Garrett Oil Only CHRA

[Gyrhead]

Any drawbacks to a CHRA that is only oil lubricated and not liquid coolant cooled on an occasionally driven, albeit spirited, SVO? I understand the coking concern, however if the car is allowed to idle prior to shutdown, will heat soak be an issue? Also with today's modern lubricants, is this as big an issue as before on street cars? Could I, or should I add a supplemental oil cooler or pre-luber. Perhaps a turbo timer? Am I just being paranoid? Would like a few folks to weigh in on this! Thanks!

[Patrick]

Just because you're paranoid doesn't mean that they're not after you!

I have some originals on 84 and 85 SVO's that are holding up just fine. Just follow the cool down procedures before shutting the engine down.

[MikeFleming]

Are you asking about a non-coolant CHRA - the ones with the air cooling fins? Or are you asking about using a water-cooled CHRA without coolant?

Former is fine, later is not a good idea. it *may* live, but so might the engine without much coolant. For awhile.

The coolant-type CHRA is not intended (by Garrett) to be air-cooled. None of the turbo rebuilders will warranty a water-cooled CHRA is used without coolant.

Is that what you're asking about? You missing the coolant tubes?

[Gyrhead]

Mike, the former...a non coolant CHRA. The reason I ask is that my new T3/T4 is set up this way and I was wondering about longevity. I have the coolant tubes...the nice stainless once from Forced 4 Sadly, I'm gonna have to omit a few

[MikeFleming]

The air/oil cooled CHRAs work just fine - and they don't need coolant. Ambient air works just fine (and trust me - you have that already).

I have no faith in pre/post oiling devices. Just don;t see a need for them. As far as oil coing, use a synthetic oil - the CHRA will never get hot enough to bake that stuff.

As an aside one of the TO3 proving tests Ford had Garrett do on the turbos (air/oil cooled at that time) was to run the engines at an EGT of 1900 F for 30 minutes then shut the engine down and measure soak-back temps to the CHRA (bearing housings). That was the test that got the cooling fins added. They did not use synthetic oil for those test cases.

Iirc the max temp the CHRAs got to - with the 1900 F EGT input - was less than 475 F on the soak-back period. I have that doc somewhere but I'm too lazy to look for it.