thicker headgaskets

[Calum]

Just wondering what you guys think of using thicker head gaskets to decrease compression? After seeing the abuse the stock bottom end has gone through, it shouldn't have any problem with the power I'm looking for. But the compression ratio and my crappy gas are going to be a problem. Of course I could use aftermarket pistons & rod, but at the ~275 whp I'm looking for they seem like a big waste of money. And I really don't think I'd need to go all the way down to 9:1 static compression.

So, does it seem reasonable to use thicker head gasket for my application?

Also, for the tuners out there. How low would I have to go with the compression to make 275-300whp reliable with 91 octane?

Thanks guys

[Mobius357]

HKS has a head gasket the reduces the CP to 12.4:1, not much of a difference.

[Tansey86]

Headgaskets arent going to lower you enough to have more boost be tolerable on pump gas.

You can make 275rwhp on less than 8 psi which is within the tolerable boost level for 93 octane.

[JP]

need to keep in mind the cam timing changes when you use a different thickness headgasket or deck the block/head.

[Calum]

Originally Posted by JP

need to keep in mind the cam timing changes when you use a different thickness headgasket or deck the block/head.

I don't think that would matter much with cam phasing and tuning, but it is a valid point to consider.

[Calum]

Originally Posted by Tansey86

Headgaskets arent going to lower you enough to have more boost be tolerable on pump gas.

You can make 275rwhp on less than 8 psi which is within the tolerable boost level for 93 octane.

Without knowing the volumes of the combustion chamber, OEM headgasket, and piston dome, I can't do the math to come up with a gasket thickness delta to compression ratio delta that's accurate. But a thicker gasket, from someone like cometic, could easily drop the compression ratio to about 11.5:1 from 12.5:1.

I know 11.5:1 still sounds scary as hell for boost but when you look at what's been done already with this engine and this combustion chamber I'm hoping it would be enough.

Also, as is stated in my original post, I have to use 91 octane.

[Tansey86]

Originally Posted by Calum

Without knowing the volumes of the combustion chamber, OEM headgasket, and piston dome, I can't do the math to come up with a gasket thickness delta to compression ratio delta that's accurate. But a thicker gasket, from someone like cometic, could easily drop the compression ratio to about 11.5:1 from 12.5:1.

I know 11.5:1 still sounds scary as hell for boost but when you look at what's been done already with this engine and this combustion chamber I'm hoping it would be enough.

Also, as is stated in my original post, I have to use 91 octane.

Ah yeah 91 octane isnt the best. If you can drop a full point im sure you will be able to run enough boost to make 275 wheel. On 93 tuners haven't been noticing any problems with almost 10psi on 93.

I'd say the biggest thing to take into consideration in your situation is your tune. Just try to get the most out of 91 by consulting a local tuner and if need be, drop the compression afterwards. Im sure a drop in compression will allow for 3-4 more psi on the safe side.

[sw20kosh]

I don't see what the worry is. Full blown kits are on like 3 customer cars running 91 octane and delivering 310 whp. If you are concerned with longevity turn down the boost on this kit.

[FullBlown]

We've done tons of S2000's with high comp and turbos. Although the S2000's compression is lower then the FA20, it is very similar when it comes to tuning. Turboing modern factory high comp motors are not as dangerous as it used to be.

We were making over 850hp on E85, which required an extra set of injectors to tune for it. When we found out that this was direct and port injection, we felt very comfortable tuning this and pushing its limits.

I have found that most of the time, the oem gasket will be more reliable then any aftermarket gaskets out there. I've seen many thick aftermarket gaskets blow out on low boost.

[Calum]

Originally Posted by FullBlown

We've done tons of S2000's with high comp and turbos. Although the S2000's compression is lower then the FA20, it is very similar when it comes to tuning. Turboing modern factory high comp motors are not as dangerous as it used to be.

We were making over 850hp on E85, which required an extra set of injectors to tune for it. When we found out that this was direct and port injection, we felt very comfortable tuning this and pushing its limits.

I have found that most of the time, the oem gasket will be more reliable then any aftermarket gaskets out there. I've seen many thick aftermarket gaskets blow out on low boost.

So, what would you suggest for my application?

[FullBlown]

You will be fine with 91 octane and that power level.

[rusty959]

If you are that concerned about it and willing to go through the difficulty and cost of replacing the headgasket, couldn't you just run meth or similar for times of "high" boost?

[TouchMyHonda]

Originally Posted by Calum

Without knowing the volumes of the combustion chamber, OEM headgasket, and piston dome, I can't do the math to come up with a gasket thickness delta to compression ratio delta that's accurate. But a thicker gasket, from someone like cometic, could easily drop the compression ratio to about 11.5:1 from 12.5:1.

I know 11.5:1 still sounds scary as hell for boost but when you look at what's been done already with this engine and this combustion chamber I'm hoping it would be enough.

Also, as is stated in my original post, I have to use 91 octane.

What you seem to over look is that this engine is also direct injected. So your crappy gas is still being burned more effectively than you think. If you have a half ass decent tuner they should have no problem mapping for the correct air to fuel ratios for Ur 91.

[Calum]

Originally Posted by TouchMyHonda

What you seem to over look is that this engine is also direct injected. So your crappy gas is still being burned more effectively than you think. If you have a half ass decent tuner they should have no problem mapping for the correct air to fuel ratios for Ur 91.

Theres a lot more to it then just getting the right air fuel ratio. If a tuner was only going to tune the fuel on this engine, even staying NA, I would run away as fast as I could.

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