Stock Yaris as fast as stock 1982 Z28 Camaro/Trans Am!!

[427chev]

Originally Posted by eric81

Even if the weight to power ratio came out to the same, that is only good for first gear. If even first gear. The gearing of a car, how much resistance you have against...

Originally Posted by GeneW

No, not quite, at least as how I see it.

Hp/Weight will give you a basis of comparison, but sometimes you have to dig a bit deeper for the details.

As one of the younger folk here proved to me, an AWD configuration does do a better job of transferring power to the street. ..

Differences in gearing and traction could significantly alter ET (time to distance), though Trap Speed (speed to distance) would remain relatively unchanged. It is for that reason that Trap Speed (along with vehicle weight) provides such a good estimate of actual peak engine horsepower.

Hale's Formula (as used by the Moroso Power/Speed Calculator):

Peak Flywheel HP = (1/4 mile Trap Speed/234)^3 * Race Weight

Example.

A stick shift, bone stock Yaris 2 door hatch traps @ roughly 81 MPH and weighs ~ 2,500 pounds with a driver and a full tank of gas

(81 MPH/234)^3 * 2,500 pounds = 103.69 peak flywheel HP

Toyota rates the Yaris @ 106 peak flywheel HP (SAE certified).

I'd call that pretty close.

The formula seemingly doesn't "work" with pre-1972 model year American cars because those published figures (SAE Gross) were essentially meaningless. Similarly some non-SAE certified SAE net figures may also be less than truthful, though far less so than the old SAE Gross figures. In either case, Hale's formula gives an excellent approximation of TRUE "as installed" peak engine HP.