Thank you for asking. Sometimes I dictate and what I'm thinking doesn't get on paper. The turbochargers are oil and water cooled/lubricated. When the car shuts off that flow stops. So even though the fans are running you have red hot turbochargers with oil sitting in them. It breaks the oil down and cooks it. So by letting the car idle you were continuing the circulation of liquids and bringing things back down to temperature before you shut it off.

Also sorry for this mess communication. We have done a turbo upgrades. Some of the cars were stock and went to a stage for while some of the cars were going from a stage two or even three. Various tuners. When the turbochargers were on the table to be modified and rebuilt… We noticed different levels of wear and tear. And you can tell generally what it is caused by. So what we found across the spectrum after consulting the clients was that how the car was driven and allowed to cool was a direct relation. Nothing else really. Only one was unsalvageable so far. Hopefully I clarified everything. Frequent oil changes and proper cooldown of at least three minutes after hard runs

 

Yeah but they blow down and the headers and cats are way beneath where they reach so both the headers and the cats radiate heat to the turbos.

 

Sam, when you say modified/rebuilt, are the turbo upgrades based on existing turbos - we need to send in our stock turbos to be modified/rebuilt. Or are they rebuilt because they were damaged due to wear and tear?

 

Makes sense. Thanks WRS.

 

Good question. We have brand-new available as well as court exchange. Or doing your own which most people like. But anytime it's opened up it goes to a full rebuild process and balancing after the upgrade. So it's essentially like new. We have had an instance where the VTG's were not able to be conditioned like new due to excessive shaft scoring end damage. This was from excessive heating and in proper maintenance.

Also, excessive shaft speed or too much load on the assembly can be a result of boost leaks or improper tuning.

I added an image of a scored shaft and turbine wheel that has oil deposits on it.

 

Got it. thanks for your explanation.

 

That is an excellent in a useful explanation. Would upgraded intercoolers reduce the amount of going to the turbos and extend her life more? Majority of people I know have these tunes regardless of the tune have the stock intercoolers. If you had one of these cars as your own and you wanted to run it hard with the tune would you upgrade the intercoolers all else being equal?

I upgraded mine because I wanted to stop heat soak power loss and because I didn't want excessive IATs. To me it is the best modification I have done. Has made the car completely different.

 

Yes it helps everything altogether. There is also less restriction/higher flow with a larger intercooler. Without too much pressure drop it's just better all around. IAT's are 40 to 50° below stock with a good intercooler. That's always good

 

I agree. I hope you AWE and champion sell lots of intercoolers. I think it's a lot better for the car if you're running a powerful tune to really cool down those intake air temperatures. Makes everything so much better.

 

Wondering if anyone has blown a turbo yet, be it stock or modified.

 

I am aware of two turbo failures on 991 Turbos

1. The one that had nitrous, C16 and water meth. This one does not trouble me in the least because the owner wanted a record and knew his car was being pushed very hard in search of that record. Most of us will never put nitrous or C16 (leads race gas) in their car (which is only designed for unleaded fuel).

2. The one that San says was not salvageable on which he did a VTG turbo upgrade. Don't know more about the car than that -- in terms of mileage, tune or tunes used, driving style of owner, etc.

It does sound like some of the other turbos had signs of wear and tear from what Sam wrote. He advises a 3 minute cool down after a hard run. Personally I think if someone is going to get a big tune on the car they would be well advised to get intercoolers to lower IATs -- now owners have at least three choices for those: Champion, ByDesign and AWE.

And I am not sure if ceramic coated headers are a good idea for the turbos in terms of heat. They concern me.

Going catless should be good for the car as well. No cats to fry and no heat source.

 

The stock headers are double walled to retain heat. Ceramic coating is just a lighter weight version of that. There shouldn't be any problems at all with ceramic coating.

- Patrick

 

Good info. Thanks Patrick.

 

I've coated and wrapped headers in many many cars, and never had a problem.

But be careful depending on it. Ceramic coatings are sacrificial,, and gradually decay with exposure to the elements. Fiberglass wraps are also available, but they fall apart with repeated heat cycles and exposure to moisture.

I have little doubt that the double-wall feature on stock headers is a very big advantage. Together with the fact that stock headers aren't equal length (and therefor required Porsche to do a lot of work to optimize), I would seriously avoid replacing them unless its with equal length headers of a specific primary length that is known-good AND one has a long-term thermal management strategy.

Very few vehicles have much to gain with aftermarket headers after 2005 or so.

 

I've done loads and loads of terrible things to turbos with regards to pushing their functionality, especially beyond their efficiency zone. I've never seriously harmed a turbo even by asking it to breath fire (out the cold side) or lead through the hot side. Pistons, certainly, but not turbos. But Sam is right... you can easily cook them and either destroy seals or bearings by driving them hard without after-care.

I bet the C16 car was run hard and put away wet if it lost a turbo (or two).