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Turbo position and mounting
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Author:  miniboy1962 [ Wed Jul 25, 2007 5:32 pm ]
Post subject:  Turbo position and mounting
Hey Guys and Gals,

I'm in the process of working out the placement of my turbo. Just a quick question.

Does the turbo (shaft) have to sit horizontally or can you mount it vertically? I was worried about extra load on the impeller?? After all, it does spin at something crazy like 60k rpm!!

Also, is it better to mount the turbo directly off the exhaust manifold, or mount it on the engine somewhere?
Author:  madmorrie [ Thu Jul 26, 2007 11:14 am ]
Post subject: 
Miniboy

I have wondered about this also, I have often thought you could get better packaging if the turbo was angled to give the exhaust a straight run, rather than a 90 degree bend right after it.
Most (all??) OE installs seem have them horizontally though so there is probably a reason. I would have thought oil draining back to sump was more of an issue than impeller load.

And yeah, better to mount the turbo on the manifold. Need to make manifold suitably strong for this reason.

Cheers

Madmorrie
Author:  madmorrie [ Thu Jul 26, 2007 11:22 am ]
Post subject: 
Found this...

Is it possible to mount a turbo vertically, without severely decreasing it's life? The main concern I thought of was thrust bearing issues. A vertically mounted turbo would have more wear. But could this be solved by using a turbonetic's style cartridge-type ball bearing (AKA no thrust bearing!)? Also, the turbine would be set below the compressor, so exhaust pressure should be pushing opposite the force of gravity.

It’s all about the bearings and seals. The thrust bearing absorbs boost and backpressure side loads and keeps the compressor and turbine wheels from moving into the center section. A turbo bearing is like crank or rod bearings: hydrodynamic and they need an oil film to function. Dynamic seals sling the oil off so it can’t pass through. If the turbo is vertically mounted (on its side basically), the seals will be flooded with oil and begin to leak. Since the oil doesn’t exactly stay in them correctly, the bearings won’t work right. You could possibly use a pump to suck the oil out, much like mounting the drain below the oil sump in the pan, but there really is no easy or correct way to do it. And when the seals leak or fail, your tailpipe will smoke more than the Marlboro man.

Seems to answer the question.
Author:  miniboy1962 [ Thu Jul 26, 2007 1:51 pm ]
Post subject: 
Thanks for that madmorrie! I'll have to make some more room to sit it horizontal....
Author:  JC [ Thu Jul 26, 2007 4:14 pm ]
Post subject: 
How come you can't attach it to the factory manifold?
Author:  miniboy1962 [ Thu Jul 26, 2007 5:36 pm ]
Post subject: 
I didn't get a factory manifold with my car... And there is not enough room for the turbo in between the front of the engine and the grill. I'm going to sit it somewhere on top of the gearbox.
Author:  '77 clubby van [ Fri Jul 27, 2007 12:29 pm ]
Post subject: 
Just want to add my 2c:
the thrust bearing will basically just be there to locate the shaft.
The axial thrust from intake impellor will be more or less cancelled out be the thrust from exhaust impellor so very small thrust forces.
The main thing to think about is the orientation of the oil system.(as previously described.)
most good turbos are "rated" to 250 000 rpm :shock: and if you get any oil stavation the bearings will fail very quickly. Bearings start to fail -> increase internal clearances -> very smokey! :(

The manufacturers will spend $$$ to get the oil system right, so its best to use the same turbo orientation as the vehicle the turbo is from. Some may be ok at a few different angles, but becareful.

P.S: I am an engineer with a bearing company.
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