Heads lifting under boost....
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Joined: Jun 2003
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"The problem is that coolant is shooting out of the small overflow canister under boost."
It's doubtful - but if it can happen once, it can happen twice. Check your hose connections at the radiator cap.
An installer on my car flipped the hoses.
Steam vent hose into the overflow tank.
Overflow into the radiator.
The steam vent hose coolant had no where to go until the radiator cap would open - and after opening into the overflow tank. Never posed a problem in cool weather but sure did fast in hot weather and under boost.
Took me 2 hours staring at the engine bay trying to figure out what was wrong and then saw the mistake. That was one mistake by the installer - the other is too stupid to post.
BTW - I was not the installer.
It's doubtful - but if it can happen once, it can happen twice. Check your hose connections at the radiator cap.
An installer on my car flipped the hoses.
Steam vent hose into the overflow tank.
Overflow into the radiator.
The steam vent hose coolant had no where to go until the radiator cap would open - and after opening into the overflow tank. Never posed a problem in cool weather but sure did fast in hot weather and under boost.
Took me 2 hours staring at the engine bay trying to figure out what was wrong and then saw the mistake. That was one mistake by the installer - the other is too stupid to post.
BTW - I was not the installer.
Last edited by dlandsvZ28; Mar 7, 2007 at 09:33 PM.
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Joined: Nov 2003
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From: Norn Iron
Originally Posted by ou812/z28
tourqing the heads to 100lbs may distort the top of the block and be the cause of the coolant being pushed out under boost.just my 2 cents.
My only concern about 100lbft, would be the fact that the fasteners were never deesigned to be used under so much tension. They may in fact clamp less under such circumstances.
Lot of engines (he has an LT1 I presume) have the head bolts threaded pretty much right into the deck and they arent blind but LS1 head bolt holes are not really a part of the deck so much.
but unless you have 1/2" or L19 studs 100ftlbs with moly is just going to stretch them out most likely..
but unless you have 1/2" or L19 studs 100ftlbs with moly is just going to stretch them out most likely..
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Verdad Gallardo Lot of threads in the block, the stud will pull apart right where the course thread meets the shank at the (point of smallest diameter out of the threads) most likely. Now if you were threading a bolt in @ 100ft lbs the threads might tear out first.
Cough....backpressure, cough cough 
. Have you checked it yet at 15psi?? Make sure the gate is shut??. Most of the LS1's I have dealt with that are turbo that have heads lifting is due to the tune , which appears you have that right, or its the backpressure created by either the turbine sizing, leaky gate, or leaky BOV. If either one leaks, you have to run a higher turbine speed to achieve boost and or create more exhaust pressure to overcome the WG.
. Have you checked it yet at 15psi?? Make sure the gate is shut??. Most of the LS1's I have dealt with that are turbo that have heads lifting is due to the tune , which appears you have that right, or its the backpressure created by either the turbine sizing, leaky gate, or leaky BOV. If either one leaks, you have to run a higher turbine speed to achieve boost and or create more exhaust pressure to overcome the WG. 
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sorry if I gave the wrong impression....
It's not pushing coolant anymore, it's at 9PSI now on pump.
But @ 15PSI and race gas and LS1SpeedInc's tune, the car makes 660RWHP, about 110RWHP more than the previous 15PSI tune that was on the car. Kinda shows you that tuning can make a difference.
I haven't ran it @15PSI yet....I'll keep you guys posted.
It's not pushing coolant anymore, it's at 9PSI now on pump.
But @ 15PSI and race gas and LS1SpeedInc's tune, the car makes 660RWHP, about 110RWHP more than the previous 15PSI tune that was on the car. Kinda shows you that tuning can make a difference.
I haven't ran it @15PSI yet....I'll keep you guys posted.
