Engine power rating on reman 5.7

[QBhoy]

Hi all.
long story short...a friend has bought a boat. Getting it delivered this week.
It originally had 5.0 twin VP with 290dps
it was reengined in 2012 with brand new marine crate engines of 5.7l each (merc black colour). Receipts all there but I don’t know the serial numbers yet, until I see it.
They are 100% vortec but have been fitted with 4 barrel Holley carbs and suited manifolds etc.
will these be 300hp engines ?

 

[Bondo]

Ayuh,..... Probably an honest 280 hp,..... 300 hp if you want it to be,.....

 

[QBhoy]

Ayuh,..... Probably an honest 280 hp,..... 300 hp if you want it to be,.....

Thanks Bondo. Appreciated. Now suspecting the B3’s modestly pitched props will be underpropped for it and likely to suit the original 5.0 VPs. May be wrong. Would have imagined that this would need b4’s or B5s on it mayne.

 

[Scott Danforth]

Would need the mix of parts that were ordered in the crate motor. IIRC the typical GM vortec marine crate motor was about 290 crank for 2012. Add a carb spacer for more mid torque

If your looking for more power, a cam change would help

 

[QBhoy]

Would need the mix of parts that were ordered in the crate motor. IIRC the typical GM vortec marine crate motor was about 290 crank for 2012. Add a carb spacer for more mid torque

If your looking for more power, a cam change would help

Thanks Scott.
yeah i have copies of all the parts used to kit it out with his boat. Looks like it was done properly with all to suit. The Holley carbs were fitted because there were no standard Rochester 4 barrel available at the time.

not looking for more power really. He is worried enough about the thirst compared to his last boat.
our concern is that it originally had 500 (5.0) VPs mated to it’s still existent 290DPs.
it has B3’s props on it. I suspect they are original and will now see it underpropped with the extra 70hp on each engine.

 

[Scott Danforth]

Fuel burn will be 0.4#/HP/hr. So tell him not to throttle past 220hp worth

If he wants fuel economy, gets sails or oars

 

[QBhoy]

Fuel burn will be 0.4#/HP/hr. So tell him not to throttle past 220hp worth

If he wants fuel economy, gets sails or oars

Haha. Oh he knows what he is in for. Just that it’s a big leap compared to the old boat. That was half the weight and 7 ft less. With a fairly frugal 4.3 DP.