ok so we have an fc with an rew motor in it, BIG street port 3mm seals, engine is kinda tired. big front mount, e11 haltech, 1600cc secondaries. new o trim exhaust wheel in s5 exhaust housing, i think it was h trim compressor, but i'm not sure. it ran fine on the street, boost was stable at about 10psi.



we took it to the track, and it lasted 5 laps. half way thru lap 5 it stopped making boost (ie put foot on gas, guage goes to zero), when you give it gas it goes to zero and makes a funny noise(high pitched) so we pull into the pits and engine is blown too.



so drive 238miles home, turbo starts smoking badly. we pull turbo off, and the edges of the exhaust wheel are melted looking, and the shaft is broken off right at the bearing housing. compressor side is cherry.



i'm kinda thinking it was too hot in there (the last turbo did almost the same thing except the turbine exited the building). but why did the motor blow? just cause? or is this related.



mike

sounds to me as if your exhaust backpressure was too high-



It had to be damn near stratospheric to melt the turbine wheel.

Aren't they usually made of inconel?

too lean with too retarded timing maps?

if anything its too much timing, 20degrees@10psi and afr in the 11's?

exhaust temps?

Did you have to machine the exhaust housing for the O trim wheel? If the wheel was hitting the housing it could have caused the problem. Once the wheel sheared and stopped moving it created alot of back pressure and heat that could have blown the motor. Are you using atkins apex's (can't take excessive heat)? Do you have any exhaust temp readings?



The high pitched squeal/screech is usually the exhaust wheel rubbing on the exhaust housing.

that sucks



atleast some good ideas so far

yeah you do have to machine the housing a little, it looks cherry. no egt guage, and its got mazda 3mm seals in it

That sucks! You got any pics?

How do the bearings look in the turbo? If you oil starve the turbo it will come apart very quickly. Seen this very recently on 2 seperate occasions. The turbo seems to work fine, right up to the point where it dies. This usually takes out the rear bearing first causing the exhaust side to destroy itself on the hard ass housing(doesn't even scratch the housing), then the rear piston ring starts blowing oil.

Pics!

Wow, that does seem to be a bit much timing. Do you know if it was ever 0'd in right?



Oh yeah, PICS! https://www.nopistons.com/forums/pub...IR#>/smile.png I'd like to see this turbo

ok i'll take pics tomorrow

Is it tomorrow yet?

Where you are at buttonwillow, mike?



C

yah, this is the beat yellow fc with the cf hood and the REALLY LOUD na its car and the stock looking gsl-se

Hmm i don't remember seeing it. What class where you in?



C

Similar thing happened to the guy who bought my T11 , when the turbos shaft broke , engine oil started flowing through the exhaust (hence the smoke) , the engine died due to oil starvation (lack of cooling and lubrication) , everything was bent and expanded out of shape and the bearings were wiped.

One thing to note , although "TURBO POWER" may be termed as free power , it still cost something !!!! , it cost a FEW ponies , sometimes up to 60 or more of them ,depending on boost pressure ratios , backpressure etc. . This power is transmitted along the shaft from turbine to the compressor , if its too much the shaft WILL break , HENCE THE REASON FOR "THE BIG SHAFT " option !! , ever wonder why the larger units utalize a larger shaft ??.

would a big shaft be heavier thus increaing lag significantly?