Bigpower

Was at the garage today and I heard someone ordering a tripple steel head gasket. After asking the owner what the hell a tripple steel head gasket was, he explained that people are usuing large head gaskets to increase the capacity of the cylinders. My question is can you get away with that without having to alter everything else to suit? I.E fuel, injectors and valves etc....

would lower compression ratio surely and would need some other mods in my limited knowledge

if you go OTT, it will lower compression ratio and retard the ignition timing.
i suppose its one way of restoring standard config if youve had the head skimmed quite a lot tho

he could have been talking about a triple layer metal headgasket tho, which is 3 slim metal gaskets, bonded in a few places. theyre stronger than the usual paper ones. i have a TTE one in my shed for when/if the head explodes on my GT4

boxy wrote:Was at the garage today and I heard someone ordering a tripple steel head gasket. he explained that people are usuing large head gaskets to increase the capacity of the cylinders

The capacity remains the same but the Compression ratio will be lowered

If a gasket is thicker, lowering compression, it must also increase the capacity.

I think the theory goes that the increase in capacity (above the swept volume of the cylinder(edit)) enables you to compress more fuel air mix into the cylinder - usually associated with running higher levels of boost.

Perhaps some of the boys running big single tubbies on r32s can advise?


~Mark

GTRJazz wrote:

boxy wrote:Was at the garage today and I heard someone ordering a tripple steel head gasket. he explained that people are usuing large head gaskets to increase the capacity of the cylinders

The capacity remains the same but the Compression ratio will be lowered

That baffles me, the piston can only go so far into the cylinder (stroke). So if the cyliner is lengthened then surely the capacity is increased and the stroke stays the same. Also surely compression will be lower as teh piston does not compress a smaller volume of air or am I talking bollocks?

Using a thicker head gasket doesn't affect the capacity, it just alters the clearance volume (and hence the compression ratio).

Since the bore and stroke don't change there's no change to the capacity

Surely that would be true in a NA application, where you are relying on the stroke to fill the capacity. But in a boosted application it is the boost that fills the capacity and this is down to volume?

Simple physics shows capacity = volume. Volume is increased by increasing the cylinder length, regardless of stroke.
http://en.wikipedia.org/wiki/Volume

isnt engine capacity

stroke x ((pi x (0.5 x bore diam)) squared) x # of cylinders