2000 SCR 2400 w/ 5.0L - carb upgrades

[kaczman]

Has anyone went from the 2 BBL to a 4 bbl carb and performer intake? Any advantages?

[jrsick]

Let us know if you try this, I'd be interested in hearing how it worked for you. I have tried similar with car engines and got no increase in HP. The limitation is that your intake runners, bore/stroke, and exhaust ports are still the same size.

[mmwjr]

Mercruiser rated the 2bbl 5.0 at 220HP and the MPI at 260HP, a 4bbl should produce about the same HP as the MPI just not over the same power band.

[kaczman]

Is this true? If so, I'd do an intake and carb in a second

[mmwjr]

Originally Posted by kaczman

Is this true? If so, I'd do an intake and carb in a second

Worst case you should get at least 20 HP increase.

[kaczman]

I 'd be happy with 20. Has anyone ever done this before, and if so whats required? I assume edlebrock 1410 750 CFM 4 bbl carb and 2516 4 bbl manifold?

[mmwjr]

Originally Posted by kaczman

I 'd be happy with 20. Has anyone ever done this before, and if so whats required? I assume edlebrock 1410 750 CFM 4 bbl carb and 2516 4 bbl manifold?

That’s too much carb for a small block, get a 1409 600 cfm. But yes changing the intake are carb is all that is required. There is other option like changing the cam and heads but at that point I would just get a 5.7.

[kaczman]

Has anyone did it in a SCR 2400? Seems like clearance would be an issue.

[mmwjr]

Originally Posted by kaczman

Has anyone did it in a SCR 2400? Seems like clearance would be an issue.

My 2400 SCR came with a 5.7LX (260 HP 4 bbl) in 2016 I repowered with a 5.7 Vortec with a new 4 bbl intake and my old carb with no problems.

[kaczman]

Originally Posted by mmwjr

My 2400 SCR came with a 5.7LX (260 HP 4 bbl) in 2016 I repowered with a 5.7 Vortec with a new 4 bbl intake and my old carb with no problems.

I assume you repowered with the same 260hp engine that originally was in it?

What is your max and cruising speed?

[mmwjr]

Originally Posted by kaczman

I assume you repowered with the same 260hp engine that originally was in it?

What is your max and cruising speed?

No the Vortec is a MPI long block rated at 320 HP, with my setup I suspect I’m at 300 HP. On flat water I can hit ~39 mph at ~ 4200 rpm just shy of hitting WOT. I just don’t push it that hard. I do have a Bravo 2 drive.

[kaczman]

Thats awesome. I will be repowering this boat with a 320hp 5.7L.

[kaczman]

Originally Posted by mmwjr

My 2400 SCR came with a 5.7LX (260 HP 4 bbl) in 2016 I repowered with a 5.7 Vortec with a new 4 bbl intake and my old carb with no problems.

Can I ask how hard the swap was, or any tips or pointers?

[donald]

Originally Posted by kaczman

Thats awesome. I will be repowering this boat with a 320hp 5.7L.

What drive do you have? If it is an alpha1 gen2 you are limited to a max 300hp as the drive will not handle any more.
Don

[kaczman]

I have a new alpha 1 gen 2. Yes, its rated for max 300 but as long as you arent hole shotting it I'll be fine.

[donald]

Good luck

[mmwjr]

Originally Posted by kaczman

Can I ask how hard the swap was, or any tips or pointers?

Other than adding a oil pressure switch to power the added electric fuel pump (no provision for a manual pump) the rest is a direct drop in.

I also added closed cooling.

[mmwjr]

Originally Posted by kaczman

I have a new alpha 1 gen 2. Yes, its rated for max 300 but as long as you arent hole shotting it I'll be fine.

Hope it’s a Mercruiser drive and not an SEI as I haven’t heard the best reviews for them. Mercruiser did offer the A1G2 behind a 454 and the service life was mixed depending on how the boats were operated.

[shrew]

Originally Posted by kaczman

I have a new alpha 1 gen 2. Yes, its rated for max 300 but as long as you arent hole shotting it I'll be fine.

I had a friend who overpowered his Alpha significantly. Zero - WOT throttle holeshots are not a good idea. At higher speeds in rougher weather, he needed to keep his hand on the throttles. The second the boat and drives come out of the water, you need to chop the throttle, then hit them very very quickly when you hit the water again. Similar to what the offshore racers do.

[mmwjr]

We’re talking 20 HP over a limited part of the power band, doubt throttle jockeying will be required.