I'm sure this is a newb question, and probably covered before. But even with use of the search option, i was unable to find the info i was looking for. anyways, can anyone here tell me the differences (if any) between the xjr's engine and its naturally aspirated counterpart? ie, compression ratios, bottom end materials, etc?

 

curiosity mostly, some manufacturers (ie, toyota) build their forced induction motors completely different from the natrually aspirated. they lower compression, ad oil squirters for the pistons, generally use forged rods and pistons as oppose to cast. some other manufacturers however simply add a super/ turbo charger to a naturally aspirated engine because they either run low boost, or have used strong forged parts all the way through and know the engine is capable of handling the abuse.

ive always wondered. the reason i ask now, is i just replaced an engine in an xj8 that had its primary chain tensioners fail, and have the old engine in my posessoin. if its an engine worth keeping ill probably keep it an rebuild it. if it isnt i wont bother.

 

so pistons and valvetrain the only differences?

and if thats the case, how different are the valvetrains? is it just cam lift and duration? or is it valve construction, size, etc in addition to the cams? thanks for the help so far.

to be clear, im attempting to establish how boost friendly (if at all) an xj8 engine is.