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Just tried dynoing a R32 on a Dynapack 4wd dyno and was getting weird results. Although the dyno does hold the engine at the correct RPM at the end of a ramp run (6000 rpm in my run), the plot only shows 4500 rpm. Figuring it was the ATTESA 4WD messing with the dyno, I tried increasing/decreasing torque sent to the front wheels through a controller box installed on the car and the plots ended up going all over the place.
Contacted Dynapack support and found out the if the front and rear hub are running at different speeds, the dyno will report a lower RPM since it uses the average hub speed. They did not provide any solution since they are not familar with the R32.
I have unplugged the wheel sensors at the front to force the car to run at 2WD for now but I fear as the tuning progress, the car will exceed the power limit of the dyno with just the rear hubs.
I have seen a number of R32s on a 4WD dynapack with all 4 wheels mounted. I'm sure those guys must have figured out a way to dyno properly under 4WD or they would not have mounted all 4 sides on the dyno?
Behind the drivers kick panel there is a single wire white connector (sorry, I can't remember the colour of the wire). It puts the 4wd pump in bleed mode and does a pretty good job of locking the system up. This my help it keep everything even.
There is also the very real possibilty that the system is not bled or functioning correctly? did you dive it at all before putting it on the dyno? or have you checked how bad the torque split is on the front to rear axle?
Thank you for the feedback. The R32 is owned by my friend. Even though he is an aggressive driver, I am not sure whether he was able to tell whether the system is properly sending torque to the front while driving.
On the dyno, the front wheels simply stay stationery most of the time on a ramp run until half way through. I was alone while doing the first few tests in AWD mode and was busy monitoring the engine reading and status so I really only caught a glimpse of it in one of the runs so to provide more details, I'll have to put the car back in AWD mode and look at it again before reporting further details.
I was always under the impression that torque will only be sent to the front wheels when the ATTESA system thinks that it needs to send traction to the front wheels to help with traction and the other 80% of the time zero torque will be sent to the front. Or is this not true and there will always be some torque sent to the front? If the first assumption is true, the plug behind the kick panel will help lock it up I guess?
You can set your Dynapack display to show you torque or hub RPM on each pod. I've used that to diagnose problems with diffs when cold that are only spinning one wheel. I make sure everything is good and warmed up (included the pods) for repeatable test results.
So I would suggest you get the RPM on each hub reading the same using your torque controller box prior to starting a ramp run.