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YermanCars YermanCars is offline
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Join Date: Jul 2002
Location: IL
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Originally posted by Porschefile
Hobieboy, I'm by no means an expert on the topic however much of this stuff is common sense and not rocket science as some might have you believe. Here are a couple examples of oil restrictors:

Link 1
Link 2

The oil "restrictor" is usually placed somewhere between the oil supply, oil supply line, and the inlet oil port on the turbo. Hobieboy, I think you are talking about the oil pressure relief valve, but that's a completely different thing. Some turbos actually come with a built in restrictor in the port itself, such as this Garrett Gt28 . Basically, it's as simple as adding a restriction to the internal oil flow of the line by necking down the internal diameter with a simple fitting like the 2 listed above. The flared AN fitting listed above is almost identical to the restrictor I'm using on the Gt35r for my 944. The exact internal diameter of the restrictor itself can differ between cars, different brand/model turbos, different motors, etc as different motors can have different oil systems that have different flow rates, etc etc. According to Garrett, it's recommended to restrict oil flow to GT series turbos to not much more than 40psi. Most cars tend to run much more than that, so most cars are going to require a restrictor. Judging by the pressures I've seen with 911's, I don't see any reason why any 911 would NOT be running an oil restrictor with a GT series. I normally see ~2bar at idle and ~5 bar under heavy load or WOT so that's quite a bit more than 40psi (~2.75bar). Hopefully some more people with them on these cars will chime in with their personal experiences as things sometimes work out different in real life than they do on paper.

Running oil through the water passages at least provides some sort of cooling to the entire bearing section as opposed to just parts of it. Running the water ports dry isn't recommended by Garrett. While I'm not an engineer and by no means have lots of first hand experience with this stuff. I would suspect part of if not the main reason why this is so is that running the ports dry would result in hot spots in certain areas of the center section which could cause abnormal wear.

Kellcats521, I completely understand and agree with your point of view. Personally, I think the best thing would be if an individual that has no personal investment, bias, etc and does not work for one of the turbo manufacturers, retailers, etc was to do some tests between 2 turbos. That would give an unbiased opinion. The nice thing about Garrett is they give you all the info you could ever want. If you want to know the turbo specs and you want to see compressor/turbine flow charts, they are all provided on Garrett's website. At least you know exactly what you are getting because of this. As far as KKK turbos go, there really isn't much info or flow charts out there so it's hard to say. With the Triple K stuff, I've seen titanium/Inconnel wheels & shafts and other neat things, however nearly every other turbo manufacturer out there has the same type of things so that alone really doesn't mean much. As far as Garrett turbos go, they are the most widely used turbos period. Garrett's, including the GT series, have been proven in every motorsport known to man and on a wide variety of vehicles for years. Unfortunately too many people in our community can't get past the fact that some products may not have already been "proven" on Porsches and so they just dismiss them as inferior. Garrett's and the GT series are proven, period. I've seen lots of people in lots of communities claiming their custom stuff is better than the GT series, and I have yet to see a single person prove it. I mean, does anyone honestly believe that some hybrid concocted in someone's garage with some dremel work (okay, that may be an exaggeration ) can top what huge teams of tens if not hundreds of engineers have accomplished using state of the art technology, equipment, and CFD software? If anything, anyone else's custom turbos, Triple K hybrids, etc are the products that need to be proven.
My custom Gt37 made 489rwhp @ 16 psi, that is proof, I still have yet to see what others have made. Some of the k series guys have some dyno sheets.
Old 01-18-2007, 11:16 AM
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