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| Choca |
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Hi,
Im just really curious to know how to convert Fly Wheel Kilowatts to Kilowatts at the Wheel? Is the formula? or is it a questamation thing? Any input would be great! Cheers CHOCA
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| 4.9 EF Futura |
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Questamation thing.
I guess the one theory we have.... Let's assume the standard EF 4.0L V8 produces 165kw at the flywheel (probably a big assumption). ON AVERAGE, these engines yield 105-110kw at the rear wheels (of course, all dynos are different, different weather etc etc.) with an automatic transmission. So 165fwkw to 110rwkw = 33% loss through drivetrain. So ppl usually assume 30% loss from fw to rw on a standard car. As for modded engines.... anyone's guess. Need some figures to compare... fwkw to rwkw.
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| Waggin |
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Shouldnt the loss, when given as a percentage remain the same, no matter what power the engine is pushing?
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| 4.9 EF Futura |
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Waggin wrote: Shouldnt the loss, when given as a percentage remain the same, no matter what power the engine is pushing?
What's to say it's not constant? i.e. 250kw engine making 195kw at wheels? i.e have seen on dyno, Gen III SS (they about 260kw, yeah?) making 208kw at the wheels.... Who knows?
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| Dellboy999 |
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Once a certain level of mods gets reached, I.E. big numbers out of the engine, the loss doesn't stay at a percentage it reaches a limit and stays there.
165fwkw - 30% loss = 115rwkw . this is a loss of 50kw 1000fwkw - 30% loss = 700rwkw . this is a loss of 300kw see it gets way to much of a loss figure the drivtrain etc will only soak up so much.
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| data_mine |
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There's also the FWKW = RWHP theory.
Ie 165FWKW = 165RWHP, then convert HP to KW 165HP = 123KW It's more optimisitc than the -30% theory, but another one to add to your list. And it works backwards too to find FWKW from RWKW. Convert RWKW into HP, and theres your FWKW number.
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| Waggin |
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I guess its a bit hard using Dyno RWKW against manufacturers claimed FWKW
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| 4.9 EF Futura |
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Waggin wrote: I guess its a bit hard using Dyno RWKW against manufacturers claimed FWKW
Lol... so when are the engine and chassis dynos goin in brad? 
We need answers!!!
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| Waggin |
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Think about how long it would take to hook an engine up onto an Engine Dyno! Yikes.
I guess you'd need engine loom and engine management out of the car to run it all too.
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| Vic |
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Isn't it true that power loss is greater through an auto box than a manual box?
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| 4.9 EF Futura |
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Vic wrote: Isn't it true that power loss is greater through an auto box than a manual box?
Yep... viscous fluid coupling (torque converter) versus a friction plate (clutch). But then, new autos have lock up torque converter clutches altho these arent usually locked when accelerating.... But then.... an auto has torque multiplication thanks to the converter....
http://www.victrans.com/multiplication.html
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| Vic |
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So how would we estimate the loss of power through a manual box then?
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| 4.9 EF Futura |
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Vic wrote: So how would we estimate the loss of power through a manual box then?
Well.... the example i posted above (165fwkw = 110rwkw) was a standard V8 automatic... i spose if you had a standard car with a 5spd and ran this on the same dyno and compare the rwkw figures?
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| Vic |
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Oh okay. I was just thinking there was some very approximate figure for manual box losses just as there is for auto boxes.
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| One Drone |
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I've been told that as flywheel power increases, rearwheel power loss decreases..
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