Need different prop for pulling

[lonewolf41]

Currently have a Volvo 3 blade stainless 14.75x21 on my 2006 Regal Destiny. I believe it is 22.5' with the swim platform and comes in about 3400lbs. Running a VOLVO Penta 270HP 5.0GXi with 1.66 SX drive. It works good for 2 people and even when we had 7, I could pull a skier with some effort. However, pulling a 3-person tube was awful. With 2 small and one large person in the tube, I couldn't get on plane. Would like something with enough oomph to get on plane with a decent load and pulling a tube. I don't care about speed as we cruise normally around 30MPH (currently @ 3000-3100 RPM) anyway, I just really need some extra power for those times we just want to play and not break any speed records. We are easy on the throttle/motor and rarely go above 4000-4200 RPM unless for a 30 second "thrill". We spend 80% of our time at 3000-3300 RPM.

I was figuring at least a 19 pitch, but a 17 might be better for this application. Assuming I would stay with aluminum due to the cost as I don't have a ton of spare funds after putting in the new motor. Also may fill up with premium as the motor will get me a few more HP with the higher octane. Appreciate any insight as to where to start looking. Thanks!

 

[jimmbo]

A 22 footer is asking a lot of a 5 liter. Even propped for the top of the WOT Range, is not gonna be a Ball of Fire out of the Hole

What WOT Rpm are you currently getting? I suspect the WOT Rpm Range for that Engine is 4600 to 5000
I would guess than with a 1.66:1 Final Drive Ratio, that a 21" is too much even under a very an empty boat.

 

[Scott Danforth]

when I had a 3.0, I had 3 props with me. a 19p for WOT runs, a 17p for most things and a 15p for watersports

as Jimmbo stated, your boat is a bit much for a 5.0

your 3400# dry weight will be closer to 4200 once you add batteries, gear, fuel, etc.

I would shoot for a 17p myself if you typically run with 7 people

 

[cyclops222]

22' must have CUBIC INCHES to not need different prop changes.
Sadly most new boat buyers are tod to buy the smallest motor. Better chance of selling the boat on price.
Screwed again. If you buy used at a low bargain price.

 

[Scott Danforth]

Also may fill up with premium as the motor will get me a few more HP with the higher octane.

unless your motor was built to need higher octane, it will NOT give you more power, it will give you less power and cost you more money at the pump

as Octane goes up, the ability for the fuel to ignite is decreased (allowing a higher base timing to move the timing curve). This is increased anti-knock and is done to allow high compression motors to get to higher RPMs. additionally the BTU rating of the fuel is decreased and the stoich point changes as the octane goes up/down

your boat motor was designed and programed to run 87 octane (R+M)/2 method of E10 (or less) . running pure fuel vs an E-blend will get you a slightly higher BTU content of the fuel and about 1-3% more power than E10

pure 87 octane fuel is about 114,000 BTU per gallon and is happy at 14.7:1 stoich. the 110 octane sunoco race fuel is 110 octane, has a stoich point of 14.9 and a BTU content of about 113,000. E10 is about 111,000 BTU per gallon, E85 is about 85,000 BTU per gallon

 

[1960 Starflite]

Might want to consider a 15p or 17p four blade prop. It improves hole shot and earlier plane.

 

[lonewolf41]

A 22 footer is asking a lot of a 5 liter. Even propped for the top of the WOT Range, is not gonna be a Ball of Fire out of the Hole

What WOT Rpm are you currently getting? I suspect the WOT Rpm Range for that Engine is 4600 to 5000
I would guess than with a 1.66:1 Final Drive Ratio, that a 21" is too much even under a very an empty boat.

Funny thing is, this boat originally had a 4.3L V6 in it. I thought it sounded small so I upgraded it when I replaced the motor to get more HP. Regal told me they offered the boat with the 5.0L and I might need a 21 due to the larger motor, so that is where I started. I believe the WOT is 4600-4800. I have never tried to see what it is or if I could reach it. I have never been interested in top speed and I think I have never been above 4400-4500 or so...and that was for a few seconds. Never needed to go that fast for any reason.

 

[Scott Danforth]

. I believe the WOT is 4600-4800. I have never tried to see what it is or if I could reach it. I have never been interested in top speed and I think I have never been above 4400-4500 or so...and that was for a few seconds. Never needed to go that fast for any reason.

You are being your own worst enemy here.....Mash that throttle on the holeshot.

It's not about speed, it's about getting that large mass moving

The 5.0 is still too small for the boat

 

[lonewolf41]

when I had a 3.0, I had 3 props with me. a 19p for WOT runs, a 17p for most things and a 15p for watersports

as Jimmbo stated, your boat is a bit much for a 5.0

your 3400# dry weight will be closer to 4200 once you add batteries, gear, fuel, etc.

I would shoot for a 17p myself if you typically run with 7 people

Thanks for the response. I would say 7 is atypical, but I am not opposed to being a little underpropped if I had a couple less onboard. It would be nice to have the ability to comfortably get on plane pulling a tube and 17 may be the sweet spot for that. I can keep the 21 for the times it is just the wife and I cruising around and swap when we have more. It seems to do pretty well when it is just us.

Hoping someone had gone through something similar and offer guidance and looks like you have. Appreciate it. On a side note, I have a couple of props from an old boat. Both brand new. Is there a place to "swap" props?

 

[lonewolf41]

unless your motor was built to need higher octane, it will NOT give you more power, it will give you less power and cost you more money at the pump

as Octane goes up, the ability for the fuel to ignite is decreased (allowing a higher base timing to move the timing curve). This is increased anti-knock and is done to allow high compression motors to get to higher RPMs. additionally the BTU rating of the fuel is decreased and the stoich point changes as the octane goes up/down

your boat motor was designed and programed to run 87 octane (R+M)/2 method of E10 (or less) . running pure fuel vs an E-blend will get you a slightly higher BTU content of the fuel and about 1-3% more power than E10

pure 87 octane fuel is about 114,000 BTU per gallon and is happy at 14.7:1 stoich. the 110 octane sunoco race fuel is 110 octane, has a stoich point of 14.9 and a BTU content of about 113,000. E10 is about 111,000 BTU per gallon, E85 is about 85,000 BTU per gallon

I was just going off this post from Don S. and the manual:

If fuels with 89 AKI pump posted (93 RON) octane number or
higher are not available, lower octane fuels (minimum 87 AKI
[90 RON] octane) can be used. With the use of lower octane fuel, a slight decrease in power can be expected.

Since I was running 87, I assumed I would get a (small) boost with 93. Should allow the ECM to advance the timing further. Thanks!

 

[lonewolf41]

Might want to consider a 15p or 17p four blade prop. It improves hole shot and earlier plane.

Thank you!

 

[lonewolf41]

You are being your own worst enemy here.....Mash that throttle on the holeshot.

It's not about speed, it's about getting that large mass moving

The 5.0 is still too small for the boat

I guess I don't understand your comment. I always go full throttle when getting on plane. It doesn't instantly rev to 4800. It will increase RPM as it comes on plane and then speeds up. Thanks.

 

[Scott Danforth]

I was just going off this post from Don S. and the manual:

If fuels with 89 AKI pump posted (93 RON) octane number or
higher are not available, lower octane fuels (minimum 87 AKI
[90 RON] octane) can be used. With the use of lower octane fuel, a slight decrease in power can be expected.

Since I was running 87, I assumed I would get a (small) boost with 93. Should allow the ECM to advance the timing further. Thanks!

AKI vs RON vs MON

The US uses the AKI or Anti-Knock Index which is RON + MON / 2

Your motor is designed to run on 87 octane pump swill

 

[jimmbo]

A GXI is a Fuel Injection Motor, correct? If so, it would have a Higher RPM range to to get 270hp out of 5 liter. The 260hp version of that motor was 4800-5200 Rpm(and it was way slower out of the hole, than my 260hp carbed 5.7 VP). Find out what it is, "I believe..." is not the correct Answer. Lugging that engine will ruin it.

Torque is needed to make the Boat move, and while the 5 liter is slightly better, than a 4.3, a 5.7 would be the absolute Minimum I would put in a 22 footer. High revving small engines, while matching bigger engines on HP, will have a lot less Torque

 

[cyclops222]

We are doing a lot of armchair racing. Facts

 

[Scott06]

Funny thing is, this boat originally had a 4.3L V6 in it. I thought it sounded small so I upgraded it when I replaced the motor to get more HP. Regal told me they offered the boat with the 5.0L and I might need a 21 due to the larger motor, so that is where I started. I believe the WOT is 4600-4800. I have never tried to see what it is or if I could reach it. I have never been interested in top speed and I think I have never been above 4400-4500 or so...and that was for a few seconds. Never needed to go that fast for any reason.

see what wot is with current prop then can make a reccomendation on how much to go down in pitch.

Had a freind with a 4.3 MPI in their 21 ft Larson, had a 19" 3 blade was only hitting 4400 at WOT, went with a 17" VP 4 blade made a world of difference in holeshot.

just need to know the current prop WOT to get there

 

[kd4pbs]

5.0 Gxi HP rating is at 4600-5000 RPM.
My opinion would be look for a 5-bladed SS prop. Had a late 80s 21' cuddy with a much weaker 5.0 2bbl Alpha. Was a dog. Put a Mercury High-5 on it (IIRC a 17" pitch) and it would yank my large rear end out of the water standing on a wakeboard like nobody's business. Lost a couple MPH on top end, but it was well worth it. Would still do about 42 MPH max.
For your horsepower rating, I'd try a 19" pitch.
I'm sure they're out there, but I've never talked to anyone who put a 5-blade prop on an underpowered boat that wasn't pleased with the performance increase. Better stern lift, much quicker holeshot... what's not to love?

 

[Scott06]

5.0 Gxi HP rating is at 4600-5000 RPM.
My opinion would be look for a 5-bladed SS prop. Had a late 80s 21' cuddy with a much weaker 5.0 2bbl Alpha. Was a dog. Put a Mercury High-5 on it (IIRC a 17" pitch) and it would yank my large rear end out of the water standing on a wakeboard like nobody's business. Lost a couple MPH on top end, but it was well worth it. Would still do about 42 MPH max.
For your horsepower rating, I'd try a 19" pitch.
I'm sure they're out there, but I've never talked to anyone who put a 5-blade prop on an underpowered boat that wasn't pleased with the performance increase. Better stern lift, much quicker holeshot... what's not to love?

I did not get good results from a high five on my 21 ft sea ray 5.0. The Revolution 4 and Vensura 4 blades I ran out performed it (even the AL Mich Vortex bettered it) . This may be particular to my boat but point being there is not one prop for all boats

 

[kd4pbs]

I have now officially heard of one person who did not have a good experience with a high-five

Scott, I'm curious as to what metric it was poorly performing. Holeshot? Tracking? Stern lift? For sure they are considerably slower top-end, but I'll trade that for higher performance everywhere else - which is what I found.
I had made the switch from what I would imagine was an OEM 3-blade aluminum prop when I got mine.

 

[Scott06]

I have now officially heard of one person who did not have a good experience with a high-five

Scott, I'm curious as to what metric it was poorly performing. Holeshot? Tracking? Stern lift? For sure they are considerably slower top-end, but I'll trade that for higher performance everywhere else - which is what I found.
I had made the switch from what I would imagine was an OEM 3-blade aluminum prop when I got mine.

Holeshot was ok but it had really high amounts of slip on top end so revs went way up with such a dramatic loss in top speed. I have seen enough folks give praise to the high 5 that for sure my boat is somewhat unique. I just think there are modern 4 blades and even higher performance 3 blades like the enertia will out perform it

Certainly will improve holeshot vs a basic Black Max type prop. Like you my previous boat was under powered ( 1991 sea ray 170/3.0). I had run 17 and 19" pitch 3 blades and switched out to relatively inexpensive Michigan Vortex 4 blades - ran a 16" for skiing (Im 285lbs..) and 18" for everything else. Holeshot , stern lift, and slower planning speed improved dramatically.

I got bets holeshot from the vensura 4 blade as the smaller (than a revolution 4) blades allowed the engine to get in the fat part of its power band. The rev 4 is almost too much blade grip for the engine i have (260 HP 5.0) , so holeshot wasn't as quite good as with the vensura. Where the rev 4 shined was in the grip on the water allowing me to fully trim out with out blowing out. Stern lift is great and due to being able to fully trim out the rev got better top end than and Enertia 3 blade, trim flattens the wake out some, which is admittedly big for skiing..