some of the Fastech's have/had 1.65 drives .....m

Bravo drives can run in either direction with no problems. A fastech 271 runs a left hand prop. I have tested a right hand prop on my fastech and it lists to one side pretty bad. That is why they run a left hand prop. With a 1.50 drive I found a 22p Bravo one 4 blade works best. Around 61 mph with a full tank of fuel and 4 passengers. I now have a 700hp 540 in my Fastech. Currently running 80 GPS with a lot of tuning to go. Jeff Wurl

93 271 SR1 stock
 

I think I have the 1.5 gear ratio. Not sure. 4800 rpm gets me 52 mph on the GPS. stock 502 MPI with 22p 4 Bravo 1 blade. Not too many places in NJ where the water is flat enough to open it up. This boat does cruise nice about in 2-3 footers off shore @ 3200 30 mph. I wonder if I would have better economy with a higher pitch?

400 hours on the motor and I want to keep it in one piece as long as possible.

You should definetly get 55 outta that boat, might wanna try a 21 mirage

Well since other people are trying to dial in a prop for their boat too ill post my findings.

Original prop on my boat when i bought it 23 mirage (test run was with 2 people and 1/4 tank of gas.)
5000 rpms at wot
57mph (not gps speed)
Tons of prop slip

Just tried a 4 blade 24 pitch yesterday on my boat with 3/4 tank of gas and 4 passengers.
4700 rpms at wot (not enough rpms for my motor)
54mph (gps Speed, The speedo guage read 57 still so really no change in speed)
No prop slip that i could tell. (motor actually felt bogged down)

Contemplating what i should do next. I think im going to try a 25 mirage plus 3 blade and get it labbed to make the rpms that i need. I think this is the prop that i need. I just think that this thing should go a little faster than that. Im going to look into a rebuild on the motor over the winter but for now i want to just play with some props.

Oh yeah, the boat is a 271 formula with a 502 mag.

Update:

I just went out today by myself with 1/2 tank of gas and got it to 58.1 mph gps. Kinda windy and chopy though so i didnt let it sit at wot for too long. With the 24 pitch 4 blade

What were your RPMs?

26 p bravo prop will get me to 62 on the gps. once and a while with a tailwind and 2 foot chop i can see 65. that is alone and 1/4 tank of fuel.

You could lab the 24" B1 that would probably get you 4,900rpm. I would Lab a 22" B1 and spin it 5200rpm low fuel, driver and no load. That should put you right around 5K witha normal load.

Well I have just the same boat a 1993 271 sr-1

My boat had a 502 carb, and it blow up when the oil cooler made a huge leak and trowed the oil into the sea.

Well it was in the middel of summer and had no time to fix the engine at that time, (I live in Norway and the summer is short)

So I bougt a new 496 Ho an installed with bravo 1 with 1.50

I called to formula and asked them what prop to use they said a 23 mirage II will be the best.

I got that with the dealer I bougt hte engine from.

At first the boat ran 56 mph, and then I removed the bottom paint it had. then I got 59 mph

Then I bougt cmi headers and it picked up some more, speed.
now my top is 63 mph.

I have then 4900 rpm at wot.
But the boat is very sensitive for weigth in the bow, if the water tank is full it will not go more than 55 mph at wot.

I have the silent thunder to but it wil be removed now together with taht heavy sun pad and those heavy chairs.

I will make a a new sun pad in divinicell and buy new chairs that are much lighter. Maby I will get a couple of more mph from that.

I did test a bavo 1 24" but then i got just 4600 rpm and 57 mph, So I think this boat is best with mirage props.

Kjetil Johansen
Arendal Norway.