# For racing purposes, engine and stuff advice



## brian_ (Feb 7, 2017)

I agree that hillclimbs are a great EV application, due to the short duration and the likely place in the rules for an unusual powertrain. Unfortunately, front wheel drive and a car full of battery mass well behind the front axle don't seem like a very good combination for traction and handling in a hillclimb.


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## Roy_bws (Apr 12, 2021)

Thanks for your reply!
I know the best it’s 4wd or rwd but here it’s not very rare to see fwd cars running on hillclimbs. Maybe i can balance it placing the batteries the nearest as possible to the mass center of the car(i will have a lot of space because it will be only the driver’s seat). And also i’m not planning to do the fastest car, it’s more important what i can learn/test.


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## brian_ (Feb 7, 2017)

Roy_bws said:


> I know the best it’s 4wd or rwd but here it’s not very rare to see fwd cars running on hillclimbs. Maybe i can balance it placing the batteries the nearest as possible to the mass center of the car(i will have a lot of space because it will be only the driver’s seat).


Some very fast hill climb cars are front wheel drive... but they don't carry a big battery. Yes, putting it as far forward as possible will help, but you don't want it high - I think the front passenger seat area is very promising.

Although rear wheel drive, both tiger82's Tesla Powered Cobra Race Car and galderdi's Aussie EV Autocross Special II place the battery extending into the space beside the driver. Here's galderdi's car, with the (small) row of Chevrolet Volt modules to the left of the driver:








... and the rear end of the Cobra's current battery:


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## Roy_bws (Apr 12, 2021)

This is the interior of the new fia rx2e electric rallycross car. Battery placed just to the side of driver’s seat. My idea it’s to do the same but at first fwd, maybe later i can think on a second evolution.
For the leaf engine what type of batteries can handle the 200-250 hp range for 10-15 minutes? I’m not sure if i’m thinking in an unrealistic autonomy.


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## brian_ (Feb 7, 2017)

Here's a video render tour of the RX2e: The NEW FIA RX2e Championship Car Design UNVEILED

That car fits about 30 kWh of battery in the entire footprint of the passenger seat space (seat and legroom). Although it is a tube-frame pure race car, similar battery packaging would work in a production body... although the seat support rails would force the battery pack to sit unfortunately higher if they're left in place. If your car's roll cage allows, the battery box could extend into the rear seat legroom. This battery is short compared to the one in the Tesla-powered Cobra, but less than half of that car's Tesla Model 3 battery's capacity.

If you discharge most of the battery capacity in 15 minutes, that's an average 4C discharge rate (120 kW for a 30 kWh battery); if it peaks at 150 to 185 kW (200 to 250 hp) that's a 5C to 6C peak discharge rate, and it's sustained for significant periods. That's asking a lot of a production EV battery, but it might work. I assume that the 15 minutes would consist of three to five runs of three to five minutes each, at full power for at least half of each run.

As an example, a two-layer-deep stack of VDA 355 format modules (each 355 x 151 x 108 mm) would roughly fit in that space, and would have about 26 to 30 kWh of capacity. That's one-third of the modules from the pack of a Jaguar I-PACE; the I-PACE battery only needs to drive 290 kW of motor, or less than 100 kW per 30 kWh of battery. Of course you expect to push a competition vehicle's battery much harder than a production car's.

One challenge is battery voltage to support the motor. The common modules in that VDA 355 format have 3S or 4S cell configurations, and 12 of them would thus be only 36S or 48S; the Leaf needs 96S (of typical cell chemistries) for full performance. This is one reason that some conversions use battery modules from plug-in hybrids (lots of voltage in a small format), but they're typically too low in capacity... only 16 kWh for a typical complete pack.


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