How much bhp is lost through gtir 4wd

[N1SMO]

Hi

Roughly how much bhp is lost through the gtir drivetrain, ie the difference between bhp at flywheel and bhp at the wheels.

also when you say i have a 400 bhp gtir is this at the wheels or at the flywheel.

 

[Fast Guy]

There's a couple of views on this.
About 28% is a resonable guess. The other line of thought is that if a 200bhp gtir uses 56bhp (28%) to drive, why would a 400bhp gtir need 112bhp (still 28%) so they seem to go on a fixed amount of bhp but I haven't seen a figure given for this way.
Go for 28% then at the worst you'll be underestimating your power.
400bhp would be at the flywheel nomally (unless it's one hell of a car ), although power can be at the hubs as well as wheels, it depends where you go.

 

[Anonymous]

Dan at Abbey Motorsport told me 30%
Pete 8)

 

[Anonymous]

at the powerstation r/r day a couple of years back,i lost 25% due to transmission losses.

 

[Davey]

have seen some peeps that take off a fixed amount, plus a small percentage, dont know who though?
Have never understood why a car producing 200bhp more than standard would lose another 80bhp or so through the same transmission?

 

[Anonymous]

have seen some peeps that take off a fixed amount, plus a small percentage, dont know who though?
Have never understood why a car producing 200bhp more than standard would lose another 80bhp or so through the same transmission?

doesn`t friction stay constant therefore no matter how much power you develop,you always lose the same percentage?

i think the only way to reduce the friction losses is to experiment with different oils/viscosities etc.

 

[celm]

on a stock GTIR,whats is the WHP rating?

 

[Davey]

dont mean to sound stupid, but if friction is constant, surely you would always lose a set amount? i can understand that you would get more frictional loss as speed increses, but not increased power? :?

 

[coxie]

i was told by my local tuner that transmission losses on a gti-r are 24% and stays fixed at that.

 

[Anonymous]

dont mean to sound stupid, but if friction is constant, surely you would always lose a set amount? i can understand that you would get more frictional loss as speed increses, but not increased power? :?

my understanding was if friction losses amounted to say 25%,then no matter what the power output you lost 25%.
if you have a 200bhp engine,you`d lose 50bhp.
if you have a 400bhp engine,you`d lose 100bhp.both instances are a 25% loss.

 

[GTIR-LOZ]

so waht your saying is if you had 1000bhp then you would lose between 240 and 300 bhp through the transmission, sorry but that is bollox!!! i agree that there must be a fixed amount lost as you are not going to increase the rotating mass or friction by adding more hp well not significantly anyways

 

[Davey]

Didnt Ivans car have a quoted transmission loss of something like 140bhp?

 

[Anonymous]

sorry but that is bollox!!! i agree that there must be a fixed amount lost as you are not going to increase the rotating mass or friction by adding more hp well not significantly anyways

well make up your mind is a fixed amount [percentage of total] lost or not.you seem to be arguing against yourself.if you look at the results from the power station r/r day on ray`s site it would appear to back me up.

this is only my understanding,if someone can come up with a more logical view point that is different from mine then i`ll be just as happy to be put right.

 

[Davey]

oap, i think what loz meant was a fixed amount of power(ie 50 bhp) is lost, no matter what the power of the engine, rather than a fixed percentage of the engine's output :? :?:
Dont think this can be right though. The way i see it, if you are applying more power(pressure to the gears for instance) then there is going to be more friction on the surface of those gears,meaning more heat, and more power lost. But, what i'm saying is, i wouldnt have thought that the friction, and loss of power would rise proportionatley(sp) with the increased power, hence why some people use the technique i suggested in my first post.
Interesting subject, would be nice to know the answer(rather than what somebody on a forum thinks might happen )

 

[Fast Guy]

The only way to find out for certain would be to put an engine on a dyno, if possible run it at two boost settings. Then put the engine in the car and run it at the same 2 boost settings and see how the dyno and rolling road powers compare for the 2 boost settings.

 

[Anonymous]

The only way to find out for certain would be to put an engine on a dyno, if possible run it at two boost settings. Then put the engine in the car and run it at the same 2 boost settings and see how the dyno and rolling road powers compare for the 2 boost settings.

that`s a hell of a lot of trouble to go to.there`s not many people would spend thousands putting it on a dyno just to settle a petty squabble.
surely it would be easier to just ask a few r/r operators then take a census.

 

[Evil_GtiR]

The only way to find out for certain would be to put an engine on a dyno, if possible run it at two boost settings. Then put the engine in the car and run it at the same 2 boost settings and see how the dyno and rolling road powers compare for the 2 boost settings.

I agree, this will be the best way to find out for yourself.

 

[Anonymous]

come on then people,who is willing to spend a minimum £3000 to put their engine into a dyno just to settle this petty topic :roll: :roll: :roll:

 

[Fast Guy]

come on then people,who is willing to spend a minimum £3000 to put their engine into a dyno just to settle this petty topic :roll: :roll: :roll:

Where did you get that figure from? I hope it's not accurate. :shock:

 

[Anonymous]

Where did you get that figure from? I hope it's not accurate. :shock:

there`s a proper full on dyno in the northampton area,try phoning them up and ask them how much they charge an hour.

then you have to get your engine in/out of the car.
make all manner of engine brackets up to mount your engine to their dyno.
all your engine control electronics have to go with the engine as well.
etc etc etc etc
you would not believe how much work there is to do to get an engine into a dyno.it`s not like just rolling your can onto the rollers of a £50 an hour r/r.