Then why doesnt top fuel use them? Ive run steel shim and copper gaskets well over 600hp with great success. Not so with the stocker. Ive ran 124+ mph a few times and had zero KR and still had failure in some instances. The engineers went to that gasket because it was better for the given application. It seals coolant better, and is more reliable over time for the hp GM intended it for. Steel shims have been known to rot out and leak in service over time. The graphite gasket was used in all 3.8 v-6's from 86 up. Even non turbocharged applications. GM never intended our engines to be anywhere near what they are today. I cant think of one car that has run more than 10 passes over 130 mph with stock gaskets and iron heads unassisted by o-rings and or pinning the heads. Even then its not worth the hassle with the gaskets available today. There are simply not enough bolts to clamp the stock gasket in these applications and the compression will burn out the gasket on the intake side and cause failure in that area from head/deck deflection under the pressures its seeing. I agree with using the stock gasket as long as the car wont go over 120mph in the quarter and it must never see detonation at all. Keep in mind, we cant simulate the procedure GM used for tourqeing the fasteners. A multi-tooled spindle that cranked them down all at once. Impossible for us to do at this time. Apparently they are working for you but that is not the majority at the hp levels we are pushing.
I have finally join the blown head gasket club
- Thread starter SloGN
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Then why doesnt top fuel use them? Ive run steel shim and copper gaskets well over 600hp with great success. Not so with the stocker. Ive ran 124+ mph a few times and had zero KR and still had failure in some instances. The engineers went to that gasket because it was better for the given application. It seals coolant better, and is more reliable over time for the hp GM intended it for. Steel shims have been known to rot out and leak in service over time. The graphite gasket was used in all 3.8 v-6's from 86 up. Even non turbocharged applications. GM never intended our engines to be anywhere near what they are today. I cant think of one car that has run more than 10 passes over 130 mph with stock gaskets and iron heads unassisted by o-rings and or pinning the heads. Even then its not worth the hassle with the gaskets available today. There are simply not enough bolts to clamp the stock gasket in these applications and the compression will burn out the gasket on the intake side and cause failure in that area from head/deck deflection under the pressures its seeing. I agree with using the stock gasket as long as the car wont go over 120mph in the quarter and it must never see detonation at all. Keep in mind, we cant simulate the procedure GM used for tourqeing the fasteners. A multi-tooled spindle that cranked them down all at once. Impossible for us to do at this time. Apparently they are working for you but that is not the majority at the hp levels we are pushing.
I agree with everything you've said except the relationship between blowing a stock gasket and HP and MPH. I think it's better to relate it to boost. I can run 126 MPH @ 20 lbs. of boost. At that amount of boost they'll never blow.I should be able to run 128-130 if I raise the boost. I think if you run a bigger turbo and injectors,instead of raising the boost,you can run 130 mph with less boost and not blow the gaskets. That's alot of power. In reality we all tend to maximize our turbos before going to a bigger one. Mostly I think the stock gasket doesn't get the respect it deserves.
I dont think the boost number means much. Ive run 30 psi on stock head gaskets on unopened engines with no problems. Cars trapped around 120 mph. The bmep in the cylinder on a similarly cammed same cube engine with similar intercoolers at the same raceweight will be very close for a given mph. Therefore the cylinder pressures are nearly the same on both engines regardless of the intake manifold pressure. But like you said its better to be able to get it done at 20 psi vs 25+. Thats a very respectable number for an iron headed car that has a 67 trim exhaust wheel with only 20 psi. Have you run the car at the stip yet? Locked or unlocked? I used my old g-tech on an old build and the mph was always 4-5 mph higher than i trapped at the strip while using it at the strip. My best on the street was 11.30@ 134.6mph
. The e.t. was always within a few hundredths at the strip depending on the depth of the stage. I give the stock gasket a lot of credit since its been run on the grenade mode for 20+ years in some instances and not failed.
This is a good example of why we shouldn't look at any one thing. Once I took the intake off and realised how restrictive the ports on the intake were (where they met the heads) I got excited about the gains I would see from matching the ports to my ported heads. Remember,the pressure we see on our boost guages is the pressure in the intake manifold. The pressure we have in the combustion chamber is another thing.I think it's correct to assume that when we go from a stock un-opened long block to a roller cam,ported head,port matched intake,the pressure in the combustion chamber rises significantly at any given boost.I think this explains why you and I were able to run more boost,more easily before we opened up our intake streams. I never blew a gasket before I did this. I lock my converter. I've never been too the strip,but a friend has. He reported that the MPH.was 3 MPH higher on the G-tech than the trap speed at the track and the time was within a tenth,SO SHUT UP. Too bad I can't leave as hard as I'd like.When I went 126 MPH recently it was with blown head gaskets. Anything above 19 PSI and I would hear that distinct popping sound. This was done with 93 octain and Lucas octain booster. No Alcohol.
