Turbo Tech Question

[Kevin]

Todd; The turbochargers start at zero... As they are VSR'd they seat in to the nominal bearing clearance. In the beginning they are Zero and nothing moves. You will see very shortly this proceedure coming out in OEM applications! The enngineering test have shown 10 to 15% jump in efficiencies. As wear sets in, the gaps do increase however, the static metal to metal is set at normal factory gaps. With the titanium billet wheels I can close the gaps even closer.

This ad is not displayed to registered and logged-in members. Register your free account today and become a member on 6SpeedOnline!

[Todd of CA]

What oils are they requiring to work with the clearances that are so much tighter??? It sounds almost like they'd be running dry if you're setting them so tight.
Also, is this just the shaft od to the bearing id, or the bearing od to the housing id also? I'm assuming again that you're still referring to the tin/floating bearings typically used in these.
And what's your theory on the 10-15% improvement in efficiency by tightening up the clearance?
Typically, when turbo's show up on our doorstep and they're too tight, they take a considerable time to break in and start performing properly, and this seems to go against your "improvement"???
I've just had two customers tell me about these, and I understand your excitement about new technology. It just doesn't make sense to me yet as I'm not quite grasping the underlying fundamental issue we're talking about yet.

[Kevin]

Todd:

It has nothing to do with the shaft to bearing clearance. It is the compressor wheel to compressor housing clearance. We are not on the same page. We are coating a housing after we CNC the compressor wheel into the compressor housing. The gap between the wheel and housing prior to coating is determined on what wheel we are running ie: Billet, Ti, Size and so on. We also CNC our own Backplates to set wheel depth. I will coat the housing to a zero clearance and go from there. And since we don't have carbon seals there is no tightness on start-up. I realize that you have been running Garretts for years, hell I give you the credit for patients. The 10-15% is coming again as stated from the factory test, on turbocharger dyno's.

The only benifit from a ball-bearing unit, is for the shaft centering ability, Garrett stresses the efficiency improvements on the GT series. This is due to the clearance being reduced. I'm taking this to a step further and getting it close to zero (minus my free float in my bearing stack)..

You do realize that if you close the gap between the two surfaces you will create efficiency. Then in theory, why can't we strive for a 100% efficient wheel. 100 air in with maximum compression with little heat due to friction and cavitation. We will never get these levels, but we will get higher numbers. Lets take for example the T28 ball-bearing Garrett, the published wheel specs for that turbo is higher than the standard SVO Mustang turbo that showed up 20 years ago. Why, the wheel is the same, hell, its the clearance, or lack of it....!

[Todd of CA]

Ok... So, that makes more sense.

So, this is only possible on bb units?
Otherwise, they'd just tear themselves up with the axial play in the bearings and side loading due to surge, etc. Or, at minimum create quite a bit more clearance for themselves...

I hope it all works out and is a long lived adventure and doesn't just go away quickly after a few thousand miles...