Smoke at idle fixes, my thoughts and notes

[08.5MS3]

Hopefully Brad can chime in on this. With the restrictor bolt in place, how much less oil is the turbo seeing? And are there any detrimental effects because it may be seeing less oil?

[bnoon]

Originally Posted by 08.5MS3 Hopefully Brad can chime in on this. With the restrictor bolt in place, how much less oil is the turbo seeing? And are there any detrimental effects because it may be seeing less oil?

That's the balancing act right there. If you restrict too much, you're keeping oil from the turbo. But... if the oil is pushing past the seal into the exhaust or intake, what good is that oil doing for lubrication? None.

Another point is that we're not starving the oil in the turbo housing. The volume remains the same because even with a restrictor in place, the oil feed side can easily supply MUCH more oil than will actually flow through the turbo center section itself. The same volume of oil is just under less pressure due to the restrictor. Now, important note here, that oil does sit in the center section longer before it cycles through the center section due to the pressure drop and this was one of my main concerns in researching my restrictor options. If the pressure were too low, the oil would stay in the center section too long and "cook". All you have to do to see if this is happening is send in your oil for an UOA, or Used Oil Analysis. I've sent in several and never once had any thermal breakdown on any of the many many oils I've tried.

If you believe that the oil has any issues with cooking, let it idle a full minute or more after hard runs before shutting the car off. This will do more for your oil than the difference in oil supply will.

I've run maybe 15+ thousand miles with the bolt in and 31,000+ miles total and never have an issue boosting to 19-20 psi. That extra psi cooks the oil more than my bolt will and I still have good UOA's.

[kkostec]

After spending hours fighting with my stock downpipe and race pipe to pop in my Turbo XS stealthback exhaust (which is hardly stealthy but amazing nonetheless), I initiated the dreaded cloud of smoke. I just ordered a Cobb Turbo inlet pipe and restrictor bolt. Hopefully these two will resolve my issue.

[G Sp33dy]

how did this work out for you ^^^?