Quote:
Originally posted by Vector:
You guys don't seem to understand what horsepower really is. It's just a way of measuring how much work is done in a specified amount of time. You can take horsepower from the engine (bhp) and that can be directly compared with other engines because it's like apples and apples. But take that same engine and put it on two different cars, say a Semi and a Mustang, you are going to get very very different rear wheel horsepower numbers. The semi is going to go way slower down the 1/4 mile than the mustang can, therefore less work done in a specified time, therefore less horsepower. A dynojet however will dyno the Semi as having the same rwhp as the Mustang because to it, the wheels spin without any resistance. This obviously is innacurate as compared with the 1/4 mile run! From what I have read, the Mustangdyno attempts to factor in these problems such as wind resistance and vehicle weight to give you an accurate hp rating down the 1/4 mile track. Which is what you want!!
Summed up, if your friends car gets the same rwhp as your car, don't expect the performance to be the same in the 1/4 mile. Weight, wind, it all matters. That's why the ET calculator has A WEIGHT FACTOR duh!
Trust me, you want the HP rating of your car as it goes down the 1/4 mile, not the HP rating of your car as it spins up the dyno.
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Stick to what you know. This argument is so flawed I'm not even sure I want to get into it.
Horsepower is ((Torque x RPM) / 5250) Please, tell me where weight enters into that equation? As far as bhp vs whp you're way off base. HP at the wheels measures power at the wheels, instead of the crank. All it's doing is showing you the frictional losses in the driveline, nothing else. A semi with an HO "engine" in it, and a Mustang with an HO "engine" in it WILL give different whp numbers. Only because the Semi has a less efficient transmission and driveline. If you were to put the engine 5.0 driveline into a semi you'd get the same whp numbers. As far as your comment about the Dynojet having no resistance? LOL. Yeah, right. Have you ever tried rolling one of the 1000lb+ drums on a dyno? That's the resistance. As far as drag, that's what the driveline is. Tranny, driveshaft, axle. It's all drag and friction.
Again weight has absolutely NOTHING to do with engine performance. Aerodynamic drag has absolutely NOTHING to do with engine performance.
I would like somebody to explain to me how a car that makes maximum peak, and average hp will be slower than it's twin, which was tuned using weight and drag in the equation (which is totally worthless)? If the engine is producing 300hp, it's making 300hp. If it's making 295, again, it's making 295. There is no way to tune an engine with better results at the track than giving it maximum power at all times. I'd hate to see the worthless numbers a Mustang Dyno would come up with if you added a ground effects package, or wing, or ram air hood. What Cd do they use then? I doubt most shops have a wind tunnel for testing on hand. What about weight? Do they have an accurate scale sitting right there for you to use as well? Or are they using book numbers, which can vary from car to car by several hundred pounds?
If they believe the hype the are spreading, people at Mustang Dyno are about as stupid as the link I saw not too long ago asking for a cars weight and hp to determine top speed.