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Old 10-11-2006, 11:04 AM
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Default Re: CMI 496 headers

We recently installed a set of the CMI onto a Baja 35 Outlaw, twin 496 HO. The installation was relatively straightforward, and the couple of problems that we did encounter were handled quickly by Fred at Trick and CMI.

The boat runs great - noticeably quicker in the middle, great sound and looks SO cool. Did we get 50hp? Maybe, we don't have a dyno... It looks like a net result of 3-5mph on top, although we are still playing with props a little to see if we can't squeak out a little more.

I have some good photos if anyone wants them (I can't seem to post them...)

-David
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Old 10-11-2006, 02:04 PM
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Default Re: CMI 496 headers

why the 92 octane in the second chart- did timing get tweaked?
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Old 10-11-2006, 02:23 PM
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Default Re: CMI 496 headers

Barometric pressure in the 28's indicates a hurricane. Relative humidity of 103 is also very unusual. These numbers indicate cheating or maybe just carelessness.
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Old 10-11-2006, 04:07 PM
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Default Re: CMI 496 headers

Originally Posted by thundermarine
We recently installed a set of the CMI onto a Baja 35 Outlaw, twin 496 HO. The installation was relatively straightforward, and the couple of problems that we did encounter were handled quickly by Fred at Trick and CMI.

The boat runs great - noticeably quicker in the middle, great sound and looks SO cool. Did we get 50hp? Maybe, we don't have a dyno... It looks like a net result of 3-5mph on top, although we are still playing with props a little to see if we can't squeak out a little more.

I have some good photos if anyone wants them (I can't seem to post them...)

-David
THUNDER MARINE
727-501-3183
this is the problem! "Maybe".....

"Looks like 3-5mph" ?? It either is or it isn't!

why does evrybody screw with more than one variable at once without gathering and writing down info after EVERY change?

can't anybody just bolt 'em on and say I gained x RPM and/or y MPH with no other changes?

and then take the next step and add prop if nec. and report the net results at that point.

for crying out loud has nobody heard of scientific method?

anybody heard of a stopwatch and repeated before and after acceleration runs from/to various speeds?

When is somebody gonna document that these things work in boats, not on a dyno?

everything I read about this upgrade is clouded with poor documentation/reporting or bad methodology.

this is not chump change for a twin engine boat! before I spend that kind of coin I want to see a well documented verifiable real world trend in dozens and dozens of boats of a dollar-worthy increase in performance. I could care less if they "sound cool" I'm not dropping 7-8K to "look awesome" "sound cool", I'm doing to increase performance including, but not limited to going faster top end. Jeez, mufflers are the norm for most of us now so who cares about "bark".

Last edited by Rippem; 10-11-2006 at 04:13 PM.
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Old 10-12-2006, 07:39 AM
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Default Re: CMI 496 headers

Well said Rippem, we have all been waiting for actual results!
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Old 10-12-2006, 11:47 AM
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Default Re: CMI 496 headers

Very well said, I agree completely..... BUT, I must admit, I am right at or very near the rev limiter with my 288 and a stock 26 B1 on my HO, so if I installed a set of headers, I would most likely need a prop change to compensate ... The correct way would be to buy a stock 28 B1 before installing headers and test before and after... most real world experience I have heard is right at 3 mph... some 2 some 4..

Also, taking out the turbolators is supposedly worth up to 15 hp,, so in essence the CMI's are producing approx 40 hp over stock, at 12-15 hp / mph, I would expect to only gain a max of 3mph,,, so for 3,500 plus another 500.00 for a new 28 B1 your looking at 4K for 3mph... Not on my budget, not yet anyway,, maybe when they come down to about 1,800 for a set...

Not to mention I have been waiting for Hardin to perform their independant dyno test on their 496 set-up for months now...

Last edited by Chris288; 10-12-2006 at 11:53 AM.
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Old 10-12-2006, 12:19 PM
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Default Re: CMI 496 headers

Originally Posted by Chris288
so if I installed a set of headers, I would most likely need a prop change to compensate ... The correct way would be to buy a stock 28 B1 before installing headers and test before and after...
right-on...

Originally Posted by Chris288
your looking at 4K for 3mph... Not on my budget, not yet anyway,, maybe when they come down to about 1,800 for a set...
try 7-8K for 3-4 in a twin app. 2K+ per MPH is at the top of the $ food chain as far as I'm concerned.

Originally Posted by Chris288
Not to mention I have been waiting for Hardin to perform their independant dyno test on their 496 set-up for months now...
alot of people are. The torque and compact design of a Tri-Y system may be as much of an advantage for more reasonable $
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Old 10-12-2006, 12:46 PM
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Default Re: CMI 496 headers

Originally Posted by Rippem
right-on...try 7-8K for 3-4 in a twin app. 2K+ per MPH is at the top of the $ food chain as far as I'm concerned.
I agree. So, do you or anyone on here know of and are willing to share how to port the stock 496 headers for more flow? I have plenty of time this winter to do a ton of hand work...
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Old 10-12-2006, 12:49 PM
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Default Re: CMI 496 headers

Originally Posted by ECeptor
I agree. So, do you or anyone on here know of and are willing to share how to port the stock 496 headers for more flow? I have plenty of time this winter to do a ton of hand work...
I believe Raylar was in the process of developing an exchange program for your stock manifolds for his ported ones...
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Old 10-12-2006, 01:28 PM
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Default Re: CMI 496 headers

not worth much tho...10-15 hp?
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