300 HP Mag Vs. 310 HP 7.4L

[KD4UPL]

I'm shopping for a 24 or 25' bowrider. I tend to boat with lots of people (10 or more, about half of them children) so I'm looking for more HP than the little 5.0 engine. Most boats seem to have the 350 Mag with 300 HP for the upgraded power plant. I've found a few with a 7.4L MPI engine that claims 310 HP. That seems kind of low; maybe it's wrong. Assuming it's correct, I know I won't notice the additional 10 HP but will the 7.4L's extra torque (which I assume it has) make much of a difference? I'm not interested in high speed. Just hole shot for water sports including multiple tubes and cruising around.
Thanks for any help.

 

[thumpar]

Keep in mine the 7.4l is going to weigh more. Personally if I was to go BB it would 496 as top pick or 502.

 

[Bondo]

Ayuh,.... The 7.4l is more like 330hp,... Marketin' keeps playin' with the numbers,....

The BBC is a Noticeable difference over a SBC,....

 

[HT32BSX115]

I'm shopping for a 24 or 25' bowrider. I tend to boat with lots of people (10 or more, about half of them children) so I'm looking for more HP than the little 5.0 engine. Most boats seem to have the 350 Mag with 300 HP for the upgraded power plant. I've found a few with a 7.4L MPI engine that claims 310 HP. That seems kind of low; maybe it's wrong. Assuming it's correct, I know I won't notice the additional 10 HP but will the 7.4L's extra torque (which I assume it has) make much of a difference? I'm not interested in high speed. Just hole shot for water sports including multiple tubes and cruising around.
Thanks for any help.

For many years MC rated the 7.4L engine at 330 crankshaft HP.

Pretty much ALL sterndrive packages nowadays are rated at propshaft HP

Mine is rated at 300hp (propshaft)

If you do get a 24' boat, and you want to haul a LOT of people around, make sure it has a Bravo III on the back!

 

[NHGuy]

I recommend the big block. My 4000+ lb deep v runabout has a 350 mag and it's not enough. It goes ok, but I am a little spoiled by previous boats that had more power to weight.
The 454 has MUCH more torque, over 100 foot lbs more probably. And that's why they get away from stops better.
Down side is they use quite a lot of fuel. So try to lake test similar boats and see what suits you. The 350 will pull out, but more gradually than a 454 or 496. And if you have to run home in a storm it will have less top speed.

 

[KD4UPL]

Thanks for all the information. I really do want something with a big block. They're just so hard to find and when you do they certainly command a premium price. I'm in no hurry so I'm trying to enjoy the fun of looking.

 

[harleyman1975]

Not to muddy the waters as I see you are trying to find the "perfect" boat but you might consider a repower with a 383 stroker motor. Still have the relative economy of a smallblock with almost as much torque as a bigblock.

 

[HT32BSX115]

Not to muddy the waters as I see you are trying to find the "perfect" boat but you might consider a repower with a 383 stroker motor. Still have the relative economy of a smallblock with almost as much torque as a bigblock.

Well, it does sort of "muddy" the waters a little........In all likelyhood, the 383 would use approx the same amount of fuel doing the same "things" as a 454. The specific fuel consumption (BFSC) of modern spark-ignited marine engines don't vary much..........

 

[Scott Danforth]

many of the mid 2000's came with the 6.2/bravo setup from the factory. Now they come with the 6.0 LS motors

however as Rick mentioned, BSFC for a spark-ignited marine motor is about .45#/HP-hr that is 0.45 lbs of fuel per every hp used per hour. doesnt really matter on which motor (3.0, to 9.4 liters).

Diesels are about 0.33

Since this is your second thread on this, I would recommend a deck boat vs a bow rider. a bit more room for people since you intend to have 10 people out at once. the 240 also has the porta-john closet since you mentioned children

 

[harleyman1975]

Well, it does sort of "muddy" the waters a little........In all likelyhood, the 383 would use approx the same amount of fuel doing the same "things" as a 454. The specific fuel consumption (BFSC) of modern spark-ignited marine engines don't vary much..........

Yes but... a small block stroker will bolt up without having to make any alterations/modifications from big block to small block...That is the reason for the suggestion.

 

[thumpar]

Yes but... a small block stroker will bolt up without having to make any alterations/modifications from big block to small block...That is the reason for the suggestion.

And be lighter doing it.

 

[HT32BSX115]

Yes but... a small block stroker will bolt up without having to make any alterations/modifications from big block to small block...That is the reason for the suggestion.

And be lighter doing it.

That's absolutely true......AND, in addition, a completely aluminum block/heads/manifolds 6.2 would probably use a little less fuel BECAUSE of the lower weight!
But the engine cost, might outweigh the advantage.........it's only money though, right?

 

[harleyman1975]

Again was just offering alternatives. If the O.P. had asked should he BUY a boat with a small block or a big block to haul his entourage around then Sure, big block all the way...However he is asking how much work is it to switch from a small block to a big block. I am not going to just assume that he is a motorhead and knows all possible engine configurations. If you don't deal with it every day, knowledge of stroker motors may elude some folks. Hopefully he will find the ideal boat with the optimum setup without having to reinvent the wheel but if he happens to come across an awesome deal on the perfect boat... except for the powerplant...well then he will have all the information he needs to make an informed decision.