Whats The Loss On A Gtr

[steven22]

Hey everyone,

I recently had my gtr tuned just after getting it rebuilt and it made 209kw at all 4. From what I have read a normal r33 gtr is capable of splitting its torque 60/40. Mine demonstrated a 50/50 torque split which I was told was because it has a healthy centre diff. But my main query is if my gtr made 209kw at the wheels, from what I've read, this would mean that it would make about 360kw or so at the flywheel. Now this seems a bit unrealistic because the only mods I have are 13.5psi, standard air box with k&n panel filter and a fujitsubo titanium cat back exhaust.

So what I want to know is, what sort of loss would I expect and therefore how much power does it make at the flywheel?

[bnr#@]

Theres almost no difference between rwd and 4wd on a gtr power wise and id expect about 20% difference from flywheel to wheels

[FULOCK]

I always hear that its approx 30% loss to the wheels (pretty much same as quoted above)

I also always hear that 4wd looses more power from flywheel to the wheels than what rwd cars do, GTR's get better readings on dynos (compared to other 4wd cars) coz they aren't full time 4wd thus less power loss.

I have no evidence to back this, just my 2c worth of what i've heard on a few occasions.......

[2rismo]

No such thing as a fixed percentage drivetrain loss.

[R-PWR]

AWD readings are always lower than RWD if a car makes 350rwkw its making around 310awkw

[steven22]

So what is the expected value of my car at the flywheel, 260awkw?

[ferni]

you said 209awkw in your first post, this post you say 260awkw? which one is it?

209awkw would be about 250-260 give or take, 260awkw would be about 310-320kw give or take...

[pixel8r]

You cant use a percentage for drivetrain loss...

for example, if the standard losses are ~80kw (which is roughly true for stageas, so maybe a touch less for a GTR, say 60-70kw?), adding more power isn't really adding any more losses to the drivetrain. The losses may increase a little as you go up in power but not as much as if you use a percentage like 30% or something.

So my guess would be to do 209+70 = about 280kw at the flywheel. That doesn't seem too far out to me.

So in short, if you gain 50kw at the wheels you'll probably have gained something pretty similar at the engine.

[djr81]

You cant use a percentage for drivetrain loss...

for example, if the standard losses are ~80kw (which is roughly true for stageas, so maybe a touch less for a GTR, say 60-70kw?), adding more power isn't really adding any more losses to the drivetrain. The losses may increase a little as you go up in power but not as much as if you use a percentage like 30% or something.

So my guess would be to do 209+70 = about 280kw at the flywheel. That doesn't seem too far out to me.

So in short, if you gain 50kw at the wheels you'll probably have gained something pretty similar at the engine.

Drivetrain losses ARE proportional to power output.

Otherwise the car in your example would need to produce 81kw to move at all.

[ferni]

exactly, but it's not a static %, which is why no one can answer your question for sure... we can only guestimate It's just a number in the end anyway...

[pixel8r]

Drivetrain losses ARE proportional to power output.

Otherwise the car in your example would need to produce 81kw to move at all.

Its not a fixed loss either. It does increase slightly as you put more strain on the drivetrain, but not by the same percentage increase as power output.

I'm guessing my stagea wouldn't move very well at all with 81kw. If you were to draw a graph, it would almost flatten out down the lower end. I'm sure there would be some complicated mathematical physics formula to work it out but for the purposes of this discussion, lets just agree that drivetrain losses ARE proportional but not "directly" proportional (ie. graphing losses against power output would not produce a straight line).

I'm happy to be proven wrong however...

[steven22]

yeah sorry I meant 260 at the fly, thanx everyone

[Sydneykid]

Drivetrain losses ARE proportional to power output.

Otherwise the car in your example would need to produce 81kw to move at all.

Torque makes the car move, not horsepower.

Cheers

Gary