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View Full Version : Repower 18';Exh Manifold



Jeff Grifith
05-16-2001, 10:47 PM
Looking to upgrade power in 18' 2+3 in next year or so. '79 260/alpha now--would like to know comparative merits of BBC vs. SBC (maybe "enhanced" 383 stroker ). 383 appears to be suited to high torque lower rpm applications--encountered in marine usage. Concerned about weight and space ("fit")issues with BBC--also handling etc.
Bravo is probably also in the future.

Also interested in comparison of IMCO and Gil exhaust manifold/ systems.Imco slightly cheaper-- but is performance substantially different? Also muffler comparison?
What differences with either-- over stock mercruiser manifolding/ systems?

My intent is to upgrade exhaust this year-- swap engine to 350 HP 383 next year-- upgrade engine and outdrive the following.(HP to 400+ ,Bravo.)

Would you recommend other alterations first?
( I know this is probably not the best way to spend the $$-- friends tell me to instead get into a 22 or something a little bigger-- but I'm nuts about my 18-- and don't think I could ever part with it)
Thanks and good boating

BigGrizzly
05-17-2001, 08:04 AM
Go the 383 route, but don't get trapped on that low torque for marine use crap. your never at low end. the real power must be at 3200 up. Remembet the water is a high stal speed torque convertor. All my marine stuff has torque ar higher end, also better for fuel economy at a cruise. I have both a 22 and a 18 and have a hard time deciding which i like best the 18 is much more responsive.

Randy

Forrest
05-19-2001, 08:28 AM
. . and if you're racking your brain trying to decide which small-block performance exhaust-manifold system will make more HP, GIL, Imco, SM, EMI, etc., there is probably not even a three HP difference between any of them under 5500 RPM. Whatever you buy, just make sure that it fits your boat.

------------------
Forrest

BigGrizzly
05-19-2001, 11:49 AM
Forrest is correct. If you have some big dollars CMI will produce more Hp but the price is high, I know I have done it on my Corsican. I will do it on the Criterian Late next year if I have the Dollars.

Randy