General question about Dyno testing results

Factory horsepower tests are conducted with JUST the engine - No rear wheels. This is something like a starter bench test at Kragen. The starter on the bench machine can spin and create a voltage almost 2 times higher than a starter in a car - Why? Simple. Because as you know, the starter interacts with the flywheel of the transmission, creating friction and putting resistance onto the starter drive.

My girlfriend's bone stock 2000 Mustang GT puts out 218 horsepower @ 5,300 RPM and 255 lb-ft of torque at 4000 RPM - Stock advertised for this car is 260 horsepower at 5250 RPM and 302 lb-ft of torque at 4000 RPM. I see a problem with this!

Kinda makes you feel like your V8 is rather anemic eh? Shoot, my "six banger" puts out 132 rear wheel horsepower - th 3.8 liter V-6 spins to produce 156... Too bad my 6 cylinder motor is housed in a shell that has a curb weight that's 400 pounds heavier. /forums/images/icons/smile.gif

Gross horsepower figures from back in the day are what alot of us relate to. In 1972 or so the factory hp numbers changed to net hp.

Gross or flywheel hp numbers were taken from a seasoned and well tuned engine on a stand. The only thing being driven were the oil pump and fuel pump. No fan, water pump, alt, ps, ac etc. No air cleaner or exhaust manifolds.

Net horsepower, like the numbers advertised today, is supposedly taken with an engine in a vehicle with all accessories hooked up. I have heard that the number is at the flywheel. But I have also heard the number is at the back end of the tranny.

Anyway, IMHO those are very good RW numbers. I wouldn't be setoff by naysayers if I were you. I also appreciate you sharing the info. Along with the other post above regarding the late model GT.

In our search for the "Holy Grail" of performance, we must use what tools we have to judge the output of our engines. Some will discount both chassis and engine dynos as being inaccurate gauges for hp/trq output. Saying that different dynos, software, operators, weather, stars or whatever, make the readings too varied. So what are we to do? Use three different dyno machines in three hours on the same day and then average them out? All we can do, is use the best that is available to us and go from there.

To others, only a time slip will do. But in order to get the hp/trq numbers we seek, we still must add et/trap speed to some other formula to try and quantify power. And believe me, quantifying horsepower is what it is all about. Just do a search for "horsepower" and see how many posts turn up. Never mind that on the street torque is more important.

So, congratulations on your numbers. How about a "huffer" on top of that crate motor? Could give you another 100+ hp you know!!!*G*