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-   -   496 Flame Arrestor (https://www.offshoreonly.com/forums/general-q/387567-496-flame-arrestor.html)

CheckmateScarab 03-10-2026 01:28 PM

I was never a fan of the clamp on style, but that looks pretty thin, seems like the wrong corner to cut when the worst case scenario is igniting your engine bay

Lots of better flowing aftermarket parts for $100-200 without introducing additional risk

boatnt 03-10-2026 02:18 PM

https://cimg1.ibsrv.net/gimg/www.off...12c8dc060.jpeg
https://cimg2.ibsrv.net/gimg/www.off...afcb0e52d.jpeg
I use K&N and they work well, and it’s your lucky day as I have a brand new extra one you can have for $65

powerboatr 03-10-2026 03:47 PM


Originally Posted by Brad Christy (Post 4944093)
Xlint,

https://cimg4.ibsrv.net/gimg/www.off...42fc6dd2e.jpeg
https://cimg5.ibsrv.net/gimg/www.off...ea3af13e5.jpeg

Little late for that. Besides…. Without a dyno specifically set up for closed cooling (consumed water), it’s nearly impossible to do a dyno pull. We could potentially just do a with/without empirical test. But, I can tell you, without a doubt, without some sort of bellmouth, the “without” flow will be worse than with the FA.

Thanks. Brad.

either way the engine room looks freaking amazing

Brad Christy 03-10-2026 04:13 PM


Originally Posted by CheckmateScarab (Post 4944143)
I was never a fan of the clamp on style, but that looks pretty thin, seems like the wrong corner to cut when the worst case scenario is igniting your engine bay

Lots of better flowing aftermarket parts for $100-200 without introducing additional risk

CheckmatScarab,

That's an OEM Merc 496 FA.

As I stated in the starting post, I have serious doubts a flame front is going to be able to travel that far, plus through the intercooler and the ProCharger.

Thanks. Brad.

Brad Christy 03-10-2026 04:17 PM


Originally Posted by boatnt (Post 4944145)
https://cimg1.ibsrv.net/gimg/www.off...12c8dc060.jpeg
https://cimg2.ibsrv.net/gimg/www.off...afcb0e52d.jpeg
I use K&N and they work well, and it’s your lucky day as I have a brand new extra one you can have for $65

BoatNT,

I've been told the K&N flows worse than the OEM 496 breather. Or, at least, they offered one at one point in time that did. Do you have any data on that one?

Thanks. Brad.

Diamond Dave 03-10-2026 04:44 PM

Brad, in that same thread I referenced, the 502MPI version of that K&N filter killed HP compared to the OEM flame arrestor. Again, different app but I bet you are correct also.

boatnt 03-10-2026 05:50 PM


Originally Posted by Diamond Dave (Post 4944161)
Brad, in that same thread I referenced, the 502MPI version of that K&N filter killed HP compared to the OEM flame arrestor. Again, different app but I bet you are correct also.

I guess different people have different experience, back when I replaced my stock flame arresters on my fountain with twin 502’s and added it KN I noticed the difference in a positive way, that was just me

boatnt 03-10-2026 05:54 PM


Originally Posted by Brad Christy (Post 4944158)
BoatNT,

I've been told the K&N flows worse than the OEM 496 breather. Or, at least, they offered one at one point in time that did. Do you have any data on that one?

Thanks. Brad.

no, I don’t have any data. I don’t get that consumed with a filter, you can remove that filter and drive your boat and I guarantee you’re not gonna see any difference so a filter is not going to help you, all I can tell you is the stock 496 flame arrestor is not providing any filtration, all the belt dust goes right through that stock filter and into your engine, I like the K&N because simply it filters better it sounds better and does not affect in a negative way and no more belt dust in my throttle body

boatnt 03-10-2026 06:01 PM

and I will tell you one more thing, and I know a lot of people are gonna disagree with me because I am full of crap, and I don’t know what I’m talking about, but in the unlikely event you ever have any kind of fire in your boat and it ends up being from a backfire and there is an investigation by the insurance or anybody else and see the flame arrestor has been modified you’re gonna have explaining to do,
let’s think about this if mercruiser could get more performance out of those engines and did not have to add the mash to their flame arrestor why would they?

Sydwayz 03-10-2026 06:13 PM


Originally Posted by CheckmateScarab (Post 4944143)
I was never a fan of the clamp on style, but that looks pretty thin, seems like the wrong corner to cut when the worst case scenario is igniting your engine bay

Lots of better flowing aftermarket parts for $100-200 without introducing additional risk

Not impossible, but unlikely for a fuel injected motor to backfire. I'm pretty safety conscious, and I'd do it.
I don't think it's really "cleaning" any air. It's typically not dusty out on the water, nor in a boat bilge.


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