Turbo Q for the knowledgeble

[boostadikt]

I remember reading somewhere that Turbos with a carbon seal were mainly used for carbureted engines where the carburetor is placed before the turbo, Whereas Dynamic seal turbo's are used for modern gasoline/fuel injected setups.

reason asking is because my turbo has started blowing oil from the center section into the compressor and exhaust, not much at all but enough that I can smell it and see a little smoke after shutdown.

The turbo has only about 4,000 miles on it since being rebuilt because of this exact problem, it started smoking slightly and then eventually gave out and just fed oil strait into the exhaust.... however i figured the main reason this happened was because it blew right after my build and i see 100+ LBS oil pressure under WOT, this WAS with no feed restrictor but now i have a .060" fitting.

So now it has started again and has me worried, the main question here is whether the seal difference is a factor, a Diesel tech said it was because EGT's are too high, but i don't believe him because he works on Diesel's (cold).

so if anyone can clarify/explain the seal differences and give input on why this would happen twice on the new motor but never on the old motor that would help. The turbo is a Roto-Master T04B, now with a Borg-Warner shaft/wheel since rebuild.

Thanks~ Steve

Cliff notes: difference between carbon and dynamic seals and applications? Other reasons for a Smoking turbo?

 

[boostadikt]

awesome... no one Knows?

 

[WhtMa71]

Right over my head. What size oil feed line are you running? .06 oil restrictor sounds about right for that..If it was a BB turbo you would want to run a .03 restrictor. Reason i ask about the oil feed is with turbo hondas you have to run an oil restrictor because most of them run 80psi and over so a restrictor is a necessity..Tho everyone has a -3an oil feed line with a .06 restrictor. All the guys that are running a -4an feed line are having problems even with the .06 restrictor because i guess it is just too much volume for the restrictor to even handle.

 

[boostadikt]

I have a -4AN feed with the .06" restrictor so that is interesting.... its a damn small hole tho, so its hard to imagine that it is still getting too much.

 

[MDCmotorsports]

You are correct with your carbon VS dynamic seal statement.

Now, having over 100psi of oil pressure to the turbo means instant death to the poor thing.

Typically, a turbo doesn't need to see any thing over 45psi @ WOT.

Theres a couple of ways around this.

Either install some sort of regulator at the turbo feed inlet, or install a restrictor.

What happens when you have too much oil psi? The seals leak, and the leaking oil out the turbine causes hard carbon to form on the turbine wheel and in the turbine seal area.

This causes an out of balance condition and seal failure.

Also, who did the rebuild/balance on the turbo? What was it balanced to? How is your PCV system hooked up?

Hope this helps.

 

[IJ.]

The very early GT BB units didn't have a restrictor so died early.....

Later ones use a pair of 1mm restrictions, .6 overall is a LOT of restriction in flow for a non BB turbo?

 

[boostadikt]

I had a local shop rebuild it... they do a lot with diesel turbo's... Industrial/CAT, etc. I don't know what it was balanced too, but it was done pretty solid. PCV is hooked up to a catch can then runs before the turbo... I don't have one on the TB.

MDC: So would the carbon seal have a higher chance of premature failure than a dynamic of the same application on a fuel injected vehicle? What is your opinion on the .060 restrictor... do you think that with that much pressure it could still be too much, I could go to a smaller feed line.

It seems that you think i am still getting too much oil, and IJ thinks that .06 is too much Restriction for the application... this is why I am confused, because i thought that it was too small as well.... but the fact is i am still pushing oil past.

Thanks for the help

 

[supraguy@aol]

You're seeing 100+psi in what car?

 

[IJ.]

Boost: Where are you draining the Turbo to?

 

[boostadikt]

Uh... my car, shimmed the oil pump, removed oil squirter's, I had very High goals for this motor. I had an pressure guage hooked up on startup...but i do not have one at the moment... I am not positive that its 100psi, but its pretty close.

 

[boostadikt]

IJ: Factory location, gradual bend and Gaskets Used... not silicone

 

[IJ.]

Hmmmm sounds like the Turbo is flooding so I'd suspect a drain issue, that might be as simple as blowby isn't letting the Oil drain fast enough.

 

[boostadikt]

Blow by as in past the piston rings? or excessive Crankcase Pressure?

pressure i can see, but i don't have any blowby, the motor is completely solid. The Drain is free and clear.

 

[IJ.]

What causes the "excessive crankcase pressure" ??

 

[MDCmotorsports]

Sounds to me like you have an unbalanced turbine situation there or the turbo has damage internally already.

Lets start from the top.

-Whats your PCV system like?
-Whats your leak down test on the cylinders like?
-What air filter are you running?
-Does the turbo have shaft play?
-Does the turbo appear to have rubbed the housings?
-Ask/call the local shop to ask them what they balanced the turbine assembly to.
-How much oil pressure are you running at idle? 3000rpm? 6000rpm?
-What weight oil are you running?
-The 0.06" restrictor may be too large still if you are indeed over 100psi oil.

As for your question about a carbon seal VS dynamic.

Carbon seals don't typically wear out faster than dynamic seals, although it is possible. You actually have a rotating part rubbing against a piece of compressed black carbon. In a dynamic seal format, if the turbine would remain balanced forever, the turbo seal could possibly run forever. (Proven by diesel trucks running 500,000+ miles on one turbo rebuild.)

IF you want, send that turbo to me. I'll inspect it for free.

 

[WhtMa71]

^Sounds like an awesome deal to me if you can afford the down time.
What size return are you using?

 

[boostadikt]

Thanks for the Help guys.... it turns out im mostly an idiot, The drain tube is getting brittle and starting to crack moslty at the top so it looks like the smoke is coming from the turbo because the center section is getting wet..... so anyways time for an SS return line.

 

[gilberjj]

where are you getting your ss return line. im running a mostly metal hard pipe return line, but the two metal tubes are connected by a brittle rubber type piece. i don't know how much longer it will last. i will sleep better at night having a ss return line.

 

[boostadikt]

My plan will probably be to go to evco house of hose and make it myself.. get the 7/8" ss line with 2 -10 an fittings, the turbo side just screws in, and then i will weld a male fitting onto a cut stock return line and bolt that to the block.