How much HP will EMI Thunder Manifolds with 4" riser/tail pipes support?

kenny that use to work for eddie marine claimed 800 hp..they are hard anodized so that makes the aluminum real hard to melt..

the problem with them is reversion with larger cams,not much better than stock merc manifolds imo.

I would call EMI..

They have reduced discharge into the tails so I am hoping that is good enough. If it is not I will go dry and discharge through my old innercooler dump.

Below is a good thread onthe topic.

http://www.offshoreonly.com/forums/d...e-exhaust.html

I have been using EMI's for over 15 yrs..as long as you pick the correct riser for your application you wont have any issues..just make sure your running at at least 130*,,they will sweat like anything that has water running through it..BTW they are loud!

We still run the same setup since the 2009 post! Engine still runs great, no issues with reversion!
Aluminum risers like ones from Kodiak Marine have the anti reversion dam into the castings. maybe the Eddie Marine castings are the same now too?! Give them a call and ask.