964 heads a removing the exhaust ceramic coating

[Sorude]

Now this is going to be controversial...

I have a set of heads on a 964 and my ceramic coating on the exhaust valves, has cracked and started to come off.

This is an NA engine and will be built to around 320hp, electronic fuel injection and ITB's.

I panicked seeing this and had no idea what to do. Noting this was picked up by the team machining the heads.

Options given to me were.

1) ignore it and just install them
2) Normally what they would do for turbo engines is remove the ceramic coating so that it doesn't damage the turbo

What I've decided to do is - After a long hard think and with a couple of engine builders advice I've decided to remove the ceramic coating and run the heads. The heads will have new valve guides and I figured it was better to remove the coating left, rather than having it floating around or more of it falling off.

This is the first time this coating was used and I figure it I'm not pushing big power, the engine will be find. Apparently a lot of engines running around with no coating.

Thoughts and comments welcome.

[Cobalt]

Did you consider reaching out to companies that do ceramic coatings and see if they can help. I would think with the exhaust temps reaching near the liquidus state of aluminum you might consider not using them or having something reapplied.

[stanglife]

Honestly, I'm surprised an experienced shop wouldn't point this out way before performing any service on the heads. Running these with no ceramic will not only transfer a lot of heat into the head, as Anthony stated - but the ceramic layer makes up a portion of the port volume and shape. I don't see how this wouldn't impact performance. You stated that you are shooting for a performance improvement, adding ITBs and (aftermarket?) ECU. The heads are probably the most significant component when it comes to making NA power.

[Bill Verburg]

I'd junk them and buy a set of Extreme heads

[colingreene]

if the liners are compromised i would not use them or try to re finish

[chucksmith]

do aftermarket heads generally have the ceramic coated exhaust ports?

[Bill Verburg]

Originally Posted by chucksmith

do aftermarket heads generally have the ceramic coated exhaust ports?

No, but the Extremes and 9Ms flow much better
here is an Extreme

[chucksmith]

So do you think that means the ceramic coating is not needed and in fact decreases the flow a bit?

[Bill Verburg]

Originally Posted by chucksmith

So do you think that means the ceramic coating is not needed and in fact decreases the flow a bit?

intact ceramic is a very good insulator and flows fine to ~300hp+/-

above that it becomes increasingly detrimental

busted up ceramic is useless and detrimental at all times, it doesn't flow well and doesn't insulate

The heads are where heat is the biggest problem, for a 3.8 to ~300 hp if the ceramic is intact it's good insurance, above that it's a budget thing until the high 300s

The pic I posted above is a Rothsport 4.0, w/ turbo fan, for additional cooing, GT3 intake ITBs, Extreme heads, ATI crank damper no expense speared & ~400 hp, It's running twin front coolers ala 993RSR.