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View Full Version : 393...408...427



sLoWnStEaDy
05-15-2007, 09:37 PM
As some may know i am doing a little swap into my RX7. Now come this winter i'll be building a new motor for it. I am going with a 351W (to use the swap kit already in the RX7), but am going to stroke it to either a 393, 408, or 427. Of course the old saying "there is no replacement for displacement" has got me tryin to decide what i wanna stroke it to. No matter which i chose, i will be using forged crank, rods and pistons, along with aluminum heads.
I was thinking about throwing all of the EFI stuff from my 5.0 onto it, but figured after buying all the stuff i would need for it to be OK on an engine that big, it would be better to just sell the entire 5.0HO engine with all the EFI stuff, and the "retro-fit" harness and just use that money to buy a nice intake, carb and ignition setup. Oh and the nitrous kit i got is adjustable up to a 275 shot so ill be cranking it past the 125-150 i am going to use on the 5.0.

So whatcha think? 393, 408 or 427
Also, the kits are all within about $100 of eachother so dont let that effect your thinking

black88gt
05-15-2007, 10:59 PM
408 ftw

69gt4speed
05-16-2007, 12:34 AM
A 351w 408 is proven and I wouldn't go over 10/1 compression so you could run junk gas w a modern alum head. They have been having real good luck with the new fel pro mls in the max classes w s/c, turbo or spray and alum heads and arp studs. Only trick is the surface needs to be fairly smooth though not as much as cometic ones. A trick some are using is a chrysler sealer used on the chrysler mls gaskets to eliminate those water leaks.

DustinsDuster
05-16-2007, 04:28 PM
408's seem to be very popular, and they all seem to run pretty well...