rpm and the power band

[badkuk]

pardon the rather naive question: usually, gas engines have maximum hp/torque at 5000-6000rpm, right? regardles of whether gas or diesel, why bother designing the engine to run up 7000, maybe even 11,000rpm, when the max hp/torque is around half of that? wouldn't all that revving beyond that point be, um, pointless?

[the_wildthing]

Because it stays around that range.

[Jun aka Pekto]

pardon the rather naive question: usually, gas engines have maximum hp/torque at 5000-6000rpm, right? regardles of whether gas or diesel, why bother designing the engine to run up 7000, maybe even 11,000rpm, when the max hp/torque is around half of that? wouldn't all that revving beyond that point be, um, pointless?

Hmmm. I always thought that maximum torque may be at a lower rpm while maximum hp could be at the higher rpm's. I'm a bit too tired to concentrate. But it goes back to the formula:

hp= (torque x rpm)/5252.

That's why some cars like the Corolla XRS needs to be literally abused to get its highest performance numbers.......

[badkuk]

pero, say your car's max hp is at 6000rpm. what's the use of designing the engine such that it revs up to 7000rpm? why not put some kind of limiter at 6000rpm, since revving any higher really doesn't do any good?

[ghosthunter]

pero, say your car's max hp is at 6000rpm. what's the use of designing the engine such that it revs up to 7000rpm? why not put some kind of limiter at 6000rpm, since revving any higher really doesn't do any good?

Assuming:
Your max HP is at 6000rpm
your max torque is at 4000rpm
your drop in RPM when shifting is 3000 rpm
so your ideal shift rpm will be 7000 rpm to maximize accelation.

[skylineGTR]

hmmm.. hindi ba mas maganda talaga pag high reving ung engine para pagnakuha mo ung max hp ng lets say 6,800 rpm kunyari and redline is 8,000 rpm, edi meron ka pang 1,200 rpm na ur running at max hp like in the skyline GTR, unlike sa mga b16b engines kunyari na max hp ka at 8,200 rpm at nasa redline ka na agad so palit ka na ulit ng gear. well this is only my opinion

[badkuk]

oooohhhh....gets ko na po B)

[niky]

Besides the shifting point angle, engine rpms aren't limited by where maximum power occurs, but as to how much the engine can take.

That's why some engines have power curves that peak very close to the limiter, because even if they could make more power at higher rpms, if you push them just a bit more, they won't survive.

Other engines peak in power way before the limiter, but since they can survive revving past that peak, the manufacturer allows them to rev that high anyway.

[GerardTagayty]

hey guys... ive been looking for a thread to post my question but i didnt want to create a thread na for it.. this is the closest i guess... just a simple naive question...

i just realized na walang redline the car that i drive most of the time... i just realized this last night as i pulled out of a gas station along macapagal last night... i stepped on the gas too fast i guess to avoid the oncoming car (which was honestly still far) and para maabutan ko yan green light...

so my tires sorta squeelezed and i slid for more than 30 seconds i guess then i looked down on my rpm thingie... it was close to 6k then i realized wala akong redline... i was sorta scared i might destroy the engine or something...

by the way the car i drive is a jumbo suv... guzzles on gas... is that possible? walang redline? i found it weird lang... coz the rest of our cars may redline naman...

[EssB]

shifting on higher revs will maximize your gear ratio - meaning as you shift to the next gear, nasa peak pa rin yung torque mo as the rev drops => giving you the optimum acceleration.