Volvo Penta DP findings-gctid803787

[Amadaies]

Last year with the 280SP my numbers were as fallows.

Getting on plane was about 10sec.

Was getting 30MPH(gps) @ 3550RPM

WOT was 4400RPM @ 40MPH(gps)

Wandered at idle docking and was "dog walking" in reverse backing away from the dock

First run this year with a 290DP with a set of B3 props

Getting on plane takes maybe 5 seconds

27MPH(gps) @ 3550 RPM

WOT 4800 @ 38MPH(gps)

I could have let to rev to maybe 5K? rpm but i backed out of it so im sure i need a different set of props. Maybe B4 or B5? props.

Seemed to not wander as much at idle when docking and backing seemed to be a little straighter with less "dog walking". Steering was pulling pretty good to the left so trim tab needs adjustment.

As a upgrade im kinda so so about it. I can't think of a thing that says OMG you need this at this point but i can tell it needs a little more dialing in and once i have iti all correct opinions might change.

Anyone have a set of props they want to swap :silly:

[builderdude]

Yea, that'd be a bit discouraging :S being that you had more throttle left and you were already at a max rpm range for your 5.7 It does sound like you need more pitch to the props.

I'm not familiar with VP but out of curiosity:

What pitch is a a B3 set of props?

What diameter are they?

What's the final drive ratio at the prop shaft and did it change from where it was with the 280SP?

[Amadaies]

Hey

My original single prop was a 15X19P Single prop lower unit with 1.61:1 GR

I think the B3 would equate to a 15X17P prop or close to it from the numbers i see. Diameter and pitch is unknown as VP does not publish that data that i can find anyway. The gear ratio now is 1.95:1

I did not have more throttle left. It was WOT and starting to level off at 4800rpm but still slowly climbing

[2850Bounty]

Be able to reach 4800 RPM, with a bit more throttle left, and hitting 38 mph is good!

If you load the boat more heavily you'll still be within your WOT range!

You may want to try the B-4s, but I doubt that you can pull off the 5s!

.

[Amadaies]

"2850Bounty" post=803818 wrote:
Be able to reach 4800 RPM with a bit more left, as near perfect if you can get.

Well if thats true i see no value at all switching to a DP $1600 for nothing. + props

[Download_Complete]

I am sensing something wrong. Even with the SP, you should be able to hit way more than 40 mph.

I see an engine pic in a bilge in your avatar, and it's not the stock 260. Let's hear about the engine.

[2850Bounty]

"Amadaies" post=803820 wrote:

"2850Bounty" post=803818 wrote:
Be able to reach 4800 RPM with a bit more left, as near perfect if you can get.

Well if thats true i see no value at all switching to a DP $1600 for nothing. + props

[color]#000088 wrote:
Ooops..... I was doing an edit to post #3 while you were posting next.

OK.... don't give up!

I have installed many Duo Prop lower units for people and none have been disappointed with the additional performance.... prior customers, friends, my son and myself included.

Make sure that you did indeed receive a 1.95:1 lower DP unit. (no other ratio will work for your engine and boat)

Make sure that your engine is in full tune...... I.E., fuel delivery, cylinder pressures, correct ignition advance (Progressive and TA), throttle is opening as it should, etc.

Make sure that you have a matched prop set and that they have NOT been trimmed down during a tune-up/repair.

Make sure that your "set pin" is in the center location.

Perhaps try a B-4 set!

This has nothing to do with performance, but be sure to now use GL-5 gear oil.... ( not 30W Engine Oil as required for the s/p drive! )

[/color]

[Amadaies]

At this point t I know my gear ratio is correct.

I think the problem is I need a set of B4 props.

That should put me back to at least the performance I had.

The engine is working fine as it should.

It is a stock rebuilt 260 HP 5.7 that I put a 1409 on with a aluminum intake is the only mods to it. Plenty of power and acceleration as it should.

[Download_Complete]

"Amadaies" post=803941 wrote:
At this point t I know my gear ratio is correct.

I think the problem is I need a set of B4 props.

That should put me back to at least the performance I had.

The engine is working fine as it should.

It is a stock rebuilt 260 HP 5.7 that I put a 1409 on with a aluminum intake is the only mods to it. Plenty of power and acceleration as it should.

I used to pilot a 1986 2450 with a 5.7. My dad ordered the boat new, and I remember that boat wrapped in plastic when it was brand new off the truck.

It was a 45 mph boat with 4 people in half-full tanks in it.

If you're only getting 40 mph out of the boat now, then something is wrong.

[Amadaies]

I was getting 40 mph with a 15x19 prop @4400 rpm and could have gotten 43/44 if I never backet out of it so even then it was slightly under propped but I felt it was good enough not to mess with it anymore.

With the new DP I'm still seeing the rpm but not as much speed @38. So I'm betting the props are wrong and a set of B4 will make the performance near what it was. And as for engine wot rpm by the book I should be between 4200 and 4400 wot.

Also this was with a normal load. Full fuel 2 adults and 150ish pounds of junk

[Amadaies]

OK. What's a set pin?

[Download_Complete]

It's the pin that your reverse latch locks onto that also determines the "trim" of the drive....a.k.a, manual trim:



Manual trim VPs have three set positions, or holes in the transom shield. Typically the middle pin provides best all around performance.

[Amadaies]

Ohya mine is in the center hole.

That being called a set pin never even crossed my mind.

[MonteVista]

Just addressing Volvo Penta SP vs DP part of this discussion, my first boat was a Stingray 250CS that came with 4.3L Volvo Penta, SP. After 1 year I upgraded to a DP drive. Like morning and night! Not only would I come on plane much faster my fuel consumption actually improved! I did not notice a big difference in my top speed at WOT (about 39 mph) but fuel consumption improved. Perhaps more noticeable was the boat started handling better in rougher seas.

My 2 cents.

Good luck!

[Amadaies]

I was not expecting more top speed but i was expecting my performance to be at least the same. It is close but falls short.

My engine rpm should be between 4200 and 4400RPM im getting 4800 and could probably hit 5K if i tried but that would be max for sure.

So the more i think about it the more im sure its wrong props with B3 being to small.

Problem is will B4 or B5's put me in the right RPM range or would J5 do it?