Dyno Delayed
 

While changing out the waste gate springs so we can run a range of 0.5-1.25Bar of boost Wayne found the turbo had seized. It's off to be rebuilt now and it's too early to predict the culprit, but to be safe when it goes back on we're plumbing oil through the coolant jacket this time...

I am by no means a turbo expert, but have read many times on this board (posted by people that seem to be turbo experts) that running oil through the water jacket is a bad idea as it overheats the oil tremendously . . .

Many threads and posts on this subject in the Turbo forum (like this one):

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/511890-cooling-gt-35r.html

Interesting, I wonder what the end result will be on the oil temps? Right now they are running nice and low, so there would be some room there to buffer hot oil. Will let you know what temp change I see if any & thanksSmileWavy

Ha - small world as there are posts of yours in the thread I linked to! :D

What is TPG in Pompano Beach? I live in West Palm Beach and never heard of it. I tried google.com and dogpile.com search engines and nothing automotive came up.
Do they have experience with a car like yours?

I too have heard it's better to run no motor oil through the water cooling jacket of a ball bearing Garret turbo on a 930. It overcooks the oil.
Hopefully you preoiled the turbo and the oil feed line and scavange system are working right.

I guess that explains why I never heard any turbo noises coming out of that beast . . .

PS - May want to concider building a passive water cooling system for it. Between convective circulation on the low end of the temp scale and steam bubbles providing additional pumping on the high end of the heat scale, a couple hoses and a heater core up under the intercooler somewhere may be all you need to give it the extra cooling that it needs to keep it from getting heat soaked.

DTA Fast - Engine Management - The Power Group

Yes, Wayne Seixas at TPG knows a thing or two about tuning 930sSmileWavy

I did pre-oil everything and it made good oil pressure too. I even pulled the oil line off the drip tank to make sure and it was oiling fine. I'm guessing something plugged/interfered with the small orifice on the oil inlet line...

I'll keep an eye on the oil for overcooking & thanks!
RC

A small aux H2O pump is an option that I've considered and will go that route if necessary...RC

IMHO pumping oil through the water jacket will only cause more problems. Oil has a higher specific heat than water. That means it will not absorb heat as quickly as water passing through the turbo. Furthermore the water jacket is designed for a much less viscous fluid than motor oil, so now you raise pressure which further effects whatever cooling properties you had hoped to gain.

In conclusion, you may create more problems, additional complexity and another point of failure in your oil system.

If your turbo blew its bearings I would check if you had sufficient oil pressure at the turbo and adequate drainage. Since its a Garrett BB turbo it has an internal restrictor. But you still need a certain range of operating pressures.

I am curious if you would have better luck running a journal bearing turbo, I would assume they would be effected less by temperature. They also run without restrictors, so it takes whatever you got for max flow.

Someone mentioned a passive cooling system. Its not a bad idea but you need to calculate the required cooling capacity. I would also mount it somewhere up front in the air dam or as low on the engine as possible to get it in the air.

My .02 cents.

Thanks Sam, we think the failure was due to a blocked oil feed line, so that restrictor will be opened up a bit in an effort to get a little more oil on the BBs and make it harder to get blocked again. We shall see if oil splashed through the cooling jacket works soon enough. If not then I'll try water. In an order to keep the warranty intact Garrett requires something besides air going through the cooling jacket, but I don't think water will be necessarySmileWavy

Not to come off like a dick. But if you modify the restrictor wont you void the warranty?

Have you considered running a CO2 sprayer on the intercooler? I can't imagine it not heat soaking sitting on top of the motor. Note: I do not have a Porsche(yet) but from experience TMIC's are OK in stock applications but not so much beyond that. I am not sure how they perform in these configurations. I havent seen any logs posted.

Does your ECU compensate for heat soak of the AIT sensor upon hot start? In my sphere we tend to put the AIT as far away from the engine as possible and those who don't require the ECU to compensate until the intake temp drops to ambient.

No worries Sam, we all gotta all learn somehow:p

The restrictor is actually a fitting I put on the end of the oil feed line at the turbo, not actually part of the turbo and no I don't think you can void the warranty changing out fittings, but what I meant to say is; if you don't run a coolant of some type then Garrett will not honor the warranty if you smoke your brgs...ask me how I know:rolleyes:

This ECU works magic that I can only imagine and yes it does have an air temp sensor on the air inlet pipe just before the throttle body...

You are right. Don't know why I assumed the restrictor was built into the oil inlet. Quick re-read of Garrett's site confirms this.

I couldn't find the info in the thread even though I went through it completely, but what ECU did you wind up running?

Sam, unlike some cars with TMICs like a subie, as long as the engine is running there is a massive fresh air flow through the intercooler thanks to it being located in the intake path for the air cooled motor fan. I forget the CFM number, but its a pretty significant volume. In the case of something like a subie, any time you arn't moving a lot of hot air is making its way up through the intercooler, heat soaking it to death.

Any turbo car is going to heat soak a lot of its plumbing when its shut down, but fortunately the nature of an air cooled porshe gives it the ability to start rapidly cooling everything once the engine is started even if the car isn't moving.

ECU Specs
 

I'm running the DTAFast S80 Pro ECU and it will do anything & everything you'd possibly want from full on race to mild mannered street machine...here's the specs: DTAfast S 80 PRO ECU

How does the community feel about Megasquirt, anybody using it or do you have other go to systems that are proven on these cars?

I ask because all my experiences with tuning EMS is with the Megasquirt.

Find a local tuner/builder/racing shop worth their salt and go with whatever they specialize in and sell. Why recreate the wheel?

I'm a DIY guy like yourself and when I was starting out the MS was recommended by the community for my car and I built it and tuned it from scratch so naturally I would go with what I am familiar with. I was just trying to see if you guys have a preference towards one particular unit due to a specific reason and you basically answered my question.