Fen

Surely the likey reason that your stock gasket blew catasrophically and the WideFire didn't go so bad, TurboX, is that the stock one was years old and the WF was new? Either that or just dumb luck.

I looked into this some time ago as we had people on the UK board thinking the WF was something other than expensive junk and someone on here (search will be your friend but I think Danno) had looked into it and found that they are the same save that the stock gasket has a steel ring that is effectively a flat section rolled, overlapped and squashed flat. In contrast the WF steel ring is only C-shaped. It extends further onto the gasket (though bizarrely on the head side rather than the block side where I'd expect the heat to be more direct) but it has only a single thickness of steel between the chamber and the fibre material of the gasket itself. The stock gasket with the rolled and overlapped ring has 2 layers of steel of course.

On that basis it looks to me like the WF isn't even as good as the stock gasket.

I have a Cometic BTW, but I haven't run the car with it yet. When I told the guy who balanced my bottom end he said they were great - he used to build engines for the Nissan team in British Touring Cars and they used them - 5 times before they replaced them! - he said he'd had one engine that detted and the top of the bore itself was destroyed but the MLS gasket was still fine.

Ian Carr

i guess im just a lucky some beach. Now if i could get it so i dont blow head gaskets at all i would be even luckier!

johne

Ian, have you check out your AFR's especially at WOT? Going lean is often a cause of detonation, which pops headgaskets.

hope this helps,
John

por4ever

<<<he said he'd had one engine that detted and the top of the bore itself was destroyed but the MLS gasket was still fine.>>>

I thought that was the point of a HG. It is supposed to blow before you destroy your head or block.

OriginalSterm

i ordered my cometic gasket directly from them. make sure you specify it's a turbo application so you get the "hp" version. costs a little more than what is shown on their pricing page though. still not installed however...

Chris White

I have ‘popped’ a Cometic – it is possible! Plastic deformation of the main gasket due to prolonged running at high boost - one hour long track session at Watkins Glen.

If you are going to use the Cometic make sure that the head and block are very straight and true, other wise they will leak compression and coolant.

I also prefer to use stock studs with the Cometic and ARP/Raceware with stock & Widefire.

Chris White

OriginalSterm

why is that?

Chris White

The whole point of the head and head gasket ‘system’ is to provide a sufficient clamping force to keep the head sealed. The stock studs are a stretch type fastener - it stretches (just a little) as you torque it to spec – kind of like a bungee cord. This allows for some movement while keeping the clamping force.

The ARP/Raceware studs are not a stretch type fastener. Any change in tolerance can result in significant changes in clamping forces.

So, it sounds backwards to suggest the combinations I mentioned – until you accept that there will be some changes in dimensions due to heating / cooling. In my opinion it is not a bad idea to have some resiliency built into the system – either through the compressible gasket (stock or widefire) or an elastic stud. The Cometic & ARP/Raceware combination will work but you have to have a perfect starting point – machined head, block and proper torque sequence.

Chris White

DanG

Chris, starting with an o-ringed head already, what gasket would you recommend for replacement - stock or WF? I don't have a groove in the block, just the oring in the head. Is it worth it to get the block grooved while everything is apart, or is the oringed head effective enough on its own?

Chris White

Wide fire is pretty much the only way to go with a head that is already Oringed.

DanG

Ok, easy enough. Thats what was in there already, just checking. Thanks.

macnewma

Chris (or anyone else), if you had your choice of Cometic, WFHG, or stock HG for the following car, what would you do?

Said 951:
1. 15 psi at most on a k26/6
2. No o-ring
3. Neither head nor block milled
4. New stock head studs

Please explain your reasoning. Thanks!

Tom M'Guinn

If any of you guys are looking for tips on how to blow a head gasket, just let me know.

Evan70

That's easy, original headgasket and 17psi of boost.

Chris White

Stock HG is fine

The widefire is needed to provide an area for the O ring to seal - no O ring no need for widefire. Then again the wide fire is not that much more $ and it won’t hurt anything.

Good points for the Cometic –
You can get it in any cylinder size – 100mm to 108mm in .5mm increments
You can get it in many different thicknesses, from stock to .065” (more if you really need it)
You can get the HG in ‘HP’ form – the cylinder rings are thicker than the block sealing area – in effect a way to increase cylinder clamping forces.

Bad points –
Can be difficult to get a good seal if all the parts are not square and flat

Chris White