reno928s

Are the heads on the turbo S the same as on a regular turbo and how about a N/A head? are they all the same?

944CS

All 2.5 N/A and Turbo heads are the same dimensionally. Turbo and Turbo S heads are the same. The difference between turbo and N/A heads, valvetrain aside, is the Turbo heads have a cast in ceramic liner in the exhaust port to keep the exhaust gas as hot as possible in order to warm up the catalytic converter as fast as possible.

Olli Snellman

Turbo S has bigger valves. Don't remember were they exhaust or intake side

maximus951

944CS is correct regarding the specs on the 944na vs 951 vs 951s - however, the primary purpose of the ceramic exhaust liners was to insulate the head from the higher temps achieved with the turbo and to retain more heat energy in the exhaust passage between the head and the turbo. The pic is from the 1991 service manual - Turbo supplement.