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Discussion Starter · #1 ·
Shortcut to low CR




I was surfing around at auto related pages when i found paeco`s site, they offer copper headgaskets who they claims are blowout proof and reusable a lot of times.
In the text about these gaskets they even talking abouth stacking the gaskets, the drawback are the prices 130$ for ,03" and 190$ for ,06" each.
But if you aint afraid of hand labour you can probably manage to make your own with the original headgasket as a template.

I have calculated an example. The engine ar a F2T with FE3 head and pistons with 11:1 CR

The stock gasket are 1,2mm thick according to Randy at Solomiata.
Buy a sheet of copper plate with a tickness of 3 or 4mm
and you get:
With 3mm gasket 60cc combustionchamber CR=ca 9,0:1
With 4mm gasket 66cc combustionchamber CR=ca 8,2:1
With these CR levels can even the impossible F2T3 be loaded with some serious boost

The text abouth Paeco`s coppergaskets can be found at http://www.paeco.com/gasket.htm

[Edited by FE3T on 03-16-2001 at 12:50 PM]
 
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larger headgasket

Although a thicker head gasket may compensate the problem of a high CR there is also a downside to changing its thickness too far from stock, without having custom worked pistons and heads. Anyways a thicker headgasket is just more likely to blow out since there is more suface area around the bore for detonation pressure to umpinge upon. Especially with high boost applications. Also a 3-4mm headgasket is seriously oversized, in turn it will make the cylinder heads quench areas ineffective, increasing the likeliness of detonation. There might be a suggested reduction of compression that certain head gaskets may indicate for specific work configurations.
 

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Discussion Starter · #3 ·
Re: larger headgasket

Thanks for the reply
I dont think the risk for blowing a copper gasket are bigger than blowing the stock composite gasket even if its 4mm thick. Copper are stronger than the cast aluminium used in the head, it has a higher melting point and a lot more heat transfer capabillity than aluminium.
But a copper gasket requires perfect even surfaces to make a perfect seal.

You claim the risk of detonation becomes higher when using a thicker gasket because this will mess up the designated quenc areas.
if i have understood the principals of using quenc areas rigth, the main function are to consentrate the volume and pressure of the gas/air mixsture around the igniting spark to avoid pockets of air/gas to detonate when the pressure and temprature rising under combustion, a thick head gasket will not affect this at all because the added colume in the combustion chamber will not change the shape of it just add distance betvin piston and the combustion chambers roof

In Norway i now many have succeded using 2 stock headgaskets to lower CR but i dont belive this vill give a long term reliable seal, i`ll rather go for copper gaskets

Of course forged pistons designated for lower CR are the best solution but they costs a lot and easy ways to earn big money are not often legal!
 

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Jsut cutting your own copper headgasket is not that easy. You are supposed to heat it up and cool it down during the process. I have a friend who does this kinda stuff for a living. He said it is a seriuos process to do it right, and I believe him.I've seen his work and trust what he says. I will have him make my headgasket when I need it. That way I know it will be right.
 

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Discussion Starter · #5 ·
Heating and cooling copper

The reason why your friend claims its nessecery to heat and cool the copper plate when cutting it are because copper has a strange capabillity to harden when it get a lot of bending. to make it soft again you have to glow it to release the stress in the material.
When cutting thin sheets of copper its difficult to do without bending the material
I belive this can be avoided with thick gaskets by using a figure saw and hand reamers when you cut it. The best way to cut copper gaskets are probably with laser but thats not a commond hobby tool
PS can you ask your friend about prices and what he thinks about using a 3 or 4mm coppergasket to lower the CR

[Edited by FE3T on 03-17-2001 at 06:30 AM]
 
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