Quick question concerning high comp. pistons

[Pa400exracer]

Sry that i had to ask suck a stupid question , but i've always wondered....HOW THE HECK DOES A HIGH COMPRESSION PISTON WORK?


If the engine is stock bore , how would the piston work? because the way it seems to me that a high compression piston would be is that iw would go up further in the cylinder , but therefore it wouldnt go down as far on the down stroke then , not as much air would be entering the cylinder to be compressed.

i apologize for the stupid ? , but its been on my mind for a while
thx for all the replys

[Ralph]

there are domes at the top of the piston which will change the total volume of the combustion chamber.

[baker250r]

there is more "piston" on top of it. therefore it makes it so there is less space when the piston is at TDC. wich makes the mixture compressed harder and u get better firing.

[wilkin250r]

Exactly. When the piston is at Top Dead Center (TDC), there is still a small space to hold the compressed fuel/air mixture. This is called the combustion chamber.

The compression ratio is defined as the total displacement volume divided by the combustion chamber volume.

For example, let's keep numbers simple. Stock bore is 397cc, but we'll just call it 400cc. Let's also say that the combustion chamber is 40cc, which would give you a compression ratio of 10:1 (400 divided by 40 is 10).

Now, let's pretend we added an additional 3cc of dome to the top of the piston. Total displacement is STILL 400cc, but now the combustion chamber is only 37cc. 400 divided by 37=10.81, so now you have a 10.8:1 compression.

[Pa400exracer]

k ., now i understand it ... thanks for all the replys