Cometic Head gasket VS Boost

[3diamond]

Question: How much boost can a Cometic headgasket handle.

15 psi, 20psi, 25psi,30psi

Seeing as they have orings in them.


I've been told by some people that they tend to move around because they are so smooth and also they eat away the cylinder head becasue its metal.

Do these headgaskets need sealant before installing, for example a spray of hylomer spray, that blue stuff.

What sort of compression ratio do thse gaskets give the engine with the engine being stock 8.5.1

If the comp ratio is 9.0.0 (roughly), how much boost could i run with that comp ratio.

 

[bazeng]

Boost would depend on fuel and turbo.
the cometic should be good for anything you throw at it providing the tuning and hardware up to the task.

They are pretty much on par with HKS / Tomei at half the price...

I've been told by some people that they tend to move around because they are so smooth and also they eat away the cylinder head becasue its metal.

Never heard that one before, but as above, it'll be just like the HKS / TOMEI..

Do these headgaskets need sealant before installing, for example a spray of hylomer spray, that blue stuff.

Use copper spray before application

What sort of compression ratio do thse gaskets give the engine with the engine being stock 8.5.1

What is the thickness of the stock gasket?
compare by that, otherwise, you'll have to CC the head / block and add the gasket thickness when compressed.. (try to get the compressed figure)

If the comp ratio is 9.0.0 (roughly), how much boost could i run with that comp ratio.

9.0 is quite high!, but if you want big boost, this comp ratio is a little high imo, aim for low 8's unless you want some big off boost torque...
but with the right fuel, you could run big boost on the comp ratio...

From what i recall, Cometic only do a 1.1mm gasket (or something like that)... HKS do a 1.6mm and 1.1mm... Tomei do a 1.1mm, 1.6mm & a 1.8mm...

Another factor to think about is HEAD STUDS, make sure u get some ARP studs, this will help hold the head down..

hope it helps

 

[3diamond]

Top stuff, in depth info greatly appreciated.

 

[EVO-00X]

From what i recall, Cometic only do a 1.1mm gasket (or something like that)... HKS do a 1.6mm and 1.1mm... Tomei do a 1.1mm, 1.6mm & a 1.8mm...

Cometic have a bunch of thicknesses to choose from so suit a 4G63T :wink: I couldnt get what I wanted from any shop in Australia that I had to order from o'seas A properly shaved and machined block/cylinder head and some ARP head studs would be recommended.

 

[bazeng]

Cometic have a bunch of thicknesses to choose from so suit a 4G63T

I tried chasing a 1.6mm gasket, but i couldn't find any (discontinued)
i had to go for the expensive jap stuff...

 

[3diamond]

What is the correct torque settings people use for the 4g63 with t6his type of gasket.

35 then
55 then
85 nm

 

[EVO-00X]

I tried chasing a 1.6mm gasket, but i couldn't find any (discontinued) i had to go for the expensive jap stuff...

Yep, thats the exact same one I got from http://www.topendperformance.com a couple years ago. Part number C4-234-065 ((86mm 0.65 MLS) (1.651mm)).