300hp vs 330hp /torque curves

captchuck

1st Mate
Joined
Dec 4, 2011
Posts
186
Likes
12
Location
Long Island
Boat Make
26' Seaway
Mercruiser 5.7 350 mpi =300hp
Crusader 5.7 350 mpi =330hp
Both motors are rated for the same max operating rpm's 4800-5200 so I am still in the air on these 2 motors. Does the 30 extra hp make a difference going in a 26 seaway? I realize the torque curves would be a better indicator than anything on whether or not the 30 extra hp makes a difference but they are not readily available for either on the web and it seems like there simply is not one available for crusader.
Any input would be great!
 
Joined
Feb 13, 2012
Posts
1,181
Likes
149
Location
Communist part of NJ
Boat Make
Bertram 33SF
an honest 30 hp might give you a half a knot, but nothing significant.

as for torque curves, to answer that question, i would need head casting numbers, cam profile, and what intake is on it. sometime's manufactures just add more hp by adding more fuel(re-jetting carbs, change programming in ecu) and ROUND OFF to the closet , so in reality there might only be a 22hp gain, yet they round it off to 30, curves will be real close.
 

twister

Captain
Joined
Jan 10, 2013
Posts
571
Likes
85
Location
RI
Boat Make
37 Mitchell cove
Is what you are replacing carbed?
 

mudhake

Captain
Joined
Oct 6, 2011
Posts
726
Likes
409
. I have used the 5.7 Indmar Marine fuel injected 320hp in 3- 25ft. B.H.Ms and 2 in the 28ft B.H.Ms and they worked out good. These motors are built for the Ski boat industry. They have good mid range tourque because they are always under a load pulling multiple skiers or wake boarders.
 

captchuck

1st Mate
Joined
Dec 4, 2011
Posts
186
Likes
12
Location
Long Island
Boat Make
26' Seaway
. I have used the 5.7 Indmar Marine fuel injected 320hp in 3- 25ft. B.H.Ms and 2 in the 28ft B.H.Ms and they worked out good. These motors are built for the Ski boat industry. They have good mid range tourque because they are always under a load pulling multiple skiers or wake boarders.

What kinda numbers did you get with your 25?
 

twister

Captain
Joined
Jan 10, 2013
Posts
571
Likes
85
Location
RI
Boat Make
37 Mitchell cove
I swapped from a HO351 to a 345 hp marine power and can cruise 2 more knots for the same mpg. I think this comes From from ditching the carb and not having the big jump in fuel when the secondaries open. Between the engine swap and playing with props you can kinda tweak your mid range and get the wot. There is a big difference between 3 and 4 blades for me both reaching the same wot
 

mudhake

Captain
Joined
Oct 6, 2011
Posts
726
Likes
409
2:1 reduction, swinging a 18x19 4blade wheel we got 28kts top speed. The boat had 90 gals of fuel under the stern washrail, A v-berth, and a head with a small holding tank, and hydroslave 10 inch hauler, and 4 people on board. We were pleased with the top speed and with an easy, fuel efficent 20knt cruise.
 


Top Bottom