turbo RPM

[veedubin]

87 7M GTE stock ct26 factory DP hollowed cats.
I was wondering about the speed of the turbo during cranking. Should the turbine/compressor move during cranking? When I say cranking, I was priming the oil system last night with fuel and spark disabled. I was almost certain that there should be some movement when cranking, but mine does not. Am I correct in my thinking?
Thanks

 

[whitemike]

That's a damn good question, I would like to know the answer to that myself.

My *guess* is that it wouldn't spin at all, considering there's only a small amount of air being let out of the exhaust valves, at a very slow rate..

 

[veedubin]

That's a damn good question, I would like to know the answer to that myself.

My *guess* is that it wouldn't spin at all, considering there's only a small amount of air being let out of the exhaust valves, at a very slow rate..

That was my thinking, just trying to get some clarity to my guessing

 

[GrimJack]

This is going to depend on a bunch of other factors... well, a couple that I can think of off the top of my head. Oil type and condition, and condition of the turbo itself.

I've seen both - ones that will spin, albeit slowly, while cranking, as well as turbos that won't spin even at idle but are still fine under boost.

 

[Poodles]

If you were priming the oil system you should have the plugs out meaning there wouldn't be any pressure going out the exhaust...

 

[GrimJack]

If you were priming the oil system you should have the plugs out meaning there wouldn't be any pressure going out the exhaust...

Good point.

 

[IJ.]

That and the Turbine,shaft and Compressor wheel weight is sitting on the bearings and the bearings are sitting down in the centre housing as they don't have enough Oil pressure to "float" yet

 

[veedubin]

That and the Turbine,shaft and Compressor wheel weight is sitting on the bearings and the bearings are sitting down in the centre housing as they don't have enough Oil pressure to "float" yet

Did it with plugs out at first then threw them in and cranked a few more times. Also, IJ thanks, that was the answer I was looking for. makes perfect sense.

 

[IJ.]

Yep there's enough weight and stiction in a journal bearing turbo to stop it turning, BB turbo's can and do turn while cranking, my 04z moves a ton of air at idle (if you run it with the TB Pipe off it'd make a good hair dryer)

 

[veedubin]

if you run it with the TB Pipe off it'd make a good hair dryer

You are a genius!!!! :biglaugh:
Now I know what to get the wife for christmas!!!!! :naughty:
The funny thing is her hair drier just broke last week