:


> Axial-flux mostly due to the amount of work and research I did on them for a school racing team I was a part of (electric land speed car). I have been thinking about the ground clearance. I thought I could maybe rotate the diff and motor assembly about the axle axis, essentially tilting the motor up to clear the bottom of the car. I'm sure that will make the subframe more "interesting" as the mounts are now at more of an angle. Any thoughts? I also like the efficiency and power density of those motors and from what I can tell they have better cooling designs (as well as less thermal mass).


I certainly understand working with what you know... but you should be aware that no one uses axial-flux motors in production.

Yes, if ground clearance is an issue rotating the assembly around the axle line a few degrees might be all you need; subframe design shouldn't be a problem with that. You can even flip the whole thing over (input shaft over the diff instead of under it), but with flipping or even any significant rotation keep in mind that the final drive unit still needs to lubricate properly, and that's based on gear oil sitting in the bottom and being drawn up by gear rotation. For the motor, check if there are angle limits due to thrust limits on the bearings.

I doubt that there is any efficiency difference between state-of-the-art axial flux and radial flux motors. The major EV manufacturers have spent billions of dollars between them developing motors, they mostly build their own motors to suit their specific desires, efficiency is critical to them... and none use axial flux.

Thermal mass is not such a bad thing in an automotive motor. Power demand is highly variable, and high thermal capacity smooths out the peaks, in the same way that a massive brake disk can handle an extreme braking demand better than a light disk which needs to dissipate heat as fast as it is generated. A land speed record car is unusual in that it uses full power (or as much as it can within traction limits) continuously for the entire run without a break to cool down; a road race car gets a break every few seconds.


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## brian_ (Feb 7, 2017)

marcellatwin said:


> RMS motor controller as I'm slightly more familiar with them.





marcellatwin said:


> Embry-Riddle Aeronautical University. Our project was called Eagle Work: Advanced Vehicle Lab.
> ...
> It uses two YASA motors driving the front wheels with two RMS PM150 motor controllers.


I didn't catch the "RMS" reference the first time, but now I realize that's _Rinehart Motion Systems_. You should be aware that they are now the inverter part of Cascadia Motion, a division of BorgWarner.


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## brian_ (Feb 7, 2017)

*Inboard brakes*


marcellatwin said:


> So I'm curious about what kind of problems they cause. I know a lot of people don't do it mostly cause there is no room with an engine taking up most of the space. I've been reading about it and I know you have the half-shaft absorb some of the shock from braking , causing a slight delay in pedal feel. I figured that could be solved by using carbon fiber drive shafts, which I was considering anyway. I also know cooling can be a challenge but with regen braking the brakes wouldn't be as heavily used as well as I would make sure there are cooling duct for them. What other problems have people had??


That's most of it. Some production designs from back when they were used (primarily the Jaguar IRS, which itself belongs in every automotive museum and on no cars which are actually driven) were very difficult to service. Also, the cars which can use inboard brakes (because they are not production-based and so not limited by modification rules) usually have aero tunnels and the brakes need to be kept out of the tunnels.

*Inboard suspension*


marcellatwin said:


> Funny I actually thought of doing tunnels in the car like the Nismo LMP race car a couple of years ago. But I have a tendency to over think sometimes on the first iteration. A couple things I thought:
> -I figured it would give me more control over angles and geometry
> -More dampening options. I really like the idea of heave dampening, which I could still do with a pushrod attached to a conventional double A-arm suspension


Inboard mounting of the spring and damping units doesn't change the arm geometry at all. The travel of the spring/shock relative to wheel travel can be tweaked with linkage design, but directly acting on the hub or a suspension arm works fine - there's no need to introduce a bunch more parts to tweak that.

Yes, if you want to link the sides in interesting ways (more than just a stabilizer bar) a linkage that brings the sides together is an advantage. This seems like a good thing to do on a later vehicle, years from now.


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## marcellatwin (May 7, 2015)

Duncan said:


> The energy requirements
> 
> F1 cars are not on "full throttle" for most of the time because they have oceans of power
> 
> ...


Good point about the more grip = more energy usage. And yeah you're right about more power = less time on throttle. Guess it depends on the type of track. VIR (Virgina International Raceway) or COTA (Circuit of the Americas) will definitely be more on throttle but smaller local tracks might be less.

Yikes, falling rate is not good. Yeah if I do a push-rod I will be designing it VERY carefully. I'll look more into that to see what I can do with the current suspension setup.


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## marcellatwin (May 7, 2015)

brian_ said:


> I didn't catch the "RMS" reference the first time, but now I realize that's _Rinehart Motion Systems_. You should be aware that they are now the inverter part of Cascadia Motion, a division of BorgWarner.


Yes I'm aware. I still view them as RMS. Lol, I still call it Winston Cup Series instead of "Insert Current Cell Phone Network" Cup Series.



brian_ said:


> Like the earlier Model S and X, the Model 3 pack is as long as can be fit between the axles. ... I have seen a couple of teardown videos, but have not heard of anyone using these modules at all. There would be very few vehicles not designed to use these long modules which could accommodate them.


Yeah, I'm waiting for someone to try to use it to see any issues. Not that many on the market either. If I place it where the passenger seat was I would have from the firewall back to the bumper and I could stack the 4 modules on top of each other. I would have to measure it but it could possibly fit. Might mess with left to right weight balance.



brian_ said:


> This is the sort of issue which has been key to various non-conventional engine designs being banned from various types of competition. ... In our nearly stock Honda I experienced extreme BMWs and Corvettes blowing past me like I was in first gear on a freeway.


Yeah that's why I'm searching for a racing body that will allow it. Good thing is every group seems to be "kinda" working on rules for electric. I think one is trying to create a production electric class. Lol, yeah I like multi-class racing. Guess could always just sign up for Super Unlimited or something similar and just compete with whoever I'm similar in speed with. That way I can still run and still have fun.



brian_ said:


> I certainly understand working with what you know... but you should be aware that no one uses axial-flux motors in production.
> 
> Yes, if ground clearance is an issue rotating the assembly around the axle line a few degrees might be all you need; subframe design shouldn't be a problem with that. You can even flip the whole thing over (input shaft over the diff instead of under it), but with flipping or even any significant rotation keep in mind that the final drive unit still needs to lubricate properly, and that's based on gear oil sitting in the bottom and being drawn up by gear rotation. For the motor, check if there are angle limits due to thrust limits on the bearings.
> ...
> Thermal mass is not such a bad thing in an automotive motor. Power demand is highly variable, and high thermal capacity smooths out the peaks...


So yes not in high volume production vehicles because of costs. But in low volume production like Koenigsegg uses them in the Regara (YASA P750s with RMS PM 150s) as well as I think Rimac (not sure though). They are also used in a couple of race cars like half of the Formula E cars and the VW ID.R and in a few electric airplanes (not prototypes but ones that are meant for production). For me it is the power density mostly. The smaller size and weight for the same power is big for me. Guess you are right they are similar efficiency on a motor level.

I didn't think about lubrication. Good to hear about the sub frame shouldn't be too bad, but yeah I'll have to reach out and ask the diff companies about their limits. Haha, I did think about rotating 90 degrees so the motor is on top. Would look kind of funny. I'll get back to everyone once I find out.

Guess you're right for daily driving, having more thermal mass. It seemed like that was one of the problems with using a Tesla drivetrain in a high-performance application that once all the thermal mass heated up, the cooling capacity couldn't keep up with it. So a smaller motor with less mass and a similar cooling capacity would not have as much heat soak issues. That was my train of thought.



brian_ said:


> Inboard brakes
> 
> That's most of it. Some production designs from back when they were used (primarily the Jaguar IRS, which itself belongs in every automotive museum and on no cars which are actually driven) were very difficult to service.
> 
> ...


Hmmm, didn't think too much about servicing. If I go the inboard route, I will have to keep that in mind. Route lines for easier bleeding, make sure I have clearance for pad changes, etc. Another reason I forgot to mention that helped justify my plan was the Renault Megane RX by Prodrive. The drivers said that the steering feel was much improved. Along with other benefits specific to rally-cross like less debris.

Now that I think about it you're right, no geometry changes but relative position and velocity to wheel travel can be changed. Yeah guess could leave heave dampening to later iterations. I know I have a problem of over engineering things.


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## Duncan (Dec 8, 2008)

Taking an existing car and modifying it - working with all of the compromises the engineers put in there for a petrol engine and for passengers is kind of not as much fun as simply building yourself a car

Mine is a road car that gets used on the track - if you are willing to use the Colin Chapman (Lotus) idea of more is less then it's probably easier and more satisfying to build yourself a car - could be a single seater - or a two seater - 
Than to modify an existing road car

If you haven't already seen them look up "Locost"

Building your own car means that you can make all of the decisions about batteries right at the start

If/when I do build again I would like to use the "folded composite" technique for my chassis


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## brian_ (Feb 7, 2017)

marcellatwin said:


> If I place it where the passenger seat was I would have from the firewall back to the bumper and I could stack the 4 modules on top of each other. I would have to measure it but it could possibly fit. Might mess with left to right weight balance.


An interesting packaging possibility, and it could work with front wheel drive, but it would be very high, as all modules would need to pass over the rear suspension. The mass distribution would be passenger-side heavy, but it would also be unfortunately rearward for a front wheel drive vehicle.


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## brian_ (Feb 7, 2017)

marcellatwin said:


> So yes not in high volume production vehicles because of costs. But in low volume production like Koenigsegg uses them in the Regara (YASA P750s with RMS PM 150s) as well as I think Rimac (not sure though). They are also used in a couple of race cars like half of the Formula E cars and the VW ID.R and in a few electric airplanes (not prototypes but ones that are meant for production). For me it is the power density mostly. The smaller size and weight for the same power is big for me. Guess you are right they are similar efficiency on a motor level.


I'm pretty sure that Rimac doesn't use YASA, but it looks like Koenigsegg does. Of course, they're barely production - more like customs which they repeat a few times - which is why they don't make their own motors. Some of Koenigsegg's hybrid powertrain designs have packaging challenges which lead them to use "pancake" motors, a factor which doesn't apply in a straight battery-electric vehicle.

I don't know of any production electric aircraft with axial-flux motors, unless Pipistrel still uses a modified Emrax... and Pipistrel is quite significant in this field. Pipistrel's information package for the Alpha Electro includes this in the FAQ:


> *Who is the motor producer?*
> Pipistrel. The base motor before extensive modification is Emrax (cooling,
> mechanical parts)


I find it interesting that Pipistrel considers the stock Emrax motor to be inadequate for aircraft service.

The Siemens and Magnix aircraft motors are "pancake" proportioned, but radial-flux.


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## brian_ (Feb 7, 2017)

marcellatwin said:


> Lol, yeah I like multi-class racing. Guess could always just sign up for Super Unlimited or something similar and just compete with whoever I'm similar in speed with. That way I can still run and still have fun.


If you're not hung up on where you stand in official results, that sounds like a great plan.


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## brian_ (Feb 7, 2017)

marcellatwin said:


> Haha, I did think about rotating 90 degrees so the motor is on top. Would look kind of funny.


There was someone promoting that configuration in this forum as if it were the greatest invention since sliced bread.  He had some reasons, but they didn't make any technical sense.


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## marcellatwin (May 7, 2015)

Duncan said:


> Taking an existing car and modifying it - working with all of the compromises the engineers put in there for a petrol engine and for passengers is kind of not as much fun as simply building yourself a car
> 
> Mine is a road car that gets used on the track - if you are willing to use the Colin Chapman (Lotus) idea of more is less then it's probably easier and more satisfying to build yourself a car - could be a single seater - or a two seater -
> Than to modify an existing road car
> ...


If I had more experience then I would totally do that. I've looked at Factory Five kits (even spoke to them about it) and similar kits, but that feels like two projects rolled into one. Build the kit, then convert to electric. Yeah I would like to build my own car, probably something really similar to Nismo LMP from a few years ago, such a great car but sad story of their demise. But one of my weak areas from engineering is chassis design. I would rather modify (lightly or heavily) an existing chassis that is also race proven, then design my own and build it. I just don't feel like I have the knowledge to take on that big of a project. But definitely one day. And I can learn more about chassis design and fabrication with this first.

"Folded composites", what is that exactly?


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## marcellatwin (May 7, 2015)

brian_ said:


> If you're not hung up on where you stand in official results, that sounds like a great plan.


Yeah guess I should have stated that more clearly in the beginning. Watching some videos about getting started in racing as an amateur gave me the idea and motivation. Don't worry about being a winner in the whole series unless you are a professional, just arrive and you will soon find a group of racers that you are close to on track and that's where you will have fun, learn, and progress.



brian_ said:


> I'm pretty sure that Rimac doesn't use YASA, but it looks like Koenigsegg does.


Yeah I'm pretty sure Rimac doesn't use YASA but I think an axial flux of some kind. Not sure by the looks of it, but you're right, could be a "pancake" form of radial. Guess I just haven't found too many high performance radial motors with the specs I'm looking for that aren't super big or super heavy.



brian_ said:


> I find it interesting that Pipistrel considers the stock Emrax motor to be inadequate for aircraft service.
> 
> The Siemens and Magnix aircraft motors are "pancake" proportioned, but radial-flux.


Interesting, I thought Magnix was axial flux. I saw them testing when Eviation was testing here in Prescott, AZ (right before they had their battery fire and burned down the prototype plane, lol, but super sad). Oh course I wish Linear Labs would come to market sooner, combination of radial AND axial flux is brilliant. Can't believe no one thought of it before lol.

Also, I've had Emrax on my list of possible motors. I just checked them out again and just noticed the price. Wow, a whole lot cheaper than YASA ($4k vs. $10k) with similar power density. This might be the motor to use.


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## kennybobby (Aug 10, 2012)

marcellatwin said:


> ...
> I saw them testing when Eviation was testing here in Prescott, AZ (right before they had their battery fire and burned down the prototype plane, lol, but super sad).


What is it about lithium batteries and AZ cowboys burning chit up?

https://www.seattletimes.com/business/787-battery-blew-up-in-rsquo06-lab-test-burned-down-building/

https://www.reuters.com/article/us-boeing-securaplane-idUSBRE90J0B320130121


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## Duncan (Dec 8, 2008)

marcellatwin said:


> "Folded composites", what is that exactly?


It's a very simple way to make a very stiff strong and LIGHT chassis

Basically you buy honeycomb panels - fiberglass/honeycomb/fiberglass

The use them for things like aircraft floors

You use a router to cut away one of the fiberglass layers to allow you to fold the panel and then use fiberglass tape and epoxy resin to reinforce the fold

electriccar.html

I don't like this design but it does show the way it works

The first composite F1 cars were made like this - about 50 years ago!


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## marcellatwin (May 7, 2015)

kennybobby said:


> What is it about lithium batteries and AZ cowboys burning chit up?


Haha, that's funny it happened here. Yeah but a lot of research has been put into why the 787 batteries have had issues and it was found out that the cell manufacture (cheaper Chinese company) made a very bad battery, poor quality, which lead to internal shorts. Boeing refused to spend the extra money on a new battery design (or even a good design in the first place) and manufacturing quality control so instead, to get FAA certification, they put the pack in a giant steel box and added a burst disk to vent pressure to the outside. They didn't change manufactures. And now with the 737 Max and COVID-19, Boeing is close to going under.


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## marcellatwin (May 7, 2015)

brian_ said:


> An interesting packaging possibility, and it could work with front wheel drive, but it would be very high, as all modules would need to pass over the rear suspension. The mass distribution would be passenger-side heavy, but it would also be unfortunately rearward for a front wheel drive vehicle.


So took me minute but I found vector drawings of the car I'm thinking of, measured the measurements to get the scale, then drew in the size of the Model 3 modules staked on top of each other. The height is... something, but not horrible. Not as long as I thought though. I could counter passenger side CG bias with the motor controller, radiator, fuseboxes, etc. But good news it looks like it should clear the rear suspension. As you can see in the picture I could also rotate the pack if it doesn't clear the rear wheel well or something. Got more options than I initially thought.


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## marcellatwin (May 7, 2015)

brian_ said:


> Yes, if ground clearance is an issue rotating the assembly around the axle line a few degrees might be all you need
> ...
> For the motor, check if there are angle limits due to thrust limits on the bearings.


So I emailed one of the diff companies asking about lubrication, but while I wait for answer, I found a problem. As you can see in the pics, if I rotate the diff so the input shaft raises up, the back of the diff that houses the quick-change gears then lowers. So the same problem. Even at 90 degrees, the housing would stick straight down. Oddly enough, if lubrication is ok, maybe rotating 120ish degrees might clear everything, but I doubt lubrication would work.

Once I select a motor I can check the bearing limits. For the land speed car, there were several bearing limits on the YASA so we had to design an entire motor block to take all the forces and not transmit anything to the YASA bearings.

Also a possible idea, which I had before I found out about the quick change diff, was using a normal diff, and adding in my own reduction gear box between the output of the motor and the input of the diff. That would lower the speed more and also allow me to raise the level of the motor. I might have to go this route to get proper ground clearance. Anybody make a reduction gearbox before? I would hope it's not too bad, as there is only one set of gears and no shifting.


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## kennybobby (Aug 10, 2012)

There is a whole thread about the Securaplane chargers and how they kept a constant trickle charge on that Lithium Pack. They are a vendor that made NiCad chargers for the older airplane batteries, but somebody didn't realize that Li cells don't like to get left on a trickle charge like Lead or NiCad cells. The first time they tested a Li pack with their charger, it burned the whole building down. After that they never tested a charger with a real battery--they used a battery simulator. 

The cells were made by GS Yuasa, a Japanese company, that has made that same cell used in all the Mitsubishi i-Mievs worldwide and never had a spontaneous eruption.

The pack was assembled and a 4-level BMS added by a French company.

Rather than re-design the charger Boeing added the Rube Goldberg vault.

What's funny is that in that same electronics cabinet are other Li batteries sitting on the shelf for other devices that get charged, never caught fire, and don't require a titanium vault. Left hand doesn't know what the right hand is doing, just buy a bunch of stuff from vendors using super detailed specifications and performance contracts. 

too many mistakes but they're too big to fail.


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## marcellatwin (May 7, 2015)

kennybobby said:


> There is a whole thread about the Securaplane chargers and how they kept a constant trickle charge on that Lithium Pack. They are a vendor that made NiCad chargers for the older airplane batteries, but somebody didn't realize that Li cells don't like to get left on a trickle charge like Lead or NiCad cells.


Wow, that's bad. Fingers crossed, that I will start my first job as an engineer as a testing engineer for electric car company, and I hope I don't make that kind of mistake and burn the building down, haha.



kennybobby said:


> too many mistakes but they're too big to fail.


I'm sorry, but that is like the best quote ever before all hell breaks loose, hahaha. Like "what could possibly go wrong". They probably said that before the banks failed a decade ago, and with GM before they went bankrupted. I thought an entire government would actually be too big to fail, then I witnessed Greece go under.


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## Frank (Dec 6, 2008)

marcellatwin said:


> Embry-Riddle Aeronautical University. Our project was called Eagle Work: Advanced Vehicle Lab. It's a student designed and built vehicle to break a record by going 250+ mph. It uses A123 26650 Lithium Iron Phosphate cells. For a few years I was the battery team lead. I helped design the battery pack. It's only 12.4 kWh but enough to run twice, required for official records. It uses two YASA motors driving the front wheels with two RMS PM150 motor controllers. They had a couple set backs so they probably won't run till next year. Here's a link to our website: http://www.eagleworksavl.com/


Thanks for the link, I was hoping to see a pic or rendering of the vehicle but didn't find it. Is it a streamliner, lakester, ??


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## Frank (Dec 6, 2008)

I wasn't going to comment on the scope of your project but now I feel obligated to mention something. Have you considered building something perhaps less complicated but more achievable in a reasonable time frame? I don't recall you mentioning how long you want to spend on this project, but given that you're freshly graduated and soon to be embroiled in day-to-day work life (hopefully sooner rather than later) - will you have the time/energy/money to complete something this ambitious? You saw yourself how much work was involved in a scratch-build car and that's with all kind of help. 

I'm a fan of drag race vehicles for this type of thing. You can use a brushed DC motor which is a lot cheaper and drop it into all kinds of vehicles. I'm assuming you're still in Arizona which has a great climate for preservation of older vehicles i.e. rear-wheel drive. Buy or build a roll-cage and you can be racing pretty quickly (w/o spending a ton of money either). Continue on with this project as a design exercise but have some fun in the meantime. Straight line racing has different challenges than track racing but is by no means "easier".

All of the above is IMHO of course! Carry on...


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## ishiwgao (May 5, 2011)

Frank said:


> I wasn't going to comment on the scope of your project but now I feel obligated to mention something. Have you considered building something perhaps less complicated but more achievable in a reasonable time frame? I don't recall you mentioning how long you want to spend on this project, but given that you're freshly graduated and soon to be embroiled in day-to-day work life (hopefully sooner rather than later) - will you have the time/energy/money to complete something this ambitious? You saw yourself how much work was involved in a scratch-build car and that's with all kind of help.


Since frank has written this, I would like say that the above too is my opinion. 

Not sure if people have told you before, but once you get a job, a major portion of your daily life disappears. Building a race car as a student is very, very different from building a race car as a hobby; the major difference being the time and energy you have.

of course, I do not mean any negativity in this post. I still wish you the best to achieve everything you have planned / are planning. it really sounds like a cool project


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## marcellatwin (May 7, 2015)

Frank said:


> Thanks for the link, I was hoping to see a pic or rendering of the vehicle but didn't find it. Is it a streamliner, lakester, ??


Interesting. Yeah just checked myself and realized they don't update the website as often as the facebook which is the main source. When you search "Eagle Works" a couple might come up on facebook, select this one:









But it is a streamliner. If you don't have facebook, here are some snap shots I took off the facebook page from 2 years ago. Sorry for the age but the team has gone through a lot of restructuring, and even a few redesigns (we've added a vertical tail on the streamliner for example). They are engineers, not marketing experts so don't criticize the lack of PR too much lol, at least we have a cool youtube video.








They will be going for the E2 class record which is 215 mph right now I think. We were originally going for E1 when I was there, but moved to E2 as we were getting just too heavy and the E1 record was 199 or something, so not a huge jump. We couldn't go for E3 record cause that is held by the Buckeye Bullet from Ohio State, who have over a million dollars for budget and backing by Venturi, has over a MW of power, and their record is 378 mph or something. So E2 it is.








This shows surface pressure. Red for high pressure and blue for lower pressure areas.








This is the inside of the aeroshell, like I said, 2 years old. As you can see we hadn't designed the rear suspension yet.








Here is a close up of the front end. That big block you see in the middle houses the two YASA motors.


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## marcellatwin (May 7, 2015)

Frank said:


> I wasn't going to comment on the scope of your project but now I feel obligated to mention something. Have you considered building something perhaps less complicated but more achievable in a reasonable time frame?
> ...
> I'm a fan of drag race vehicles for this type of thing. You can use a brushed DC motor which is a lot cheaper and drop it into all kinds of vehicles. I'm assuming you're still in Arizona which has a great climate for preservation of older vehicles i.e. rear-wheel drive.
> ...
> All of the above is IMHO of course! Carry on...


So I am technically stuck in Arizona because of the virus right as I was about to start working. Where I'm suppose to be working (once I sign a contract hopefully soon) is Newark, CA (next to Fremont, Bay Area). So you can imagine there is no moving there right now, lol. Once the virus subsides a little then I'll be moving. I haven't really considered that too much mostly cause I'm not the biggest fan of drag racing. I don't think I would enjoy it that much, it's over so quick. Also GT racing is something I've been watching and wanting to do since I was a kid so there's a lot of motivation there. But I do appreciate the opinion and insight.



ishiwgao said:


> Since frank has written this, I would like say that the above too is my opinion.
> 
> Not sure if people have told you before, but once you get a job, a major portion of your daily life disappears. Building a race car as a student is very, very different from building a race car as a hobby; the major difference being the time and energy you have.
> 
> of course, I do not mean any negativity in this post. I still wish you the best to achieve everything you have planned / are planning. it really sounds like a cool project


I actually think the opposite. I will have more free time, let me explain. So while I was in school, I always felt guilty do anything that wasn't homework. If it was the weekend and you wanted to go see a movie, some friends would say, nah I got to study. There was always some homework or studying to be doing. Aerospace engineering with a Computer Science minor was a 24/7 endeavor. I would still try to do my own projects and have fun, but it always came with guilt or served a purpose for school, like the land speed project. But when I had my internships over the summer, one in the bay area and another in North Carolina, my free time increased. Once I was off work I could finally shut off and think about other things. Watch movies, play video games and not feel guilty about it. Weekends also freed up, I could travel, read, do nothing but binge Netflix in my PJs, lol. The military was also like that, I had time to do whatever when I wasn't working.

Now yes I know things are different now that I'm married. I have a family to take care of (just two puppies right now, but maybe one day soon... little tiny monsters, I mean kids, haha). So I know it will be a challenge but I think it is doable to set aside time every other day or on Saturday mornings, whatever, to work on this.

So I really do appreciate the thoughts though, makes me think a little more, maybe take more baby steps (like no custom suspension, no fancy aero, etc.). I also want to thank everyone for continuing to converse. This is helping to stave off the boredom from being stuck inside with nothing to do.


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## brian_ (Feb 7, 2017)

marcellatwin said:


> I've looked at Factory Five kits (even spoke to them about it) and similar kits, but that feels like two projects rolled into one. Build the kit, then convert to electric. Yeah I would like to build my own car, probably something really similar to Nismo LMP from a few years ago, such a great car but sad story of their demise. But one of my weak areas from engineering is chassis design. I would rather modify (lightly or heavily) an existing chassis that is also race proven, then design my own and build it. I just don't feel like I have the knowledge to take on that big of a project. But definitely one day. And I can learn more about chassis design and fabrication with this first.


Yes, an EV conversion of a gasoline-engine kit would be two projects in one, and making it a race car would be three projects. In an ideal world, you would

buy and run (without modification) a race car to learn about racing
modify a production street or race car to learn about chassis modification
convert a car to learn about EV conversion
build a kit car to learn about making a kit into an actually functional car
... and keep those as separate projects to keep one aspect from stopping progress in another aspect. Unfortunately, the world is not ideal, and both time and funds are limited.

An advantage of a typical kit over a normal production car is that it likely has (and does in the case of any of the Factory Five kits) a structure of steel tubing. That can be easier to work with than a production unibody when mounting a very different powertrain or suspension.

There have been EV conversions of various kit cars, including Factory Five's 818. In this forum, there are 

Electric Supercar - Attack K1 kit with Tesla Model S rear drive unit and suspension, in progress
Electric MEV rocket kit car - MEV Rocket kit with AC23 motors and chain drive
Factory Five 818SEx4 AWD Dual AC drive - primarily in another forum; unknown final status
... and probably others.

I should also note that despite the "racy" looks, Factory Five kits are generally street cars, not serious racing machines. Kit cars are limited in racing by being ineligible for production-based classes, and uncompetitive in race car classes, so they are mostly good for solo events ("time trial", "time attack") and recreational track lapping. Real race cars are generally impractical to adapt for street use.


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## Duncan (Dec 8, 2008)

I am going to differ from Brian here

If you convert or build an ordinary car then the actual running gear - suspension, brakes, chassis, motor

Is only 10% of the build

90% of the build is the creature comforts

If you want a race car or a minimalistic car (like mine) then it's actually EASIER than converting a modern car

And a LOT easier than trying to build something that has most of the features of a modern car

While I would agree that kits like the Factory Five are not suited to the track the original Lotus Seven and it's derivatives/sisters like the Mallock were very very much suited to the track

If it looks like a GT40 or a Ferrari then making it work well will take ten times as long to build as a simple machine like a Lotus Seven or a "Locost"


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## Frank (Dec 6, 2008)

@marcellatwin: thanks for the FB info, I'll follow and see how they make out.

Duncan makes a good point about original builds but I'm going to add the caveat that you may need more space and facilities for a longer period of time. If your career plans have you in one place for several years that's probably feasible. In my own case (also an engineer), I moved around a lot during the early parts of my career which is one reason I switched to motorcycles: less space, easier, cheaper, etc. I am racing a converted F500 car at this time though (drags, land speed). Converting a formula car might be another avenue for you to pursue.


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## marcellatwin (May 7, 2015)

brian_ said:


> Yes, an EV conversion of a gasoline-engine kit would be two projects in one, and making it a race car would be three projects. In an ideal world, you would
> 
> buy and run (without modification) a race car to learn about racing
> modify a production street or race car to learn about chassis modification
> ...


Brian, yes I agree in an ideal world I would keep them all separate. And yes, I amend my previous statement that any car, mine or a kit, would be 3 projects: build/strip, convert, make into a race car. For me a typical car would be like 2.5 thou. Because my plan right now is to buy an EG hatch, running or not with no rust, and strip it down to a bare shell. To me that is like half a project. I've seen people strip a car like that in a day. Modern cars are a little more work. I'm not keep ANYTHING except the chassis, suspension, brakes, and steering rack. So, being the first strip down that I've done, might take a week or two. It'll be more of a challenge selling off the parts I think lol. Then the converting part (motor, batteries, controller, etc.), then the race car part (roll cage, upgrade suspension, safety harnesses, etc.)

I've been following the K1 kit guy, especially about the power distribution, making your own cables, and battery stuff. I'll look more into the other two.

And you're right, I just discovered that one of the classes I wanted to run in #Gridlife have to be production based, meaning kit cars are not allowed. So I might have more opportunities keeping it production based.



Duncan said:


> I am going to differ from Brian here
> 
> If you convert or build an ordinary car then the actual running gear - suspension, brakes, chassis, motor
> 
> ...


I agree with you Duncan that for the kit car, I will only need the rolling chassis. Because even the electronics would be changed for EV stuff. So that could be cheaper. One of the other reasons for going with the hatch over a kit was price. The kits I looked at are over $10k, while a not running or shell of a EG can be had for $1k or less. Now I know price shouldn't be that big of a deal when I'm willing to spend $15k on a motor, but hey, save where I can, plus I think the EG hatch looks better.



Frank said:


> @marcellatwin: thanks for the FB info, I'll follow and see how they make out.
> 
> Duncan makes a good point about original builds but I'm going to add the caveat that you may need more space and facilities for a longer period of time. If your career plans have you in one place for several years that's probably feasible. In my own case (also an engineer), I moved around a lot during the early parts of my career which is one reason I switched to motorcycles: less space, easier, cheaper, etc. I am racing a converted F500 car at this time though (drags, land speed). Converting a formula car might be another avenue for you to pursue.


That's a really good point that I forgot about. So a few years ago, right around the time my soon-to-be-wife moved in, I was considering doing a Factory-5 kit car. Ambitious, but still something. I'm glad I didn't cause the military moved me from an oversized two car garage with a motorcycle and a car and a big driveway, to two cars and a motorcycle on a single parking spot in an apartment underground parking lot. So yeah space is a real factor. I'll have to see once I move what kind of space I'll have. Also, while I ride motorcycles I don't have the desire to race them, but still follow some of the builds to learn from. Just recently started talking to some of the guys at Lightning Motorcycles, already learning lots.


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## brian_ (Feb 7, 2017)

marcellatwin said:


> One of the other reasons for going with the hatch over a kit was price. The kits I looked at are over $10k, while a not running or shell of a EG can be had for $1k or less.


You're comparing a new kit to a used 25+ year old basic production car. I wonder what an old kit car costs? It doesn't have to be a Factory Five.


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## brian_ (Feb 7, 2017)

Duncan said:


> While I would agree that kits like the Factory Five are not suited to the track the original Lotus Seven and it's derivatives/sisters like the Mallock were very very much suited to the track


A Factory Five kit and Lotus Seven (or more likely clone or general imitation of a Seven) are comparably suitable for a race track - neither one is competitive as a pure race car, and most of the FF kits are fundamentally superior designs for track use. The advantage of the Seven is that one might (depending on the origin of the car and the race sanctioning body) be able to pass it off as a "production car", avoiding the need to compete with pure racing machines.

I've never heard of a Mallock street car. Mallocks were sports racers of the 1960's and 1970's, distinctive because they still had the engine in front of the driver (well, more like in what would have been the passenger footwell if the car could hold a passenger), after the racing world had generally gone to mid-engine designs. There are no concessions to road use (passenger seat, adequate ground clearance, etc) in a Mallock, and a "sevenesque" car is not a Mallock.


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## Duncan (Dec 8, 2008)

A Mallock is basically a Lotus Seven taken to the extremes - and all of the mid engines and independently sprung race cars would struggle to match their performance on the track

Today they are rare - but they are still capable of beating the majority of modern machinery with the same engines and tyres

The example of a fully developed "older design" still beating all but the very very best of the "new design"


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## Duncan (Dec 8, 2008)

marcellatwin

While a Factory Five kit may be $10,000 a "Locost" - which has the potential to absolutely destroy the Factory Five on the track - will cost a few hundred dollars in steel tubes

There is definitely a Locost Racing series in the UK and I believe there is one in the USA

https://www.locostusa.com/forums/viewforum.php?f=38

IMHO constructing a chassis and roll cage will take LESS time than converting a Hatchback body shell to race spec


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## marcellatwin (May 7, 2015)

brian_ said:


> You're comparing a new kit to a used 25+ year old basic production car. I wonder what an old kit car costs? It doesn't have to be a Factory Five.


I'll have to look at that.

Looking at those a little bit more closely though, I don't think I would have the space for batteries. I'm leaning more towards a larger pack (600+ V, 50+ kWh) and while those lightweight cars are small and lightweight, they don't have as much space. That's another reason I like the hatch, large volume with a flat floor to mount odd shaped batteries without getting creative with mounting.

On another note, I have some good news. I thought the only racing bodies in the US were SCCA and NASA and both don't have EV classes. NASA says they are working on an EV class but it is suppose to be production based with very light modifications, like Tesla vs Porsche Taycan. But then I discovered #Gridlife. At first I just thought it was a video series on YouTube, but come to find out that it is a sanctioning body that wants to open up the rules a little more for cheaper but fun and safe close competition. Their rule book is only 18 pages compared to SCCA's 690 pages lol. They are mostly Time Attack, but added a Touring Cup last year for wheel to wheel racing. But what looks really exciting is the Track Battle, a lead-follow "Touge" style bracket race. The big thing for us is they just added 2 EV class. Here is a snippit from the rules on the two EV classes:



> TRACKBATTLE EV
> TrackBattle EV is the beginning of a wave of electrified racecars. This class is intended for electric/electric converted vehicles that can be extensively modified for track and competition use. This class is for drivers that have participated in competitive driving previously.
> 
> ELECTRIC PRO TOURING
> ...


They also have this tidbit in their rules from a few years ago:



> Electric vehicles are permitted, however they must be classified by Gridlife staff prior to the start of an event.


So things are looking up. Only problem right now is they are mostly on the East coast while I'm going to be living on the West, but they are growing.


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## _Hunter (Jun 19, 2020)

Ill just leave this here...

https://www.aemev.com/

These guys know a thing or two about racecars take a close look at the CD-7 for a digital display and data logger it has two canbus inputs that are completely user configurable and can provide you with a tremendous about of data for both driver and vehicle development.


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## MattsAwesomeStuff (Aug 10, 2017)

_Hunter said:


> Ill just leave this here...


Can you leave it, and then you leave?

All you've contributed is spam for your company.

*points to the door*


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## Tremelune (Dec 8, 2009)

marcellatwin said:


> But no fabrication experience. I am also an engineer with programming and CAN experience.


Your goals are out of my league of knowledge, but I can tell you that fabrication will need to become a part of your skillset. They just...don't make brackets or kits. You're gonna need to cut stuff and you're gonna need to weld stuff.

The good news is that it's not that hard to learn. I bought a $300 stick welder and a $50 mask and just...started practicing. A few months later I had a much better understanding of what I was doing and what my needs were. I now have a TiG setup with a pedal and some gas, as well as a great helmet that I can actually see through. I also have another grinder, magnets, a grinding wheel dedicated to tungsten, etc etc...

My plan was to have someone else do the welding for me, but that never would have been practical. Sometimes you just need a stupid little adapter and don't want to wait a day. Sometimes you have to position the motor motor perfectly, and do some welding on the car, or at least near to check fitment. It's tricky.


Your CAN programming experience would be _extremely_ useful for decoding and controlling various cheap and excellent OEM components, but I'm not sure what components those would be for a race car (as I assume almost everything would be aftermarket).

My advice to you, as someone who just randomly decided to build an EV for fun is to start as small and simple as possible. This project has taken _way_ more time than expected, and I'm only on-budget because I knew to over-budget. Your $30-100k budget sounds very healthy...but I've never raced in a series.

Build a simple car that can finish a race, and build the Real one next year. You'll have learned a shit-ton in that time, and you'll be much more likely to succeed.


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## Duncan (Dec 8, 2008)

Hi marcellatwin

When thinking about your car - when building a "race car" you built it around the engine/gearbox and the driver

For an EV that equation changes - you build it around the battery

Your battery will be the heaviest part of your car - it needs to be as low as possible 
The motor/drive unit is smaller and lighter 

ANY conversion - even your kit car - will NOT be designed around your battery

If I was starting again I would look at the C Type Jag as a model - the driver and passenger sit in the middle with huge sills outside of them for the batteries


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## Jeremyfc1 (Feb 5, 2016)

so i actually work for evsr and can add some information about how the car is built and how it performs..

we use a 27kwh battery pack made up of 50 calb 180ah cells lifepo4 as it is the safest chemistry we have found. the pack weighs 600 lbs total we put 25 cells on each side of the driver. we use a hpevs ac34x2 with dual curtis controllers. 500 amps each for a total output of 150kw. driving a bmw rear diff with 4.27 gears for a top speed of 130mph at 8000 rpm. the cars run a fast spec miata pace for about 25 min can detune the car a little and run mid pack miata pace for 30 min. we charge with manzanita chargers at about 65amps at pack voltage . we have found regen does not give us much back for two reasons first you are only on the brake for .5 sec then back into the throttle and second we are rear drive and if you have aggressive regen it upsets the cars handling especially when the pack is near full charge the regen will kick on and off as it atempts to not over charge the batteries. 

something to be aware of we run scca and nasa events but it is still up to the track on weather we are allowed to enter. recently new Jersey Motorsports park decided to ban ev from track use. interestingly the Porsche hybrid is still allowed to enter and has the same lithium chemistry as most plug in evs.

i also will plug the aem dash as we put them into our gen 2 cars and they are a wonderful display and easy to work with.


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