Emi exhaust still reverting
06-17-2015, 08:54 AM
#11
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I have always wondered about those. They look like they would absolutely work as they appear to be just a check valve as flappers are also, just to a lesser degree. My question has always been how much of a restriction they would be. Over the years, I have come to really enjoy silent choice, but I still enjoy hi-performance engines and that can be limiting as to what you can do. It would be interesting to know what HP limits Merc claims for these, kind of like we know that the Y-pipe becomes restrictive at somewhere just over 300 HP.
06-17-2015, 09:02 AM
#12
If the timing chain has stretched I believe that can also retard the cam and possibly cause reversion on an engine that is on the edge.
06-17-2015, 09:22 AM
#13
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06-17-2015, 11:35 AM
#15
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06-17-2015, 11:38 AM
#16
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Teenage boy walks into the kitechen and nervously asks his parents:
"Mom/dad - Can I go to the 50¢ concert ?"
They both reply without looking :
"Sure. Here's a buck. Take your little sister."
"Mom/dad - Can I go to the 50¢ concert ?"
They both reply without looking :
"Sure. Here's a buck. Take your little sister."
06-17-2015, 01:59 PM
#18
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35Fountain, the Merc resonator looks interesting, but first I would try installing some salisbury type flappers on the ends of your tips to see if this dampens the back pulses enough to tame the reversion. I have a long thread on here about reversion with a mildly cammed engine when I was running mine on a test stand, and I found that simply installing the flappers significantly cut down on the reversion. Before doing this I could hold a $20 bill in front of the tailpipe and it would suck it right out of my hand - proof positive that boats eat money! 
It is strange how one engine with what appears to be a mild cam setup will revert, while others that seem to be more on the ragged edge run happily along without apparent problems. My suspicion is that there are a lot of boats running around out there with some degree of reversion occurring, and no one knows about it.
It is strange how one engine with what appears to be a mild cam setup will revert, while others that seem to be more on the ragged edge run happily along without apparent problems. My suspicion is that there are a lot of boats running around out there with some degree of reversion occurring, and no one knows about it.
Mercury Marine part number 860222A1 RESONATOR-EXHAUST is used on the below models
454 MAG MPI BRAVO (GEN VI) GM 454 V-8 1998
454 MAG. BRAVO (GEN. V) GM 454 V-8 1996-1997
454 MAG. BRAVO MPI (GEN VI) GM 454 V-8 1996-1997
454 MAG. MPI BRAVO (GEN VI) GM 454 V-8
454 MAG. MPI HORIZON (GEN. VI) GM 454 V-8
496 MAG (Base Model)
496 MAG (H.O. Model)
496 MAG EC (Base Model)
496 MAG EC (H.O. Model)
502 MAG MPI BRAVO (GEN VI) GM 502 V-8 1998
502 MAG. MPI (GEN VI) GM 502 V-8 1996
502 MAG. MPI BRAVO (GEN VI) GM 502 V-8
7.4L BRAVO (GEN. VI) GM 454 V-8 1996-1997
7.4L BRAVO (MPI)(GEN. VI) GM 454 V-8 1998-2000
7.4L MPI MIE (L29) GEN. VI GM 454 V-8 1998-2000
8.1L INBOARD (Base)
8.1L INBOARD (Base) EC
8.1L INBOARD (H.O.)
8.1L INBOARD (H.O.) EC
8.1L TOWSPORT (Base)
8.2L Mag (Base Model)
8.2L Mag (H.O. Model)
8.2L MIE MPI (GEN. VI) GM 502 V-8
Last edited by 35fountain; 06-17-2015 at 02:17 PM.
06-17-2015, 02:16 PM
#19
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I have always wondered about those. They look like they would absolutely work as they appear to be just a check valve as flappers are also, just to a lesser degree. My question has always been how much of a restriction they would be. Over the years, I have come to really enjoy silent choice, but I still enjoy hi-performance engines and that can be limiting as to what you can do. It would be interesting to know what HP limits Merc claims for these, kind of like we know that the Y-pipe becomes restrictive at somewhere just over 300 HP.
06-17-2015, 02:59 PM
#20
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