Your turbo coolant lines are all f*cked up?
Nice thoughts... But simplify the situation.
When the water in my turbo is boiling after the shutdown it is f*cking hot compared to the water anywhere in the block. As long the turbo is f*cking hot the water will flow through it. But for it to run by itself it needs to rise up, thermal siphoning depends on it. And the only place for the feed lower enough is in the bottom of the block next to the oil feed (94-95, MSM's and 1.6).
When the water in my turbo is boiling after the shutdown it is f*cking hot compared to the water anywhere in the block. As long the turbo is f*cking hot the water will flow through it. But for it to run by itself it needs to rise up, thermal siphoning depends on it. And the only place for the feed lower enough is in the bottom of the block next to the oil feed (94-95, MSM's and 1.6).
The only time the difference is drastic enough to be as significant as you want is right before and right after the rad.
Do you have proof otherwise?
And if your proof is "I hear water boiling somewhere" then you're going to get ridiculed and treated like an idiot.
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I imagine though if you are picturing boiling water in the turbo, you will have a high pressure zone, no longer just temperature gradients with slightly different densities causing a flow, and it will just pressurize both water lines, similar to my situation with the two feed locations being the same temp, nothing will flow into a high pressure zone and there is no way you can expect the high pressure to only relieve itself in one direction based on a very slight height difference. I think pressurized orifice would trump any slight density difference based fluid flow
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Thread Starter
Junior Member
Joined: Jan 2014
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From: Finland
You seem to think there are insanely drastic water temperature differences between different areas of the block.
The only time the difference is drastic enough to be as significant as you want is right before and right after the rad.
Do you have proof otherwise?
And if your proof is "I hear water boiling somewhere" then you're going to get ridiculed and treated like an idiot.
The only time the difference is drastic enough to be as significant as you want is right before and right after the rad.
Do you have proof otherwise?
And if your proof is "I hear water boiling somewhere" then you're going to get ridiculed and treated like an idiot.
But yeah... Garrett has got it wrong, as well as car manufacturers here in europe and s2k/honda/nissan/bmw tuners and racers that get this
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gotta stop the heat soakback, bro, it's destroying all our turbos. So glad you joined the site to fight the power.
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Elite Member
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The coolant at the inlet of the water pump is typically 20*F cooler than at the outlet of the head (going to the radiator). I measured it.
When you shut down, this delta T should persist for a while. So it stands to reason that you will get said thermal siphoning if you use these 2 points for the turbo cooling.
I would imagine that if the car is driven hard then the engine is turned off, you may get coking without this siphoning. In normal driving, you probably drive relatively gently the last minute; and on the track without an off, you get a cooldown lap (or you idle in place).
When you shut down, this delta T should persist for a while. So it stands to reason that you will get said thermal siphoning if you use these 2 points for the turbo cooling.
I would imagine that if the car is driven hard then the engine is turned off, you may get coking without this siphoning. In normal driving, you probably drive relatively gently the last minute; and on the track without an off, you get a cooldown lap (or you idle in place).
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Last week it was -15F.. my trubo didnt freeze.
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Thread Starter
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Joined: Jan 2014
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From: Finland
Straight from the Garrett white paper:
Water cooling’s main benefit actually occurs after the engine has been shut down. Heat stored in the turbine housing and exhaust manifold “soaks back” into the center section of the turbocharger after shutdown. If water is not plumbed correctly, this intense heat can potentially destroy the bearing system and the oil-sealing piston ring behind the turbine wheel.
How does water-cooling work?
The physical process of turbocharger water-cooling is an interesting one, and works in a different way than what might seem obvious. It is true that during normal engine operation water flows through the turbocharger mostly due to pressure created by the engine’s water pump. However, an additional phenomenon known as “thermal siphoning” pulls water through the turbo’s center housing if the water lines are properly routed, even after the engine is shut off and the water pump is no longer pumping. Heat in the center housing is transferred to the water via conduction, like the cooling effect that occurs inside a typical water-cooled engine (with a water jacket surrounding each cylinder and running through the cylinder head). If the water running through a turbocharger is allowed to escape freely after absorbing heat, it will rise through the cooling system pulling cooler water into the turbocharger along with it. In this way the intense heat that has soaked back into the turbo after engine shutdown is wicked away from the bearings and seals, and prevented from causing serious damage without assistance from the engine’s water pump.
How does water-cooling work?
The physical process of turbocharger water-cooling is an interesting one, and works in a different way than what might seem obvious. It is true that during normal engine operation water flows through the turbocharger mostly due to pressure created by the engine’s water pump. However, an additional phenomenon known as “thermal siphoning” pulls water through the turbo’s center housing if the water lines are properly routed, even after the engine is shut off and the water pump is no longer pumping. Heat in the center housing is transferred to the water via conduction, like the cooling effect that occurs inside a typical water-cooled engine (with a water jacket surrounding each cylinder and running through the cylinder head). If the water running through a turbocharger is allowed to escape freely after absorbing heat, it will rise through the cooling system pulling cooler water into the turbocharger along with it. In this way the intense heat that has soaked back into the turbo after engine shutdown is wicked away from the bearings and seals, and prevented from causing serious damage without assistance from the engine’s water pump.
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Thread Starter
Junior Member
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From: Finland
Here's a nice example of OEM application which works. CHRA is rotated, water feed comes nicely under the turbo uphill and water return goes uphill from the turbo. In this setup thermo siphoning works.
This european manufacturer has made thermo siphoning work since 1980's on their turbos.
This european manufacturer has made thermo siphoning work since 1980's on their turbos.
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While I get what you're trying to say, I don't think it makes enough difference in our particular world to be a concern.
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Joined: Apr 2011
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From: Martin, Slovakia
Great information Tomi.
People here are in the habit of clocking turbos when the oil feed is not exactly vertical. What is particularly interesting is being able to rotate the chra by 20 degrees without negative consequences.
People here are in the habit of clocking turbos when the oil feed is not exactly vertical. What is particularly interesting is being able to rotate the chra by 20 degrees without negative consequences.
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The coolant at the inlet of the water pump is typically 20*F cooler than at the outlet of the head (going to the radiator). I measured it.
When you shut down, this delta T should persist for a while. So it stands to reason that you will get said thermal siphoning if you use these 2 points for the turbo cooling.
When you shut down, this delta T should persist for a while. So it stands to reason that you will get said thermal siphoning if you use these 2 points for the turbo cooling.
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Elite Member
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From: Newcastle, Australia
I know I will get flamed for this, but OP is right and everyone who is confused is either not reading his posts or failed highschool science.
Having said that if nothing is coking, I wouldnt stress. BUT if you have boiling coolant you might consider doign it properly as OP is suggesting.
2c.
Dann
Having said that if nothing is coking, I wouldnt stress. BUT if you have boiling coolant you might consider doign it properly as OP is suggesting.
2c.
Dann
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