Hello. This is George from GearTech, builder of Chris' car. Generally I think coolant lines are more a headache than good. System complexity increases (I like simple setups), more sources for leaks, you can really harm the heater core or head (depends on where you take coolant from) and generally if you take good care of letting the turbo cool down, you will have no problem at moderate boost levels Chris is planning to run.

On the other hand, if you definately want to install the coolant lines, you must pay extra attention and not just use two hoses. You must 'use' the thermal siphon effect thus you must determine the flow direction (which is not so evident after all). We have never seen a turbo fail from not using coolant even after tenths of thousand miles.

 

Now it gets confusing

 

If you use the supplied elongated banjo fittings for the coolant lines, the lines won't touch anything, and you simply connect the lines to the oil cooler lines...putting the turbo in the loop. The higher line goes to the top of the turbo, the lower line to the bottom of the turbo. Again I had a factory radiator and never had any cooling issues. With your Koyo you have a much greater cooling capacity.

That turbo was DESIGNED to use coolant to cool the turbo THROUGHOUT the driving of the car...not just at the end of driving, although after driving is when the oil can coke up the most. It will be hottest at full boost when the most exhaust is flowing through it and without coolant it will cook the oil flowing through it since the oil will not have sufficient volume to cool the turbo seeing as how this is a BALL BEARING turbo, not a JOURNAL bearing, which cools the turbo with oil. Ball bearing turbos use much less oil by design and it only drips in too lubricate the bearings, if you remove the oil restrictor than you will have too much oil in the turbo for it to handle due to smaller oil passages and it will leak by the turbo seals causing your exhaust to smoke and getting oil into the intake...which is very bad.

So please use the turbo as designed, run the coolant lines, and leave the oil restrictor in place...not that you said anything about removing it...but I'm sure the idea would come up with someone on here to remove it to allow the oil to cool it since there is no coolant run to it. The oil passages inside the ball bearing turbo are far too small to be used for cooling the turbo, only lubrication.

Heat is the number one killer of turbo life, and engine life for that matter. Besides the obvious "running out of oil" scenario LOL! That is why ball bearing turbos use coolant...to increase the life of the turbo by cooling it more. Ball bearing turbos last longer, run cooler, spool faster, and generally produce more power than journal bearing turbos (see also, oil cooled/no coolant running through it) b/c of their design. This also makes them more expensive. If the turbo did not need coolant to cool it, the manufacturer would not have put passages for coolant and required you to use them. Not using coolant voids any warranty on the turbo as well.

This is taken directly from the manufacturers website and should give you a description of why they cool it with coolant rather than oil:




Oil & Water Plumbing

The intake and exhaust plumbing often receives the focus leaving the oil and water plumbing neglected.

Garrett ball bearing turbochargers require less oil than journal bearing turbos. Therefore an oil inlet restrictor is recommended if you have oil pressure over about 60 psig. The oil outlet should be plumbed to the oil pan above the oil level (for wet sump systems). Since the oil drain is gravity fed, it is important that the oil outlet points downward, and that the drain tube does not become horizontal or go “uphill” at any point.

Following a hot shutdown of a turbocharger, heat soak begins. This means that the heat in the head, exhaust manifold, and turbine housing finds it way to the turbo’s center housing, raising its temperature. These extreme temperatures in the center housing can result in oil coking.

To minimize the effects of heat soak-back, water-cooled center housings were introduced. These use coolant from the engine to act as a heat sink after engine shutdown, preventing the oil from coking. The water lines utilize a thermal siphon effect to reduce the peak heat soak-back temperature after engine shut down . The layout of the pipes should minimize peaks and troughs with the (cool) water inlet on the low side. To help this along, it is advantageous to tilt the turbocharger about 25° about the axis of shaft rotation.

Many Garrett turbos are water-cooled for enhanced durability.

 

Also, this link

http://www.turbobygarrett.com/turbobygarre...01.html?#t101_5

Will show you the difference between journal bearing turbos (oil cooled) and ball bearing turbos (water cooled). It also shows the difference in response times, ball bearing being faster. If you don't use the coolant lines you can expect the response times to drop rapidly, and the turbo to eventually fail. I hit full spool by about 4200RPM. That will help you gauge your performance.

 

Precision billet 5857 has no coolant lines and they say its not necessary for their new turbo design. That is why I said it depends on which turbo the op has.

 

Everything has a reason and I am not here to argue if a BB turbo fails with no coolant. I am just talking based on my experience. Even a 10-year old can understand that a BB turbo with CORRECT coolant flow will last longer. BUT the question is how much longer? Is it 1k miles, 10k miles or 100k miles longer? If it no1, I really do not care. I would not even care about no2. Can someone based on his experience answer if water flow increases the turbo life by X percent? I did 15K miles on my GT35R with NO coolant and the bearings are BRAND NEW after recent inspection. I was running just 12psi though. So I am open to all success/horrow stories, we are here to share information.

It's something like the 'oil jet' issue, we all know Honda put them there for a reason but most US engine builders simply do not use them (in B series build ups). WE all know they lower oil pressure but they prolong engine life and piston cooling.

 

The water cooling is one of the things that make new turbo cars drive 4 times longer without changing turbo. In the 80´s they changed turbo and spark plugs at the same milage.

Oil cooled turbo´s are great for drag and race cars to keep the water temp down but not in a car made to use.

 

WOooooo!!!!!!!!! YAAAAAAAA Christos!! SEXY SEXY !!! looks great man!!

 

You are right...they have one version of the 5857 turbo without coolant lines. The one that is not ball bearing. Precision offers two types of the 5857 turbo, one with coolant lines, one without. The two types of turbos (loosely defined) are journal bearing turbos...and ball bearing turbos. The turbo Chris is using is ball bearing, a GT35R, which requires coolant lines.

 

I didn't say a BB turbo would fail immediately without coolant...but it will reduce the life of the turbo greatly. BB turbos last 3 to 4 times longer than journal turbos...about 100K+miles if taken care of. Most journal turbos have a service life of 30-50K miles depending on manufacturer/size. Just b/c someone has a journal turbo in a car for 80K miles and hasn't replaced it doesn't mean its working properly...it may be leaking oil into the exhaust and spooling up incredibly slow...and just b/c you have a GT35R that has had no coolant running through it for 15K miles doesn't mean it is working properly either. Not sure what kind of engine it is on so it would be hard to compare spool up times with mine but as I said before...my GT35R spooled at 4200 consistently.

What I'm saying is that a journal bearing turbo uses no coolant lines b/c it wasn't designed to use them...and it uses the appropriate amount of oil to cool the turbo.

Ball bearing turbos, like the one Chris has, don't have huge amounts of oil dumping through them...just enough to lubricate the bearings...not enough to cool the turbo properly. That is what the coolant is for. If he was drag racing the car I'd say go for it...it would lower your temps a bit and the turbo wouldn't be in use long enough to matter. But since it'll be driven normally it will seriously hinder spool time and service life and when it comes to a $1300 turbo I would want to make it last as long as possible and care less about looks and a slight increase in engine temps...which I never had even with a stock radiator. If it came to it Chris could throw on a cooler thermostat.