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Discussion Starter · #1 ·
My son and I are into Autocross. We are exploring the idea of a Miata or a Boxster EV track day autocross GT driver.

With the Mata packaging will be more of a challenge, but perhaps less power required. One of the ideas I was thinking would be to get a wrecked Chevy Bolt 200hp 266ft#, or Chevy Spark 140hp 280ft#, and repurposing all the bits and repackaging all the bits and package into an old Miata. Part of the exercise is to keep weight down, would it be possible to package extra battery capacity (perhaps a generator would be the practical solution, but I would like clean) on a small trailer which would also carry track tires, tools and such. Range is an issue as most venues are at least 30 miles away. Ideally we would want more than a 100 mile range (which seems as though it may be ambitious.

It appears the Boxster is more friendly for packaging. Bolt power would be comparable to stock, so it would be cool to put in more power.
 

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What you're looking for isn't at all unreasonable. There have been LOADS of miata conversions.

My reccommendation would be to buy a salvage Nissan leaf and take the motor and battery from it. Then all you need is a VCU (look up Thunderstruck VCU) and a charger, DCDC converter, and BMS and that's just about all you would need. Probably around $10k all in. Not as much performance than a Chevy bolt or spark motor, but it will feel pretty quick, especially on a small, light, miata. The Leafs come in a few different pack sizes. The 24kwh model will probably get you 70-90 miles of range. 40kwh model 150ish I'd guess.

Unless, of course, you want to really dust people on the track. Then your only realistic option is a Tesla swap using a salvaged Tesla motor. Batteries would be tough for that though.
 

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Discussion Starter · #3 ·
Is it possible or practical to repurpose controllers from the donor EV? Is this super complicated.
My thought is that as long as I was going through all the trouble, I may as well optimize the power. My initial thought was that 200 hp and 250 #ft would be the sweet spot (this is what most Miata ICE swaps recommend). A salvage Leaf Plus fits criteria, but may be spendy idk.

I was shying away from the Leaf as I have gleaned they have had battery degradation issues.
 

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Discussion Starter · #4 ·
My thought would be to repurpose as much as practical from a donor EV.
My son and I autocross, so the build would attempt to optimize for hooligan driving around cones and double as a daily driver.
 

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Is it possible or practical to repurpose controllers from the donor EV? Is this super complicated.
My thought is that as long as I was going through all the trouble, I may as well optimize the power. My initial thought was that 200 hp and 250 #ft would be the sweet spot (this is what most Miata ICE swaps recommend). A salvage Leaf Plus fits criteria, but may be spendy idk.

I was shying away from the Leaf as I have gleaned they have had battery degradation issues.
Yes you're right, leaf batteries aren't the best. But the motors and inverters are pretty good. So you can pair the leaf motor and inverter with a different battery pack. A lot of people use packs from plug in hybrid cars like the chevy volt.

Keep in mind that an electric motor will feel a lot more powerful than an ICE engine with the same HP rating, since electric motors have the maximum torque from 0 rpms.

This is the budget-friendly choice. You can also go with a tesla swap, which takes quite a bit more work to get it to fit, but will get you anywhere from 250-500 hp depending on what drive unit you choose.
 

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Two ways of doing that
(1) - use a leaf motor -

(2) Use a DC forklift motor

My car is very like an unsophisticated Miata

I use a Hitachi forklift motor - direct drive to a Subaru diff - with most of a Chevy Volt battery in the front

The motor is where you would normally put a gearbox

I only have 50 km range at highway speeds - but my aerodynamics are TERRIBLE - a Miata would go further on the same batteries

As far as power is concerned - I have something like 500 hp - this is well over the top for the motor and the batteries - but you can only use full power for
a couple of seconds

On grass (or normal driving) I have a 40% power switch - which is more than enough!
On Tarmac with my sticky tyres ... 100% is fun

Crude and unsophisticated!

On the grass autocrosses I normally slot in right next to the Miata's competing - my additional power is cancelled out by their superior driving skills
 
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