271 fastech propping
 

Hey guys,

I've got a prop question for the guys with the 271 fastechs. A friend of mine has an 06' with the 496ho, low hours, 28p labbed prop and 1.63 geared bravo x drive. from my searching on here, this was the factory prop that came with this hull from the formula factory. The problem is his slip numbers. At WOT, I remember running 65.5 mph GPS at 5150 rpm which is 22%. Also at cruise he can barely run 45-46 mph GPS at 4000 rpm which the slip is close to 30%. In the spring we are thinking about trying a 26p stainless and see what his numbers are. Any other 271 owners have similar results? What do you guys think?

I know heavier hulls generally run a touch higher on slip numbers than lighter. For example my fountain runs 11-16% depending on conditions and load. Also 1 more question. I run a 26p right hand, his runs left. Could we try my prop on his drive, running the boat in reverse gear with a bravo x drive? Are the gears helical? Although I've never done it myself, they say it could be done with my xr drive because the gears are straight cut. Any info is appreciated, thanks guys

Yes You can

Try a Bravo one four blade 28p. Just because the prop is labbed doesn't mean anything. I have a labbed prope and it slips like crazy just like his. It is worse than before labbing

Yes agreed, also a 26p stainless might be worth trying. I think the lab finish is part of the reason for the high slip numbers. A 5 blade was mentioned by another person but I would think the 5 blade would be hard on the drive at launch. Also I wouldn't think the boat would able to swing it to have a decent top end vs a 4 blade. Has anyone on here played the prop game with the hull?

My 271 came with a labbed 28 4 blade bravo prop and it was terrible wide open was the only time it worked.I switched to a p5x 24p 5 blade and results were great,got on plane easier and stayed on plane at low speed and lost 1or 2 mph.65 mph is good for 496 best speed so far 68-69 at 5300rpm with heavy load,always seem to have way to much fuel.

That engine package would have come with 1.65:1 Outdrive ratio and PROP B1 28" LH 48-831915L65LAB
15.25 4 BLD SS MERCURY BRANDED. If you need anymore information please contact me directly at [email protected]

Sorry forgot to post engine 525 EFI XR drive LH .

Thanks for the info guys. I realize the boat with this power package is right in the 64-66mph top end range which he is in the ball park currently even with 20% slip. His cruise is really where improvement is needed. His gallons per hour usage is higher than it should be, due to having to run 4000+ rpm just to cruise at 45 mph. I'd like to think you could find a prop that could get him in that range running 3500-3600rpm. Do you guys think this is attainable with a 4 blade? Or is a 5 blade the only option? Wouldn't a 5 blade be harder on a bravo x drive?

Hi Its not easy to find the perfect prop :-)

I have a Formula 271 SR1 2009 496 HO Bravo1 XR drive 1.50 Bravo 1 24 pich prop ( real average pich 22,5)
If you messure the Bravo1 props they actually have 1 to 1,5 less pich then whats printed on the prop
If you consider this your Slipp number will be better ...

My top speed are 61 mph 5100 rpm
46 mph 4000 rpm
40 mph 3500 rpm
34 mph 3000 rpm

I fell that I have a couple of mph on the top speed, and I also hope for a litle more speed at the 3 "crusing speed" levels. I am sure that the Bravo 1 26' is to high
I woul like trying to cup the blades on my 24 ' to get a better grip and a litle more natural bow lift ??

In your friend case maybe it s a solution to cup the blades as well ??

Any comments ??

The silent thunder is removed and when the transom (rotten) was rebuild the drive was monted a bit higher then original.