If you want to dig a few hundred horsepower out of a junkyard to stuff in your project car, you’d be hard-pressed to find a better deal than a GM LS engine. These V8s are plentiful, relatively cheap, and there are aftermarket parts out the wazoo to crank out whatever amount of horsepower you want. But what if you don’t want to internally combust? What if you’re looking for some more environmentally friendly hot rodding? What then do you drop in your Karmann Ghia? Well, the answer to that question seems to be the Tesla Model S drive unit and Chevy Volt battery combination.
I’ve spent the last ten years as an electric vehicle engineer, mostly at Tesla, but also Canoo, and the last twenty digging through the ass-end of the automotive supply chain to find parts for my various hot rods (including my hybrid Honda S600). As such, I’m interested in how electric hot rodding is shaping up, and what solutions people are finding in junkyards.
If you want to squeeze more than a couple hundred horsepower out of an electric junkyard motor, your choices are limited. The only high power electric car that has been around long enough, and sold enough, to be junked at any quantity is the Model S. This may change in the future as eco-conscious drivers high center their I-PACEs or e-trons on strip mall boulders, but for the time being, Tesla Model S (or X) is the one (two?).
Batteries are a different story. Used Chevy Volt batteries are cheaper than Tesla batteries, although they are heavier for a given capacity. However, most of these hot rod motor swaps are not looking for range; they’re looking for power.
Batteries have a maximum current you can pull out of them that is expressed as a C rating. This rating is a multiple of the battery’s capacity. As an example, if you have a 5C battery that has a capacity of 10 amp-hours, then the maximum current you can draw from it is 5C * 10Ah = 50 Amps. Published C ratings are for continuous maximum current draw, but you’re never continuously at wide-open throttle, so the actual, realistic peak current is somewhat less specific. Several people are claiming the Volt batteries are capable of 10C and a few people are claiming 20C with up to 40C in short bursts. (I used a couple of Volt modules in my hybrid build and I was only at about 7C. I’ll try harder next time.)
40C seems like a lot, but let’s say we’re comfortable with 15C. At that C rating, a Chevy Volt battery pack will supply 350 horsepower. So for a little over 400 pounds and much less than a used Tesla battery, you can supply electrons to your electric hot rod.
Remember that Teslonda, that gasser-style electric 1981 Honda Accord? It’s making 536 horsepower with a Tesla motor and Volt battery. A drag racing electric S2000? Tesla motor and two Volt batteries. There is an AWD 1000 hp 3000GT project in progress (#3000EV) with two Tesla motors and three Volt packs. I came across a YouTube channel today of a guy who is building two identical cars, except that one is powered by a supercharged V8 and the other is an EV with… anyone? Anyone? A Tesla motor and Volt batteries.
Will there be a better combination in the future? Probably. I don’t see the Volt battery holding out as the best solution much longer, if for no other reason than there are just so many hybrid and electric vehicles with continuously improving battery technology. Time will tell, but for now, if you’re thinking about an EV swap, This is a good place to start.
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