Cylinder Head
#2
Join Date: Feb 2014
Location: Crossroads of America
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Hi Nick,
According to the Electronic Parts Catalog (EPC), which you can download from this forum, the part numbers for the N/A and SC cylinder heads (less cams and valves) are different:
N/A to engine 128486: NBC2510BA
N/A from engine 128487: NBC2510CA
SC: JLM12075
My assumption would be that the SC head is designed for lower compression than the N/A head, but one of our tech gurus will know for certain.
Cheers,
Don
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The difference in compression ratio between naturally aspirated AJ16 engines and the supercharged versions was achieved entirely through the design of the piston crown, which was dished on the AJ16 SC engine. After 20 years I can't remember using different cyl heads castings in development, so it must have been quite a subtle / late change. My guess is that higher exhaust valve seat insert material was specified for the SC engine, if the part numbers for the two bare heads are different. In which case, the two heads would be physically interchangeable and the cyl head for an NA engine would probably last on an SC engine unless you were conducting an engine dyno durability test (eg >100hrs running at peak power - not really likely in a car)
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