Help with exhaust ports
07-09-2014, 02:22 PM
#1
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Help with exhaust ports
In the midst of an update to my 964 c4 turbo build. Removed the headers last night and found this on the exhaust ports. Any of you seasoned owners know what this is? Sorry about the blurry pics
07-09-2014, 03:35 PM
#2
Rennlist Member
The exhaust ports have a "Ceramic" liner incorporated into the casting. These are prone to cracking over time. Not much you can do about it, other than buying new heads. On a NA engine, I wouldn't worry too much, but on a turbo engine, I could see some of those pieces go through the turbine and ruin it.
07-14-2014, 12:07 PM
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Also what are thoughts on the 9m billet heads without ceramic liners? Anyone use it on a turbo 964 build with success? Please let me know as I am researching my options at this point.
07-14-2014, 02:16 PM
#6
Three Wheelin'
Seems like all of these heads are bound to end up like this sooner or later. I don't know how long a good used set would last before you see the same thing. If the turbine wheel still looks good up until now, I don't know that I would worry about it. The 944 turbo folks must have the same problem with the ceramic liners. You might want to see what they've come up with, or if it's worth worrying about.
Good luck!
Good luck!
07-14-2014, 04:03 PM
#7
Three Wheelin'
For what is worth, my heads were replaced with used ones die to the ceramic liners flaking. Weren't easy to find, and wasn't cheap either. New head options were crazy money. Nick is right, this is gonna be an ongoing issue as more and more motors need rebuilds.
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07-14-2014, 05:41 PM
#8
Three Wheelin'
And according to Porsche, it may have rolled off the assembly line that way-
http://www.pcarworkshop.com/images/e...1590geolab.pdf
"ATTENTION:
Service Manager/Service Technician
Models Affected:
911 Carrera 2 and 911 Carrera 4
Concern:
Cracks or breaks in ceramic exhaust port liners.
Repair Information:
Small cracks and/or breaks in the ceramic port liners in the area of the valve guides are sometimes visible even on new cylinder heads (See Figure 1). They do not influence the function of the port liners.
Cylinder heads must not be replaced for the above mentioned symptoms unless 1) breaks go down to the base material of the cylinder head, 2) broken surface area is larger than 1 sq.cm (0.155 sq.in.) or 3) the cracks extend from valve guide to the edge of the ceramic liner (on the valve seat or exhaust flange area). "
http://www.pcarworkshop.com/images/e...1590geolab.pdf
"ATTENTION:
Service Manager/Service Technician
Models Affected:
911 Carrera 2 and 911 Carrera 4
Concern:
Cracks or breaks in ceramic exhaust port liners.
Repair Information:
Small cracks and/or breaks in the ceramic port liners in the area of the valve guides are sometimes visible even on new cylinder heads (See Figure 1). They do not influence the function of the port liners.
Cylinder heads must not be replaced for the above mentioned symptoms unless 1) breaks go down to the base material of the cylinder head, 2) broken surface area is larger than 1 sq.cm (0.155 sq.in.) or 3) the cracks extend from valve guide to the edge of the ceramic liner (on the valve seat or exhaust flange area). "