cmi vs gill w/silent choice
 

Hey all, what's the hp diff between the 2. Say I had a dyno of 600hp with cmi-& then switched to gill......same or what's plus/minus

I too would like to know, if you gain any hp with the E-Tops versus the Gils, or is the hp gain negligible, or do you need to go the full length sport tubes to gain hp? Have any of the engine builders on this board tested (dyno) the difference?

Good question, Paintman...

My $.02 opinion, I would think that the E-Top and Gils wopuld produce similar hp number for your example (600 hp engine). The sport tube (longer runner length) would produce more hp, at a higher cost too ($$$).

hey smarty thanks.............i was "told" that the gill would be 50hp less:eek:............. i switched from the etops , wanted the silent choice but if there is that much hp diff maybe i should have just added the mufflers :lolhit:

It is one of those it depends answers? I have Gils with Silent Choice, and cannot run a big cam due to reversion issues, if I got rid of the Silent Choice, I could have the water mix later and run a bigger cam and get more hp, but with my set-up it is a domino effect of a larger intake/plenum, larger injectors (more psi), ECU reprogram...to compliment the bigger cam.

My father (this was his boat and motors) wanted his 540 cu.in EFI motors to be mild, and run quiet, and hp was the trade-off with the Gils, but I would think Gils would last longer than welded headers ( he worried about cracked headers with the CMI's). I am not expert, so maybe the more experienced OSO brotheren will comment.

hey maybe i shouldnt have used a name brand in the title?...just wantin some feed back theres gotta be somebody who has ran the #'s

Myth Busting
 

There was a test on here some time ago where an engine builder did some head to head comparison....not sure if it fits all your criteria but some at least....


Click on the "View High performance Projects" in red on left side...

Next click on top link "496 Mag Dyno Testing......."

http://www.fullthrottlemarine.com/

No way it will be a 50hp. Maybe 10-15hp. I switched from Gils to CMI's on my 525SC and saw no difference at all in top speed.
Make sure you don't have reversion issues if using the short silent choice risers.

I agree, if that !!!!

and u will not feel it at all !

Headers are ment for high RPM aplications...below 5500 i think it really does not make any differents ecsept for look and maybe sound if u go dry !!!!!