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Old 12-22-2008, 11:41 PM
roche314 roche314 is offline
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Question Turbo going bad?

The other day I was driving up a hill, about 3/4 throttle. The car was making about 5psi constant boost. Then I looked in my rear view to see a cloud of smoke. I slowed down and a few seconds later the smoke cleared. I then stepped on it a again, and once it started making boost it started smoking again.

At first I thought I pushed out a head gasket, but I felt no loss of power, and the oil looks fine, and there is no water missing from the radiator. So I am leaning towards a bad turbo, as the motor only has about 1k on it since a rebuild, and the turbo is stock.

Questions:
1. How can I tell if a turbo is going bad?

2. If my turbo is going bad, how bad is it too continue to drive the car?

3. Can anyone recommend a replacement turbo. I would like a turbo has the same mounting as the stock turbo. The car isn't quite a daily driver, but I like to drive it alot. I would like something that is streetable and runs on 91. But I can also turn up the boost, bump up the octane and have some fun at the track.

Here is a list of the mods on my car:

cam: 206/206 .447/.447
CNC ported stock heads from ESP
Headers from Poston
60lb injectors
racing girdle, billet main caps, je pistons, stock rods & crank.
chip from Turbo tweak (of course I'll have to get a new one when i replace the turbo)
stock intercooler
2800 torque converter
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Old 12-23-2008, 01:03 AM
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Lightbulb Re: Turbo going bad?

You're going in a few different directions here...

Some important questions...
- What color was the smoke? (i.e. blue = oil, white = oil)
- Is the smoke coming out the tailpipe?

Its important to check your oil and coolant. A head gasket failure can blow (a) outside from the exhaust (b) outside from the intake side (c) across intake/exhaust/coolant in a myriad of undersireable ways. Option (c) can really ruin your day. (i.e. coolant in oil, oil in coolant, coolant in combustion chamber, etc...)

Provided none of those are true (which could be checked with a compression test) it could be a turbo issue. "Turbo going bad" makes about as much sense as a doctor diagnosing you by saying "you're sick".

If the turbo is the cause, most likely fault is either an oil seal or bearing failure. Neither is good, but the latter can be much worse, as it means the pieces of it may be already in your oil.

To answer your questions:

1) Remove the inlet tubing, and inlet bell if applicable. If you see a lot of oil, that is not a good sign. Take the compressor wheel and try to move it up/down/fore/aft/in/out with your fingers. Movement should be very minimal. Should it be more than perhaps a few thousandths of an inch. Should the wheel actually contact the compressor housing when moved up/down/fore/aft, the bearings are likely toast.

Examining the exhaust side is a little more difficult, but usually you can tell what is going on from the compressor side OK.

2) If the bearings are bad, pieces of them will circulate in the oil...of your new engine. If you have wheel / housing contact, the wheel will be getting damaged and pieces of it sent into your IC, and then into your intake.

3) You have a good buildup, and could probably make use of a pretty nice sized turbo. However, one concern stands out that might be a limiting factor. That is your converter. A 2800 stall doesn't have a lot of room for a much larger turbo. You could go to a TA49/TE44 with no issues and it would match nicely with that converter. But that engine build just screams for so much more.

You could go larger by using a ball bearing turbo and not feel like you were tied to a tree at the starting line or stop lights. However, I still think your options would be somewhat limited to the smaller end of the scale. With more stall, the options would be much greater; ball bearing or not.

My suggestion is to decide on some target for ET/HP. And also for cost. Keep in mind that ball bearing variant turbos get more expensive very quickly. Also decide how you would use it in a race environment. i.e. Pump gas, alcohol injection, or race gas. Don't forget: larger turbos are not as responsive at lower boost.

Work out your needs, your wants, and your desires, and we can try to help you weed through the data.
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Old 12-24-2008, 12:36 AM
roche314 roche314 is offline
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Default Re: Turbo going bad?

Thanks Scott.

To answer your questions, the smoke looked white, but it was pretty bright out and i was looking out the rear-view. As far as I can tell it was coming out the tailpipe. (the motor is pretty clean everywhere, and there is a bunch of oil around the rear bumper behind the tailpipe.)

I did a compression test and everything was between 125-135, the oil & H2O look fine. So I think the head gaskets are intact.

I pulled the inlet off the turbo and there was a small amount of oil. There is a lot of play in the compressor wheel. I would say about 45 thousandths, it looks like it might have been barely scrapping the wall of the turbo. So I think we can conclude that the bearings are shot and the car is sitting until I replace the turbo.

With that said, I have been trying to research turbos, and come up with a desired et/hp.

Here is a list of my goals/requirements for the car:
1. Runs on pump gas.
2. If possible I would like the turbo to be stock appearing. (the car has to go through California smog)
3. I think somewhere around 400hp/mid 11s would be reasonable.

Here is what my race plans would be
1. Pump gas w/octane booster or race gas.
2. Turn up boost
3. Possible slicks

With that said, I have been looking around and it looks like a CPT-66 would fit the bill, but I would need to replace my torque converter with something in the 3200-3400 range. Am I on the right track?

thanks again
-steve
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Old 12-24-2008, 02:42 AM
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Lightbulb Re: Turbo going bad?

I think you are pretty much on track. A few comments:

- The CPT-66 Turbonetics turbo is not stock appearing to my knowledge, in any of its various forms.
- I would NOT recommend octane booster for your race tune. It really doesn't "boost" quite as much as you would think, plus it leaves a lot of nasty deposits behind. Stick to pump gas on the street, and either true race gas or pump + alcohol injection at the track.

To truly be "stock appearing" for emissions, a TA-series turbo might be the best option. Other than the larger wheels, they are externally identical. They still use the bolt on inlet bells and everything. Whether this is necessary to please the California emissions Gods...perhaps those in Cali will respond.

Especially with your motor build, accomplishing your goals with something like a TA61 (perhaps even a TA60, TA53, or TA54) should be no problem at all. I just put a used TA61 on my car, and it was previously on David Day's (then) very stock GN with a completely unopened motor plus an "old school" Mark Jackson "intercooler and a half" (one and a half stock ICs welded vertically together) plus slicks. On that car, in good air, it went 11.20 with 42.5# injectors.
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Old 12-24-2008, 12:56 PM
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Default Re: Turbo going bad?

scott,

thanks for the info.

i just talked to jack cotton, and he recommended going with a cpt-60. Anything larger would require a different torque converter and an intercooler upgrade. Even though it isn't completely stock appearing, the stock heat shield still fit over it, and I think it will make it through emissions.
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Old 12-24-2008, 01:34 PM
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Default Re: Turbo going bad?

Quote:
Originally Posted by roche314 View Post
scott,

thanks for the info.

i just talked to jack cotton, and he recommended going with a cpt-60. Anything larger would require a different torque converter and an intercooler upgrade. Even though it isn't completely stock appearing, the stock heat shield still fit over it, and I think it will make it through emissions.

What I had to do to mine when I was in CA, was to get a piece of hard rubber tubing (like you can get at BIG truck stores) with a bit of a bend in it, then I went to an auto parts store and bought hard plastic tube/grommet thing that usually plugs into valve covers for a breather tube that would normally run to an aircleaner. I drilled a hole in the hard rubber tube (it will fit over the bell mouth of the turbo) and glued the plastic tube to it. I then had to get a very short piece of 3" metal tube to slide into the hard rubber piece so my stock maf tube would have something to slide over and clamp to.

This is what my stock valve cover breather tube then fit onto, making it a near perfect replica of the stock breather setup. I still made it though visual even with a fmic because I had all the stock breather/aircleaner setup to put on just for smog inspection.
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Old 12-24-2008, 02:15 PM
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Lightbulb Re: Turbo going bad?

I see no issue going a bit more conservative in size. I question whether a TO4E style compressor housing will make it through California emissions on visual inspection, but that may not be a problem. Just something I'd think would be good to confirm with those in your area. Perhaps even Turbonetics, who are in California.

http://www.turboneticsinc.com/

The intercooler can always be upgraded later if desired or needed.
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Old 12-24-2008, 03:01 PM
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Default Re: Turbo going bad?

I had no problem (PTE44), but that probably isn't definitive either.
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Old 12-24-2008, 04:07 PM
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Thumbs up Re: Turbo going bad?

No, but that is a good sign. Of course you went the extra steps to fab the faux vent system that made things look quasi-legit, which helps.
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