scarabfun

i like gil it's a great product for the $ and price is not bad. my last set's lasted 12 yrs. or so. they also provide exel. performance. i have the dry-pipe's with muffler's, sounds great.

JRalston

any updates to the 496 testing? would like to see how the cmi's compare to the dana's. Also, would like to see the results using cmi e-tops.

Baja_man

See post #1...It goes into comparision of the Dana's but not the new CMI's. I've come to the conclusion on any stock engine the results will be minimal.

"Results are in. I’ve finally completed some comprehensive dyno testing of a 496HO and various exhaust systems. It’s rather lengthy so I published it on our web site. Please check it out. I spent all the time and effort for you guys. Go to www.fullthrottlemarine.com and click on high performance projects.

Bob"

bobl

Here is a dyno test I did this summer. It is a prop shaft test on a stock 496 Mag HO and a second test after adding CMI sport tube headers. Disregard the A/F data, the wideband was not connected to the dyno during this test.

Bob

Keith Atlanta

That is pretty impressive. I have to say, I was skeptical but now I am going to order a set...

Thanks BobL for the dyno info. I have been waiting to see some numbers that looked this good.

JRalston

Bob, so am i understanding that the cmi's were essentially the same as the dana's performance wise?

Thanks for all the work and knowledge on the 496's!

bobl

I would say yes to that. Might be a couple of hp difference but you'd never notice it. So it comes down to cost, fitment and bling. Dana wins in the first 2 cases. But, you can't beat the looks of the CMIs. IMO

emilsr

Dana recommends increasing fuel pressure on late model HO's to keep from going lean in the midrange when using their exhaust. Does this also apply to CMI's or other true headers?

Raylar

Yes, whenever a true set of headers or header manifolds is installed on a 2004 or newer 496 MAG or HO engine the air fuel ratios should be rechecked if possible at full throttle, if not at least increase the fuel pressure about 3-4 lbs to help get the WOT fuel ratios closer in line.
Mercury used a different fuel program in the newer 496's since 2004 that was to help eliminate the "fat" rich condtion that appeared in earlier engines and caused a lot more transom soot and such.

Best Regards,
Ray @ Raylar

emilsr

Thanks Ray!