Heating up definately helps, I heat them to 200 degres farenheit, use a blunt object through the injector port and and a hammer to punch them out. Don't ceramic coat those chambers eithers, leave them in, I havent had good luck with CC'ing them.

Don't ceramic coat those chambers eithers, leave them in, I havent had good luck with CC'ing them.

I know that somebody saw no benefit to coating only the prechamber inserts, but I thought that coating the entire chamber would result in less heat loss to the coolant, and therefore easier cold starts and more efficiency. Is there a bad side to coating the prechambers?

i kind of doubt it would help cold starting

The theory is, it should keep more heat in the chamber as the piston nears TDC, instead of losing it into the aluminum walls of the chamber (aluminum is a good thermal conductor, which is why it is often used for computer CPU heat sinks and automotive radiators).

Not sure how dramatic the effect will be, though. If it's significant, I'm sure lots of folks would love to reduce the C/R of their TD's (so they can run more boost) without making it impossible to start in the winter. Us N/A guys would also love it if we never had to buy new glow plugs.

Ceramic coating the pre cups is not a great idea, it keeps heat out of the actual prechamber which slows down the combustion process.

Don't ceramic coat anything in there, trust me I tried all sorts of variations, you need that heat. The only thing I would reccomend ceramic coating in that area would be the intake and exhaust valves, the exhaust ports (only if the particular coater is set up for doing so) and piston tops.

And really I think the only one thats worth the time or money is the piston tops.

Yep, no noticeable gains found. What are you hoping to accomplish?

I had the exact opposite results, the lack of heat kept in the combustion area meant a colder less complete combustion= poorer starting and less power per amount of fuel injected = less mpg.