carbon seals and clocking turbos

[85typet]

ok so whats the deal with carbon seal and turbos? what do those seals do and what will happen if i try to clock a turbo without carbon seals? also what turbos come with carbon seals?

 

[charlief1]

The seal has noting to do with whether or not you can clock it. It has to do with the type of car you have. A HA car needs a carbon seal so that it the turbo will keep oil in it. Because of where the throttle body is if the turbo doesn't have a carbon seal in it you will be sucking oil into the engine under deceleration.

 

[bison]

A carbon seal is a positive seal. When it's installed air/liquid can't flow past it in either direction. It's used most commonly on applications where the compressor side of the turbo is subjected to vacuum. The downside is it has a little more drag than a dynamic type seal setup that uses a piston ring and and slinger for oil control. It is common to see oil in the compressor outlet with a dynamic seal if you prime the system with oil and the turbine isn't revolving. The slinging action is not there and the oil leaks past the piston ring into the housing. Contrary to what people often say and post you can't blow the seals in a turbo. They can become damaged but they won't fail under normal conditions and really should last as long as any other part of the turbo. The ex side uses a piston ring also which is not positive and leaks exhaust into the crankcase. A dynamic seal leaks small amount of compressed air into the crankcase also when there is a higher pressure in the compressor housing than the crankcase. A crankcase blow by problem often causes some to think the seals are bad but in fact the pressure differential in the crankcase vs the ex and compressor housing causes oil leaks into them. Poor oil drainback often causes oil leakage past sealing rings and is not because the turbos seals are bad.