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erobinson erobinson is offline
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Join Date: Aug 2004
Location: georgia
Posts: 185
Question Piston suggestion for a CIS 2.7

Okay guys, I have a trashed Alusil cylinder (looks burnt....very strange) and I am looking at a fairly major rebuild. Also dumped a set of valve guides.

My current engine is a 76 vintage 2.7 with CIS injection and crossover exhaust, no thermal reactors, factory bosch cd box, pretty much your plain jane 2.7, except will be rebuilt with a 11 blade turbine.

Tomorrow I going to dig through a friend's 2.7 junk searching for a set of usable nikasils and matching pistons. If I find these then this post irrelevant. But the very real possibility of P&C replacement is looming....

My question is as follows. Due to current budget constraints I plan on retaining the CIS injection and probably the cams that are in the engine atleast for the time being. Should I go back with the CIS style dome piston and then change it later if I move away from that injection ($$$ for the second set of pistons) or will a set of more performance oriented domes live in there (although I fully realise they will never live up to their potential with the cis and may even hurt performance a little due to the cams)?

I understand that the CIS cams have very little overlap so the static compression ratio is pretty much the same as what really occurs. So if I raise the static ratio with different P&C will I dramatically shorten the life due to possible detonation and increased overall heat? Will making the changes outlined in "making power with a cis rebuild" tech article with regards to cam help a non cis dome live?

I will probably change induction systems at some point so i am looking to build a decent bottom end for a halfway decent price that I can kind of grow with so to speak.

Eli
Old 09-12-2004, 07:50 PM
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