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!