Effect for SHORT piping exhaust?

[D7zul]

err I'm sorry but there's a bit of a contradiction here. horsepower is a function of torque.

HP = Torque x RPM ÷ 5252

Where torque increases, hp will increase. so you can't say "improves hp but not torque". if it improves hp but not torque then the equation will be an inverse relationship.

What you mean is the powerband moves up, so there's a loss of torque in the lower regions.

yes.. you're right..

when i say lesser torque means.. lower low end power

and higher hp means.. higher high end power

 

[syimirmazlan]

err I'm sorry but there's a bit of a contradiction here. horsepower is a function of torque.

HP = Torque x RPM ÷ 5252

Where torque increases, hp will increase. so you can't say "improves hp but not torque". if it improves hp but not torque then the equation will be an inverse relationship.

What you mean is the powerband moves up, so there's a loss of torque in the lower regions.

yup ur right...thnx for getting it right...a highly modded car not necessarily can beat a lightly modded car if the powerband is not right...no useful torque when needed eventhough high horsepower are achieved...this is based on my experience in modifying my car...i have a kinda high figure for my 4g91 which is 160hp, but not that fast because of less torque when needed....

 

[^pomen_GTR^]

err I'm sorry but there's a bit of a contradiction here. horsepower is a function of torque.

HP = Torque x RPM ÷ 5252

Where torque increases, hp will increase. so you can't say "improves hp but not torque". if it improves hp but not torque then the equation will be an inverse relationship.

What you mean is the powerband moves up, so there's a loss of torque in the lower regions.

i would says that saymir is correct.....but not a story as a whole....

the reason cannot achieving topspeed is because the powerband already shifted into higher
rev range....and since most stock standard gearbox on almost all car having a gearbox ratio best for daily driving,thus the ratio (especially on top gear) would be the cruise gear that keep the rev low and to save fuel...including to avoid stresing the engine at high rpm for long time.....


in racing the gearboxes ratio re-arranged to match the powerband....and so there's the acceleration and topspeed....


*another related issue to this shifted powerband is the myth of using lightweight flywheel/skimming flywheel for road car....

 

[neohadri]

thanks pomen GTR, that's explain why auto box not suitable to use free flowing exhaust i.e straight flow muffler or 4-1 extractor

 

[syimirmazlan]

yup hp and torque have a relation as a general,when calculated through the whole powerband. but a car with a higher peak hp, does not necessarily produces higher peak torque than a car with lesser peak hp.so as to my opinion, short exhaust piping can improves peak hp, but it may affect the torque that the car needed to push it on a upper speed.