HP vs Torque vs Revs for acceleration?

[Granto]

"I have tested a blacktop 20V to 8500 rpm and it didnt drop off HP but a silvertop drops off power at around 7800 so I wouldent rev it past that."


BT: Blacktop 20v 4age
ST: Silvertop 20v 4age

this may sound stupid, but I expect the ST and BT make simular torque curves right?

dropping off at around the same spots, but the BT makes more HP at higher rpms, that is, it dosen't drop off?

okay, I'm a bit confused about this..

what would this mean for say, racing the car along?

the BT can increase speed quicker than the ST at above 7800 RPM, that is, the ST wouldn't get much faster, where as the BT would still be increasing car speed?

I don't really have a good understanding of torque/rpm/hp for driveability (other than, more torque makes you take off quicker.. that's about it really..) oh and torque x rpm = hp? which makes me think, if the torque curve stays flat and dosen't drop off, the more you rev an engine, the more power it'll make..

just very confused about "torque" and "power" for cars acceleration..

I might walk away from the comp for 20 minutes and think about this, and re-write this in a more english friendly way

Thanks, Grant.

Grant.

[Medwin_3sGTE_AE86]

what u've said is correct...

Power (kw or hp) is the amount of energy produced. the more energy produced the more work u can do, ie. accelerate a car, produce electricity. Torque is purely a twisting force that is produced.

Torque is what accelerates the car, but its not the torque produced at the engine, its the torque produced at the wheels. So u need to take gear ratio into consideration (torque multiplier effect)... u can have a car reving higher producing same hp but less torque and still produce identical (peak) torque at the wheels. But the power delivery will be different.

Because acceleration requires increase in rpm, u must consider the power/torque produced throughout the rpm range where ur acceleration taking place. taking weight out of the equation, if u maped out the torque produced at the wheels for the rpms the acceleration is taking place, the greater area under the graph, the greater the acceleration.

about what TRD said, BT's power dont drop off as quickly as ST's after 8000rpms... basically it means that if both cars are making the same power and torque (say peak hp at 7500)...and u were to have a drag race... there'd wont be much difference as ur not gonna be reving it to there. however if u have to stretch a gear for consecutive corners on a race track, the difference would showup. Or in dorifto terms, u can make more smoke and hold it side ways for longer in a BT...lol..

hope this helps...

[Granto]

thanks for that, helped a lot actually

but after writing the question out i think i kinda figured it out.. but posted it anyway

but thank you for the clarification..

but in a dragrace, the BT would be able to pull longer in a gear without losing any power, thus change into the next gear higher up in the rev range? basically? hmm

I guess you'd shift the torque curve around via the way the car sucks and blows out air? i.e. different extractors would make a different exhaust effect, and different inlet, quads vs a big manifold, vs quads with long trumpets etc would make it produce different amounts of torque at different rpms?

but maybe that stuff is over my head.

Grant.

[mattysshop]

remember hp is torque x rpm..

my 2c..

[SPEEDCORE]

/5252

[Medwin_3sGTE_AE86]

Quote
"but in a dragrace, the BT would be able to pull longer in a gear without losing any power, thus change into the next gear higher up in the rev range? basically?"

That would depend on the gear ratio and the area under the torque curve. Just by reving higher doesnt automatically mean ur accelerating faster, optimising the shift points to the torque curve would. I ran some programs using std t50 gear ratios and peak hp at 8000 peak torque at 6000... only first gear is really worth reving well past peak hp because the gap between 1st and 2nd is pretty wide. all other gears, shift a couple hundred rpms past heap hp.

Of course this is all theory....