So here is the story. Sorry for the long read.............
VE HSV GTS, LS2 stroked to 408, rebuilt to be good for 15 psi, drive train upgrade etc etc. Twin turbo'd. XR6 Garrett style turbos, turbo bearing oil and turbo cooling water fed. Water is plumbed into the normal cooling system, water flow through the turbos is good.
Car is running at 9psi boost and makes great power and torque.
Car does not overheat, even on dyno run.
Water pump and radiator and 2 stage electric fans all working fine.
Correct coolant and mix.
However, even after a cooldown idle, about 10 seconds after the car is turned off, the water in the lines,immediately near the turbo casing boils.( I actually replaced this piece of hose with a clear section, and can see it occuring)
This to me is understandable, as the water has stopped flowing, and is now stationary, and subject to the full heat load that is now trapped in the turbo.
The downside to this is that the water in the turbo cooling line turns to steam, and thus over pressurises the radiator, and it dumps its coolant to the overflow bottle. Yes it does siphon back in to the radiator, once cooled down, but it just seems no good to me.
I am told by turbo people that it is not normal.
I am also told that -
To allow for ""auto siphoning"" in the turbo water lines ( where the local water from the turbo gets really hot after turn off , more water will sort of be naturally pulled through the turbo just by the fact that the hot water will rise and pull more water through.) anyway , to achieve this, I am told that -
1 The turbo shouldnt be the highest point in the water sytem - they arent the highest point.
2 The turbo mounting/water lines ( in versus out) should be skewed about 6 degrees uphill to help with the auto siphoning - they are at 6 degrees.
Thus, the installation seems OK.
Having fiddled with this for months on and off I am now at the point of thinking -
1 Its all too hard, should have gone S/C instead.
2 Run the turbo water to an independant/seperate cooling system and keep it electrically circulating after turn off, for a few minutes. This would be painful in my mind as it would need a pump, mini radiator, cooling fan, more plumbing etc etc. i.e more failure points.
The engine bay is already 99% full.
3 Swap out water pump to electric style, but unsure i we can fit it in, as that area is already full of catch can, 2 x wastegates/dump pipes etc etc.
4 Try some of this waterless coolant stuff, boils at 375F / 190C.
To try this will cost around $500, and I'm not sure it's as good as they claim.?
Has anyone used it?
Any experience with this turbo/turn off heat issue??
Thanks in advance.