Talkin' Headers

[mrfixit0623]

Looking for info on SBC headers I can run in a closed compartment. Most say for open compartment only. Also is there a big difference in "water injected" vs "water jacketed? Do the Imco style manifolds work as well?
This is for a 85 Checkmate Diplomat with a modified 305 pushin 300 hp.http://www.checkmate-boats.com/images/memberpics/P1000137.JPG

[Raceman]

I'm not aware of any non jacketed headers that are appropriate for a closed hatch. As far as "big difference", I'd say there's a lot of difference in temperature between the two, but probably not in performance, since jacketed headers typically inject water into the exhaust flow also for noise control. The obvious big difference besides the temperature is the price. I've got CMI's on my only sterndrive boat and their quality is unsurpassed. Mine are over 10 years old and still look and perform as new.

As far as aftermarket manifolds, I'd think they'd do just as well as headers on a 305. I doubt that you'll see huge increases by freeing up the exhaust on an engine that small anyway, even considering the mods.

[Firestarter]

If you want a true header, it needs to be water jacketed, CMI is the only way to go, if you are just looking for a free flowing exhaust for a small block, then I would suggest Stainless Marine. There system is 90% if the CMI and 1/3 the cost.

RT