CMI 496 headers
 

Any more results? Seems lots are being sold, but limited info. re: real-world results.

Re: CMI 496 headers
 

I'd like to hear about some results also.....

Re: CMI 496 headers
 

The January SpeedBoat magazine has an article on this topic.
Save 28 pounds per motor in weight.
Claimed peak per engine 80 HP, average numbers were 55 HP.
$4100 gets one set and a new ECU according to this article.
Test boat gained 3 mph on a single engine application.
Bryan

Re: CMI 496 headers
 

Bryan, mind me asking what the test boat was ??

This is the first I have heard about a new ECU, Anybody else heard about this ???

Re: CMI 496 headers
 

ECU mapping not required.

Re: CMI 496 headers
 

Here's the dyno sheet!!

Re: CMI 496 headers
 

Is it just me or is the Baro pressure and relative humidity all over the map between the two dyno runs.
Just curious...
Thanks,
Dave

Re: CMI 496 headers
 

somebody just post a picture of the CMI's on a twin 496 application so that I can start drooling :D

Re: CMI 496 headers
 

The uncorrected numbers go up by 35hp, not bad. An ECU remap probably wouldn't hurt.

Re: CMI 496 headers
 

Hey Fred,
I understand that very clearly :rolleyes:
It just seems that with the Baro and Humidity on the second run that they were testing it out in the rain???
Just trying to understand.
It seems that it would take no more than 1/2 hour to swap the headers on the dyno so why not back to back?

BTW, the custom tailed platniums worked out perfect on the Bulldog.
Thanks,
Dave

Re: CMI 496 headers
 

The 496 Kit

Complete with Headers, distribution tubes, all required hoses and brackets for relocating of accessories.

If anyone requires more information or details, please contact us at (847) 623-2737 or [email protected]

Hope everyone has a safe and enjoyable 4th of July Weekend!!

Re: CMI 496 headers
 

Dave, I was wondering about that humidity too. However, I plugged all the numbers into my dyno correction tables and it doesn't make much difference, maybe 1/2% correction. The low Baro accounts for 2% more correction. Must of been one hell of a rain storm that came through on that test...LOL. It's nice to see a dyno sheet with all the data, for us analytical types. The raw numbers are impressive though, and the second run would warrant about 2.5% additional correction than the stock run. Are these the runs that Tyler Crocket did or a seperate test?

Re: CMI 496 headers
 

A dyno run can say anything, back to the original question of this thread, any more real world results out there, that's all that matters. Would love to hear.

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
THUNDER MARINE
727-501-3183

Re: CMI 496 headers
 

why the 92 octane in the second chart- did timing get tweaked?

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.

Re: CMI 496 headers
 

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".

Re: CMI 496 headers
 

Well said Rippem, we have all been waiting for actual results!

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... :cool:

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

Re: CMI 496 headers
 

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.

alot of people are. The torque and compact design of a Tri-Y system may be as much of an advantage for more reasonable $

Re: CMI 496 headers
 

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...

Re: CMI 496 headers
 

I believe Raylar was in the process of developing an exchange program for your stock manifolds for his ported ones...

Re: CMI 496 headers
 

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

Re: CMI 496 headers
 

Run a search and you'll find results from end users.......

......have been running them for several weeks with what I would consider fairly good results. I am running a Velocity 290, with a Bravo 1 labbed 28. Started at @ 4900 RPM, 72-73 on spedo. I am now at @5150, 76-77 on spedo, but running out of prop at times. Tried a Bravo 1 labbed 30, but it was a bit too much prop. Ran close to 4900 RPM, but speed was not there. That prop is being worked on now to hopefully allow me to run at 5050, and perhaps gain another MPH or so. Velocity hulls react very well to minimal power, so other hulls may not see the same results. If I maintain a consistent 4, I will be satisfied. I always run above half full on fuel, so that is not an issue.

.....Results are in on the 496 CMIs, 482hp with no other mods. Sounds good. See latest Powerboat Mag

Re: CMI 496 headers
 

well if we all went by speedo #'s I wouldnt need these headers... :D :D

Re: CMI 496 headers
 

The part about Velocity's bottom responding very well to power(among the best) is certianly true. Owned 2.

like I said earlier, single engine fast bottoms/lighter boats seem to be the ones getting the gains for the $$.

So you guys have it made at 1K per MPH. :D

Point me in the direction of documented results on 9-10 thousand pound twin boats.



57 HP? That's a new high quote. :eek:

Again Dyno...CMI buy a big ad in PB this month?

Just kidding! :p

Re: CMI 496 headers
 

I'm not busting vendor's balls...

CMI's for pricing is more to the point, price 'em like (and make them in satin) satin elbow tops and they'll sell like hotcakes. :p

no one's guinnepigging them on heavy twins.

Give me a couple pair. After 200+ hours on my 353 I know where my boat stands in terms of performance. I'll report accurately and scientifically. :D

Re: CMI 496 headers
 

Then I'd just need another winter project to keep me busy! The power gain isn't the point...it's the time in my shop that really makes it a worth while endevor. Far cheaper than visiting a shrink! :drink:

Re: CMI 496 headers
 

Somebody has the specs. on the DIY manifold porting, ask 26Sonic from the board, I think he knows who has the blue-print..

Re: CMI 496 headers
 

Guys, let's be realistic. They are worth some performance gains. Maybe not as much as billet throttles, colored bezels, mirrored hatches or any of the thousands of other parts we spend a ton of $$ on and install on our boats for that little something extra.

CMI makes a great performing and looking product that may not be for everyone or everyone's budget. Do they enhance the performance of the engine? Yes. Is going to get you into the record books with stock power? Probably not. Do they perform and look cool - YES!!

Re: CMI 496 headers
 

so conservatively call it 80-100 horse for twins- that's got to be good for something- compared to the more intrusive options of the Raylar kit (worthy) and the Whipple SC (also worthy) at a higher expense.

I'd like to see some documented twin results too- but the first ones I see may be my own. something is coming- just not sure how soon (Antbody want to buy a nice Pantera- CMI's included :evilb: )

Re: CMI 496 headers
 

I'm sure the CMI's would perform unbelievably on your cat!! Maybe even get you in the record books . . . :evilb:

Re: CMI 496 headers
 

8 grand will buy one helluva lot of anodized bezel and powder coated bling... easily making my boat 3 MPH faster at the dock. :evilb:

right back at 'ya. :D

(just having fun now...)

Re: CMI 496 headers
 

Thats why we all look so fast sitting at the docks!!! Good luck with whatever you do. As long as we're having fun doing what we enjoy right?! :drink:

Re: CMI 496 headers
 

I can provide a few names and phone numbers to customers who would be willing to share the results of twin installations.

If you're seriously considering an upgrade of exhaust, give me a call and I'll send you in the right direction for real world numbers from the users mouths. ;).

Re: CMI 496 headers
 

Thank You...and absolutely! :cool:

Re: CMI 496 headers
 

Thanks Fred. I would come to you first no question as I have been most pleased with my purchasing experiences from Trick.

I had sold you a pair of flame arrestors for the Mistress before there was a Trick Marine...

hope it wasn't buying accessories from me that drove you to open your own store. :eek: :p

Re: CMI 496 headers
 

The openings at the header flange are already too big so don't touch them. The biggest problem in in the plenium. No two ports are the same. The manifold's port openings (or exits) are small in the plenium but keep in mind the head uses a 1.720 exhaust valve and a very small exhaust port VS 1.880 for the blue motors. I don't have any AB dyno numbers but what I did was equalize the port dimentions. Use some inside dividers and measure the largest of the center runners and open the smaller one to match. One runner on the end is much bigger than the other so don't try to match you may end up in water. Don't touch the riser or the opening on the manifold. Keep in mind when grinding, the wider you make the ports, the shorter the lenth of the pipe. My guess is there is at least another 20 hp gain if done correctly.

cmi headers 496
 

im getting cmi e top re program and new prop on my 07 26 outlaw. Is this a good combo?

If you get all three at the same time how will you know what worked and what did what??

No reprogram of a stock 496 is going to net any real gain unless you raise the rev-limiter and on stock 496 valve train that is like playing Russian roulette with 4 bullets in a six shot clip!
If a prop is not just right for any boat, proper prop rework will usuallly add 1-3 mph on average.
As for the CMI e-tops for the 496 Merc, my info is about 15-20HP max over the pretty good Merc stock exhaust system.

good Luck

Best Regards,
Ray @ Raylar