Bone stock 350

[tice652]

I Have a 300 horse 350 with a bravo and 23 pitch mirage in an 18c. It runs 68 -69 gps. How is it possible that a 410 horse 18 only gains 4-5 mph? I would like to upgrade power eventually but it almost seems pointless. Anyone have insight with this?

[chappy]

Lot's of variables as far as the speed comparison between the two. I'd be thinking of a shorty if you want a few more mph.

Then you can tweek the motor.:lookaroun:

[VetteLT193]

The point of diminishing returns....

Adding power to a certain setup will gain something. but efficiency is key. Drive setup as previously mentioned etc. all plays into the efficiency and helps raise the point of diminishing returns.

My brother had a stock 22, 454/330HP with an Alpha 1 that ran 65 all day long with zero problems. Now it's upgraded to Merc Racing HP500 (+++some updates), Bravo 1, hydraulic steering, etc... If he did it over, he'd have a stock engine in his boat, same drive, etc. Not worth the PITA if you actually use the boat in his opinion (my opinion too). He's at about 1800 hours on it now though. Can't say there are too many people that use their boats that much so that's a big factor.

[BlownCrewCab]

Whats the 410hp motor? I had a 408ci small block that I figure had about 400+hp and it ran 77 @ 5500 with a Bravo drive and a 23 Mirage. I had the Rev Limiter set at 5500 and could bump it, with a 24 Bravo one 4 blade it only turned 5K @ 70-72mph.

[axelkloehn]

What I have learned is it's unfortunately not a straight relation like you add 10 horses you gain 1 mph... it's a curve which is based on hydrodynamics, design of the hull and a bit aerodynamics and the effectiveness of your outdrive/prop.
It can end up in adding unbelievably horses and just gaining a few mphs...

But it's not just the flat out, it's torque, it's driving with more friends and not loosing speed, and the fun of taking care of your engine with some nice, shiny aftermarket equipment :yes:

Cheers, Axel :germany:

[tice652]

The 410hp (sb) is in the for sale section. I would expect upper 70s with just a prop change - and would expect to tickle 80's ass with a pink feather with a shortie. Is this not feasible?

[fogducker III]

One thing I have noticed that is not right are these horsepower numbers being thrown around, just because an engine states or is dyno'd that it is 300hp, 310hp, 500hp...etc etc...does NOT mean those hp's are getting to the prop...:nilly:


My engine states on the label on top - 377hp....but if you look at the specs it points out it is only 350hp at the prop, which is where it matters.


My 18C with 350hp, Imco shortie and what I believe to be a well balanced boat, hits mid 70s any time......as stated previously, it is all hydro dynamics and set-up that makes one boat faster then another with the same horse power. PROPS are one of the biggest contributors to final numbers as well as seat time....:yes:

[Planetwarmer]

Keep your motor and add a rocket.

[osur866]

I'll add something else into the mix, doesn't matter how much HP you've got if the set-up isn't dialed in, meaning have a well dialed in 300 hp 18 vrs. A 400 hp boat that is non controllable. I'm running a stock 6.2 rated @ 320 hp and before I made and mods was a chine walking bow steering handful to drive @ WOT after a few mods is much much better to run @ WOT even tho I only picked a few mph on top I can run it wide open for long runs and have much better control over it. So it's set-up along with hp that will get you running higher speeds on top. Steve

[BigGrizzly]

The horse power you state/speed is about right. for that boat but set up makes all the difference.

[tice652]

My upgrade count down is close - just over a year - I have to wait till i'm done paying for it to have this sort of "maintnance" done to it. Definately windshield time helps but it takes windshield time and brass balls to stand on a basketball at 70 mph