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Rwkw Vs 4wkw

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The Alchemist Collaborator

The Alchemist

Posted
Posted

Hi, just my 2c worth.

I have a R32 GTR and, believe it or not, a FWD mazda 626 with quad throttle body injection on it.

Both have aftermarket fuel injection on them. Both have known/measured CC/Min injectors in them. Both have a known fuel pressure at peak power. Both have a known AFR at peak power off the dyno.

Both have known duty cycle/ms delivery time at their peak KW/HP off the laptop which allows me to calculate actual fuel consumption for each engine.

This fuel consumption directly relates to kw/hp produced by the engine.

The formula that defines this relationship does not change after a good arguement ( thank god for that )

Rather than bore you with the calculations here are the results instead.

R32 GTR in 2WD mode on a dyno dymanics dyno 260rwkw/348hp> Calculated HP at the engine 530hp

or a 35% transmission loss/tire frictional losses etc etc

Mazda 626 quad T/B injection 91 FWKW/ 121 hp at the wheels > calculated HP at engine 168hp

or a 27% loss for the front wheel drive.

These are typical figures on our dyno for most rwd or fwd vehicles > ie: repeatable results

hope this helps,

Mike

Denver Grand Master

Denver

Posted
Posted
R32 GTR in 2WD mode on a dyno dymanics dyno 260rwkw/348hp> Calculated HP at the engine 530hp

or a 35% transmission loss/tire frictional losses etc etc

just shy of 200hp loss, in RWD mode?

righhhhtttttt

your maths is incredibly wrong somewhere, or your dyno reads incredibly low, 200hp of loss is a MONSTEROUS amount..

mazgtr Community Regular

mazgtr

Posted
Posted (edited)

As it was stated before, a % power loss is not accurate. A 700BHP GTR isnt going to lose any more power through its drivetrain than a 400BHP GTR, providing they have the same transmission/gearbox/clutch/flywheel/fluid.

Its much more logical that its a fixed amount. Someone suggested about 50-60KW of power loss from engine to rear wheel figure. And about 3-4% difference from this to an AWKW figure...

Edited by mazgtr
Turbz_13 Experienced

Turbz_13

Posted
Posted

with my gtr there was i think 27kw(just under 30kw's) different from awkw's to rwkw's.

and somewhat the same kinda power loss with a friend of mines gtr as well. (dyno'd at the same place)

i have heard that through the attessa there is a power loss of 35% from the engine to all four wheels(the total figure put out).

T04GTR Grand Master

T04GTR

Posted
Posted
True, ive seen a car with "420RWKW" only clock 119MPH. And another GTR with 390RWKW clock 136MPH. Both on stock transmission.

Clearly one car is makeing a lot more power than the other...

yes tru tru :P

my old dr30 did 11.8 @128 mph with 329rwkw

my gtr does 11.7@116mph with 315.9 rwkw.

im sure the wieght diferance will contribute but 12mph is a pretty big diff

Denver Grand Master

Denver

Posted
Posted
yes tru tru >_<

my old dr30 did 11.8 @128 mph with 329rwkw

my gtr does 11.7@116mph with 315.9 rwkw.

im sure the wieght diferance will contribute but 12mph is a pretty big diff

probably all in the launch, gt-r im guessing gets out of the hole better than the DR did, meaning it gets a good first 1/4 of the track but looses out on the top end mph, where as the dr might be boggy/wheel spinning out of the hole, but has the bigger mph to get to an almost identical time..

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