mbobb

Cool setup! Just a suggestion you may want to just double check all of your measurements since the turbos will likely be in a different (probably higher) location so you may have issues with hatch clearance and also need to reroute all of your piping. I'm not familiar with boat turbo set ups but from the picture it doesn't look like you even have a riser (where the dry-joint comes into play); it looks like your turbo is the riser if I'm seeing correctly? With a 496 style exhaust would you be using the 496 riser and then mounting the turbo behind it?

sutphen 30

good plan,,I love it.
cable operated or drive by wire?

phughes69

Im going to do cable operated. Its just the easiest way.

phughes69

Your right. I looked at the centerline of the turbos and it is above the rocker cover rail. Using a 496 center riser manifold would run the outlets of the turbo right into the side of the intercooler and it would not be inline with the existing holes in the transom for the exhaust. My original plan was to make an adapter block to mount the turbo to that would then bolt to the manifold. Currently the assembled exhaust order is
1. exhaust manifold
2. wastergate plate (1/2 thick steel with hole thru it from the exhaust manifold to the turbo adapter)
3. turbo adapter (this is watercooled also and the water exits to the inlet of the turbo shield on the other side of the motor)
4. turbo charger.

scarab31

My Scarab is naturally aspirated, carb only with no turbo or supercharger...496 manifolds and risers were a direct drop-in change with zero height issues from the old exhaust. I actually have two extra sets of the 496 risers at home and if your in St Clair MI still I am an hour away from you in Oakland county.

phughes69

What kind of manifolds did you have before you put the 496 manifolds on?

scarab31

My boat had the stock cast iron behemoths from 1989 that were used on the Mag egines. I don't think that Mercury used a different manifold on the 330 vs 365 hhp engines. I did a mild refresh with new intakes, carbs, cam and valvetrain and wanted to take advantage of the more efficient exhaust of the 496. I reused the original exhaust hose too.[ATTACH=CONFIG]542258[/ATTACH]

DanWentworth

@Scarab31,
I have a 1989 Scarab III with 454 Mag Gen 4 engines . I am pulling the motors this offseason for a refresh.
I am considering replacing the Stock Cast Iron Manifolds.
Are all the 496 manifolds a direct bolt up? Or are there differences in the 496 manifolds over the years to be concerned with?

Any other issues I should be concerned with?
Thanks in advance.
Dan

f_inscreenname

Just a FYI, there is different 496 manifolds and different riser heights. Pay attention when buying. Saw a lot of people fooled over the years.
Some of the real old manifolds are cast iron. Others come with a water rails at the bottom. IMHO you do not want either one. A simple replacement are the aluminum manifolds with a single water input. Then the risers also come in two heights. I don't remember the sizes but there is about 2 inches difference between the two. I know a guy that can extend or shorten them as needed being thy are just stainless steel tube.
If you do get the manifolds spend a little time opening up the exhaust runner ports. Just use the exhaust gasket as a guide. Its aluminum so its not hard to do and its free hp.

Last I'm sad to say I wish I would never opened up my mouth. I used to buy new take off sets for a couple hundred bucks back in the day. Half the time shipping cost more then the manifolds and I did it to 20 boats around here and told everyone I could about it online. I guess they listened because you don't see that anymore.

Also, the riser studs and bolts are metric and if you have a remote oil filter on the front of the motor you will have to make a bracket for it to hang on.

scarab31

I have the aluminum manifolds with the single water inlet at the bottom of each manifold. I am not aware of Mercury using different manifold or riser heights...doesn't mean they don't exist...these are marine engines after all.