Usable powerbands
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TECH Senior Member
Joined: Jan 2004
Posts: 5,798
Likes: 16
From: St.Charles MO
Usable powerbands This isnt really a drag racing thing, but it should go in the racing tech section somewhere.
Ok im going to make this short and simple.
Someone is telling me that the Elise's (Celica GTS) engine has a more usable powerband then the LS1/6. He is using a bogus formula that is biased toward higher revving engines to prove so. He claims that all racers use this formula to get "usable power" out of their engines. Its simply to take 20% of the RPM at which the peak power, and peak torque occur. For example
Elise
Peak HP- 7800RPMs - 20% - 6240RPMs
Peak TQ-6800RPMs - 20% - 5440RPMs
LS6
Peak HP- 6000RPMs - 20% - 4800
Peak TQ- 48000RPMs - 20% - 3840
So by that it shows that the rev range is longer, bla bla bla.
Anyway is this a bogus formula or what?
Ok im going to make this short and simple.
Someone is telling me that the Elise's (Celica GTS) engine has a more usable powerband then the LS1/6. He is using a bogus formula that is biased toward higher revving engines to prove so. He claims that all racers use this formula to get "usable power" out of their engines. Its simply to take 20% of the RPM at which the peak power, and peak torque occur. For example
Elise
Peak HP- 7800RPMs - 20% - 6240RPMs
Peak TQ-6800RPMs - 20% - 5440RPMs
LS6
Peak HP- 6000RPMs - 20% - 4800
Peak TQ- 48000RPMs - 20% - 3840
So by that it shows that the rev range is longer, bla bla bla.
Anyway is this a bogus formula or what?
Tell him he is a dumbass and that he needs to step away from the technical discussion immediately 
First of all, every engine is designed with its own target powerband rpm range. You can change that location with cams, mods, etc.. to move your powerband up or down. First, determine how much the RPM drops when you upshift into the next gear. Then you have your high rpm value (shift point) and your low rpm value (where the rpm drops to in the next gear).
Between those two rpm points (your powerband), you will have your HP curve (dynojet graph will work). Calculate the total area under that hp curve between those two rpm points. That will give you your average hp across your powerband.
V8 engines tend to have very broad curves. Very good for keeping the average hp numbers up. Little engines typically have very peaky hp curves, which hurt their average hp.
First of all, every engine is designed with its own target powerband rpm range. You can change that location with cams, mods, etc.. to move your powerband up or down. First, determine how much the RPM drops when you upshift into the next gear. Then you have your high rpm value (shift point) and your low rpm value (where the rpm drops to in the next gear).
Between those two rpm points (your powerband), you will have your HP curve (dynojet graph will work). Calculate the total area under that hp curve between those two rpm points. That will give you your average hp across your powerband.
V8 engines tend to have very broad curves. Very good for keeping the average hp numbers up. Little engines typically have very peaky hp curves, which hurt their average hp.
Bhp@RPM 190 @ 7800
Torque (lb.-ft.)@RPM 138 @ 6800
Cylinders 4
Displacement (cc) 1975
Can you say peaky 4 cylinder?
The Lotus Elise is also a 1975 lb car.
This is a goofy comparo.
Torque (lb.-ft.)@RPM 138 @ 6800
Cylinders 4
Displacement (cc) 1975
Can you say peaky 4 cylinder?
The Lotus Elise is also a 1975 lb car.
This is a goofy comparo.
