Hp@rpm

  • Thread starter Thread starter sinharvest24
  • 6 comments
  • 847 views
sinharvest24

sinharvest24

Messages
147
Messages
sinharvest24
Here's the lowdown, i've been fiddling with certain parts, trying to get the most hp for a pp range. What i don't really understand, is what does (ok i'm just gonna use imaginary numbers for explanation) 300HP@8000RPM really means? Because when i was filling around with certain parts i can get the same hp but at different RPM.


What the difference between 300HP@5000RPM and 300HP@6000RPM? Which one is better?

What i understand about HP@RPM is that when your rev reaches that amount of RPM that's when you're at said/given HP.

Does it play a role in when i should change gears and how i should set the ratios?
 
To answer your last question - yes; you should set your gear ratios according to your powerband.

There is no answer to the other question you are asking - since you are giving only hypothetical numbers at 1 RPM. What matters also is torque/area under the power curve.

So I'd need to understand how quickly the power drops off for your example of 300HP@5000RPM vs. how much torque you are giving up to make that extra HP in the upper RPM range.

It also depends on the circuit - lots of straights and few corners; I'll take peak power (i.e. as much HP; don't care about my torque curve); if lot's of corners, little high-speed, I want as much area under my torque curve as possible.
 
In almost all cases 300hp @ 5000 rpm is preferred to 300hp @ 6000 because you get the max power sooner. Gear ratios should be set to both take advantage of the cars power curve as well as the track being raced.

Edit: this is an overly simplified explanation by the way. There are several other factors to take into account
 
INFO: 300HP@5000RPM
Redlines@8000RPM


Lets say i'm in 3rd gear and i'm @7000RPM, if i were to change to 4th gear, the RPM drops to 5500 RPM.

Should i change my gear even though i haven't reached the redline yet or should i wait to redline then change gear or should i plan to switch gear so that when i change the RPM drops right above 5000?
 
sinharvest24
INFO: 300HP@5000RPM
Redlines@8000RPM


Lets say i'm in 3rd gear and i'm @7000RPM, if i were to change to 4th gear, the RPM drops to 5500 RPM.

Should i change my gear even though i haven't reached the redline yet or should i wait to redline then change gear or should i plan to switch gear so that when i change the RPM drops right above 5000?
Click to expand...

we need torque numbers and gear ratios (specifically the drop in rpms between gear changes) ideally you would want to see an accurate dyno graph (not what is provided in gt5)

more than likely you will want to shift at or just after 5000rpm.
 
I just wanted to get the general idea.

Well here's the specs.

Car: Rx7 Spirit R
Max Power: 336@6700RPM
Max Torque: 275@4900RPM


I set up my gear ratios so that each time i shift it stays above 6700RPM.

Am i doing i right?
 
if it peaks at 6700 rpm then no youre doing it wrong.if it drops off after 6700 (and i dont know because i dont know what that cars power curve looks like) then you are loosing power the whole time youre in the gear, not good. lets say 500 rpm more or less you are making 50 hp less than you where at 6700 (where peak power is) then thats probably about where you want the rpm to drop to when you shift, then go past 6700 rpm by 500 rpm and shift again. This is assuming you dont hit youre rev limiter. Now lets say that it makes peak power at 6700rpm and then stays relativly flat, no more than 10hp lost all the way to red line. In this case shift so that the rpms drop to 6700 isnt a bad thing. Most engines make hp and torque on a curve so you want to adjust the gears so that you have the most avg hp through out the gear. Some motors make peak hp at peak RPM in this case its good to keep the gears as close as possable. Hope that all made sense, you need to look at the graph on the right of the screen that shows hp and torque vs RPM and set the gears so that you have the most avg hp and torque at all times.

Side note hp is a result of a calculation, HP=torque X RPM / 5252, so hp will always equal torque at 5252rpm
 
Back