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jasegould
Guest
In relation to power/torque graphs...what causes the torque to drop off??
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antilag
Guest
i dnt quite no wat u mean but i didnt realise ya torque is measured at the last point b4 u cum on boost cos my car is definatly alot quicker then the last time it was rolling roaded but my torques down and it turns out that it gets its reading off boost
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jasegould
Guest
Power is dependant on volumetric efficiency..ie max power occurs at max VE...i think torque drop off is to do with the length of torque pulses from each cylinder being reduced due to the higher engine speed if you c what i mean :?: :? :?: :?
Doesnt matter now as thats what ive put in my assignment
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AJ4
Guest
The torque drops off for lots of reasons, the main one being that each stroke is too quick at high rpm to fill the cylinder properly. When the piston is hacking up and down, the intake valve can only open for so long to let air / fuel in. The higher the rpm, the shorter the time becomes to get the charge in.
Also affected by cam lift / duration, flow rate of inlet manifold ( not so much exhaust on a turbo ).
BTW, the actual torque value doesn't matter as much as how flat it is and how much it extends into the rpms. Its possible to have a lower peak torque figure and still be a lot faster, because the lower torque is available for a longer period of time.
To make your car faster you either need to push the peak torque higher up the rpm range ( more horsepower ) or flatten the torque off so it is usable over a wider range.
Also affected by cam lift / duration, flow rate of inlet manifold ( not so much exhaust on a turbo ).
BTW, the actual torque value doesn't matter as much as how flat it is and how much it extends into the rpms. Its possible to have a lower peak torque figure and still be a lot faster, because the lower torque is available for a longer period of time.
To make your car faster you either need to push the peak torque higher up the rpm range ( more horsepower ) or flatten the torque off so it is usable over a wider range.
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Olly
Guest
Car on rollers and lack of cool air and most still have inter warmers top mounted and are blowing in hot air less dense so less torque surely one of many reasons? 8)
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jasegould
Guest
I didnt mean it as R specific, just in general.
I know some of the rteasons why torque drops off, but was wondering why it drops off before power.....if if was because of air flow into the cylinder being reduced at high speeds max torque would be produced right up until max power :?I dunno, wouldnt worry too mucgh about it
its because horse power is HP=TORQUE X RPM / 5252
so a cylinder combustion produces a torque which is a force around an object the unit of torque is one pound per foot
work is a force operating through a distance. work is one foot per pound
power is defined as how much work can be done in a unit of time.
if i remember correctly torque always drop off at around the 2.5--3.5 k RPM
so a cylinder combustion produces a torque which is a force around an object the unit of torque is one pound per foot
work is a force operating through a distance. work is one foot per pound
power is defined as how much work can be done in a unit of time.
if i remember correctly torque always drop off at around the 2.5--3.5 k RPM
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AJ4
Guest
I think your getting BHP and torque mixed up
Torque is a measure of power, BHP is a measure of how fast that torque can be produced and is a calculated figure from the torque and rpm.
BHP = (torque*rpm)/5252
( useless fact, bhp and torque are always equal at 5252 rpm because of the above formula. If you get a RR printout that shows them crossing at different points then its been fiddled )
The peak bhp is almost always higher up the rev range than torque, purely because the rpm is still rising, but at a higher rate proportionally to the torque dropping. Eventually the torque falls to such a level that no matter how high the engine spins, no more power is produced and it starts to drop.
Sorry for the suck-eggs science lesson
Torque is a measure of power, BHP is a measure of how fast that torque can be produced and is a calculated figure from the torque and rpm.
BHP = (torque*rpm)/5252
( useless fact, bhp and torque are always equal at 5252 rpm because of the above formula. If you get a RR printout that shows them crossing at different points then its been fiddled
)The peak bhp is almost always higher up the rev range than torque, purely because the rpm is still rising, but at a higher rate proportionally to the torque dropping. Eventually the torque falls to such a level that no matter how high the engine spins, no more power is produced and it starts to drop.
Sorry for the suck-eggs science lesson
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AJ4
Guest
Sorry Sypher, you just beat me to it