New to turbos, not new to engines. Have a couple questions..

[Chippyonetwo]

I'm the proud new owner of an 87 GN. The engine runs EXTREMELY strong.

I have two problems though. One, under heavy boost, AND ONLY WHILE UNDER BOOST, I have blue smoke. if its at idle, or under normal acceleration, before the turbo spools, there is no sign of smoke.

Another thing, the turbo appears to cut out around 14lbs.

I am clueless on turbos, but have worked on a bunch of NA engines..

Can anyone lead me in the proper direction? And thanks for the help

 

[87geeinn]

You may have leaking turbo seals which will eventually cause the turbo to peter out on you. Take off the air inlet tube/hose and see if you have oil coating the compressor wheel. It should be bone dry. Also CAREFULLY see if you have up and down movement of the wheel. If so, does the fins appear to be striking the edge? A little bit of in and out play is normal.

It's also a possibility that the drain tube is partially blocked causing oil to back up into the turbo, but unlikely.

The stock boost level on a 86 and 87 GN was about 14.7psi.

 

[Chippyonetwo]

You may have leaking turbo seals which will eventually cause the turbo to peter out on you. Take off the air inlet tube/hose and see if you have oil coating the compressor wheel. It should be bone dry. Also CAREFULLY see if you have up and down movement of the wheel. If so, does the fins appear to be striking the edge? A little bit of in and out play is normal.

It's also a possibility that the drain tube is partially blocked causing oil to back up into the turbo, but unlikely.

The stock boost level on a 86 and 87 GN was about 14.7psi.

Thank you for the information. Before I rip this stuff apart, is there any gaskets and/or seals I should replace while I'm in there? Or is it a sealed setup?

Also, a stupid question I'm sure, but what lubricates the turbo setup itself? what holds the lubrication/oil?

I just wanted to gain some knowledge before diving in!

 

[87geeinn]

Whoa! Whoa! You don't have to take anything apart to visually inspect the compressor wheel. Take the inlet tube off and that fan thingy is the compressor wheel. The other side, the one that the headers run into is the "hot side" or turbine wheel. In between these two is the seal/bearing assembly. This part is internal and the turbo must be removed a disassembled for a rebuild. I've never attempted a rebuild or had the need too (yet) and from what I know, it's not the easiest thing to do. However, there are turbo rebuilt kits available for the DIY'er.

The following is all assuming a stock turbo setup: The turbo is lubed with the motor oil. Take off the heat shield and there will be a hard line running from near the top and middle portion of the turbo. This is the feed line and can be traced down toward the oil pump. After traveling through the tubo, the oil drains into the turbo oil drain pipe which attaches underneath the turbo with two 1/2 inch bolts. It is a ribbed, flexible hose (much larger than the feed line) that runs down into the block.

However, we need some more info on your setup. Do you know if it is a stock turbo? If so, how many miles are on it or the car? Don't go tearing the turbo off quite yet until you checked the shaft play as detailed in my previous post.

Oh yeah, and welcome to the dark side. Yes, that is a cheesy line, but you'll understand it better once you become hooked. :biggrin:

 

[Chippyonetwo]

However, we need some more info on your setup. Do you know if it is a stock turbo? If so, how many miles are on it or the car? Don't go tearing the turbo off quite yet until you checked the shaft play as detailed in my previous post.

The engine has aprox 14,000 miles. It has had some work done to it, unfortunetly I do not know the history of it. This was purchased from a widow, who knew nothing about it.

Dyno runs tell me it is yielding 370 RWHP.. Not sure if that helps or not..

3 dyno runs, 367, 371 and 376. and this is with the turbo cutting out at 14lbs.

 

[machinegun]

Not to be a pain, but when looking at the Turbo, a slight up down action is ok and I do mean slight. The in/out play should be non existtant. This is the thrust play abd is very important fir sealing the oil side of the turbo along with not allowing it to strike the housing. It sounds like the Turbo. I personally would have the turbo rebuilt by John Craig of Limit Engineering. Although you can rebuild it yourself as they are not that bad to do, the good rebuilders know what to look for where to find it and they have parts in stock. I have rebuilt one and it did not last that long. At the speeds these spin, balancing is very important. Also you can pull the up pipe and see if there is any oil in there or pull the down pipe / exhaust elbow and see if you see oil there. The description of the smokin though leads pretty good to a turbo leaking.

 

[ES1]

The cutting out as you call it may be the computer pulling timing from the motor because of knock.
Do you have a knock gauge or scantool to monitor knock?

 

[Chippyonetwo]

The cutting out as you call it may be the computer pulling timing from the motor because of knock.
Do you have a knock gauge or scantool to monitor knock?

No. And the gas I am using is the same tank that was sitting for awhile. It is almost gone, and will be replaced with some new high octane fuel.

Thanks for all the insight.

 

[rodman99999]

I agree with the knock retard being what you are feeling as a drop in power. With these cars: a Scanmaster(at least), or some other scanning tool is critical for tuning. You HAVE to keep tabs on knock retard!! I'll bet if you were to toss some race gas in the tank on top of the old stuff in there- that power loss would disappear. If it hasn't been done yet: look at replacing the fuel pump, getting an adjustable fuel pressure regulator, and hot wiring the pump as well. Of course: that's after your certain nothing's rubbing in the turbo. Have fun with your new ride!

 

[ES1]

You have a very stong ride with the HP numbers you put down with 14# of boost.
Was this pump gas?
You really need to get a handle on what you have.
I feel a knock gauge, a scantool, & FP gauge you can read under boost are a must have.

 

[Chippyonetwo]

You have a very stong ride with the HP numbers you put down with 14# of boost.
Was this pump gas?
You really need to get a handle on what you have.
I feel a knock gauge, a scantool, & FP gauge you can read under boost are a must have.

Not sure what fuel is in it. I put 5 gallons of race fuel into it about an hour ago, swapped out plugs, and the MAF, and now I am fubar'd..

The thing won't idle, and I have a service engine soon light on..

Of course I had to mess with it..

Oh well, Thank god I have two great parts stores within 3 miles

 

[ES1]

Put the old MAF back on.
Why did you swap?
Unplug - the plug back in, the orange wire by the battery.
This will reset the computer.

 

[David65]

I feel a knock gauge, a scantool, & FP gauge you can read under boost are a must have.

Wise suggestions! Especially the scantool. A Scanmaster from http://www.fullthrottlespeed.com/ will be of great assistance and can help save a lot of money down the road. It should be one of if not the first things you buy after getting one of these cars...