1992 271 SR1 Prop?
 

I bought the boat on Friday. I'm trying to dial it in and bring my cruise speed up. 502 with a Bravo 1 drive, don't know the gear ratio. It had a 14 X 21p 3 blade on it. Top speed I saw was about 57 MPH at 5000 RPM's, cruising was running about 34 MPH at 3800 RPM's. I tried a friend's Hill 4 blade 22p on Saturday when we went away. It brought the cruise speed to 37 mph at 3600 rpm, top speed was mid 50's.

Guy that owns the local marina said the original prop's diameter was too small and that I should run a 15.25 X 21p on it. I just picked up a 14 X 21p blade to try.

I think someone said these boats came with a 23p from Formula? What props are you guys running on the single engine setup? I would like my cruise to be about 45 MPH at 3800 but don't know if that's realistic considering its weight and only having a single engine? I really don't care at this time what my top speed is but the cruise speed is more important to me.

Any input would be appreciated....

I have the same boat 1992 271 SR1. I had contacted Formula a few weeks ago when looking for a new prop. I was told the Mercury Mirage Plus 23P (14 5/8 R23) is what came on the boat from the factory so that's what I bought. I also saw 57MPH as my top speed, but have been told the boat should be around 60-63 MPH. I bought mine through iboats.com and spoke with Grant. Very helpful had I had the prop delivered 2nd day shipping for $550.

Hi guys

I have a 1993 271 Bravo1 XR 2009 Mercruiser 496 HO 425 Hp bravo1 24 pich prop

Best i have seen on the Gps so far is :
Alone with less then 1/2 tank of gas 60 mph 5000 rpm
3100 rpm 34,5 mph
3600 rpm 40,5 mph
4000 rpm 46 mph
4 people and 1/2 tank of gas 58,5 mph

I am going to try a Mirage 25 + if I can spin 5000 rpm with that maybe I will reach 62 mph
I am very happy with the Bravo1 24 gives a good all over performance

Ciao from Oslo Norway ;-)

I have not had the boat for a long time, so still figuring it out.
3500 rpm and 40 mph is a good cruise speed and you save a bit of gas
Compare with cruising at 4000 and 46 mph

Willm try a Bravo1 prop 22 or 24 pich :-)

I ran a Hydromotive Quad IV 21 pitch on my 1993 271. Came on plane very well with 4-6 people on board and top speed of 58 MPH.

mine was a 93, 502 carb, on the tired side, 21 mirage plus, 4900 58 mph, 4 blade will bring cruise up, take a cpl off the top, unless you have a buddy your running neck n neck with i'd go 4, actually wanting to try some 4 blades on my boat just never have gotten around to it, but I expect similar results

88242LS

If you read my results so far, do you think there are a couple of mph to gain by a mirage 23 or 25 plus ??

maybe, whats your top rpm now? I think a 25 will be too much, and kill your outta the whole, no matter what the 271 will not be a rocket out of the whole, but you don't want to over work the drive either

What was your cruise speed and at what RPM?

I ran a 15 1/4" x 23 last night and cruise was 44-45 at 3600-3700 and top speed was about 57 at 4800 trimmed up. Seems like it would only run to 4000 with the drive all the way down then I would gain the rest with trim. Does this sound about right? I liked the performance of the prop once running but it was a total pig out of the hole!

The Bravo1 prop 24' 5000 rpm 60 mph Bravo 1XR drive 1.50

So here is what I have so far for numbers:

15.25" X 23 3 Blade - Cruise 42 MPH @ 3600 RPM
Top Speed 57 MPH @ 4800 RPM
Overall prop slip 19%

Hill 22p 4 Blade Clever - Cruise 36 MPH @ 3600
Top Speed 51 MPH @ 4800 RPM
Overall prop slip 24 %

14" X 21 Quicksilver Typhoon 4 blade - Cruise 35 MPH @ 3800 RPM
Overall prop slip 29%

The 3 blade 23 gave me the best numbers so far but it seemed like the boat was a total pig coming out of the water. Would changing to a four blade 23 give me better results coming up on plane? Would a four blade 24 give me worse results? I'm really trying to cruise at 45 MPH at between 3600-3800 rpm. Is this unrealistic to think I can be there?

you need to try a 22p bravo 1. Or different brand 21p 4 blade. As for 45 at those rpm you are a little off

21" Rev4 would work well.

I think I found my prop. Bravo 1 24p. 3600 RPM 46 MPH. 4500 RPM saw 60 on gps. Engine won't turn much past 4500-4600. Hole shot is awesome and climbs great to cruise speed. Very responsive overall.

Do these hulls run with that much prop slip? 19% and up is very inefficient (29%??).

How does the 271 compare to the 242?

Saturday i tested a 3 blade Mirage plus 23 pich 62 mph 2 People and 3/4 tank of gas (no water in the water tank, you can loose some mph with water in tank)

Saltwater but very flat, I think I will reach 63 with less fuel a little chop and alone in the boat ....

This is so far the best I have reached :-) Not to bad for a SR1 without step ;-) I

Ps my boat has one layer of Hard Racing bottom paint ....