goin from xrs 1.5 to bmax 1.3 very soon and need some advise on where to start with props. current set up is 500efis with wipples at 5lbs, dyno at 750s hp and low 800 tq, 1.5 xr standard lower with nose cones and extention boxes, spinning 30p bravo 1s at 5800rpm. goin to bmax 1.3s standard lower and extention boxes. do you guys think i should go -1 or -2 on the new lowers with the boxes? whats props should i start with? 26p? 28p? i know im goin to loss a couple mph with the bmax, but dont wana loss a bunch with the 1.3 ratio........thanks, ted

I'm not running near the power you are. NA motors dyno'ed at 580 hp each turning 28P Bravo's with 1.36 gears. Best for boat is 93-94 mph small chop and light on fuel. I think I need a tad less pitch because I can't turn them over 5000.

I think you should easily turn 28's. Maybe even a 28 five blade....

I would say the 28 4bl at that HP,if its to much you can lab them.I would think the extension boxes should help.

What was your rpm at peek hp?

Rob

well ran the boat last sunday, turning a custom set of 27p bravo 1 4blades on a 1.3 gear. boat turned 5600rpm (right at the limiter) at 98mph, with 2 people and a full tank of fuel.

I shot this for Spyder. Thats one sweet ride! http://www.youtube.com/watch?v=aiPPb-5qrPA

I agree. My buddy has a 388 with 850 NA's, B-max 1.3's and boxes. He is running B1 4 blade 30's get 95-97 mph.

Your boat would be a lot faster if you could get some B-max's with the 1.50.

I would say 31 or 32 4 blade would be close. Mabe lab finished. I have 850 hp. B max with 1.3 went 100 mph. Switched to herring 5 blade 30s got another 8 mph. But I don't run boxes so I'm not sure about that.