Copper Head gaskets. any good??

[Fast31]

im in the process of putting together a RB25, and my dyno tuner has suggested using a copper head gasket to reduce the compression to around 8.4:1.

i know a HKS gasket would be the best bet but im not paying the massive money they want.

What are your experiences?

[adam 32]

sydneykid posted some really useful information about head gaskets a while ago, altho i cant remember exactly what he said! maybe try a search and see if u can dig up the thread

[DennisRB30]

I have heard that reducing CR with a thicker gasket does not do as much good as it might seem. Apparently it interferes with the combustion chambers squish area, its sort of 2 steps forward one step back. The turbulence in the combustion chamber gets reduced because the piston no longer comes close enough to the squish area in the head, this effect somewhat offsets the lower CR (turbulence caused by the squish area is important for mixing the fuel and air to reduce detonation) It makes enough sense, exactly how important it is I don't know? It's worth a looking into anyway.

[wcbjr]

I have heard you need to use sealant for copper gaskets.

I doubt there is much negative effect of a thicker gasket, HKS, Tomei, etc. all sell thicker gaskets. They are the only ones I see being used on high horsepower cars.

[amosite]

Never ending dramas with leaking water jackets!

They are a thing of the past and will stay there.

Do japs use them?

Do Yanks use them?

[Steve]

If you need a HKS gasket, I think Merli had one he was selling for a very reasonable price, around $500, think it was a 1.6mm which will drop CR to 8.6:1.

The japanese have been running 300+rwkw with these gaskets no probs, so I think they are good insurance if you are thinking of heading up around that hp. An 8.6:1 CR will definately be more boost friendly than the stock 9:1 - never hurts to have a bit of insurance, probably why the GTR runs 8.5:1 CR.

[lukevl]

DennisRB30: What you said is correct and very important. There is a lot of R&D in the squish area of each (good) IC engine. While the thickness increase is not much, and the effect of turbulence isn't much either, it sort of is a step back at the same time. Look at the US Hondas- high CR and turbos, fast times, because of Honda's superior squish design. (Combustion chamber and pistons)

The best way to decrease compression would be via different piston crowns. The people in the piston manufacturing business are very knowledgeable in this area. Although not cheap.

For an application that isn't insane, the thicker gasket would suffice I believe. But the more boost, RPM and power that is involved, the more it would take its tole.

[GiJOr33]

you can use the standard nissan head gasket if the block is O-Ringed. I like the idea of 9:1 CR as it means a good power curve and better off boost drivability. I spose if you have forged pistons and rods you can have high CR (or at least stock 9:1) and high boost 1.2bar +

[Sydneykid]

Aahh amosite, sorry but I just gotta respond

*Never ending dramas with leaking water jackets!

I have not had that problem, what engines?

*They are a thing of the past and will stay there.

Shoot I did a 900 bhp engine with one last week, is that past enough for you?

*Do japs use them?

Don't know, I haven't asked the 127 million (based on the 2000 census) of them yet, might get around it next millenium.

*Do Yanks use them?

Do they ever! I was at Indianapolis Motorsport Week last year and there were over 1,000 engines there and almost all had copper head gaskets.

Like all things mechanical, there is a right place and a wrong place for most things. Don't knock it until you are sure you have explored all the facts.

[Sydneykid]

As others have posted, I am a big fan of the standard Nissan head gasket with stainless steel O'rings, preferably in the block, but the head can substitute if necessary.

[Fast31]

what do you use to seal them up sydneykid????? and do you anneal them first

[Sydneykid]

O'ring the block and no annealing