Imco vs. CMI vs. Eddie Marine
 

I have a 454 Mag MPI. Plan to add Vortec power package and exhaust manifold to existing Corsa exhaust. It's been recommended that I go with Imco PowerFlow Plus and SS riser. Which exhaust manifold is better and why?

Thanks,
Dig Deep

Do yourself a favor. Buy the parts separately and exclude the MSD box. It won't help one bit.

As far as exhaust goes, I would go with CMI unless you are have diverters that you are trying to keep. The diverter setup for CMI adds a lot of expense. Otherwise, the CMI's are great for performance and allow you to use a wide variety of cam profiles without worrying about water reversion.

I personally have Gil Magnum Choice on my 454 Mag MPI, but I've always heard good things about the IMCO Powerflows. Teague pushes these hard for near-stock engines. They claim IMCO's offer a better performance gain than anything out there, but I think they are overselling. They claim you will see 4-6mph with the IMCO's on a stock motor. But beware, it ain't gonna happen !! I even spoke with the guys at IMCO about Teague's claims. They appreciated Teague's devotion to their products, but also felt they were overselling. Even IMCO says their performance gain is comparable to Gil.

The ONLY problem with IMCO is that they do not use the dry-joint concept (which Gil and Eddie Marine do), so you can end up with the same kind of catastrophic riser gasket failure as the stock manifolds.

Without a doubt, go with CMI Elbow-tops if you don't want diverters. Otherwise, IMCO is a good second choice as long as you understand the risk of riser gasket failure. On the other hand, I've never heard anyone complain about IMCO's.

I'm running The Eddie Marine's on Supercharged 557inch motors making 850HP...2 seasons in freshwater, no problems to date.
On that small of a cubic inch motor you could even get away with using the stock cast iron ones with mild boost.

:cool:

WOW, those are beautiful engines. I switched from Gil to K Eickert on HP500 and really like them, a little louder though.

Is this a supercharged engine? If so, then scavange isn't as critical. That's not to say that it wouldn't hurt. If you can afford them, you won't go wrong with elbow tops. Because they are no standard on Hp500's, you should be able to find a used pair for significantly less.

CMI E-Tops with their diverters and my Corsa solinoids.

Thanks for the feedback gents.

DigDeep

Could you post a pic of those on there?
Thanks

Sorry I don't have any side shots, they aren' t real pretty but they work great, I think KE s web site has a dyno graph of all the different exhausts and these are similiar to CMI big tube.