5w20 in High Performance Turbo Engine

[Max_Wander]

absolutely! the turbos can get pretty big out there...

 

[cfromc]

Rather than total engine bhp, wouldn't it be more accurate to compare hp per cylinder and take into consideration design hp vs. "modified" hp? The VW likely has more hp per cylinder (isn't it a 4 cylinder?) and is operating with more hp than the engine was originally designed for. BTW, how has the Redline held up to those 600hp engines? Any UOAs?

 

[Drew99GT]

Quote:

---

So you're saying the gryoscopic effect centers the wheels?
And it's ok to start-up a turbo car and rev the [censored] out of the engine before the oil pressure comes up?
On a journal bearing turbo the wheel is gonna hit the housing. It needs pressure to keep from wobbling.
Ever grab a turbo wheel and try to move it around? It's got a fair amount of play to it.
A little radial play is normal, axial (in/out) is BAD.

And if turbo's don't need oil pressure, just lube, why send pressure to them?
They lower the pressure for a ball bearing turbo but not for a journal bearing one...
And all newer turbos are water-cooled so don't try pulling oil-cooling...

I'd suggest the both of you have another look at Bernoulli's equations. As I understand it the smaller passages in the turbo (bearings) create higher oil pressures as the oil flows thru them. It's this pressure that holds the wheels. I don't believe it's a thin film like in rod or main bearings. But that might be true for ball bearing turbos.

---

If your turbo has shaft wobble or end play just sitting on a work bench, then you need a new turbo!

 

[AEHaas]

Not sure. In general I believe that turbos would rather have a higher flow of thinner oil than a lower flow rate of thicker oil - if that can be achieved. The turbo will not actually have much load at all regardless of the boost. As long as there is no coke formation from over heating then the turbo should last the life of the engine.

aehaas