There could be some correlation, but I would be surprised if its extremely significant. Perhaps there is some resonant frequency or something occurring somewhere in the upper range that is rocking the cylinders. I would say that torque output is a far less convoluted indication of cylinder pressures than horsepower (torque at higher RPM) or boost levels.

Just because yours failed at 700 doesnt mean it couldnt hold 800-900-1000, or could have failed eventually at 600. Dont forget the fatigue and wear factor. Just like we can run a stock engine at 800 for a while... it will eventually fail, but when it does, you might only be running 600 at that moment.

Actually there was a guy on the forum several years ago Hojin and he had his manifold fail at least twice at 25 and 26 psi. I believe he was at 9:1 compression.

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Compression ratio wouldn’t make a difference. 25-26 is pretty high for a VQ, as they will generally be nearly 1000whp by then if the turbo system is staying efficient. Probably an exceptional case. Seems like 1000hp is right on the tipping point in more ways than one.

Agreed, and that is what he was pushing.

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Yea as Bob (hotrodz) mentioned, if it aint broke, don't fix it. lol. I was trying to fix BEFORE it broke but it sounds like many are having great look with the OEM manifold. Really appreciate the feedback all that the stock manifold can hang

Wouldn't the closed deck and the Cosworth upgraded Head Gasket help with that?

I miss Hojin! Dude became a Dad and then *poof*. lol

I hadn't realized he had his manifold blow, wonder what he did to correct the issue. I'd imagine if it did crack, it's not a devastating repair.

They may help or extend the life of the headgasket seal, but we have discovered they are not an end-all fix for the 1000+ HP VQ. They are still letting go in that power range.

Bob sold him his GTR manifold upgrade a long time ago. LOL
As far as the Cosworth head gasket. There is a better quality one out there. Seb knows which one it is. I gave that info to him and he ordered one to check it out. He liked it from what I gathered.

When my motor was built I was told that Cosworth discontinued the VQ head gaskets so I had to get Cometics. When I had my boost cut issues , I was spiking 27.3psi and after going back to a lower map at 18psi there was no problem. As for the question of compression ratio I'm one of the few tweeners running 10:1. I'll say again I low key wish I had gone with 11:1.
And for sure Seb is gonna grill you to death about the build. I was legit panhandle begging, complete with puppy dog whining to get him to give me 21psi and it did'nt help that the gf was sitting there reading and supervising my response to his email. GF: "You don't argue with Seb, he said that's enough so you're done!!!" Me ( In my Slingblade voice ) : "Aight den."

He never recovered after the last failure. He said he was going get the car up and running again and then he had another baby.:bowrofl:

Hopefully he still has it and didn't sell it.

We talking whp range or base? Really liking being able to keep the Z at that 875whp Mark. It’s so beautiful. Lol

Since its a gray area you could consider it either/or. 875whp is beyond what some cars have lost headgaskets at already.

Just be aware, it can cost you 20k if a headgasket let's go and a long wait. You may get lucky and have no block damage which means it will be cheaper if you want the same result. It's a crap shoot.

Ya its very hard to say. Nobody has pinpoint a root cause of the failures yet. There is a handful of suspects, but none that are really standing out. We will figure out more in time, as more people seem to want to push higher power lately... or at least those who are, are being open about it and sharing information. Who knows, you may be in the clear. There could be some factor or "magic" combination in your engine that does the trick. So I/we arent trying to scare you so much as just warn you that so far, everyone else on record is having issues in that territory. Most people, including me, have only had a single headgasket failure occur in our own hands. So the examples are still few.