exactly how does a high comp headgasket work?

[Dirtbag]

My current knowledge of a headgasket is seals the head and block on each other, i hear about thinner high compression headgaskets, this brings the head closer to the block, meaning less room above the piston at the top of its stroke thus high compression?
With this decrease in space, does that also decrease the total displacement of the engine? And if so, is there some trade off for higher comp versus displacement?
And what kinda difference would be expected if you fitted a higher comp head gasket on an engine, such as mine, 20v silvertop? more power somewhere in the range? less fuel usage more fuel usage? birds pooing on car more?

I am kinda baffled about the whole thing

[crnkin]

the capacity is measured by the bore and stroke of the piston, the headgasket changes the capacity in the combustion chamber, thus changing comp ratio.

Higher comp means lots of things, but not capacity, if you wanna know more start a thread maybe about high/low comp, but im assuming you know most of the basics

yall

[Dirtbag]

ahh i see, so would higher compression headgasket make any difference for my engine if i got one?

[RomanV]

the capacity is measured by the bore and stroke of the piston, the headgasket changes the capacity in the combustion chamber, thus changing comp ratio.

Higher comp means lots of things, but not capacity, if you wanna know more start a thread maybe about high/low comp, but im assuming you know most of the basics

yall

The combustion chamber consists of two parts:
A fixed volume, and a variable volume.

A thinner head gasket removes some of the fixed volume, making the effects of the varaible volume more pronounced. (eg. it raises the compression ratio)

So what he's saying is technically correct, you do lose a small amount of displacement in real terms, but not according to how combustion volume is calculated.

[crnkin]

yes, but i thought that was obvious ... anyways, high comp possibly equals more power, dependant on a few things

[matt dunn]

you do lose a small amount of displacement in real terms,

No you dont loose any displacment.

You can pull the head of an engine and throw it away,
then you can get out your calipers, measure and work out the displacement, so how the hell can a gasket change it.


Displacement in the bore X stroke.
A 1600cc engine has 1600cc of volume displaced by the piston between TDC and BDC, which does not include the space in the combustion area.

[CozmoNz]

so why do they make a huge deal in motorsport events? eg the ca18det being a 1809cc engine, is not allowed into 1.8 litre classes....

when therefore all the 1799cc engines will ACTUALLY be closer to 1805cc with the fixed combustion chamber volume calculated and added....

odd....

[SUBARUCONVERT]

i think u will find the Combustion chamber will be alot bigger than 1cc. Its nothing to do with the combustion chamber when calculating displacment. The ca18 is 1809cc how u have stated, obviously it wont be let in to a XXXX-1799cc class as its bore and stroke exceds the limit, u could have a combustion chamber 2000cc in volume, they dont care.

[matt dunn]

when therefore all the 1799cc engines will ACTUALLY be closer to 1805cc with the fixed combustion chamber volume calculated and added....

odd....

Thats like saying why cant a six year old enter in the under 5's rugby?
Because he's too big.

0m -1800 cc clases are 0 -1800cc you have to draw the line somewhere,

If you allow 1809, why not 1819, or 1850, or 1950, ??