Cosworth head gasket. Better?

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project-c2
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Cosworth head gasket. Better?

Post by project-c2 »

I currently have the setup below:
Doc Race turbo mani
Turbonetics T04E
Stock cylinder head mild port job
236/242 OEM cams
Eagle H Beams
Wiseco pistons (9:1)
ARP head studs
Felpro HG
ID1000 injectors
Z32 MAF
Nistune ECU

I have checked the block and head for warpage and get nothing. Well, a .001" feeler gauge will not fit under my straight edge. I take my car to the dyno and is laying down 431 HP and 442 TQ. Everything looks good on the dyno and it is a clean run. But I have been noticing that I am getting combustion pressure leakage into my cooling system (verified with a block test) This is the 3rd set of ARP studs and HG I have changed for this issue. I was wondering if I would have better luck with a Cosworth HG? I have tried Cometics before and blew it at 10 psi boost. But is the Cosworth really that much better??? Also I tried the search button but there is really nothing on surface prep for this gasket.

Thanks in advance,
Cory
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nissanfanatic
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Re: Cosworth head gasket. Better?

Post by nissanfanatic »

What are you torquing the head studs to? I never torque past factory spec on the 10mm studs.

Seems extremely odd that you blew a Cometic at 10psi...(?) I never had a problem on Cometic+ARP up to 32psi on a T04R.
-Cory

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supakat
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Re: Cosworth head gasket. Better?

Post by supakat »

I have had better result with Cosworth over Cometic but I also had advanced boost timing with Cometic that lifted the head and separated fire ring. What degree are you at with 10psi? 93 or E85?
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project-c2
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Re: Cosworth head gasket. Better?

Post by project-c2 »

nissanfanatic wrote:What are you torquing the head studs to? I never torque past factory spec on the 10mm studs.

Seems extremely odd that you blew a Cometic at 10psi...(?) I never had a problem on Cometic+ARP up to 32psi on a T04R.
Torqued headstuds to instructed 70 ft/lbs with Snap On electronic torque wrench.
project-c2
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Re: Cosworth head gasket. Better?

Post by project-c2 »

supakat wrote:I have had better result with Cosworth over Cometic but I also had advanced boost timing with Cometic that lifted the head and separated fire ring. What degree are you at with 10psi? 93 or E85?
15* ish on the last load cells on the max rpm (6800 rpm) and running 19% alchohol, 65% 92 pump, 16% toluene IDK gasohol blend that we are experimenting with. No knocking or detonation via plug chop. Also no damage to anything else verified with a bore scope. EGT stable around 1300 deg on the top end. Although the first time around I stretched the heads studs and had to replace everything. Could it be too aggressive of a timing on the bottom end? I do peak 442 ft lbs @ 4500 rpm.
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nissanfanatic
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Re: Cosworth head gasket. Better?

Post by nissanfanatic »

I did too originally and they stretched. Now I only torque to 60lbs ft. YMMV.
-Cory

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project-c2
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Re: Cosworth head gasket. Better?

Post by project-c2 »

nissanfanatic wrote:I did too originally and they stretched. Now I only torque to 60lbs ft. YMMV.
Cool. Another Cory. LOL Hmm sounds like a good theory.
ka240de
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Re: Cosworth head gasket. Better?

Post by ka240de »

yeah i once torqued my arp 10mm to 73 ft-lbs but it wasn't started. hopefully i didnt wreck them. i see id probably only torque them to 60 ft-lbs for an n/a build and maybe 65 or so if i boosted. but i do plan on going bigger studs one day.

no one has mentioned ;
kedbmx's 12mm arp2000's held 10:1 compression , 42 lbs of boost, 8000+ rpm, and 225 horsepower per cylinder !
cosworth gasket correct me if i'm wrong
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