643 Castings

[brettmc]

I am presently running a set of AI 200cc lt1 643 casting # heads. Right now, it's NA but plans are afoot to put a Precision 7675 on it...with all the necessary mods that need to happen, of course.

my question is... will the 643s handle around 20 psi and 900-1k crank hp?

[shownomercy]

I do not think that turbo will have the steam or lack of back pressure for 20psi/1k hp.

I make ~700whp with a 76gts (old 7675) at only 10psi and stock ported heads. I think your biggest foe will be cylinder pressure vs deck strength.

[SwampWS6]

I do not think that turbo will have the steam or lack of back pressure for 20psi/1k hp.

I make ~700whp with a 76gts (old 7675) at only 10psi and stock ported heads. I think your biggest foe will be cylinder pressure vs deck strength.

I agree. You will need something larger to even achieve that number.

SNM, whats your compression? Thats a badass number! :D

[shownomercy]

Mid 9s SCR.

[brettmc]

well, there's no telling when that 7675 will start to lose it's luster. lol

so, back to the original question... will the stock castings hold that number? or should i go with aftermarket castings now before the engine goes in?