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

[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 the engine (air flow restrictions, rotating mass, gear ratios, etc...) also matter a lot. The yaris does 32 mph in first gear, 61 in second, and close to 90 in third. I haven't removed the limiter yet, so I have no clue where 4th stops, except the whole car tops at 117 (stupid govener). Now, once you take into effect drag coefficients, and weight, and top RPM, and all the other bits, the only real info that counts in the end is the 1/4 mile, 1/2 mile, and 0-60 times. My Yaris is far from stock, and before I had my header on there, I killed my boss's (somewhere around 2000) mustang. It was all stock, and was a 5 gear manual like my Yaris. His car weighed a LOT more, and we were already going about 50. I switched to 2nd (close to top of that gear, and he hit 3rd, and I blew past him, slowing when I got to 80+ mph. He chewed me a new one when he finally got to work later. Then, I've had a civic destroy my car at a light. I wrap around turns though, and everyone hates it when I do that, so I do it all the time. You should hear my wife freak out when she's in the car and I put the car to it's max around a corner. She'll grab the door, the dash, me, EVERYTHING within reach and start yelling like crazy for me to slow down. My car does seem to be suffering here in Colorado though. I have to get the MAP sensor reset. My car is used to 10 ft of elevation, now I'm at 4,700 ft. A little less air up here. But back to the subject... it isn't the BHP, or the weight, or the year... in the end, it's everything all wrapped into one giant number. So, yes, this could go on forever. Everyone should also rip out the smaller of the two air filters in their stock intake. Yes, there are two. The second one is for "blow back" or some junk like that. Take it out and you will see the tach move just a little faster.

[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.

[GeneW]

Originally Posted by 427chev

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.

I'd agree that the formula is within a reasonable variation about two percent difference. Close enough for "Government Work" as we used to say.

Originally Posted by 427chev

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.

I recall hearing this story myself but I'm unclear about the circumstances. I've heard histories and opinions about it in the past but I'm unclear myself about when HP calculations and measurement standards were changed, but I have heard that they were changed.

Gene

[427chev]

Originally Posted by GeneW

...I recall hearing this story myself but I'm unclear about the circumstances. I've heard histories and opinions about it in the past but I'm unclear myself about when HP calculations and measurement standards were changed, but I have heard that they were changed.

Gene

The "legendary" 7.0 liter (427 cid), aluminum block/head ZL1 (a whole 69 of them were sold to the public) was essentially a street legal Chevy racing engine, circa 1969. As such, it was arguably the most powerful "production engine" of the entire "muscle car" era. The engine option was more expensive than an entire base model Camaro. The engine required 103 octane minimum (RON) gasoline per Chevrolet and would barely run on the street without over-heating, fouling plugs, etc. Urban legend would have us believe that the ZL1 was "under-rated (@ 430 Gross HP) for insurance purposes and actually produced 575 HP."

A quick check of the facts proves otherwise and demonstrates just how weak the old engines were by modern standards. (Consider than a base engine, 6.2 liter LS3 Corvette produces 430 REAL (certified SAE Net HP) from 91 octane unleaded gas and will idle all day in traffic with the AC on while meeting stringent, modern day emissions and fuel economy standards.)

http://www.camaros.org/copo.shtml

A good running, well tuned but production line stock '69 - '71 street hemi made slightly less power than that and it was all downhill from there.

A good article addressing the Gross HP issue: