redcorvetteman3

Was wanting everyones opinion on a exhaust question . I seem too be having a reversion problem. If I was too take the stock merc manifold and exstend the center exhaust area with tubing wouldint I be creating the same thing as a performence type manifold where the water is mixed much later down the system thus decreasing the chances for reversion. thanks

ninjaturtle

HAVE TOU TRYED THIS YET ? IM THINKING OF DOING THE SAME THING.

PAST DUE

have you changed something in the motor to cause the reversion or is it an ongoing problem?

redcorvetteman3

Yes the exhaust extensions did decrease the amount of reversion. Mine were about 8'' long muffler tubing brased too the stock manifolds. I was able to see a visable amount of reduction thru the pryometer hole that I have in the risers , you can actualy see a mist at low idle. Of coarse increasing the idle helps and eventualy stops the problem.

Ryan00TJ

I have also done this. I was using Imco stainless short risers and had reversion with my stroker and larger cam. I welded on 22" 3" ID exhaust tube extensions onto the risers. They extend into the exhaust tip and water does not mix in until there also. Much louder and no more reversion. Should be some performance increase to boot. Just keep the extensions away from the exhaust hose to prevent them from burning.

383 small block video....

http://www.youtube.com/watch?v=gbnBNN3NjGY

http://www.youtube.com/watch?v=rxT0v...eature=channel

PJDiesel

I did this to "Fastglass" stainless risers attached to stock cast manifolds. I wasn't looking to solve a problem per se', just wanting to eliminate the possibility. I bumped up my cam to something that is borderline, so figured it would be wise.

I simply bought 3" stainless tubing, cut 7" lengths, welded them solid to my existing riser outlet. This way, the mix is MUCH closer to the transom, further down hill and further away from my risers.

Somewhat noisy, but hey, it's a boat.

Oh, and what Ryan said, keep them good and centered up, or you'll be melting hoses......

Griff

This modification is bandaid. If you put in more cam to make more power, then it needs better exhaust to allow the engine to breath. Stock exhaust is marginal on even a stock 502mag.

redcorvetteman3

If you put the very best exhaust you can on any motor doesent only increase hp about 40 50 over stock ? So If I spend the 1500 to 5k on other parts say like heads or big bore or stroke Would it not be the same ? Oh yea also hp improvments when small never show up on a boat ... unlike a car takes much more hp for 1 mph on a boat

PJDiesel

......................or NONE.

I'll agree, once you get to a point, exhaust is absolutely necessary, up to said point, it can do from very very little to absolutely nothing.

Considering how ridiculously expensive exhaust is, I would spend the money elsewhere, unless, that is you are talking 500+ HP.

GB

Totally agree with you