Boost on composite gasket

[blk92suprat]

For the people who have installed oem style composite head gaskets with arp headbolts> > what boost pressure do you run on a normal basis?

Trying to get an estimate on how durable a composite head gasket is when torqued down properly givin that the engine and cooling system are in good working order.

Im doing 10-11 psi for around 2 years now.

 

[starscream5000]

I wouldn't personally wouldn't go much higher than that. 12 at most if it was my car and setup.

 

[viper92086]

13psi on na-t for about 1.5 years daily driven up until this summer

 

[Doward]

Depends on the turbo you use. Low IATs will help for sure.

That said, I ran 16psi from a 57 trim CT26 and the 212k mile rings let go before the fresh FelPro head gasket.

 

[Angry7M]

Ive been running a Fel Pro head gasket at 10 psi for almost a year now.

 

[blk92suprat]

Depends on the turbo you use. Low IATs will help for sure.

That said, I ran 16psi from a 57 trim CT26 and the 212k mile rings let go before the fresh FelPro head gasket.

Thats pretty sweet. The gasket problems are due to low torque specifications. A fresh FelPro gasket with arp bolts torqued properly should last at moderately elevated boost pressures. ( 12-14 psi)

Im refering to CT-26 stock or upgraded.

 

[GrimJack]

Depends on the turbo you use. Low IATs will help for sure.

That said, I ran 16psi from a 57 trim CT26 and the 212k mile rings let go before the fresh FelPro head gasket.

QFT. Too many variables to try to figure out a realistic value. Intake temps are affected by a lot of things, intercooler type, turbo, IC pipe routing, cold air intake or not, etc. Then add in the fact that every turbo / ic / ic piping setup produces different psi readings... and you end up trying to calculate an equation with 40 variable inputs to guess at a sliding target.

Best bet is to take it to a dyno and crank up the boost until you can hear knock starting with a set of electric ears, then turn it back down some.

 

[IJ.]

Keep it out of detonation and it won't fail.

I used to run 30Psi on my old tt 3.4L Toyota V8 in the 240z and never suffered a failure as it NEVER skirted detonation.

Tune on the ragged edge and you're asking for trouble on any gasket as the stronger the HG means you're just moving the point of failure to the next weakest point (ringlands in this case)

 

[suprabad]

I used to run 30Psi on my old tt 3.4L Toyota V8 in the 240z and never suffered a failure...

I'm pretty sure your abilities and access to info as well as proper equipment are not representitive of the average crescent wrench wielding "I better check with my mechanic" tinkerer on this site...

If you get much past 10psi and experience any detonation with a composite head gasket.....ka-pop!

Hell...composite hg's fail at much lower boost if something else on the motor isn't right (cooling system, tune, etc.)

 

[IJ.]

I have a crescent wrench or two

My point is a comp HG isn't the instant fail that everyone makes it out to be just as a MHG isn't the fix all everyone seems to make it out to be in a 7M

Either done badly WILL fail.

 

[Quin]

Keep it out of detonation and it won't fail.

I used to run 30Psi on my old tt 3.4L Toyota V8 in the 240z and never suffered a failure as it NEVER skirted detonation.

Tune on the ragged edge and you're asking for trouble on any gasket as the stronger the HG means you're just moving the point of failure to the next weakest point (ringlands in this case)

This. I ran 15PSI on a 60-1 (as did the previous owner, he did a few bursts of 17PSI as well from what I understand) and boosted quite a lot (again, as did the PO) and the HG looked perfect when I took it off, no signs of it starting to give anywhere. Mk3Brent ran 20+ PSI on some serious turbos for a long time on a stock HG, and his only ended up failing because of detonation. I know there are others making good power on relatively high boost with no issues on composite head gaskets, and they're doing just fine because they're staying out of detonation. Personally, I'd rather BHG than break a ring land (having just finished repairing both (not really a blow HG, just had a serious problem and I was nervous about it so I replaced the HG before the motor went back in).

Another interesting bit, not DIRECTLY related but of the same concept. I know several domestic guys spraying pretty big shots of nitrous on composites (they all swear by Fel-Pros too). Some of them have even re-used Fel-Pros and been fine. I wouldn't recommend the latter at all, but it serves as an illustration, it's not the composite HG that's the problem.