" I double checked with Bruce Anderson on this, and he points out that 911's worked fine forever without ceramic liners. I believe it was an optimization for emissions as much as anything else, to get more heat into the cats more quickly. My understanding is that when machine shops redo late model heads if there is a problem with the ceramic liners they just get rid of the material. This is also done by necessity whenever the ports are enlarged for performance applications. I don't know if anyone has tried to have them recoated. Most everyone seems comfortable not worrying about it though. But if you think the cracking is enough to where pieces could flake off, and clog up the cat, then have the shop work the ports now to shake free anything that is going to fall off eventually. You might want to just have them take the stuff out and polish the ports. If you really want to replace the heads, I would shop around some of the Porsche salvage yards that advertise in Panorama magazine. There are good used heads out there at a fraction of the new prices, which are astronomical.
" I double checked with Bruce Anderson on this, and he points out that 911's worked fine forever without ceramic liners. I believe it was an optimization for emissions as much as anything else, to get more heat into the cats more quickly. My understanding is that when machine shops redo late model heads if there is a problem with the ceramic liners they just get rid of the material. This is also done by necessity whenever the ports are enlarged for performance applications. I don't know if anyone has tried to have them recoated. Most everyone seems comfortable not worrying about it though. But if you think the cracking is enough to where pieces could flake off, and clog up the cat, then have the shop work the ports now to shake free anything that is going to fall off eventually. You might want to just have them take the stuff out and polish the ports. If you really want to replace the heads, I would shop around some of the Porsche salvage yards that advertise in Panorama magazine. There are good used heads out there at a fraction of the new prices, which are astronomical.
Joel Reiser"