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CMI 496 Sport Tube

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Old 10-12-2005, 12:08 AM
  #11
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Default Re: CMI 496 Sport Tube

Quote:
Originally Posted by C_Spray
Playing with the calculator, I get something like a 48 hp increase.....
that is about what they advertise.... go figure....
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Old 10-12-2005, 12:15 AM
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Default Re: CMI 496 Sport Tube

Thats great...love to see some good mods for the mildly priced powertrains.
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Old 10-12-2005, 08:19 AM
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Default Re: CMI 496 Sport Tube

Nice pics Oh-Deere,

It's hard to tell by the pics but do the headers add any additional height or length to the motor? It looks like the oil filter assembly might of moved forward a bit. I have VERY LITTLE room to go up or forward in my engine compartment. If anything sticks out past the flame arrestor it won't work for me.

Dave M.
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Old 10-12-2005, 08:28 AM
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Default Re: CMI 496 Sport Tube

I have tried a few different prop setups and have found that 496 with headers performs best at higher RPM's (5050+). Tried more pitch which ran @ 5000 RPM, but found that the smaller wheel felt better all around. In my opinion, if someone is currently running 4900 RPM or less, they may not need to make a prop change and will gain the MPH through increased RPM. Fine tuning of their current prop may be all that is needed. I may stay with the labbed 28 and just have the ECU reprogrammed to keep me out of the rev limiter and perhaps gain a bit there. Will have to play with it a bit more in the Spring. All things considered, they worked for me.
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Old 10-12-2005, 09:04 AM
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Default Re: CMI 496 Sport Tube

I believe there are Three or more examples of similar results in the other Two threads. Why not PM those members before the insinuations?
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Old 10-12-2005, 09:47 AM
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Default Re: CMI 496 Sport Tube

Dave,
I will take some height measurements from a common point on the motor this weekend. Even with the 3" spacer for the cowling, I did choose to trim it a bit, as you can see in the previous pics. The highest point would be the forward header on each side. The cowling could be set lower, with additional trimming and shorter spacers, so that should not be an issue. You should have no problem with forward space, as you can see in this pic.
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Old 10-12-2005, 10:31 AM
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Default Re: CMI 496 Sport Tube

Shorter, narrower, wider, straight back, down turned, above swim deck, below, with the right measurement input, you can have headers any way you want them.
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Old 10-12-2005, 11:27 AM
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Default Re: CMI 496 Sport Tube

Oh Deere,
I have been reading your posts and congrats on your success with these headers.

Sean H,
I do not believe anybody including myself said 4more mph sucked. I think that this is very impressive to be honest with you and I am very much considering adding them to my boat. As my post read I have not been able to find other threads other than this one to base any type of real numbers and opinions. As you know many different boats have different setups so this could definitely change the performance from boat to boat.

jrz,
I am not insinuating anything. If you would have read my post a little closer you would have noticed that I asked if there were other threads that had any real numbers and opinions. I am only looking for info and not trying to bad talk the product.
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Old 10-12-2005, 12:06 PM
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Default Re: CMI 496 Sport Tube

Joe I ran my outerlimits (finally) the headers and mufflers worked perfect, waiting for the weather to try different props and rotation
Gary told me you got a new boat, hows it running?

Brooks
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Old 10-12-2005, 12:29 PM
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Default Re: CMI 496 Sport Tube

Hi Brooks. I was wondering who the Wisconsin/Florida Outerlimits owner was. I bought a used 38 Fountain with Staggered 525's. Other than the better air why did you wait until October to start testing? I might try larger ID headers, ECU's, 2" shorter sportmasters, and Herring 5 blades. Just to keep it stock.
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