So we all know how green the Prius is, how much gas it saves, how it’s partial zero emission, yadda-yadda-yadda. That's all fine and dandy but how much power does the hybrid make? Under full throttle, what hp does the electric motor put out and the gas motor after the transition. All we needed was a Prius and a dyno...
Lucky for us, Toyota gave us one to try out and Troy and Pete over at XS Engineering is a hop, skip and three freeway exits away (the sole perk of my daily commute from LA to the OC every damn day). Unlucky for us, the Prius took to XS's Dynamic dynamometer like a paraplegic a treadmill.
To calibrate a new car to XS’s dyno, the first thing you have to do is match it to the engine rpm. Easy, right? On a normal car, yes, on a Prius, no. First off, the Prius doesn’t have a tachometer. It’s a hybrid, an automatic one at that, so Toyota engineers probably assumed you wouldn’t be flogging the engine to its upper extremities and shifting nano-seconds before catastrophic failure.
Secondly, the Prius, being a hybrid, runs on an electric motor in idle and low speeds and swaps to its gas motor at higher speeds. Electric motors, believe it or not, doesn’t have rpms. Well, not in the conventional sense and so finding an appropriate four-stroke rpm took some thinking.
Pete at XS, being the whiz that he is, removed a coil and hooked up a wire to bridge the ignition to the spark plug and clipped a Snap-On timing light to the jerry-rigged wire to read the rpm. Only thing left was to get the engine to turn on and get a proper reading. If life were only that simple.
Turns out, the Prius would only stay in electric mode on the dyno. The combustion motor would turn on, but only seemingly to recharge the depleting batteries so the electric motor could keep going. Think Energizer bunny. That, and the gears didn’t seem to change and an ominous check engine light the size of a woman’s fist kept flashing. Think Engergizer bunny holding a women’s fist thumping your head--repeatedly. We did get a reading but it was some crazy 200+ hp at 15k rpm that didn’t make any sense.