Upgrading a 57L Mercruiser

"Hi all,

I'm thinking o

"Hi all,

I'm thinking of upgrading my current 5.7L Mercruiser sterndrive with a 6.3L with fuel injection (about 20% more power). Is this advisable ? Will I need to change the leg (currently and Alpha) ? How do I find out if it's suitable for the boat (a Maxum 2700SCR) ? Is is worth the extra cost and fuel ?

Thanks."

"alphas are good to 300hp and

"alphas are good to 300hp and your around 260hp, so I would consider intake, cam, carb and maybe
exhuast upgrades to bring her up to 300hp.
I upgraded intake, carb, and exhuast only and
got alot more power and 68+ mph gps and 5000 rpm
on 23p prop. I use 21 for heavy loads and wake boarding.
upgrades as follows;
edelbrock air gap dual plane non egr intake
750 cfm marine carb
switchable through hull or prop exhuast
Does much bettor through the hull!!! but like to be quiet most times.

Or if you engine is tired you may consider making a stroker out of your 350.
A 400 crank and high silicone pistons (dished)
with 30 over bores would bring you to 6.2 liter.
using stock merc cam should put you about 300-325
horses and should be safe with alpha drive. You could even use old carb with rejetting for displacment increase.


kurt"

"I installed a Merc drop in 6.

"I installed a Merc drop in 6.2 MAG MPI package last year in place of a carbed 4.3
Great swap; runs like heck, pulls lke a bear, and no chokes or carbs to mess with. I am running a 21" High Five prop and have seen 60+ MPH so far. The boat is 20.5 ft and weighs about 2600 lbs empty.

I re-geared my Alpha Gen II to 1.47 and its running well. The 6.2 is rated at 320 shaft hp, so I am kind of on the ragged edge of the Alpha, but so far, so good.

I don't think I added more than 100 lbs of weight, and in your case there is no weight additional. Great swap for a 5.7.

Rod"