The Garrett T3 I am going to use on my Europa has provisions for water cooling the bearing housing.
I am going to an aluminum radiator on my Europa but don't want to add to the cooling system's burden.
Has anyone tried a thermosiphon system on their turbo? I know it adds some more pieces but hopefully
it would add to the turbo's lifespan and possibly reduce oil temperature? Maybe a tranny cooler as the turbo's
"radiator"?
When Saab added water cooling to their turbocharged cars (fitted with T3s, incidentally) in the mid-80s, they basically did what you want to do, by using the existing coolant system.
Coolant enters the center housing from above, exits the bottom, and is conveyed back into the main lower coolant hose *after* the radiator. That is, coolant exiting the turbo doesn't actually pass directly through the radiator. I think it's safe to infer that this coolant isn't appreciably adding heat to the system.
Somewhere in their literature, Saab said that the coolant is mostly for when the engine isn't running, to prevent the oil from coking at shutdown.
Regarding the post-shutdown cool-down, the following is from one of their manuals for the 9000 model:
When the engine is switched off and the coolant pump has stopped pumping, the coolant in the system will circulate on its own by means of the thermo-siphon effect.
FWIW (n = 1): my '89 900 Turbo with ~260k miles is on the original T3, always on conventional oil.
Water cooling the center section will add fairly significantly to the thermal load on the cooling system. We did a bunch of instrumentation on Miatas on this and while the exact percentage escapes me now, it's huge. Even if plumbed properly, you're still putting heat into the coolant. Ideally it goes straight into the radiator and not into the block. In your case, I'm not sure I'd do it if the cooling is borderline.
Just drive like a responsible human for the last mile of your journey and it'll be okay without water cooling the center section.
My understanding is the Europa cooling system can be marginal...using an aluminum radiator and
fabricated aluminum coolant lines so hopefully it is better..... maybe I will plumb the turbo in and see how it goes...
just thinking many steps ahead...
When Ford brought out the SVO Mustang in 84 it used a T3 without water cooling and they had a lot of problems with oil coking in the turbo. Later versions used a water cooled cartridge with all the associated plumbing and such. Nowadays, with far better oils and, like Keith said, a little driver attention to letting the turbo relax a little before shutting off the engine, most people I know who still run the T3 do so without the water cooling. I myself, on my race SVO, run a stock cartridge T3 that has the water jacket, but I do not run coolant through it. I always let the engine idle for a minute or two after coming off the track before shut down. I run Mobil 1 15W-50 oil exclusively and I haven't ever had any issues with the turbo.
I have owned an '86 TurboCoupe, '86 Comp Prep SVO and this turbo came off an XR4Ti, just want it to last as long as the ones on those cars:)
Subaru EJ engines cooled the turbos with what looks to be the thermosiphon effect. At least, that is the only way I can figure the rationale for the weird second coolant tank and two different pressure rated caps.
Is there room to add a small motorcycle radiator with its own electric water pump?
I am hoping to keep it simple and avoid a pump. I will probably tie into the existing cooling system and see how it works and revise if necessary....
If you're just doing it to keep the bearings from coking up a "turbo timer" (remember those?) will do the trick.....but with today's oils I don't know if that's necessary.
My 2009 MINI has an electric pump to circulate water thru the turbo after shutdown, when the engine is running the regular flow of coolant thru the engine cools the turbo too.
It does add some complexity between the temp sensor, timer relay and so on, but you could just do it with a switch and a small electric pump. Just remember to shut it off so you don't kill the battery!
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