New Prop arrived.

[Sdc77]

No ballast for now on mine. We mostly do wakeboarding, and 4-6 people always on the boat.
I start thinking to put a sac in the ski dock and one another Under the bow seats. But I would like first to slove my fuel consumption issue ...

2500HD for surfing it makes sense to have a low pitch, sorry for the confuse

[2500HD]

one thing i learned about the new props vs old props is that the new ones have so much more surface area it allows you to drop pitch with out loosing much performance.

[SquamInboards]

one thing i learned about the new props vs old props is that the new ones have so much more surface area it allows you to drop pitch with out loosing much performance.

^^ This. See attached picture of an OEM 13x13 from an 80's Nautique, and the Acme recommended replacement, 13x11.5. Massive difference, hence the change in pitch. Plus the old one had been repaired at least once, as many old props have been, and the actual measured diameter isn't 13" anymore.

prop comparison.jpg

[gogger]

Just topped off the tank. Last time out we ran for 5 hours. 7 people on board. Spent the first two boarding and surfing, then about three tubing. We pulled a slalom tube for a while then big paparazzi tube the rest of the night. With a new holley 750 carb and still running points. We burned just under 25 gallons of fuel. And we ran hard while tubing as I had five guys I work with that hadn't been out before and had to show off a bit. So we burned about 5 gallons an hour. Which is what I figured last year. Also running the 541 still.

[Sdc77]

gogger, that is really interresting and make me happy to know the 454 should drink less than 8-10 gallons/h (my actual consumption)
I check with my buddies and will order the 541 and a new carburetor (a Q-jet as it seems to be the most efficient carbs arround)

[wotan2525]

I think your 850cfm carb is the problem. Sucking that much air means sucking that much fuel. I've got a 600cfm edelbrock and burn ~6gallons/hour.

[Sdc77]

600cfm isn't it too much restrictive for a 454 marine ?
With the online cfm calculator I also find 600cfm for the maximum rpm of our engine, but is this calculator ok for marine application ?

Wotan, you also run a HV 50kv distributor and a performance intake manifold. Can it make also a difference ?

[SquamInboards]

That and see page two. Large pics I posted if you want to see difference.

Yep your pics are better, didn't see that at first haha. Should have read the whole thread! Anyway that's exactly why the new prop specs are so different.

Maybe there should be a sticky PROP SPECS thread where you can just say "I have a (year) Supra with (engine) (hp) (transmission) and my prop is (specs) and I use my boat for (whatever) and it turns (RPM @ WOT)" ??? Mods?

[Jetlink]

Maybe there should be a sticky PROP SPECS thread where you can just say "I have a (year) Supra with (engine) (hp) (transmission) and my prop is (specs) and I use my boat for (whatever) and it turns (RPM @ WOT)" ??? Mods?

Someone start one and I am sure one of us will make it happen. I personally am still running the original prop on my boat so I don't have anything to really contribute at the moment.

[SquamInboards]

Someone start one and I am sure one of us will make it happen. I personally am still running the original prop on my boat so I don't have anything to really contribute at the moment.

Cool. It's still valuable info if you wanted to know what an OEM prop would do, or if you have one or want to buy one as a spare, rather than buying two $500 Acme props or something. I kept my old OJ as a spare.