Bravo Three props

[HaxbySpeed]

I just put a Raylar kit on a customers boat. He mostly uses it for skiing, tubing and whatever but wanted some more top end too. Has anyone tried the newer 4blade 3blade combo from the 3X?
It's a 1.81 ratio with 26's and was doing 62@ 4850rpm running exh thru the drive, stock 496Mag. The raylar kit and thru hull exh has got to be worth about 125-150hp. Thanks, Alex

[MarylandMark]

What kind of boat? I'm hoping a Formula SS!!

[HaxbySpeed]

Nope, a 21' bowrider

[macjazzy]

Not sure about Bravo 3's specifically but I have duoprop drives on My Formula 330 ss I looked into making it faster. Found out that my 375hp engines are only a cam change away from being 425's. But I am already running 60mph and according to everyone I spoke with these drives run into a wall around 60. So I could add all that extra power and only get a mile or 2 out of it due to the drives.

Bravo 3's may be the same, at 62 he may be close to the hydrodynamic limit of his drive and take huge power increases to see little gain.

[MarylandMark]

If you do the cam I think you have to do the ECU as well but going off my memory vs looking it up right now so wouldn't doubt it if I'm mistaken.

http://www.raylarengine.com/kits.html

106 kit = 550+ HP! That with the XR B3 to keep the cruise/mid-range and tracking would be awesome.

[HaxbySpeed]

I'm thinking 70 ish is more likely the wall. I've been 68 with a stock B3 no problem and 71 with the volvo. Unfortunately his boat came with a 1.81 ratio instead of the 2:1 so I can't just swap the lower, it would make it a 1:36. It's hard to justify buying a new drive to pick up a couple mph in a 21' bowrider that's only got 90 hours on it. I'll let you know how it works out.

[macjazzy]

Mark, You are right the ECU's need to be swapped out or reprogrammed. Raylar said they could reprogram them for me. I used a little short hand in my description. The cam swap would be the "big" part of the job. If I went to the trouble of swapping cams, swapping ECU's would be gravy.

HaxbySpeed, That is a lot faster than I was told Duoprops would go without crazy power. Did you do that in regular DPS drives or the high performance DPX;s they used to build? Was it a single or twin engine boat?

Maybe I need to look back into bumping my engines up to 425's a 70mph 330ss Would be bad a$$

[MarylandMark]

a 70mph 330ss Would be bad a$$

That was going to be my plan but my new boat dreams are on hold right now

Sorry about the hijack HaxbySpeed..

[HaxbySpeed]

It's all good, I was trying to get my post count up to ten anyways!

I was the head mechanic at a volvo penta dealership for a couple years so I got to experiment with all kinds of different drives and motor combos. If you are running the euro style 290DP then you're right sixty is about the limit only because of case blowout. They do, or at least used to, make nose cones for them that would bring them closer to seventy. The newer DP's based on the SX drive have no problem hitting seventy. I have only tried them with single engines in 22' to 24' boats, but it wasn't taking stupid power to get there so I don't think twins would be a problem. Forget the cam and computer swap and just put a pair of whipples on there. It'll be the best money you ever spent!

[macjazzy]

Sorry about the hijack Haxbyspeed but now you have my interest peaked.

My boat has 2005 duoprop drives I believe they are called DPS drives. Anyway the other issue I was afraid of was prop selection. My boat originally came with F7 prop sets but for whatever reason after the engines got broken in I was all over the rev limiters with the F7's so I'm now running F8's which seems perfect. I'm pretty sure F9's are as big as they get for my drive. So my worry would be to do an upgrade like cam/ecu swap or Whipple, or exhaust, whatever and not be able to get a propset for it. I can't imagine it would take much power for me to need more than a F9 if I'm already at F8.

[HaxbySpeed]

This is the problem a lot of people find themselves in. It's easy to make more power, but are the gains worth it?
You may have 1.95 gear ratios because of the size of your boat, changing to a 1.78 will give you some more prop options. There are some different and bigger props available but they are harder to come by. If it were me I would probably do the cam swap, Dana exh, and have Dustin reprogram the ECM with a 5500 rev limit. Throw on the 9's and you'll be cruisin. On the other hand for the for the 12k it's going to cost you, you could go buy a used 16 Donzi and tow it around as a go-fast dinghy

[macjazzy]

Thanks, Haxbyspeed for the info. Apologize again for the hijack

[Knot 4 Me]

I just put a Raylar kit on a customers boat. He mostly uses it for skiing, tubing and whatever but wanted some more top end too. Has anyone tried the newer 4blade 3blade combo from the 3X?
It's a 1.81 ratio with 26's and was doing 62@ 4850rpm running exh thru the drive, stock 496Mag. The raylar kit and thru hull exh has got to be worth about 125-150hp. Thanks, Alex

Talk to Brett at BBlades about the new 4/3 Bravo III prop sets. If you want more top end, my guess is he will suggest working the existing 3/3 set.

[bbladesprops]

Hey Alex,

I think we spoke on this one. Yeah, the 3x3 is faster with the right Lab.

However, the 4x3 is sweet for heavy loads and cruising.

Thing is, 6 blades is already a bunch. The 4x3 was developed to reduce cav burns on heavy load high HP applications.

[HaxbySpeed]

Welcome to the dark side Brett! Thanks for all your help and the information.

[HaxbySpeed]

Couldn't get the Bravo three to work, so I swapped for a B1. Only thing is it's a 1.65 ratio... Yesterday I got 76mph @ 5350ish with a 28pitch B1, it was a pretty scary ride in the little bowrider! I tried a labbed 27 mirage plus, but was on the limiter before I could even touch the trim and had a lot more slip coming out of the hole. It was much more stable however, but I'm not sure if that's because I wasn't running much trim yet.. Any ideas anyone..

[MarylandMark]

Yesterday I got 76mph @ 5350ish with a 28pitch B1

What's wrong with this?

[HaxbySpeed]

It might have to do.. It felt like it was getting too much stern lift and might have a couple more mph if I could get past the violent chine walk. If I can get rid of a bit of prop torque I think the customer will have an easier time with it.

[bbladesprops]

Wedge the blades on a 30B1 and add a little rake to the blades to carry the bow. Should be worth another 2-3 mph.

[MOBILEMERCMAN]

It might have to do.. It felt like it was getting too much stern lift and might have a couple more mph if I could get past the violent chine walk. If I can get rid of a bit of prop torque I think the customer will have an easier time with it.

In addition to Bretts recommendations I would suggest external steering. The slop in standard steering at those speeds can amplify chine walking issues. Plus I think any boat going that fast should have ext. steering for safety.

As far as the hydrodynamic limit goes I expect it is much higher than 70mph