bouncedcheque

Been following threads here and on hotboat.net and some have claimed speed increases of 1 to 3 mph by removing the "turbulator" plates between the exhaust manifold and riser. Does anyone here have any recent results, and if so are you getting the results while also running switchable exhaust and/or mufflers? I've got corsa quick and quiet plus and am wondering if I'm likely to see results with that set-up. Thanks.

bouncedcheque

ttt !

Pwrbt33

iTrader: (2)

Well, I can see why no one will respond. If you are out of Mercury warranty I can see you wanting to do something. If you are still in warranty, I suggest to leave it alone. Another problem is that if someone says its ok to take them out, then they are liable for engine problems if something happens to your engine. Raylar has an engine kit that includes removing the plate as well as grinding the exhaust runners in the manifold to open the exhaust runners for better flow. He says this gives great benefits. I am surprised he hasnt responded as well. He would be the one to give you a HP gain I think.

Anyone else?

My .02.

John S.

mwdill

waiting for my gaskets to get here, will let you know what i find out.

hillbilly24

It is good for a little bit of power. When I went to Merc school last year the instructor told us that they were for colder climates and were designed to catch condensation and burn it off when the engine was run. Wne I worked at a shop in California we removed severeal sets for customers and they were pleased with the results. We did however inform them that they would not have a warranty against water reversion anymore. Im not recomending that you do it but there are some power gains to be had.

Kokopelli

When you pull the risers off to take out the plates, take the risers down to your local polishing shop and get them polished. Cost me about $50 and they look great! I'm sure the polishing made me faster as well

Raylar

The turbulator plates in between the risers and the main exhaust manifold on the Merc 496's are not to stop reversion, they are as someone else here stated to catch some of the moisture in the exhaust and burn it off because the stock engines have iron seats and steel valves that easily rust when exposed to moisture when stored, especially in the water. The problem is not encountered with our kits because our aluminum heads are equipped with special nitrided stainless valves that do not rust in the engine and our seats are also alloys that are very rust resistant. We also give our kit purchasers details on how to do some slight porting on the Merc 496 manifolds where we have been able to get them to flow much better with just small changes. We have made in excess of 550 Hp on the Merc 496 manifolds and risers with our kits and manifold mods. They are really nice parts for stock manifolds as compared to many after market manifolds who make horsepower claims based on comparisons to the old Merc "log type" exhaust manifolds. Don't be to quick to abandon them for the promise of big horsepower increases from some other manifold manufacuturers. We have tested quite a few and we know along with various headers systems how they all tend to affect power output of the 496MAGS and HO's These plates can be removed in stock 496's and because they restrict the exhaust opening diameter from 3-1/4" to just about 2-1/4" in diameter and with this restriction they have a moderate affect on the power of the engine especially above 4000 rpms. We have seen about 10 to 15 addtional horsepower at 5000rpms on the dyno and there are several boaters who have removed them and seen measurable increases in power and speed. You should not need to buy new gaskets to remove them as there are two gaskets at this flange now, one on each side of the turbulator plate. We have always found in most cases that carefull removal of these graphite coated gaskets will usually allow one to be reused, as this is all that is required when reinstalling the risers less the turbulator plates. The warranty could be a problem with Mercury if the motor is still in warranty and expierences any problems, since they may use this as a reason to dishoner the warranty, although your own Mercury dealer has some discretion here, depending on how he looks at the actual problem., ie: was it caused by this removal or was it an entirely different issue. It will always be our recommendation that you the boat and motor owner will have to decide what you choose to do to your Merc 496 package when it comes to warranty issues or not. I know our kits will not have problems with turbulator removal issues but as for stock motors, that's going to have to be based on your use conditions and your personal choice.
Just some facts and thoughts

Ray @ Raylar

Pwrbt33

iTrader: (2)

Thanks Ray,
I knew you could shed some light on this area.

John S.

96f350psd

On a 454 and 502 there is a resinator in the riser. Will removal of this net you any gains also?

Raylar

No, no such animals in the 454 - 502 packages that I know of, seems this is a 496 "exclusive" Ha!
Ray @ Raylar