GT12 water ports-2 questions

[Turbogt12]

Hi,
1.Does it matter which nipple/port will be the outlet and which will be inlet?
2.there's a plug besides one of the nipples-can this port be used as the inlet/outlet instead?(and the plug will be used to shut the inlet besides of it instead...)
Thanks for the help ahead!

[Turbogt12]

Hi,
1.Does it matter which nipple/port will be the outlet and which will be inlet?
2.there's a plug besides one of the nipples-can this port be used as the inlet/outlet instead?(and the plug will be used to shut the inlet besides of it instead...)
Thanks for the help ahead!

[Kirk Feldkamp]

The turbo's bearings are cooled by the oil during engine operation. When the oil flow stops after shutdown, the water surrounding the bearing cavity will boil off as it cools the housing, thus drawing in cool water behind it. As you can see, the water cooling works on the principle of a thermal syphon. You will need to make sure there is an "uphill slope" (with no high points that will trap steam) in the return hose all the way back to where you dump it.

The ports are simply openings into a cavity surrounding the oil cavity. You will need to choose one of the two on either side (one for entry, one for exit). Don't forget the "uphill slope" needs to be considered as you go through the center housing. This should help you decide which water ports to use.

Hopefully you have gathered that it is unnecessary to pump water through the turbo during engine operation. Also note the water fed to the center housing does not necessarily need to come from the engine's cooling system.

-Kirk

[Turbogt12]

Hi kirk,
Tnx for the answer...
but,as for my question about plug:do you know if i can switch the nipple with the plug besides it?i think that the plug is covering an opening which leads to the same water cavity/jackets of the around the bearing housing.
Tnx again

[Kirk Feldkamp]

I know what you were asking... but you need to think about what I said.

The space behind the plug connects to the same cavity as the other port. I'm not saying you can't use it, but given what I said in my previous reply, it's probably better if you can use the port that the fitting originally attaches to. Think about what's going to happen to the steam. What will happen if you don't have a path with an "upward slope" through the water jacket?

-Kirk

[drivetrainUW-Platt]

Why don't aftermarket turbos use water cooling?

[Kirk Feldkamp]

If you're asking about Garrett aftermarket turbos...

I believe ALL of our aftermarket ball bearing turbos DO use water cooling. Our general ball bearing cages are made of a phenolic plastic that will melt if the water cooling isn't used. Journal bearing turobs can benefit from water cooling, but often the additional cost doesn't always offset the benefit. Water cooling helps eliminate/reduce oil coking caused during hot shutdown soak-back.

"Turbo 101" (http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech101.html?#t101_3)

It is possible to make the ball bearing cage out of metal, which eliminates the requirement of water cooling. Racing customers place a premium on weight minimization, and the center housing water jackets and all of the associated water lines/fittings can be eliminated if a metal cage is used. I think the cost of the bearing cartridges roughly doubles when a metal cage is utilized, so these bearings are only offered in our super-duper racing turbos. (Think LeMans, WRC, etc.)

-Kirk