Cmi hp gains
 

Hi,

i have a 600hp engine and i am currently running GIL exhausts on it with dry tail pipes.....i will be putting a new set of CMI e top headers and would like to know if i will notice any difference when it comes to acceleration, throttle response and so on.....will i gain any hp ?

thanks any info would be greatly appreciated....

Fixx
 

no!...YOU MAY LOOSE TORQUE..

Just curious, why?

Needs a certain amount of backpressure

I can understand that. Is it that much of a difference? I am curios cause I am keeping my CMI headers but changing to 5"dry tails.

i changed from an old set of lightning headers on a 700hp engine to a new set of cmi's. wet vs dry tail pipes. $5000 later i saw no performance improvement.

Do a little reading on exhaust scavenging and you can learn quite a bit. Sometimes bigger isnt always better. depending on heads cam and such, a little back pressure will help and create more power. if exhaust is too free flowing, that second that both valves are open if the exhaust is flowing too much it can pull unburned charge out of the combustion chamber, therefore nullifying all the effects that you were going for.

I have a 496HO and I purchased the CMI sport tubes. Before installation I was running about 4900rpm with a 24" brovo 1 prop an 68mph. With the CMI sport tubes installed I was hitting the revlimiter, I changed to a Brovo 1 26" prop rpms changed to 4800 and I was seeing 69.4 on my GPS

And how is your out of the hole ,and midrange acceleration with the 2 inch bigger prop ?

Had a customers boat lose 3 mph and 200 rpm going from leaking cmi's to used Gil's..... That come to find out we're leaking at higher pressure also! Doh!