Warrior II

I have a 1987 454 Mag and was wondering if the riser and manifold setup from a 2004 496 Mag HO would work on the 454? Thank you!

Dennis Moore

The 496 manifolds and risers will bolt to the 454 engine but the rest of the exhaust will need to be modified to connect to the 496 riser outlet position.
Dennis

Warrior II

Thanks for the respons Dennis. Could you please explain a little on what mods to the exhaust outlet would have to take place? The current exhaust is thru-hull. Also, does anyone know if there will be any ill effects to performance or tuning mods that will need to be performed if I use the 496 manifolds and risers? Thank you!

Dave M

Not the exact same situation, but....I repowered my last boat, went from 454 Mag MPI to a 496HO. If you are using rubber exhaust hose from the risers to the tips you should be able to make it work. The difference is not that drastic. I used the Trident exhaust hose that seems to be a little more flexible.

wjb21ndtown

I agree... The 496 risers have a slight downward angle, opposed to the straight out 454 risers. I didn't have a problem making it work with 3' of rubber hose though. It was enough to eat the bend and mount the same with no real crimping of the hose. I had to open up the holes in the 496 manifolds to get them to bolt on properly.

Warrior II

Ok...my boat is only used in salt water, so which years of 496 manifolds and risers are best suited for this condition? I do flush for 10 min after every outing. Thanks everyone!

wjb21ndtown

Someone else can chime in about the use of the cast aluminum manifolds in salt. It seems to me that Merc switched for a reason, and I'd take a couple years of longevity over a 30-40lb weight savings.

Carolina_Sx

So does this mean that 454 Manifolds and Risers will work on a 496? I have a buddy that has several sets of 454's but I didnt think the bolts would line up on my 496

HTRDLNCN

we switched from merc 454 stockers to the 496 manifolds on a 454 Mag and had to change absolutely nothing, didnt have to change hoses,drill holes, make holes bigger, zero,it was a straight up swap..
Yes the outlet is a bit angled down but nothing the exhaust hose cant handle.

Warrior II

So, going from a wet system to a dry system is a direct swap?