Merc 454
 

Have a bone stock 89 454 engine... Looking to upgrade a couple things first a stainless marine exhaust system & new carburetor. Does anyone have any suggestions on what carb to go with cfm's etc??

750 holley marine.

What was the stock Cfm?? Are the Edelbrocks any good?

Edelbrock carbs are alright, but you can't mod them and tune them to the extent that you can mod and tune a Holley. Your stock CFM should also be "750," but your performance gains will come by way of the ability to tune the Holley to fit your application and upgrade it.

If all you're doing is an exh. and carb. a Holley 750 marine carb is the way to go. You may want to consider an Edelbrock intake (performer/performer RPM or Airgap).

What HP version of the 454 do you have? 330, 365, etc? Do you plan to do any other upgrades besides exhaust in the future?

If all you are doing is exhaust, you wont gain anything from ditching the stock carb performance wise, and going to a holley you might lose some fuel efficiency.

if you have a 365HP version, a cam swap, carb, intake, and rockers can really wake it up. Or better yet, slap on a small 177 or 250 supercharger.

I have the 330 version not the mag. Could you put the supercharger on the stock engine??

I wouldn't supercharge a 330. It has cast internals and would likely come apart. You could (and probably should) consider picking up a couple of Edelbrock Performer intake manifolds for the peanut port heads, or if you have the budget for it, pick up a couple of pairs of large oval heads and a Edelbrock Performer RPM heads.

You'll notice small gains from everything that you're doing. To really notice a big gain though, you're going to have to do more. Cams would make a big difference too, but you'll likely have to pull the motors, but you have to decide if you want to take on that sort of commitment.

**Edit (the edit function won't work for some reason)

That's supposed to say "Edelbrock Performer RPM intakes" not "heads" if you upgrade your heads to large ovals.

Some guy have put blowers on your motor with the stock cast internals, and have had good luck. It would probably be ok with low boost, good fuel. the cast pistons wont hold up to any detonation as good as a forged piston. Personally, i wouldnt do it.

I wouldnt go crazy spending a ton of money on your motor. Leave it stock, and save up some dough. Then, when your ready, you can buy a nice motor, and sell off your stock one. Trust me, it will be cheaper that way!

You ain't kiddin...

You get to a point with these 330s where you're better off just buying a 370-500hp Merc motor used, and doing a refresh on it before you put it in. You can pick up 50ish Hp and 5ish mph out of putting new heads, intakes, carbs, 1.7 roller rockers, exh., etc. on them, but you still have a tired cast internal motor, and to make any real power you have to change the cams anyhow. If you're pulling the motors and changing the cams, you're better off doing a motor swap.

The single biggest power adder, if you want to keep it cheap, is changing the heads. The peanut port heads are the biggest power drain on that motor. You could upgrade the heads, intake, carb for less than the cost of the Stainless Marine exh. manifolds. If you're not willing to make the commitment to change the motor completely you'll be better off swapping everything but the exh. If you want to later swap the motor the Stainless Marine exh. would likely be the only thing you want to use off of your old motor (aside from accessories). You just have to figure out how far you want to take it.