What head gaskets do I need for 20+ PSI? Felpro 1003's failed twice. Any suggestions? Saw 17.5 lbs. of boost by 5000 RPM.

EDITED-1003's-not wireloc's-Sorry.

 

sounds like a cylinder pressue issue.....

i know some people who use 20psi on stock felpros and they live

looks like its o-ring and copper head gasket time for you

 

Thanks ProCharged- did a little test drive today and boom. Hit recall on the tach-6000+-oops.

Any brand recommendations? Looking at the Milodon copper.

 

My machinist freind was telling me about these, he says they make a superior design "loc wire" copy but I didnt see them listed here but you may wish to check into it. cometic has their own web site but the link is temporarily down. http://www.brodix.com/New/page7/cometic.html

 

I'm only running Felpro 1034 gaskets and I haven't had any problems with 20-25 psi of boost on pump gas. I'd be looking into your tune and checking for signs of detonation. You shouldn't be blowing Loc-wire gaskets with just 20 psi of boost.

Cometic makes some very nice gaskets. I've been working on another turbo SBC (1000+hp single turbo 383), and that's what we're using on that one.

I know there are plenty of people who manage to run copper gaskets on the street without too many coolant leaks, but I'd always consider them a last resort for a street app if you cant get a composite or Loc-wire gasket to work.

 

I have to agree with Monty on this one. What is your total timing? Also, how is your fuel system, is it up to par? You shouldn't be having head gasket problems with the lockwire's and 20psi.

 

Thanks guys- the tune is conservative, (22 degrees timing) and I am running 100 unleaded. I do NOT have the heads/block
o-ringed. The gaskets were 1003's.

 

bbunting, i replied to your post on cz28.com with about the same things that blownbird and monty said.

Good luck. Your having some **** luck there right now it sounds like.

 

Thanks-as the tuner at they dyno said- "when you get to the level of horspower you are at now, weaknesses apear one at a time. That is the price you pay to play."

Can I o-ring only the heads? or the block has to be done also? Not familiar with the process. Is it gasket dependent? Thanks

PS- just did a test for effective compression ratio:

Static Compression Ratio 9.2: 1
Boost (psi) 20

Result:
21.72 : 1 Effective Compr. Ratio.

Isn't that diesel territory regardless of gaskets and fuel?

 

You can run the Felpro Lock-wire head gaskets, they require machining of the heads only. I had the lock wire treatment on my last set of heads, and it seemed to work well (I was only seeing 15# though). You may want to seriously think about an intercooler also, your inlet temps are probably through the roof at those boost levels. Without an intercooler, you may want to run race fuel such as VP c16. It is a leaded fuel, but with such a high octane rating, it will have a slower burn rate, and will help with detonation. I highly recommend a LARGE intercooler.
Just my .02, hope it helps.

 

I have seen instances where having a set of very milled heads caused them to blow all the time can this or a block deck surface problem be the case?

 

the block is decked, and the heads have been trued. I think that the seal was good, just too much cylinder pressure? Might have to change to a smaller pulley on the charger?

 

Depending on your tune, i've heard stories of head gaskets going from too rich of a condition...like REALLY rich

 

sometimes too ideal of a cam can actually be a problem, generating too much cylinder pressure for any head gasket to hold back. a goo example is the hott cam, it is designed so well to generate awesome cylinder pressure that in some cases when used with heavy boost no gaskets can hold back the cylinder pressure. sometimes bleeding off a little cylinder pressure is required to have some consistent and dependable gasket sealing the old cant get something for nothing and dealing with comprimise is required. top fuelers blow the head gaskets every pass. EZ street cars get only one or two passes on a set as well. I wrote about it here https://www.thirdgen.org/techbb2/sho...threadid=83372 and someone else made a worthy contribution too.

 

Is possible that the work performed was not good enough for an extreme situation as yourself.

Also doesn't the finish on deack/cylinder heads have to be rough enough so that the mating surface can "bite" into the gasket material.

If the gasket(s) are failing in the same area, I'd would check to see if there was a "low" spot there, either deck or cylinder head.

 

Good point-the first time the gaslets failed, it was one side of the motor, and we resurfaced the heads (was a small gap). The block was decked prior to assembly. This time BOTH sides failed.

 

Where did the gaskets fail?

a common problem with big boosted motors is between the adjacent cylinders on each bank. An old trick is to tap off the water pump and drill/tap into the water jacket of the cylinder head between the siamesed combustion chambers. This is where detonation starts and cylinder pressure is high also and it is common for them to break there

maybe tap off the water pump and bring a line there and see what happens

 

that is the other thing see sometimes when a certain amount of material has been removed from heads/deck sealing can be a prob due to distortion (I could only imagine what kind of forces exerted with 20#)