944 vs 951 head

[edbaus]

What is the difference between the NA and the turbo heads.

Thanks

Ed

[smokin_944]

For one, the turbo head has ceramic liners in the exhaust ports and sodium filled valves, the N/A does not.

[v2rocket_aka944]

turbo has sodium filled exhaust valves, ceramic liners in exhaust ports as mentioned and better valve springs. believe the intake valves are larger also,

[Porsche-O-Phile]

However (something to consider) because of the ceramic liners in the 951 heads, it is impossible to increase the size of the exhaust ports. Very highly built 951s often use the NA heads for this reason (flow becomes an issue).

[HondaDustR]

The ceramic liners also have a tendancy to crack. Lindsey Racing does alot of work on turbo stuff and claims they can significantly increase the flow through the exhaust ports without doing anything to the ceramic liner, which would be better overall, since it keeps the exhaust hot and the head cooler.