Is CMI the best marine header

[Sofa King]

for my 454? I have 385 hp now, can I get a 10% gain (38.5) or am I dreamin'.
They sure are proud of em about 5g's lis LOL. Thinking about doint that and a IMCO extreme.

Arip

[oldandtired]

I picked up about 200-300 rpm and about 3-4 mph with a set of CMI tube tops (semi dry) and no mufflers on a 502 mag. The real benefit to the headers is the ability to improve in other areas of the motor (heads, cams) and reduction in weight. I personally think that the Dana flo-torques are the best deal around and they look good. I picked up the CMI's for a great price used but would otherwise have gone with the Danas.

Rene

[Sofa King]

I'm looking at the elbow unitops that list at $2999. I wonder if they'll line up with my factory transom holes? Rene, Do u have the silencer/ capn call on em? Wonder if I need it. I have it now and more of a novelty than anything.
Wonder what the Danas are listing at and the most IMPORTANT thing which one fits the best?

Arip

[oldandtired]

I have a diverter system that I never bothered to install, but I really don't think that it would make much of a difference. It still exhausts out the back, but it diverts the exhaust down in the water with an insignificant baffle in the diverter. I was looking at the Danas 8 months ago and they were around 1800 with the vortex tips straight from Dana (www.danamarineproducts.com). The CMI's are really nice but kind of pricey. What bothers me about the e-tops is that the primary length is only about 15 inches. I am sure that that is better than the stock manifolds, but it seems too short to make a significant difference. The majority of header for the big blocks have 32 inch primaries, I can't remember exactly how long the Danas are, but they were in the 20 something range. Either setup should be a straightforward installation. In the end, headers are not the greatest performance investment in the boat unless you are combing them with significant engine mods. Once you have the right exhaust, you can do cam work which opens up all kinds of possibilities that you shouldn't pursue without the headers. The headers are pretty though.

Rene

[mrfixxall]

for my 454? I have 385 hp now, can I get a 10% gain (38.5) or am I dreamin'.
They sure are proud of em about 5g's lis LOL. Thinking about doint that and a IMCO extreme.
Arip


no,,stelling is....

[Pismo]

KE Eickert were the highest HP on that dyno spreadsheet that was floating around. CMIs were near the top too.

[Moody Blu']

i like my hi teks, there a one piece design and cost alot less then other headers they come with a zinc anode which can be chanegd out for that extra protection.

Its hard to say what i gained because i had my prop repitched from 22p to 24 1/2p and i only lost about 200-300 rpm.I use to redline at 5000 now i hit 4700-4800 with the new prop. so i def gained around 30+hp

my old glenwood manifolds were really holding me back

they come with a 5 year waranty as well

http://www.hitekmarine.com.au/

[Pismo]

Found that spreadsheet. If anyone knows how to post a .xls file please let me know and I'll post it.

[mrfixxall]

are we talking stock or modified applications?

most of the big boats i work on have stellings in them..their pretty much bullit proof and never had an issue of them braking or rotting out from salt water...stelling uses a 316 grade ss which wont rot out,some of the others use 409 ss which has high carbon and will rot out..they all work well just make sure your getting a true 316 inner and outter tube style header..