Can carbon on your piston tops...

[echrisconnor]

Can carbon on your piston tops increase your compression ratio? Yes this may be a silly question, but think about it. Say you've got .5mm or more of carbon build up on your piston tops. Isn't this almost effectively increasing your piston dome size. .5mm could translate to almost a half point increase in CR.

Not that this is an effective way to increase your CR, but is it ever a factor?

[Rot 911]

Yes it can. Of course when you get that much carbon build up you will probably get a case of serious engine run on when that hot carbon ignites the gas/air mixture when you turn the car off. And the carbon will not build up evenly on the piston so you will get a more uneven burn pattern. So while compression may go up, that does not necessarily translate to more hp.

[Wayne 962]

Yes, this does happen...

-Wayne

[1fastredsc]

Also if you search the forum, there are many who have described a procedure for easily removing the internal carbon from your motor.

[Wayne 962]

Early_S_man has a good procedure somewhere in the archives, that uses berryman chemtool...

-Wayne

[Henry Schmidt]

Carbon can be removed from piston tops every easily. In the eighties BMW had this problem with 6 cylinder engines and they ( BMW factory ) recommended pouring a small amount of water into each cylinder while the engine was running. The steam produced caused the carbon to break loose. Their problem if i remember correctly, was pour idle and detonation caused by higher compression.

[thor]

It increases the compression but creates somes thermal problems i.e at the valves (hot spots) then it s not recommended to have to much carbon in the combustion chamber.