R33 Gtr On Awd Dyno With G Sensor Disabled

[JD_R33]

Did a search of the forums, but came up empty hence the question.

Took my R33 GTR v-spec to a dyno day (AWD dyno) recently and the workshop tech disabled the g-sensor unit in the console before the run.

I assumed this was done because the Attesa system would be getting wheel speed input but no g-force input. I couldn't workout how disabling the g sensor (i.e. no g-force input) would help.

Is this common practice when running a GTR on AWD dyno, and can someone explain why it's done?

[R31Nismoid]

You MUST drop the driveshaft for R33/R34 - otherwise you'll f**k the transfer case

[RPMGTR]

You MUST drop the driveshaft for R33/R34 - otherwise you'll f**k the transfer case

Chill Ash, the OP stated it was an AWD dyno.

If you disable the 4wd by unplugging the g force sensor, it can make a better/more consistant number as very little drive is now sent to the front wheels.

It is more representative of how a GTR works in the real world. Excess power is sent to the front wheels only when the rears slip.

[JD_R33]

You MUST drop the driveshaft for R33/R34 - otherwise you'll f**k the transfer case

Thanks for the speedy reply. Does the driveshaft really need to be removed on a 4WD dyno? If so, what's the point of even having a 4WD dyno, or is it just the case for GTR's?

That really surprises me that they didn't do it then, as it was an experienced mechanic at a well regarded local performance workshop, and I even recall someone telling me he owns/has owned a GTR himself.

[R31Nismoid]

Chill Ash, the OP stated it was an AWD dyno.

If you disable the 4wd by unplugging the g force sensor, it can make a better/more consistant number as very little drive is now sent to the front wheels.

It is more representative of how a GTR works in the real world. Excess power is sent to the front wheels only when the rears slip.

Oh whops

indeed - my bad

[blind_elk]

Chill Ash, the OP stated it was an AWD dyno.

If you disable the 4wd by unplugging the g force sensor, it can make a better/more consistant number as very little drive is now sent to the front wheels.

It is more representative of how a GTR works in the real world. Excess power is sent to the front wheels only when the rears slip.

The wheels drive the rollers, the rollers don't drive the wheels.

So, if you start "driving" on the dyno, the rear wheels start driving the (rear) rollers but the front wheels are stationary. WHEEL SPIN! There would be no G-forces involved, because the car is stationary.

I've never had the G-sensor disabled when AWD dynoing my (R32) GTS4. Not even when 2WD dynoing (pulled fuse) it on a AWD dyno.

[JD_R33]

Ok, now i'm really confused.

If the rear wheels are spinning but the front aren't, wouldn't the Attesa ECU see that as "wheel spin" according to the ABS sensors, and try to send 50% power to the front?

Or does disabling the G-force sensor shut down the torque split control completely?

Sorry if these seem like dumb questions, but i'm still trying to get my head around how this system actually works on a dyno.....

[nIsMo86]

If you disable the 4wd by unplugging the g force sensor, it can make a better/more consistant number as very little drive is now sent to the front wheels.

Doesnt this above post answer your question?? ^^^^^^

[JD_R33]

Doesnt this above post answer your question?? ^^^^^^

haha.....almost.......just still not quite clear in my mind, because I thought that if disconnecting it disabled 4wd there would be *zero* power going to the front, as opposed to *very little*.

But I guess that's near enough - thanks guys

[Duncan]

when you disable the g sensor the 4wd system shows a fault and won't run 4wd, thats all. It would work on a 2wd dyno for an r32 as well. Its exactly the same trick most cheap 4wd controllers use for rwd only mode

[RPMGTR]

haha.....almost.......just still not quite clear in my mind, because I thought that if disconnecting it disabled 4wd there would be *zero* power going to the front, as opposed to *very little*.

But I guess that's near enough - thanks guys

True, disabling the 4wd means there is no electronic drive being sent to the front wheels.

But the 33/34's have a small amount of hydraulic preload in the system which sends some mech drive to the front wheels even when the torque gauge says zero.

That is why the front shaft should be removed on a 2wd dyno. (otherwise the transfer case gets very hot and kills the driveplates :0 )

This preload is enough to drive the AWD rollers but not transfer any substantial amount of power.

cheers