A post Rick put up on VWROC
"Golf R Turbo Failures
Hello all,
long time no post, lots going on here, tuning development etc etc.
I have tuned over 80 Golf R's, and of those cars 4 have had turbo failures. That's 1 in 20, which is not a good stat. I have also had a number of customers that have booked their car in have to cancel, due to to the turbo failing on completely standard tune.
The last of these failures occurred earlier this week while on my dyno. This was frustrating but as I was logging at the time it allowed me to study first hand. The car had done one flawless power run, and then failed on the second. Data logs showed everything was perfect, with boost at 1.5 bar at the time of failure. This is less boost than virtually every tune available for the Golf R runs.
So what's happening? Obviously I was keen to find out. The IS38 turbo borrows technology from Motorsport and employs a "zero clearance" compressor design. There is (virtually) no clearance between the compressor wheel and housing. This improves efficiency and contributes to the incredible performance of the turbo. The compressor housing is lined with a Teflon insert, as the compressor wheel will come into contact with it in normal operation.
The issue is that batches of the turbo have not been balanced properly. A number of turbos have now been stripped and examined, only to find the balancing is out by a very large margin on a number of turbos. This causes the compressor wheel to move off centre slightly. On a "normal" turbo this wouldn't be an issue, but on the IS38 the compressor wheel is hitting the Teflon insert, digging in - and snapping the shaft instantly. In other cases, it is undoing the the retaining nut and then causing even more of a mess. The shaft diameter is considerable - it's a very strong shaft but when it suddenly goes form 100,000 Rpm to zero something is going to give.
Early 2014 cars have had the most failures, but the failures are not isolated to these. We have seen failures on 16 and 66 plate cars as well. No failures yet seen on 15 plate cars, including mine which had run well over 2 bar during development.
The IS20 found in the Golf GTI turbo does not suffer from this issue, it also has a much smaller/weaker shaft diameter but is properly balanced.
We are now recommending that anyone tuning their Golf R has the turbo checked over for balance. Pricing is not expensive - around £250 - but there is obviously the labour involved in removing the turbo, and the 3-4 days the car would have to be off the road. The compressor insert is checked and re profiled to correct clearances, and then the rotating assembly placed on a VSR balancer to check and be adjusted as required. Options to hybrid the turbo will also soon be available but these are not required for Stage1/2 tunes.
This is not any kind of ploy to extract money out of anyone, but born out of the frustration of trying to tune an incredible platform with a major weakness. Anyone is free to send their turbo to any specialist turbo company that can perform a proper balancing operation.
Thanks, Rick"