turbo seized?

[H2Ogbodies]

Okay, before I find out what actually happened, I have a customer with a 4.6 Mustang running an 88mm Precision turbo which last week was running pretty hard when there was a mild (pop) heard and suddenly boost dropped to nothing and we have yet to tear into the turbo yet but, we have no boost at all. I am guessing the turbine shaft broke in two because that's the only thing I can come up with. Anybody have a similar situation happen? The turbo is engine oil fed and I am wondering whether the oil simply got too hot and broke down to the point of letting the turbo impeller shaft get superheated until it cracked then broke. What do ya'll think? I'll be looking at it tonight. I'm gonna start with looking down into the compressor housing with the engine running to see if the compressor turbine is even moving at all. This is a 1000+ hp car at the wheels and builds stupid crazy boost-I can't believe the turbo would have broke already...engine has maybe 40 good dyno pulls and about 800 street miles on it.

[camcojb]

it's possible, I haven't seen a shaft break though unless something got into the turbo. Usually if the bearing in the turbo goes the impeller hits the case, shavings in the engine, etc. I would think with a "pop" sound it blew a boot loose or split a hose. At least hoping so as that's much cheaper............

Jody

[H2Ogbodies]

Well, it appears after seeing the compressor impellars not moving at all with the engine running that most likely the blades most likely got sheared to a grinding halt. Even with the engine off, you can't even move them by hand. I guess I'll have to see what (if any) warranty by Precision will cover and if not, I have a local turbo speed shop that can rebuild the unit....hopefully. I wonder why it shelled...bad/scorched bearing leading to high speed failure? I wonder if a dedicated oil supply through a big cooler will help in the future? What are your thoughts Jody?

[camcojb]

sounds like a seized shaft which is usually an oiling issue. This is not a ball bearing water cooled turbo? What size oil line are you running and what pressure to the turbo? Is there an oil restrictor at the turbo, and was it supplied with the turbo from Precision?

Jody

[H2Ogbodies]

It not water cooled, it has a -4 AN line coming from an oil filter adapter block at the motor. Not sure on the pressure....may be a good idea (in the future) to put an underhood gauge near it. From what I can remember, the oil line was not part of the Precision turbo. The customer runs 5W-20 Motorcraft oil. I think that was a huge problem in the beginning myself. I tried to convince him to run 5W-30 Mobil 1. Seems indeed like an oiling issue.

[MonzaRacer]

If running that big turbo I would use the Ford 5w40 full synthetic and as for an oil filter adapter feed, uh no, if you use wrong filter, less oil. And absolutely stay away from any Fram products.
Restrictive and cheap and worthless. The -4 an line should feed right off an oil gallery to the turbo in my opinion. Also upgrading oil feed volume and capacity is really needed.

[H2Ogbodies]

The oil feed comes directly from a pressurized plate on the LH side of the 4.6 motor. The car is not one I built but will most likely have to clean things up. Kansas City House of Boost in MO built the engine. It has little issues like the exhaust cut-outs not working properly, wrong stall converter (has a 3000 but requires about a 5500) the car is pedestrian for the most part until you hit about 70 mph then all hell brakes loose. I wonder too how well the exhaust is routed to the turbo...seems to me like a lot of velocity loss due to the routing...might be a contributing factor in the huge turbo lag in addition to the stall converter.