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R32 Gtr Drivetrain Losses Awd V Rwd

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redot Apprentice

redot

Posted
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Hey guys I was told when I purchased my car that it made 314kw however when it was recently dynod it only made 280kw at all 4. I'd like to think it did intact make 314 kW but in rwd.

My question is how much of a power difference can you expect between an awd dyno run and a rwd dyno run? I've heard numbers like 12-15% thrown around but I'm wondering if anyone has actual figures from their own experience.

Thanks in advance

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Hadouken Grand Master

Hadouken

Posted
Posted

This has been discussed numerous times on sau man.

The rb26 gtr is a majority rear wheel drive car. It's Not like a evo or wrx where the car has a exact percentage split front to back.

I have seen people dyno their car in awd and then rwd in a gtr and the reading was marginally different.

That being said, different dynos tell different stories. And how the tuner sets it all up.

GTSBoy Grand Master

GTSBoy

Posted
Posted

Plus, the majority of the losses are not in the drivetrain - they occur at the tyre/roller interface. As mentioned above, the GTR's AWD characteristics make it very difficult to work out whether the effect of having 4 places to lose power (through roller slip) is more significant than spreading the power delivery around to 4 places so you actually get less slip.

redot Apprentice

redot

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Posted (edited)

Yeah fair enough. My car was dynod on a hub dyno when it made 280kw, so you'd think with tyre slip out of the equation it would actually make more power.

Was hoping to see some dyno graphs of someone doing a rwd run then awd run back to back. But I understand what you're saying about it being different to a evo style awd

Edited by redot
Ben C34 Grand Master

Ben C34

Posted
Posted

Why would anyone bother doing back to back comparisons?

A dyno is a tuning tool. Make as much power as possible on the dyno it's on when being tuned. Comparing dyno readings will end in tears.

You mod a car to make power so it goes faster, not for a line on a page.

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scotty nm35 Grand Master

scotty nm35

Posted
Posted

Yeah fair enough. My car was dynod on a hub dyno when it made 280kw, so you'd think with tyre slip out of the equation it would actually make more power.

A hub dyno doesn't require any downforce on the rear axle. If you strap a car down hard to get grip on rollers you lose many powerz. More power the more it needs to be strapped down.

You can see why hub dyno's are prefered...

redot Apprentice

redot

Posted
  • Author
Posted

Yeah I was just curious to see if there was a difference on paper between awd/rwd irrespective of tuning...

Rb26 forged, gt3582r, 850cc injectors, power fc dejetro, pulp, 14psi

Car made 354kw on 20psi at all 4 after the tune

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

Actually in the interests of science Shred Industries Performance did this test on an R32 GTR in 2011 and got 200.6KW and 189.7KW.

Don't know what kind of dyno - was a Dynapack but don't know if rollers or hub.

I have the chart if anyone is really keen to see it.

post-49463-0-55700700-1417823425_thumb.jpg

redot Apprentice

redot

Posted
  • Author
Posted

Actually in the interests of science Shred Industries Performance did this test on an R32 GTR in 2011 and got 200.6KW and 189.7KW.

Don't know what kind of dyno - was a Dynapack but don't know if rollers or hub.

I have the chart if anyone is really keen to see it.

Awesome mate, thanks for that! Yeah I would love a look

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