575 6.2L Ford ROUSHcharged Raptor vs 556hp Supercharged LSA ?

[The Hulk]

If the LSA can handle a 16 x16 on a 1:1.48 g23 then no reason it can't handle 15x17. Smaller diameter 15" is much easier for engine than a big ol 16" so going up in pitch would be similar or more than likely still take less power than a monster 16x16. I'll have to order a 15 x17 for spring and do some comparison for everyone

[TenTwentyOne]

Ya, LSA should do a 15x17 on a 1.5:1 gearbox in a 247. Both my X30, and X23, came from the factory with a 15x17.5 prop with the 7.4l and 1.5:1.

[DarkSide]

Ten, thank you for extra reassurance.

[nyryan2001]

I love the 16x16.

It can do anything surfing wise. Most of my surfing now is at 2600-2900rpm. 25mph cruise is at 2900rpm. my new GPH average is 5-8 vs 7-9 on the OEM 15x14.25.

You DO loose a little 0-23 acceleration for wakeboard speeds going that big of a prop, and you give up a little capacity in carrying the heaviest weights over OEM ballast. But OEM ballast is the heaviest I'd ever need to go at 20-24mph wake speeds. I got way over OEM ballast for surfing and the 16x16 eats it up 0-12mph.

[JoeA]

LOL, that isn't really the issue, the issue is i run out of gas. I have had my low fuel warning the last two outings. So gaining even a little efficiency would get me through the day. I just need 10% efficiency gain! Malibu made the tank 8 gallons smaller from '14 to '15.

It sucks deciding whether to go home or go to the marina. Not having to cut the last hour of the day because i am out of gas would be AWESOME!

And $20 is beer money...LOL

I know I am a little late to the party but i felt compelled to jump in here as I have the same engine but PCM.

IF you don't drive over 25 MPH you will save a ton of gas. If you start cranking over 3,200 RPMs and up your boat will be thirsty. Now you're at 9 GPH which I think is very respectable. When we surf with a small crew of four people I am getting 6.9 GPH on the 15x14.25 prop. When we add more people and ballast I could care less about GPH. Entertaining lots of people for hours is why I work hard M-F.

If you want to save money don't buy a boat. If you want to enjoy life boat as often as possible.

[The Hulk]

Ya, LSA should do a 15x17 on a 1.5:1 gearbox in a 247. Both my X30, and X23, came from the factory with a 15x17.5 prop with the 7.4l and 1.5:1.

What was your avg surf rpm in the x30 ? Top end?

[DarkSide]

I know I am a little late to the party but i felt compelled to jump in here as I have the same engine but PCM.

IF you don't drive over 25 MPH you will save a ton of gas. If you start cranking over 3,200 RPMs and up your boat will be thirsty. Now you're at 9 GPH which I think is very respectable. When we surf with a small crew of four people I am getting 6.9 GPH on the 15x14.25 prop. When we add more people and ballast I could care less about GPH. Entertaining lots of people for hours is why I work hard M-F.

If you want to save money don't buy a boat. If you want to enjoy life boat as often as possible.

I can get it lower by simply lowering the wedge 2 clicks, however that is a significant change to the wave. We usually have 6~8 people on a given Saturday. I would rather spend $20 extra on gas and produce phenomenal waves, then constantly watching the fuel guage. I just want to make it through a full day and have a gallon or two to get back to the docks.

[The Hulk]

i'm just going for better performance regardless of if it cost more or not, but in this case it would save a tiny bit but mainly give me better bottom end and perhaps a tad on the top end. win win!

i'll give OJ a call on monday to see how long it'll take but i doubt with my work schedule i'll be able to test it this season depending how long prop takes.

[TenTwentyOne]

What was your avg surf rpm in the x30 ? Top end?

Doc might be able to answer this more correct, as it has been a little while for me. (Doc has the same engine and prop combo)

If I remember correctly, surf rpm was 2700-2800 at 11.5 mph. I do remember top speed on that boat. She would do 53 mph with that setup, and maintain enough engine load to keep the max rpms at about 5700. (7.4 is good up to 6100)

[justgary]

Doc is busy these days.

Those numbers sound correct from riding on his boat. That engine and the automatic tabs work together to create a wave very quickly with very little effort.

The engine never strained, and the deepwater barefoot hole shot was plenty fast. For such an enormous boat, I was impressed with the power.

[DarkSide]

Hey Dark, do me a favor... next time you are surfing snap a pic of your center screen and post it up.

Ok here is setup.

Full MLS

Bomb wake - 500 bow, 150 walkway, 100 each rear tub, 200 surf side 1050 total

PNP~ custom sacs roughly 1200~1250 each.

6 adults ranging 170~270 each.

Edited August 30, 2015 by DarkSide

[DarkSide]

Hulk,

I just ran numbers using my 2014 MXZ w/ LS3 and 2419 (15x12) with that combination and similar weight i would run 4100 RPM. (31.48 MPH of thrust) the LSA with 2247 (15x14.25) i am running 3500 so (31.91 MPH of thrust) so this again points to 15 x 17ish maybe 15x18. The LSA does have a fairly flat torque curve so we should still have enough power to swing the larger pitch.

[The Hulk]

so your thrust was nearly identical yet you dropped 600rpms by an increase in 2.25" pitch. Dang that calcs are nearly perfect. That means you could drop down in the 2750-2800rpm range with a 15x18 ish depending when and where the engine meets its match or perhaps it does not it my guess. you would get about 31.7mph Thrust with the 15x18 @ 2750rpms! ummm thats NUTS (about 700 rpm savings!!!!) and at 2750 vs 3500rpm for the LSA not a ton of difference in power vs the other engine options. Now you would have to look up the GPH chart to see the difference haha.

didnt you say there was an ACME 2357 15x17.75" perhaps thats a ticket but after all the lingo i'm tempted for the 15x18.

yes looking at your power chart like you said from nearly idle you have tons of power, thats why i'm questioning going with 15x18 after looking at the power curve you have power from the get go! and like you said the more rpms you throw at it your dong gain much hp/tq just spin the prop faster and go faster.

MC putting a 15x17.50" means we should be good with at least that. or was that a typo and MC is using the 15x17.75? if they are then that or the 15x18 is the ticket IMO.

I'm currently running around 2600-2800rpms (2700 avg) loaded up in the 2013 23lsv surfing at 9.8mph i know i know we are slow...speeding up would only help prop angle so that will be more interesting as thrust would become more and more effective.

2700rpms = 24.6mph thrust with the 14.5x14.25

2100 rpms = 24.2mph thrust with the 15x18 plus however the extra 0.5" diameter helps.

Dang thats a lot of RPM savings if we know what were talking about???

Edited September 1, 2015 by The Hulk

[The Hulk]

spreadsheet calcs

[DarkSide]

spreadsheet calcs

Ordered 15x17 OJ this morning, Hopefully it gets here in time for Friday morning session.