Bravo 3 conversion?

[1kwik72]

I've got to have more power in my boat. It's a SeaRay Amberjack 255 that's about 26', 10' beam and weighs in at about 8000 lbs. It came with a 5.7/alpha setup and it's anemic at best. I've got a bigger engine in the shop (454 with about 365hp) and I'm considering a Bravo 3. Which gear ratio would be best for this combination? I see them with 1.81:1, 2.0:1 and 2.21:1. I just don't know what I need with this particular boat.

My goal, ultimately, it more top end, lower planing rpm and speed and a higher cruise speed.

 

[MarkSee]

Re: Bravo 3 conversion?

Well, my year 2000 454/7.4 310hp and Bravo 3 uses a 2.0 gear ratio. I'm not sure what determines when you uses the different ratios but I'm some of the others can fill in that blank.

This combo will push my 9000+ pound 270 'Dancer to almost 40 mph...depending on load and conditions. I'm very happy with it but note, it will such gas and incredible rate when flying along.

Mark

 

[1kwik72]

Re: Bravo 3 conversion?

Well, my year 2000 454/7.4 310hp and Bravo 3 uses a 2.0 gear ratio. I'm not sure what determines when you uses the different ratios but I'm some of the others can fill in that blank.

This combo will push my 9000+ pound 270 'Dancer to almost 40 mph...depending on load and conditions. I'm very happy with it but note, it will such gas and incredible rate when flying along.

Mark

At least it won't be burning all that fuel in one spot... Glad to hear that it will push a comparable boat that nicely. I mainly want to be able to cruise around at about 25mph or so without running 4000rpms all day.

What's the beam on that Sundancer?

 

[HT32BSX115]

Re: Bravo 3 conversion?

I've got to have more power in my boat. It's a SeaRay Amberjack 255 that's about 26', 10' beam and weighs in at about 8000 lbs. It came with a 5.7/alpha setup and it's anemic at best. I've got a bigger engine in the shop (454 with about 365hp) and I'm considering a Bravo 3. Which gear ratio would be best for this combination? I see them with 1.81:1, 2.0:1 and 2.21:1. I just don't know what I need with this particular boat.

My goal, ultimately, it more top end, lower planing rpm and speed and a higher cruise speed.

Howdy,


I have a 1.81:1 Bravo III in my 21' FourWinns (about 4200lbs) that I replaced the 1.43:1 KingKobra with.

I started with 24p props and went to 26p props.

You have an 8000lb boat. Pretty much all the BIG boats use either a 2.00:1 or 2.20:1 drive.

I did a little searching around and top speed for a 255 seems to be around 35-40 MPH

Using a Prop-slip Calc Prop Slip Calculator and about 15% slip (which is conservative but maybe less)

If that speed is true, a carbed 454 (which likes 4600 RPM WOT RPM ) with a 2.20:1 drive and 22p props, would give you close to that.

An MPI or a built up (5000 WOT) might give you a little more power.

You'll want to talk to people that have that combination (454/B3) to get ball park info.


I would absolutely do the swap! It'll make a HUGE difference! (It did for me!)

Cheers,


Rick

 

[270win]

Re: Bravo 3 conversion?

There a guy I know with the exact same boat as me, but he has a 496/Bravo 3 setup in his boat. He's getting low 40's out of his. Not sure what gear he's running in his B3. I think his has 425hp??? Could be wrong there though.

 

[MarkSee]

Re: Bravo 3 conversion?

What's the beam on that Sundancer?

9' 2" and compared to a 260 'Dancer that is 8' 6", it does seem quite a bit wider down below.

And yes, I do pay CALTRANS the ~$95 a year for an oversize load permit and hang the yellow "Wide Load" sign across the transom when trailering; want to be legal just in case.

Mark

 

[1kwik72]

Re: Bravo 3 conversion?

9' 2" and compared to a 260 'Dancer that is 8' 6", it does seem quite a bit wider down below.

And yes, I do pay CALTRANS the ~$95 a year for an oversize load permit and hang the yellow "Wide Load" sign across the transom when trailering; want to be legal just in case.

Mark

I agree, 10' beam on this Amberjack makes for an extremely roomy cockpit!

Oh, and I stand corrected, my friend has a Bravo 1 with the 496 and he gets 43mph top end. I'm really thinking the 7.4 B3 will be a good combination for this boat. The B3 makes docking much easier too!

 

[HT32BSX115]

Re: Bravo 3 conversion?

I'm at Shasta now wishing I had the Searay 280 of my dreams! (twin 5.0/5.7L+Bravo III's)

Oh, and I stand corrected, my friend has a Bravo 1 with the 496 and he gets 43mph top end. I'm really thinking the 7.4 B3 will be a good combination for this boat. The B3 makes docking much easier too!

For a BIG boat, There's nocomparison when considering idle speed handling