Awd And Rwd Dynos

[allblitz]

Had a friend who just dyno'd his GTR on an AWD dyno.

Results were 211awkw. The people who dyno'd his car said to add around 50kw to convert that to rwkw.

Sounds far fetched in my opinion - thats quite an increase when converting to rwd.

Is there a forumla to work out the conversion from awkw to rwkw?

Regards,

Husnu (Hus)

[Ronin 09]

there was a thread in 'General Automotive' not even 3 weeks ago

search.

[Marko R1]

this is an old thread - ive searched all over the forum but yet to find out the same answer.

is there a formula or calculation which can work out the diff between awkw v's rwkw???

ive always wanted to know what my car would equate to in rwkw as i had it tuned on a 4wheel dyno (& my mates always want to compare my gtr output to their 'falcadore' lol) - has anyone actually done this to see the difference back to back?

[GeeTR]

I believe @ ~200rwkw, id say around ~5-15kw... ~5-10%, not much diff at all.

pun intended

[Swiper the Fox]

We tested this theory in front of 100's of people at Autosalon...the difference was 1KW...Mainline Dynolog Dyno uses different modes to read 2WD and 4WD. We did the same thing with dyno dynamics and the difference was 25KW...but that was with a 450kw car...would be less with lower power.

so GeeTR's prediction was about spot on.

Edited June 26, 2008 by DiRTgarage

[**RB2530**]

There is a few possibilities here,

Basically your driveline absorbs power due to friction...start from flywheel you have gearset friction, unijoint friction, diff friction, cv joint friction, wheel bearing friction and friction between tyres and rollers...

So for a GTR you have additional power loss from transfer case, front tailshaft, front diff, front drive shafts and front wheel bearings and tyres...

so if you have the car in rear wheel drive mode on a rear wheel drive dyno, you only have power loss from the rear wheel drive train...

if you have the car on a 4WD dyno and the car is in 2WD you should expect a higher power figure at the rear wheels than if the car is in 4WD simply because the extra driveline in 4WD mode consumes additional power just to turn it...

But

On the road in a GTR you cant ignore the loss from the front driveline even if you are in 2WD...The front wheels are turned by the road and the front driveline is still spinning and therefore consuming power...So the numbers you should always be interested in are power at all four wheels...looking at any power figures other this is false economy....

[Marko R1]

We tested this theory in front of 100's of people at Autosalon...the difference was 1KW...Mainline Dynolog Dyno uses different modes to read 2WD and 4WD. We did the same thing with dyno dynamics and the difference was 25KW...but that was with a 450kw car...would be less with lower power.

so GeeTR's prediction was about spot on.

this sounds right - when i had mine tuned @ crd jim mentioned its 25kw diff between rwkw & awkw - thanks paul!