repower 23 cc inboard

[Fr. Frank]

That's too small. It won't have the torque to get you on plane.

[GetReel]

Diesel hp and gas hp ratings are not measured the same, diesel hp is rated at the shaft, thus, the hp rating isnt the same bro...a 240 hp diesel will push that boat at 25 cruise with ease..its been done, why would anyone put in $22,500 to not get up on plane while you can put in an equivalent gas 350 for half that.

[riprunner]

Jeff,

Will the 5.9 Cummins fit in there? I have 2 370B's coming in any day from Cummins, but they are going in my Blackfin. Would be cool to know I could put one of these in the 23 as well with a lower hp rating.

[workinpr0gress]

Rather have a stout 3.9,4b cummins.

[77SceptreOB]

Diesel hp and gas hp ratings are not measured the same, diesel hp is rated at the shaft, thus, the hp rating isnt the same bro...

Huh?... HP is HP. HP is the same Diesel or Gas.

Horsepower = Engine Torque (Foot Lbs) x Engine Speed (RPM) then divide by 5252. That is how HP is measured. The TORQUE (ablility to rotate mass)of an engine is a huge component of the POWER of the engine.

Gas engines make their high HP DUE TO RPM.
Diesel engines make there HP DUE TO TORQUE.

Hence, a 180 HP Diesel provides the same Performance as an approx 250 HP gas engine does at low RPM aka Taking off and getting on a plane, but may not have the same great top end MPH performance.

[GetReel]

hey thanks.....thats correct....exactly the point..way to go.

[BigLew]

Huh?... HP is HP. HP is the same Diesel or Gas.

Horsepower = Engine Torque (Foot Lbs) x Engine Speed (RPM) then divide by 5252. That is how HP is measured. The TORQUE (ablility to rotate mass)of an engine is a huge component of the POWER of the engine.

Gas engines make their high HP DUE TO RPM.
Diesel engines make there HP DUE TO TORQUE.

Hence, a 180 HP Diesel provides the same Performance as an approx 250 HP gas engine does at low RPM aka Taking off and getting on a plane, but may not have the same great top end MPH performance.

Thus am I correct that the higher torque of the diesel enables it to turn a higher pitch prop, thus greater travel distance/revolution, thus higher speed for the diesel for the same RPM?

[Fr. Frank]

Thus am I correct that the higher torque of the diesel enables it to turn a higher pitch prop, thus greater travel distance/revolution, thus higher speed for the diesel for the same RPM?

Yes, you are correct. But with, say, only 2800-3000 rpms from a diesel, (depending on the motor) the top speed is affected.

[riprunner]

Yes, you are correct. But with, say, only 2800-3000 rpms from a diesel, (depending on the motor) the top speed is affected.

That is true that top speed could be affected, but who cares. Let's face it, these boats are not even close to being fast especially in today's standards. The most important thing for an inboard Seacraft is a solid economic cruise speed. Nothing will do this better than a diesel.

I would love to be able to cruise at 24-25 knots, but with a 350 gas motor, it will never happen on my boat.

[KenB]

That is true that top speed could be affected, but who cares. Let's face it, these boats are not even close to being fast especially in today's standards. The most important thing for an inboard Seacraft is a solid economic cruise speed. Nothing will do this better than a diesel.

I would love to be able to cruise at 24-25 knots, but with a 350 gas motor, it will never happen on my boat.

Which is I guess why mosely preferred outboards on his race boats? To bring it full circle?

I am pretty sure I saw an article on one of those gofast boats, or an SKA hull, where they compared, as closely as possible, three different outboard options (like triple verado 250s, twin yami 350s, triple etec) versus diesel i/o with jackshaft. From what I recall, the diesel I/O was not that far off on top speed. Like maybe less than 10%? Where as MPG as cruise was like 2x or 3x... price was about the same.