Originally Posted by kaczman
Hi all. have a 1999 Maxum SCR 2400 with a 5.0L Mercruiser LX carbed motor in it (220hp). I have a spare 5.7L 260 from my other boat, but wanted to save as a backup. Trying to get anywhere near 300hp as it has an alpha one on it. From doing some research, looks like my best options may be doing TBI fuel injection
and a performance intake.
5.0L and 5.7L four barrel hi-rise Vortec intake manifold (96-08)
Supposedly, the intake and a holly 4 barrel carb is good for around 40hp. Im assuming TBI fuel injection and the intake would be better. Any other suggestions / ideas?
You cannot use this Vortec 8 bolt intake on your older engines with have 12 bolt intakes. Frankly I don't believe you would get more than a 20 HP gain with this modification alone. Secondly fuel injection doesn't provide more HP, what it does provide is better performance across the power band.
When my 1997 5.7LX died I replaced it with a 5.7 Vortec long block (MPI engine) and installed a 4 bbl intake and reused my Weber carb. This engine is rated for 320HP and with my induction system should be at least 300HP. However my 2400 has a B II drive but as long as you are not playing speed boat the Alpha should hold up.
You could put Vortec heads onto your block to gain HP and this will allow the use of the 8 bolt intake, just not sure if any modifications are required.