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496 Mag - 360 hrs - time for manifolds?

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Old 04-15-2011, 04:48 PM
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HGE makes a great replacement and they do not have the casting issues that GLM has had in the past. Never owned a GLM product so that is strictly on reviews that I have read. I do own two sets of HGE that came on the boat and they are a good fit, just really heavy. I just ordered a couple sets of the aluminum HGEs and have heard good things about them.
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Old 04-15-2011, 05:53 PM
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I cant belive that you havent gone thru heat exchangers yet.. mine went at 200 hours and I flush every time..
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Old 04-17-2011, 03:39 PM
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Wink Results????? & Justifications?????

Manifolds generally do not add any power over stock 496 Mercruiser exhaust systems, headers or header manifolds do to varying degrees. If you are inclined to spend between $2500 & $5000 you can find a good set of REAL long tube tuned manifold headers or headers that will add a real measurable amount of power , usually about 25-40HP on a stock engine and in your hull type it may translate to 1-2 miles per hour, so if that is worthwhile for you, go for it!
I will say that Mercruisers 496 exhaust manifold systems are about as good as any marine engine manufacturer has ever achieved with their stock exhaust and our findings as well as others here on OSO and in the industry have found with testing, regular exhaust manifolds by most manufacturers in the after market do not make any more power or work better than the stock exhaust. You can check with Mark at Precision Marine, he just finished a real world test on his dyno between the stock Mercury manifolds on a stock 496 and a Brand X manufacturer of a $2000 plus manifold system and the results back up exactly what I and others are saying. He netted +1 HP on the test!!
So , in this case you may be worlds better off by buying a good used set of stock Merc 496 (iron) lower manifolds for about $400-$500 bucks ( the risers are stainless and fit all models and do not corrode or rust thru and can be re-used) and replace your older manifolds and use the money saved to buy more of that new EXPENSIVE GAS we now have and boat more and enjoy more this season!!
Real results and benefits are the answer in Today's performance boating!

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Ray @ Raylar
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Old 04-17-2011, 03:51 PM
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Originally Posted by Fivefasts View Post
thanks everybody

I thought (was hoping) you would all be more insistent to use this opportunity to add some performance (its easier to convince the wife if i am replacing something that needs replacing!) manifolds. From what i read, the manifolds are the least expensive way to add a little HP. I figured if i have to replace them anyway... : )

Does the serial number of the motor confirm its mfg date?

Its a 2005 Cobalt 255, but maybe the motor was built in 2004?
I have a set of stock 496 manifolds for sale if interested. Fresh water and ~140 hours on them.
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Old 04-17-2011, 05:29 PM
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Originally Posted by wstultz View Post
HGE makes a great replacement and they do not have the casting issues that GLM has had in the past. Never owned a GLM product so that is strictly on reviews that I have read. I do own two sets of HGE that came on the boat and they are a good fit, just really heavy. I just ordered a couple sets of the aluminum HGEs and have heard good things about them.
Never heard of these until now. I checked there website...how do they compare pricewise to osco/barr replacements?
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Old 04-18-2011, 09:03 PM
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Hey Tim (from OCM)
how much do you want for those Merc manifolds?
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Old 04-28-2011, 03:34 PM
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Originally Posted by Fivefasts View Post
thanks everybody

I thought (was hoping) you would all be more insistent to use this opportunity to add some performance (its easier to convince the wife if i am replacing something that needs replacing!) manifolds. From what i read, the manifolds are the least expensive way to add a little HP. I figured if i have to replace them anyway... : )

Does the serial number of the motor confirm its mfg date?

Its a 2005 Cobalt 255, but maybe the motor was built in 2004?
If you forward the engine serial numbers to me i can tell you what you need. No pressure to buy.


Russ
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Old 04-28-2011, 03:39 PM
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Never heard of these until now. I checked there website...how do they compare pricewise to osco/barr replacements?
They are about 100 dollars less for a set - in general terms. I know it's a global economy...I get it. But when it comes to parts that can strand me on the water, I'm a little less inclined to purchase from overseas.
I got stranded once and was seriously scary.

A t-shirt...sure...I'll do that.

We don't sell anything not made in the USA nowadays. That's a recent change for us.


Russ

Last edited by Mr. Cool; 04-28-2011 at 03:41 PM.
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Old 05-02-2011, 07:31 AM
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Originally Posted by Fivefasts View Post
Hey All
My Cobalt 255 has 5 seasons and 360 hours on it. The last 3 seasons running in the salt.

At this stage, is it even worth having the manifolds and heat exchanger boiled and inspected or do you just replace the parts now?

Is it worth buying OEM or is this a legitimate opportunity to buy on a reliable after market product that ups the HP without sacrificing reliability or fuel consumption too much?

thanks in advance for the opinions.
Why are you replacing these parts ? Unless I missed
something 360 hr doesnt mean you have to start replacing
parts. I have 760 hrs on my 496 s and never a problem due
to having to many hours, change fluids and filters often and
dont try and build those motors bigger they should last a
long time.

Last edited by bajarick; 05-02-2011 at 07:34 AM.
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