3X4 or 4X4 props

roccopep

roccopep

New Member
Apr 19, 2012
23
Atlantic City ,NJ
Boat Info
2003 260DA
Engines
350MPI Bravo 3 20p
I have a 2003 260 Sundancer with 350 MPI Bravo3. I have been looking to improve my performance and see Mercruiser is now offering a 3X4 prop configuration. I also see a 4X4 set available. My question is, Has anyone change props and has there been any significant change in performance ? ps. I have a 20p set on the boat now .It runs around 36MPH at 5100 rpm WOT and needs 3500 rpm to stay on plane.
 
I have no experience with those props, but honestly, I can't imagine they're going to make $1,500+ worth of difference... or whatever they're going for now.

That being said... something's not right with your RPM or speed. You should be getting more out of it. Changing props (or any other mod's) now would only be a band aid and would not be solving the underlying problem. More info about condition of bottom, props, GPS speed, etc is needed. Also, are you trimming the drive properly? Please explain how you use the drive trim and the tabs.
 
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Lazy Daze said:
I have no experience with those props, but honestly, I can't imagine they're going to make $1,500+ worth of difference... or whatever they're going for now.

That being said... something's not right with your RPM or speed. You should be getting more out of it. Changing props (or any other mod's) now would only be a band aid and would not be solving the underlying problem. More info about condition of bottom, props, GPS speed, etc is needed. Also, are you trimming the drive properly? Please explain how you use the drive trim and the tabs.
Click to expand...

The bottom is fine I keep on a lift .At WOT i have the trim tabs up and the drive trimmed out not cavitating. I'm thinking the props could use a little more pitch
 
More pitch... maybe, maybe not... you're running right there at the top end of your WOT for that engine, which is good. Speed verified by GPS?
 
I had a 99 270 with a 454 bravo 3. I went from 21p 3x3 to20p 4x4 I loved them. Much lower plane time much lower rpm cruise at about the same speed. Improved fuel economy and they held there bit on turns. U bought them from a place un cali. Forgot the name but I think it was 1200 $ to my door with a prop wrench. They also have used one's in stock. There very helpful and run deals all the time. Have your gear ratio or oytdrive serial number , current prop info and current rpm to mph info ready. They will be asking you for them. Good luck.
 
Thanks , The reason I'm asking is , my last boat was a 31ft go fast, big blocks and Bravo 2's. I changed out my 3 blade Mirage props for 4 bladed props and realized a significant improvement in cruising range.
 
Let's try this, as well - if for nothing else than to help eliminate variables... What is your drive ratio and your drive serial number? I'll look up what it came with from the factory as far as ratio (and I'll see if I can dig up the props, too). If you don't know your drive #, engine # will work... but drive # is better in case a previous owner swapped drives sometime over the years.

You'll notice much more of a comparative change from one prop to another in a go-fast given the hull design. Cruiser's are a whole different ball game and they don't inherently lend themselves to as much of a change.

BUT... given your 36MPH is GPS, going to a higher pitch is going to drop that speed. That's why I still think something else is going on. What kind of load is in the boat?

FYI, you probably had Bravo I's on the go fast?
 
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My neighbor was the previous owner the drive was never changed .I can not find the number right now but believe the ratio is 1:50. The boat probably has a gross weight of 8K lbs. figure on average 65 gal fuel ,20 gal water 5k kohler gen. My othert boat did have 2's on it
 
roccopep said:
My othert boat did have 2's on it
Click to expand...

That's odd for a go fast boat. Bravo I's are for speed and B2's are for cruisers.

When you get the number, post back and I'll look it up (including props) for you.

For what it's worth, I get 40MPH out of my boat.
 
No genny, but usually full of water, gas. Plenty of gear - never on the light side. Gross of close to 8k sounds about right.
 
Not really concerned about top end but more of staying on plan a lower rpm. That's why I'm inquireing about the 4X4 props
 
I'd still like to figure out what's up with the speed, though. It's too slow.

But, aside from that, if all you want is a lower planing speed... proper use of your drive trim and trim tabs are FREE! :smt001 If you're already using them properly, then we're right back to something else is going on.
 
I have a 28' cruiser, about the same weight, with the 350mag. Had 20p 3x3 props. 40 mph, 5100 wot rpm, best efficiency was 3900 rpm and 31 mph. Switched to Ron Hill 22p 4x4 props. 5000 rpm wot, 40 mph top speed, optimum cruise speed is 32 mph at 3600 rpm. Fuel use went from 2.1 mpg to 2.3 mpg at the optimum cruise. Also, all prop cavitation dropped off at higher trim, no blow out on harder turns either. Minimum plane speed went from about 24mph down to 20 ish.

My holeshot was spectacular with the 20p, truly amazing for a single engine cruiser. It is still very strong With the 22s. I can still get on plane with full gear and full passenger load in a reasonable distance.
 
I changed out the 20" 3 blade merc props, for the 20" 4x4's from signature. In my case the 4x4's didn't help much. In fact I had to send them back to Signature to get them adjusted twice. $50.00 bucks shipping each time. Signature didn't charge me to adjust them (that was nice), but they still didn't do what I hope they would.

I started experimenting with different configurations. 3blade front, 4 blade rear..........ect. I got the best set up with a four blade front and three blade rear.

So, I don't feel the money was worth the difference. I run them in the config I mentioned but what else am I going to do with them. (one prop sits in the shop on the floor, good paper weight I guess)
I have a 240da with a 5.0l merc.
 
I had 28p stock BIIIs and switched to 28p hill marine 4x4s on my 340da. I got much better low speed handling, much better time to plane, lower planning speeds and better mid-range speed for a given rpm. Top speed and mpg didn't change. Most important to me they eliminated the cavitation on turns and in heavy seas when I come off the back of a wave.
 
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