Jay Gadsby

Hey gents! I hope everyone's holidays are treating them well! Well, we dont have a lot going on out here, so I have been watching the few videos you all post, and looking at Nordic pics to keep me sane. Well, as is the case for every vehicle I have ever owned, I want to go faster, lol. I was reading around and found that the 496/B1X setup usually comes with a 26P B1 prop. From what I have also read, the 500EF1/BXR usually rocks a 28P. My boat was not a natural 500EFI, therefore I am sporting a B1X on the back with a 26P B1 prop. I have also been reading some of you larger HP guys (this is me being jealous) utilize a drive spacer in order to get that prop a little lower in the water. My boat at WOT, 4 people, 1/2 tank of fuel, tops out at roughly 74mph @ 5350ish RPMS. Now, from the calculators, that is about 16% slip. And now my expertise hits a wall. I am trying to learn, so please feel free to detail up the responses for me. Should I A) try a new prop and see how she runs, get the RPMS down a little, B) try a spacer to get the prop a little lower in the water to theoretically reduce the slip, or C) both. Thanks a lot guys!

Steve Zuckerman

Hello Jay,
I hope your doing OK over there in Iraq. I thought we were supposed to be drawing down our forces by the end of the year. Of course I realize we will still have a smaller presence there for years to come.
Most of the step hull boats do have a relatively high X dimension, in the neighborhood of 19"s. What the factory was trying to achieve was a more efficient (less hydrodynamic drag) setup. However, they did overdo it. They went too high, and most of the boats lack bow lift with a 4 blade at that height (19"s). The fixes are (generally) a 1" spacer, a 5 blade propeller, or modifying your exsting propeller with more cup to reduce slip.
Lowering the propeller will lower your slip % by increasing the submerged blade area, and give the prop more leverage to lift the bow of the boat, decreasing slip and increasing efficiency.
Fortunately your buddy and our's BobL knows all this stuff and has been down the same road with the rest of us. You probably noticed Bob runs 5 blades on his personal boat. So do I, as well as a 1" spacer. Bob can hook you up.
Stay safe Jay!
Best Regards,
Steve

JD Dearden

At low elevation I was running a 26P in my Heat with as you know a 496. I think you could run a nice 28 no problem. What RPM can you run with your prop now?

By the way I sold the Heat

nedpoole

iTrader: (1)

Jay,

is that 74mph on GPS?

-Ned

JFT

Hi Jay

Did not realize you are not so far from me. I am in Qatar.

Hi neighbor.

Good luck with your quest for speed.

JF

bobl

Those are really good numbers. Mark's Heat ran a best of 72 at 5200 RPM with a 26 Bravo 1 prop and 1" drive spacer. That was with a Raylar 496 that dyno'd at 554 HP. I would suggest running a digital tach or scan tool and gps to make sure all your data is accurate before making any changes. Usually a drive spacer will pick up some speed, but you never really know where your X dimension is set. You need to measure it to be sure. Peak HP is 5200-5300 on a stock 500efi. So, if your rpm is correct you are a little underpropped. But that is probably about right for hot weather and a heavier load. You will lose a couple of hundred rpm in the summer.

Bob

Jay Gadsby

Steve- I will definitely be dropping Bob a line, just didnt want to personally bother him with my trivial questions

Jared- Congrats man!! When are we going to see the next one?

Ned- It was not sadly. According to Bob, the speedo is damn near spot on between 70 and 80, so here is to hoping. My Pachanga that did GPS at 64mph, got pulled on like she was stalled out by the Nordic when me and my father in law had them both out. So we know it beats that speed at least lol. I cant wait to get home and get real numbers, and video and all that fun stuff.

Jay Gadsby

Thanks Bob- I have a better idea, if you are up to it, next year, when I get home we will take her out and you can tell me where I Need to be I would hate to guess and jack it all up.

Oh, and I am not in Iraq anymore at least, now I am stuck in Kuwait for the time being.

JD Dearden

Hopefully soon...

nedpoole

iTrader: (1)

I have the same year heat w around 600-650 HP and without the spacer in my drive my slip was in the high teens \ low 20s. I also noticed less chine walk w the spacer too. My boat likes the merc labbed bravo 4 blade props w the 1" spacer.

-Ned