lifting the heads?

2 weeks ago when i was on the dyno when we moved the car off the dyno i had 2 little puddles of coolant and on further investigation it was coming from the head gasket. I have no coolant in the oil, and i am no longer loosing any coolant, and i am not overheating. I haven't been getting on it much either, as i have no place to work on my car right now (building new garage)

Are the head gaskets shot now (again) and if they ar should the heads be milled to prevent this. I didn't mill the heads the last time i blew thehead gasket, but i should have. Let me know what ya think.

Bill

I had my heads O-ringed. Sure your not detonating. I would assume if your heads where lifting coolant would make it other places than under the car. Power would drop bigtime, and I would think you could hear the compression seeping out (Being on a dyno). Checking for blown head gaskets is easy. I just dont think your lifting your head, but what do I know:confused: . How much Boost?

Its never a bad idea to have the heads re-surfaced after a high temp or high mile motor.


The other Bill

It was hitting 18 psi. The coolant was seeping from the outside lower edge of the head on the corners, not flowing or spurting or anything. Like i said, i haven't had any problems since. Car runs great. Should i just let it go?

Mar car lifted the heads last year quite often. I had arp bolts and felpro 1074 gaskets. It never blew a gasket or caused any other problems that I could see... I let it go all summer until "winter teardown" where I changed to Cometic gaskets and ARP studs..

..and FWIW, I lifted the head(s?) Sunday, at a minimum.. The car won't run as of now.. :confused:

Originally posted by SMOKNZ
It was hitting 18 psi. The coolant was seeping from the outside lower edge of the head on the corners, not flowing or spurting or anything. Like i said, i haven't had any problems since. Car runs great. Should i just let it go?

Personally I think you are lucky and should consider the seapage as a warning of worse things to come. My engine blew the fire rings into the cylinders and ended up blowing the lower radiator hose off. Fire rings are hard and dent the heck out of pistons, not to mention what would have happened if I blew the hose off going down the track! I strongly suggest fixing the problem before it causes more damage.

94Slug: With a nitrous or supercharged car, if you lifted the heads you would notice a drop in power. But one thing I've noticed with turbo motors is that they'll run the same no matter what. We've blown heag gaskets between cylinders before where the two cylinders showed 60-70 leakdown. The motor made the same power and the car ran the same et. I've got a friend with a 800hp T72 powered 4 cylinder SVO with two of the cylinders showing over 25% leakdown. Still ran a 9.23 at 146mph. A turbo will just keep filling the cylinders as long as it's not compressor limited.

My opinion is that if you lifted the heads once, you'll do it again. You need to find out why it's happeneing.

What was your A/F ratio on the dyno?

With 18psi I would expect that you would make more power than that, like over 600, maybe 650rwhp?

I have done a lot of research into FI tuning, and I see a lot of fast folks who run in racing series reccomending me that I run 11:1 - 11.5:1 AF on a Dynojet.

A/F ratio was around 11.5:1 thru the whole rpm band, give or take a few tenths. Yeah I think the power should have been more, but maybe the small crossover and log header are now becoming a big restriction.

Bill

I think the problem with lifting the heads is your header. Its creating so much backpressure thats its reverting back into the exhaust runner. Which will create alot of heat and eat up those gaskets fairly quick.

Jose

Jose, if the world broke out into nuclear war, you'd probably blame it on the header.:D

9 times out of 10 when folks do a post mortem, assuming they did not screw up the initial install, it's detonation. If you burned up the gasket between cylinders that might not show as much but it's going to get worse I would bet.

Here's another huge generalization, but when I looked at turbocharging my car when I would see modest HP @'s coupled with big torque numbers it seemed like that's the result of a restriction.

hehe, nahh, actually Bill has a good setup and his 355 definitely has potential to make alot more power. But when the entire motor is flowing through a 2.5" pipe, it doesn't take rocket science to figure out what his bottleneck is. I think if the log was 3" the car would probably pickup a ton of power

I agree.

Not to start a tangent, but itsn't Intmd8 running thru a small log and crossover? JZ what mph does your car run?

John, actually Intmd8 if I remember correctly is running true headers and they are VERY nicely done. I think they are 1 5/8 primaries with a 2.5" crossover pipe. My car isn't done just yet. I'm waiting on some last detail parts from PTK to get this thing going. I really have no idea how it will run. I will be testing 2 different header setups for PTK, so it will be nice to see what the differences are.

One sure way to tell if backpressure is causing problems is to log the torque on the lower head bolts/studs. If you see the torque value on the lower nut drop(but not the top ones), then it's almost a certain bet that it's backpressure. It will most certainly drop once after it's first fired, but once you retorque them they should stay consistent.

Every single lower bolt was loose the last time the head gasket went. Wether or not that was due to backpressure or stretching of the TTY bolts, i don't know. I have never retorqued the head gaskets after initial install. Am i not doing this right? Should it be run and then retorqued after one heat cycle? This would be a HUGE PITA, but if its necessary....

Heat is being kept in the exhaust port due to backpressure and over not much time at all, through normal expansion and contraction of the head, the bolts will loosen. On most turbo cars, we do retorque the head bolts after a few hard passes.