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Need to clarify some head facts


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Alright ive been reading up on converting an f54, p90 head motor to a carb set up. Im unsure the differences in heads. I have read that the p79, p90, and p90a heads have the same valve size, combustion chambers, and intake runners. The exhaust ports differ from the p79 ( they have diamond shaped inserted exhaust runners) head to the p90, p90a. Is this true? Im wondering because i have read the p90 and p90a heads have larger combustion chamber because they were designed for the turbo motor.

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The difference in compression between turbo (P90 and P90a heads) and non turbo (P79)  motors is due to the pistons.  P79 headed motors have flat tops. Turbo motots as well as N/A engines that came with N series heads (N42 and N47) have dished pistons. .  

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