Running RB25 Turbo with Oil Lines Only

[northstar ninja]

what the f*** are you babbling bout?

no. once it boils thats it, the large majority will escape the system and never come back. it leaves by way of bypassing the radiator cap because of the pressure relief valve.

and you need to drop your little know it all attitude, newbie. i will not tolerate you being a jackass to other members.

Joe, not to be a D*** but Hes right -sort of... - In a closed system, the coolant is NOT supposed to boil, as there shouldn't be air in the coolant system. The reason its pressurized is to effectively raise the boiling point of coolant, so it does NOT boil. The radiator cap only dumps coolant if the max pressure the system is rated for is surpassed. For that to happen there has to be something malfunctioning in the system... and it only turns to steam as it hits open air/atmospheric pressure...

Think of a boiler system for a steam engine- as temp goes up so does pressure, right? If the pressure is contained, the temp of the water can greatly surpass the 100degress C that water boils at...

[northstar ninja]

...uhh sorry Joe, disregard that last post... I didn't read all of the subsequent ones... :fail

Either way there should be no steam in anyones turbo or motor, nor should coolant escape to atmosphere...

[Joe]

...uhh sorry Joe, disregard that last post... I didn't read all of the subsequent ones... :fail

Either way there should be no steam in anyones turbo or motor, nor should coolant escape to atmosphere...

i was just about to correct you

[Buddabeast]

Water is mainly for cooling after the engine is off. Oil stops moving via the oil pump stopping and likely drains out to the sump.
The water pump also stops however a mechanism called 'thermal syphoning' keeps the water moving through the turbo until the temperature drops low enough to break the syphon. This is how Garrett turbos opearte anyway - if the coolant lines are routed properly.
Will the water boil in the housing? Maybe - I'm sure adding coolant would raise the boiling point a bit but the boiling temperature would still be around 100oC+ maybe 110oC.
The pressure of the water in the turbo has NO effect on its boiling point. Nothing will change that unless you are driving up a mountain and that's only going to lower the boiling point. You are confusing water pressure with atmospheric pressure.
So if water does get locked up in the turbo after the water pump stops for whatever reason I am sure it will boil off a bit.
It is a closed system so it will gas off then condense, the heat energy put into the vaporization of water is a lot true which will take from the turbo heat.
That steam will travel through the water lines and end up somewhere or condense on its way. But hopefully water won't be stopping in the turbo until the temp has lowered to safe levels anyway.
Whether water keeps moving or stops in the turbo when the engine is turned off I am not 100% sure but either way seems to do the cooling in my opinion.

[Buddabeast]

Coolant water in an engine vs a pressurized boiler is an interesting one.
As a boiler builds up with steam the pressure increases inside and the boiling point of the water increases.
If water boils off in a turbo the pressure will build up too and yes the water boiling point will rise.
But the pressure in a welded pressure vessel will be much higher than a engine coolant system which has rubber hoses and clamps.
So I doubt the water boiling point would raise much before a fitting or a pressure relief went off.
For instance to raise the boiling point of water to 180deg C the pressure on the water needs to be 10bar (10x atmospheric pressure) or 145psi.
180deg C aint very high and that's a s*** load of pressure the coolant system won't handle. Would it?

Anywho I am just trying to fill some time on my night shift! Thanks!

[Seishuku]

If there's no air in the cooling system, steam should never be produced... If the temps ever got high enough to super heat the coolant enough to actually flash it into steam, then you've got MUCH bigger issues.

In an automotive setup, the coolant WILL dump out of the system FAR before before steam is made... UNLESS there's an air pocket that the extra heated coolant hits. But that shouldn't happen if the system is air free, as it should be.

I used to have an S13 T25G on my SR, I didn't use coolant on it and never had issues, I also beat the crap out of that thing at 17PSI.
I now have a Saab T3 turbo (also oil/coolant cooled), but I don't use the coolant lines on it either. I don't worry about it.