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Headers on a 496 HO
https://cimg6.ibsrv.net/gimg/www.off...b643705ff2.jpg
https://cimg7.ibsrv.net/gimg/www.off...27761fe908.jpg Hi guys I need to change my manifoils and raisers on my 2009 496 HO I have got a very good offer to buy these used headers (see photo) They have been on a 496 HO before same type of boat Formula 271 SR1 before I am going to pressure test before buing of course… Anyone know which brand7producer it can be ?, no logos on the headers What kind of performance benefits can I expect compare with the stock exhaust ? more hp, higer top speed etc.. Greetings from Oslo, Norway |
I'm guessing you will get a wide range of answers but I put CMI sport tubes on my 496 several yrs ago when they first came out and while the looked cool and even sounded better I didn't see any performance gains.
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ZERO to 3 mph MAX gain would be a winner at best if even that ---- with the install stock app to stock app.
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I counted 44 hose clamps on this set of headers. There must be a better way... |
Old CMI split top headers with a short homemade welded on tail.
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Well at least better sound and a lighter boat :-) Thanks for the reply Boatfreak
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Thanks for the reply BUP :-) I am trying to reach 65 mph, so what you telling me can get me there ;-)
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Thank you SB ;-). Very intersting article, I thougt that the 496 HO had 425 hp at the prop shaft ….
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ZAC F100 I did the same ;-) Very interested to hear suggestions how to doing it another way, safe and with out leaks :-)
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Thank you Griff now I know what kind of headers I might end up buying
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Personally I’d skip adding headers on a 496...the cons (leaking welds) far outweighs the benefits (looks and sound). Just my 0.02. |
Originally Posted by 1MOSES1
(Post 4657669)
Personally I’d skip adding headers on a 496...the cons (leaking welds) far outweighs the benefits (looks and sound). Just my 0.02. |
The reason I consider this option are because I need to change next season, engine are a 2009 model not changed before.
The CMI Split Top Headers are almost not used even though they have some years, and I can get them for 450 USD I do not think they have any leaks but I are going to pressure test them anyway.. If they are ok, its a good deal .. Keith Atlanta what kind of engines du you have in your Baja ?? |
not sure as I do not recall ---- Maybe when CMI first came out with marine headers - did they have external welds ? ?? Possible a knock off header ??. And Yes CMI did have headers like the ones in the pics but I do not recall being external welded.
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The visible external welds are normal on satin finish CMI's from what I have owned and seen.
I think CMI smooths them out on the polished versions so they become virtually invisible. |
I sent the pictures to Custom Marine and they confirmed that they are CMI top split headers sold in the 90s replaced by the CMI Sport Tubes
Price at the time they where sold aprox 3.500 usd |
Personally, if I had it all to do over again I’d buy a good set of manifolds instead of the old CMI headers that I got. They were fresh water units and pressure checked, but a few months later my engine wouldn’t turn over because the #5 cylinder was full of water. Unless you’re going for a big power build with all brand new parts I’d stick with some good manifolds. That’s my $0.02. But best of luck however you go! |
Originally Posted by Monaco20
(Post 4657678)
The reason I consider this option are because I need to change next season, engine are a 2009 model not changed before.
The CMI Split Top Headers are almost not used even though they have some years, and I can get them for 450 USD I do not think they have any leaks but I are going to pressure test them anyway. If they are ok, its a good deal .. Keith Atlanta what kind of engines du you have in your Baja ?? |
https://cimg9.ibsrv.net/gimg/www.off...f3801c0f99.png
Nice package, I have been thinking about install a Procharger on my 496 HO, with a mild boost 3,5 psi should give me aprox 550 HP |
Originally Posted by Monaco20
(Post 4657718)
https://cimg9.ibsrv.net/gimg/www.off...f3801c0f99.png
Nice package, I have been thinking about install a Procharger on my 496 HO, with a mild boost 3,5 psi should give me aprox 550 HP |
Originally Posted by boatfreak
(Post 4657720)
If you enjoy using your boat without wondering if the engine is going to grenade every time you take it out I would advise against that.
The cast pistons cant handle it. If you upgrade the pistons, rockers and valve springs you might have a chance. Otherwise several of us have proven that the 496 isnt a great platform to upgrade with bolt-ons unless you upgrade the internals. |
Originally Posted by Monaco20
(Post 4657708)
I sent the pictures to Custom Marine and they confirmed that they are CMI top split headers sold in the 90s replaced by the CMI Sport Tubes
Price at the time they where sold aprox 3.500 usd You will see 0-1 mph if you are lucky. |
20 year old headers=15 year old leaks. |
Well Normally I agree with that :-)
These headers has very few hours on them, garage kept the last 10 years ... |
I have also heard that, I have a couple of friends that has 300 hour plus on a stock 496 HO with this Procharger
one with 5,0 Psi and the other has 3,5 psi pressure. Both says that a lot depend on the hand on the trotle ;-) Again it can also be that they have been lucky so far... I am very unsure about this, so probably I want do it ;-) |
Originally Posted by Monaco20
(Post 4657718)
https://cimg9.ibsrv.net/gimg/www.off...f3801c0f99.png
Nice package, I have been thinking about install a Procharger on my 496 HO, with a mild boost 3,5 psi should give me aprox 550 HP Probably need to upgrade your drive and prop, maybe raise the x-dimension by fitting a shortie. Have you got full hydraulic steering? What size tabs are you running? Blueprinting the hull, tearing the cabin out to lighten her up..... Where does it end? I would leave stock alone, everything I've read says the 496ho is a great engine if it's left alone. Just run it sensibly and service it, you'll get trouble free boating. That's why I bought one. :) RR . |
I had a Whipple charger kit running 7-8lbs.boost on a 2004 HO that ran perfect for 5 yrs. Sold it to a friend of mine who ran it 2 more years. Then he sold it.... Totally stock
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Originally Posted by rak rua
(Post 4657815)
sounds good in theory. Simply bolt on an extra 125 hp, how easy is that? Probably need to upgrade your drive and prop, maybe raise the x-dimension by fitting a shortie. Have you got full hydraulic steering? What size tabs are you running? Blueprinting the hull, tearing the cabin out to lighten her up..... Where does it end? I would leave stock alone, everything i've read says the 496ho is a great engine if it's left alone. Just run it sensibly and service it, you'll get trouble free boating. That's why i bought one. :) rr . |
Thanks for the reply ;-)
And yes my plan was to be all stock, have given me 3 seasons with care free boating ;) I am not a crazy speed freak at all, then I Would had another boat, not a Fromula 271 Sr1. Most of my boating are done at 40 mph 3600 rpm or slower and a Poker Run now and then. It would have been fun to go 70 mph + when I want to though ;-) Now I am doing 63,6 GPS mph .. Mirage 23+ prop drive ratio 1:5 I have an almost new Bravo1 X drive and 280S K-Plane, No hydralic steering yet.. |
Thank you for the reply
From what most people are saying that is not possible … SO you where lucky ,ot drove with a light hand on your throtle ? With out knowing to much about this, I am sure of one thing, if you leave your engine stock, it will be more durable then taking more HP out of it, no matter if its 350, 454 Mag, 502 or a 496 So it comes down to evaluate the risk, and be careful. ;-) |
Those headers are 20 years old. Gains will be minimal at best. The juice isn’t worth the squeeze. |
3.5#’s on the procharger kit you should be fine. Procharger tends to send a pretty rich running tune up for safety. The procharger boost does not have the quick torque like a Whipple so the drive should last as long as your not coming in and out of the water a lot. We had the “good” 496 2003 and they said 5#’s was the max we ran 7 with no issues. |
I had ITS Merc XR drive and drove it like a normal high performance boat. The inner cooler and package designed for the motor that Whipple developed works as they say it will. The original setup made 5-6 lbs of boost. Dustin remapped my computer again and gave me a smaller pulley to make 7-8 lbs. Never an issue. 71-73 mph then 81 or so with 5-6lbs then 84+ with 7-8lbs. 86.7 with 5 blade prop worked from B blades. 30' Superboat y2k
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Originally Posted by boatfreak
(Post 4657547)
I'm guessing you will get a wide range of answers but I put CMI sport tubes on my 496 several yrs ago when they first came out and while the looked cool and even sounded better I didn't see any performance gains.
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Thanks for the replies
Thats a lot of money for only the look and sound :-) I am going to pay 400, if its pas the pressure test :-) And the fact that I should change my manifolds next season (2009 model engine) makes it kind of interesting |
I’d pass even if they were free... |
Originally Posted by Monaco20
(Post 4658134)
Thanks for the replies
Thats a lot of money for only the look and sound :-) I am going to pay 400, if its pas the pressure test :-) And the fact that I should change my manifolds next season (2009 model engine) makes it kind of interesting My 496 manifolds (aluminum) are 15 years old and still going strong. |
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