01-02-2013, 07:06 PM
(01-02-2013, 05:24 PM)Toms306 Wrote: you 'can' get overboost problems show up with 'quick' cars.
It all depends on the weight of the rollers and/or the brake used (if any is used). Too light rollers and you'll not get as fast turbo spool as on the road, and you'll not see the full torque.
Also measured MAF is lower when doing a powerrun on the rollers compared to when it is on the road.
The rollers I normally use have two 1t rollers - I normally get clutch slipping on it when doing a pull in 4th. I do not get any clutch slipping when on the road with slightly more diesel. (it slips @ 430Nm on the rollers)
(01-02-2013, 05:24 PM)Toms306 Wrote: Basically in normal driving youre on full throttle for only few seconds usually as thats all it takes to get to illegal speeds, on the dyno it takes 10+ seconds so the turbo gets more abuse than normal. I got an overboost fault doing my second run and put the car into limp mode, but apparently its not uncommon.
A powerrun should not be shorter than ~18 seconds -if it is, then the possibility of getting a duff reading is substantially higher.