Electric 818 | AC & LiFePO4 configuration

[sponaugle]

...which the graph does not appear to show. There is no 'advantage' off the line shown here that we would expect from the torquey EV. Of course, this is for starting at 10 MPH, not off-the-line, but still. It seems 'off' to see such 'linear' speed curve comparisons when one vehicle is all torque, the other high HP.

It is critical to understand this is not an EV vs Gas Engine comparison. This is a very low power EV engine compared to a high HP gas engine. The STI engine in this case makes more torque at 2500 rpm then the EV does ever. It is true the EV makes more torque at 500 rpm then the STI at 500rpm, but the gearing the subaru transmission does not take advantage of that.

There are some obvious advantages even this underpowered EV car would have. In a real like situation the if both cars were cruising along at 10mph and punched it, the EV car would pull ahead almost instantly. In this case that instant would last about a second then the STI would trounce it. This is an unfair comparison of a 350hp engine vs a 75hp one. It is amazing the 75hp one is even in the running.

In a real zero speed launch however, the STI would have an advantage. When I use launch control to launch my car, my RPMs never drop below 3000 rpm. I effectively have an engine that produces 200+ lb-ft of torque at zero mph. There is of course loss in the clutch slipping (which is critical to the lack of link between engine rpm and speed), however in all cases the limiting factor is traction. The EV car would instantly break the rear tires loose, and the 4WD STI would have a tractive advantage.

That's really enlightening. There is one thing that's making me scratch my head, and I'm not sure if it's just the EV system described here or something else. I've seen EVs literally leave in the dust cars with engines that make significantly more HP than the STi described here (and weight about the same). This was mostly at speeds less than 100 mph, and because of the RPM limitations of motors, I assume said car would eventually catch up. The point is, there was no denying the acceleration advantage provided by the torque of the motor vs. a more powerful engine.

The head scratching part is a combination of a few things.. First I suspect in many cases the EV car was lighter. In a drag car case you only need enough batter for a run... while the gas car carries the full weight of the engine and empty tank.

Second, this is not a high output EV motor. Consider the Tesla NON-S motor is 362hp, and the S is 416hp. Those are high output EV motors, and indeed they could potentially trounce an equal or more gas engine.

The thing to get across is in the phrase 'the torque of the motor'. This EV motor does not have much torque. The one in the Tesla does.

I do believe the long term future of performance cars lies in the electric motor. One drive in a Tesla S can confer that quickly.

Also, I'll make some graphs using a stock WRX engine for comparison... that will be more instructive..


Jeff