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What is heat soak?

-Alex
 

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What is heat soak?

-Alex
basically what happens with heat soak is that when you drive your car hard for example, and then are forced to shut down for any reason such as traffic, there is a lot of stored heat energy in the engine bay that was being passed into the air, but since you were forced to shut down, your cooling has been reduced a lot because there is no longer that air to help cool. Therefore your engine gets hotter then when it was at before. that is basic heatsoak.
-Thomas
 

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Discussion Starter #3
Forced to shut down? Does that mean the cars shuts off? Sorry for the newb questions, but I remember reading about this a long time ago but don't remember it exactly.
 

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basically what happens with heat soak is that when you drive your car hard for example, and then are forced to shut down for any reason such as traffic, there is a lot of stored heat energy in the engine bay that was being passed into the air, but since you were forced to shut down, your cooling has been reduced a lot because there is no longer that air to help cool. Therefore your engine gets hotter then when it was at before. that is basic heatsoak.
-Thomas
yeah he pretty much hit it right on.....for example if you drive your car around hard for awhile....then say you get home and shut if off...it will continue to get hotter for period of time because there is no more coolant circulating through the engine....and no air goin through the engine compartment....but the engine and turbo are still hot and heating up the engine bay temps....so when you start it 5 minutes later....its hotter than when you turned it off....;
 

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yeah he pretty much hit it right on.....for example if you drive your car around hard for awhile....then say you get home and shut if off...it will continue to get hotter for period of time because there is no more coolant circulating through the engine....and no air goin through the engine compartment....but the engine and turbo are still hot and heating up the engine bay temps....so when you start it 5 minutes later....its hotter than when you turned it off....;
and that can cook shit right?! LIKE OIL IN YOUR TURBO! :) which is why you turbo guys have turbo timers?! i just let my cars idle for a min after i get home if i drive it hard, ive done that for years.
 

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I could be way off, but I was always under the impression that heat soak can be in a car's natural tendencies, not so much whether you were beating on it (though I am sure that does not help). Also, I thought the actual hard-starting part came from the fuel in the fuel rail being boiled due to the heat in the engine bay being conducted to the rail from the exhaust and turbo.
 

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I guess the big question here is, "What are we heat soaking?"

Heat soaking is exactly what it sounds like... something getting too hot, causing negative effects.

I'm most familiar with heat soaking the intercooler. That's generally from sitting at a stop light or something where there is little or no air flowing through your intercooler. The intercooler gets VERY warm, and when you first launch, you're pulling air through a HOT intercooler until the ambient air has a chance to cool it down again. It's a killer on 1/4 mile tracks when you're sitting there idling warm in the lineup for like 20 mins.
 

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and that can cook shit right?! LIKE OIL IN YOUR TURBO! :) which is why you turbo guys have turbo timers?! i just let my cars idle for a min after i get home if i drive it hard, ive done that for years.
it dosent really cook stuff its just a natural thing that happens with cars...more so with turbo cars......it will cost your horsepower when you first start it back up...or a few tenths if your at the track....but dosent really hurt anything in the long run....as far as oil cookin in the turbo.....you have to be reallyyy boosting for that to happen....under alot of boost the turbo can get so hot it will actually turn red.....so if youve been running the car real hard on the boost......you have to let it idle down so the oil dosent boil in the turbo from the bearings being so hot...and yes thats what the timers are for...its one of those things that dosent happen alot.....but its best to let the car idle down just to be safe.....
 

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I guess the big question here is, "What are we heat soaking?"

Heat soaking is exactly what it sounds like... something getting too hot, causing negative effects.

I'm most familiar with heat soaking the intercooler. That's generally from sitting at a stop light or something where there is little or no air flowing through your intercooler. The intercooler gets VERY warm, and when you first launch, you're pulling air through a HOT intercooler until the ambient air has a chance to cool it down again. It's a killer on 1/4 mile tracks when you're sitting there idling warm in the lineup for like 20 mins.
is there anything you could do to help with this? (while waiting at the track)
 

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heat soak can be producing too much heat for your radiator to handle, or your IC to handle, ect...

heat soak can also cause issues with electric parts. More heat = more resistance = more heat = more resistance, ect ect...

That's called thermal runaway and usually ends horrible. In our cars it's usually minor (hard to start cause the battery's too hot, wiring is too hot, ect...)
 

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^^^^

that is the main thing with mk3's with heat soak, it will either boil the fuel in the line or make electric connections crap (usually cps's but also fuel pressure relay, vsv, etx)

result is when you turn the car off that when its hot its either hard to turn over or wont start at all, there are a number of fixes for it.

<l><l>
 

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like $1k worth of OEM parts (main engine wiring harness and CPS)
 
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