chewymalone

Was the motor dynoed when he built it? If so, look at the powerband to see where max HP is made and prop to that. I would not go with the Bravo One. Its diameter is more than you need to carry the bow of that boat and you'll be trying to spin more prop than you need... which will rob top end.

The smaller V-hulls like yours really like three blades for top end speed. They may slip or even blow out a little coming on plane, but I'd welcome that if you're running 350HP through an Alpha.

I think the Mirage suggestions were spot on. If the 23 is too small, try a 25, or a 27, or a 29, or whatever it takes. That's going to be your best bet for top end and not trashing your drive.

jctexas07

I contacted the guy who built it and he said it is actually pushing about 400 horsepower..it has roller assembly, cam, summit racing aluminum heads, msd ignition, high compression pistons, etc. At this point i am torn between the bravo 1 24p or the mirage plus 25p. I agree on the diameter being a bit large on the bravo 1 and usually use my trim tabs to plane and reset from there when cruising.

According to the mercury racing website, they rate the mirage plus at 50+ mph and the bravo 1 at 60+. Honestly, i feel this setup on the motor i have will easily do 65+ while lowering rpms. With that said, would a 25p mirage cause too much slippage........?

jctexas07

What about a revolution 4 14 5/8 x 25...? That would give me the lift and possibly lower rpms while increasing top end a bit...

SDFever

Stop in your tracks and call Brett @ BBlades. Not only will he eventually nail it down, he's the only guy I know renting props to keep you from buying and trying an endless array of possibilities.

Otherwise, you're throwing darts at a wall; in the dark; using the wrong hand; standing outside where there may not even be a wall; and the wind just started blowing...

And make sure you have an accurate means of monitoring RPM. Gauges suck for what you're doing.

indywhsle

One prop I would suggest is a 24p Turbo 3 blade. When I had my 272 with a 502 efi I ran a mirage 23p and it ran 65 mph. I went to the 24 turbo and picked up 2 mph. The turbo was a little slower to get on plane but not much. I did have a bravo drive so I don't know it would work on an alpha.


If you are concerned about the alpha drive I can hook you up with a complete Bravo transom assy. if you decide to go to a bravo setup.

jctexas07

I will make a few more phone calls monday. I appreciate all of your insights an information...just damn frustrating. At bblades, do you happen to have a ballpark on the cost of renting a prop and do they ship it, etc...?

A.O. Razor

SDFever is right, get Bblades to help with the test props.

If you want to run 4 blades, go with the rev 4. You don't need that big a dia. on that short hull. It WILL slow you down big time. If you could push 70+ mph, the mirage 25 will be bang on, unless you need 5200+ rpms.

jctexas07

I have ordered the standard mirage plus 23. I am expecting it in next week and will post numbers with it. This week, I am going to GPS the 13.5 x 21 pos Laser II I have on there now and see what the difference in gain is.

Gear ratio 1.5 WOT 6000+ HP 350+

indywhsle

As was asked earlier, was the motor dynoed? If so what rpm are you trying to prop it at? If you are truly trying to lower your rpm by 1000 rpm I think you may be jumping the gun on buying the 23 mirage plus.

jctexas07

Well, I have had 2 good questions...

Was the motor dynoed? I am under the impression it was not. Simply giving myself a rough estimate based on the major upgrades done to the motor alone.

Am I truly hitting 6000 rpms? Meaning is my tach 100% accurate? Well, they look like the same gauges from 15 years ago. Not to mention, I am turning an alpha 1, not a bravo 1, which is rated for the 270hp motors.

Balls out, I would go with a 25 and up, and turn it like crazy. However, I am trying not to do the bravo 1 upgrade this season, if you know what I mean.

Going up 1 inch in diameter in prop will reduce rpms and going up to a 25 pitch from a 21 will reduce them approximately 700 to 800 rpms. What a mind game.....