Power Loss Through Drivetrain

[TUFF_350]

Hey guys,

just wondering if anyone knows a rough % figure of the power lost through the drivetrain? Eg my R33 came with 187kw @the fly, so minus the figure it had roughly "x" @the wheels.

Also do the GTRs suffer more as they are AWD or less?

Thanx in advanced

[Krishy]

to answer one of your questions....i think the % power loss is something like 20-30%.....not quiet sure on that maybe someone can elaborate

[Damo_R34]

Im pretty sure it varies from car to car, you could pull two stock cars from the factory and get different readings

[Madaz]

Yes i was going to say about 30%

and yes GTR's fm suffer a little bit more but not heaps

[TUFF_350]

So to be safe,

round 30% loss for GTS-T and 35% GTR...holy hell thats a fair slice.

[Inline 6]

if you work for nissan though you would argue its 5% and claim the engine dosnt have that much power as has happened with the 275hp agreement

[Krishy]

So to be safe,

round 30% loss for GTS-T and 35% GTR...holy hell thats a fair slice.

i would say more like 20-25% for gtst and about 25-30% for a GTR

[D_Stirls]

FWD ~15%

RWD ~25%

4WD ~35%+

[Damo_R34]

to answer one of your questions....i think the % power loss is something like 20-30%.....not quiet sure on that maybe someone can elaborate

Yes i was going to say about 30%

and yes GTR's fm suffer a little bit more but not heaps

i would say more like 20-25% for gtst and about 25-30% for a GTR

FWD ~15%

RWD ~25%

4WD ~35%+

See, depends who you ask

[(OO)Firty Free(OO)]

Ive been told to roughly take 60rwkw off for manual and 70-80rwkw for an auto by a few different people so i tend to use this rough guide, how accurate it is who knows! Percentages have never sat too well with me....

[Madaz]

I would say Dale would have the most idea, thats my more better engrish

[SLED]

Ive been told to roughly take 60rwkw off for manual and 70-80rwkw for an auto by a few different people so i tend to use this rough guide, how accurate it is who knows! Percentages have never sat too well with me....

that can't be right bud.....you definitely have to look at percentages otherwise a car with 100kw at the flywheel would have about 20kw at the wheels

I would say Dale would have the most idea, thats my more better engrish

yeah those figures make more sense Dale & Steve

[(OO)Firty Free(OO)]

that can't be right bud.....you definitely have to look at percentages otherwise a car with 100kw at the flywheel would have about 20kw at the wheels

yeah those figures make more sense Dale & Steve

It's only when engines start putting out decent numbers that i question the 25% loss rule.....Take for instance a 400rwkw engine +25% driveline loss = 500fwkw thats 100rwkw loss through the driveline i would think 60rwkw more realistic. Just my opinion of course.

[SLED]

It's only when engines start putting out decent numbers that i question the 25% loss rule.....Take for instance a 400rwkw engine +25% driveline loss = 500fwkw thats 100rwkw loss through the driveline i would think 60rwkw more realistic. Just my opinion of course.

yeah fair enough

[Hillzy]

I have read and heard numerous people quote 13-14% of power is lost through a 2wd drivetrain.

[4door_Sleeper]

Rather than re-write it all again, here is a comment that sums it up quite well from another thread.

Before everyone gets way off the mark here..

Drive train losses remain static, they do not change, give or take a hp or two, due to better oils etc..

Don't follow the % rule, its wrong, and % losses calculated by coast down calcualtions are incorrect..

best way to explain this is like so, roughly a RWD car will loose about 25ish hp, as your only driving a couple of gears in the box, at 1 to 1 ratio, and the diff gears, so, if your car is making 200hp to begin with, you could say roughly, your making is 230 at the fly wheel, if you then mod the motor, but alter nothing in the driveline, and it now makes 400 at the wheels, its only going to make 430 at the fly wheel, not 460 for example if you where to use the % rule..

Automatic, and 4wd losses are higher, due to the nature in which they operate, but again the figures remain pretty constant, better oils, or driveline components alter this, but again the figure doesn't really move a heck of a lot, it remainds pretty constant, unless of course something is broken, and there is greater friction..

the 60kw figure quoted before im pretty sure is the loss you'll see from a gt-r in 4wd mode, as 60kw is a LOT of power loss for a manual RWD car..

also, a large portion of the driveline loss you see on rolling road dynos, is from the tyres, stuff like over/under inflation of the tyres, weight in the car, and tyre wrap around on the roller affect the figures, so if you dyno your car one day with the tyres at 36psi, then a week later they've gone down to 20psi, you will see less power, as the tyre is wraping around the roller more, more wrap, more friction, more friction the more power needed to over come it, so a lower reading will be seen, hub dynos eliminate this, which is why you will always see a slighly higher reading, and in some cases a bigger reading by comparision to a roller, as you eliminate wheel spin on the roller..

If you took the 25-30% rule and apply this to a high KW car, the loss of power is huge, now convert that into Joules (most power loss is converted to heat, and a small portion into noise) and you have a car that will change the climate for anyone within a few blocks.

[Madaz]

hahaha my car makes 770400000 Kj

[Damo_R34]

656640000 here

[D_Stirls]

It's only ever going to be a rough guide anyway, because every gearbox design would be different and the weight of your box oil would have a fair effect on power loss as well.

[Ryanrb25]

In a GTR its not only the added weight of the drive chain and all 8 clutch plates in the transfer case, extra tailshaft, diff centre, drive shafts, brake rotors, wheels etc, but friction between all these individual components, also heat and energy being dispersed in many little directions by vibration can also cause loss of power. Remember the more power you have the more friction is created between components like gearsets etc. A GTR we had on the dyno had 270AWkw and then 330rwkw. So there's 60kilowats just in the removal of the front driveline, remove the rear driveline to get flywheel kilowatts and your probably looking at another 35-40kw+++

Edited July 18, 2008 by Ryanrb25