View Poll Results: HP -> Acceleration... not Torque!
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HP -> Acceleration... not Torque!
#301
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Originally posted by KnightRider
What about the rest of the post? Do you just read one line and ignore the rest?
I think when most people talk about acceration in a car they are talking about going faster. The equations that we are posting are for static acceleration. Unless there is a change in time there is no change in velocity. In the real world there is time. You can't ignore that.
What about the rest of the post? Do you just read one line and ignore the rest?
I think when most people talk about acceration in a car they are talking about going faster. The equations that we are posting are for static acceleration. Unless there is a change in time there is no change in velocity. In the real world there is time. You can't ignore that.
Water -> Wet... not Dry!
#303
Lets say we are using a dyno to measure the TQ of an engine. This works by what? The wheels turning creating a certain force? Now if the wheel size was increased would the TQ measured change? If the gear ratio was changed on an S2000 say from 4.1(stock) to 4.44 what happens? They say the 4.44 is like more TQ at the wheel
From now on, I'll respond to your posts by arguing for RPM in the same way you are arguing for torque. I won't be any less (or more) right in my arguments than you are.
When you change gears from 4.1 to 4.44, you are increasing engine RPM at the same ground speed, therefore more acceleration happens at any given speed because at the crankshaft P=T*w, and w went up (w=omega, sorry greek doesn't show up). Engine torque did not change, but power went up, leading to more acceleration.
I'm really lost as to the other argument going on, torque + RPM does move your car, the more gearing you can run the more torque you can shove to the wheels, using enough gearing to make your car redline at your HP peak will produce the most wheel torque because even though torque has dropped, its the highest point of RPM that you can get before torque drops too fast to make up for the extra RPMs available. I hope all this argument isnt over him saying torque instead of wheel torque, semantics arguments get old real quick.
#307
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Wow.... I just read this entire thread, I feel like I've just given birth. As I see it, no one is arguing that Wheel Torque isn't important in accelerating the car, however Wheel Torque is dependant on Engine HP. Therefore HP is the deciding factor in acceleration. If I'm wrong about that please do correct me.
#308
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My opinion, without reading the whole thread, is that you need a healthy combination of both. The piece of information that tells me the most about at engine is the area under the curve, i.e. the total work that the engine can do (work is the integral of the power).
A car with high horsepower is great, but if the torque falls off too quickly then the power you get after peak is wasted. An ideal engine has peak power at close to redline (like ours) which allows the driver to take the most advantage of the power for the most amount of time.
rpace, you are wrong HP is derived from torque. Torque is the deciding factor in acceleration, as that is the measurement of force. Force = mass*acceleration, acceleration=force/mass. When you're in a car that *feels* like it's accelerating fast, what you're feeling is a positive change in the delivered torque. That's what you feel in the s2k when you go into vtec, you feel the rapid change in torque. Constant torque across the rpm range means the engine accelerates at the same rate across the rpm band.
A car with high horsepower is great, but if the torque falls off too quickly then the power you get after peak is wasted. An ideal engine has peak power at close to redline (like ours) which allows the driver to take the most advantage of the power for the most amount of time.
rpace, you are wrong HP is derived from torque. Torque is the deciding factor in acceleration, as that is the measurement of force. Force = mass*acceleration, acceleration=force/mass. When you're in a car that *feels* like it's accelerating fast, what you're feeling is a positive change in the delivered torque. That's what you feel in the s2k when you go into vtec, you feel the rapid change in torque. Constant torque across the rpm range means the engine accelerates at the same rate across the rpm band.