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what is your top speed, prop setup for 272 owners

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Old 02-12-2013, 09:14 PM
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Originally Posted by mthammer
i have a 1990 272 450hp each runs 75 thinking of putting on 2"shortys i havent heard of anyone running them anyone know if its worth it ?
I heard of a guy with the fastest 272 sr1 here that he gained a lot of speed with shorties , do a search "fastest 272 " you will find him. He did like 103mph, lots of power though.
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Old 02-25-2013, 11:09 AM
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Originally Posted by mrfixxall
we ditched the twin big blocks,,glassed up the transom,installed a ssm#5a. on a box-2up..in front of that we installed a 632..best speed with a 28p 4 blade was 96mph @ 5800..that was years ago and a few computor crash's ago..since them i pulled the engine,sold the drive and still have some parts like the crank from the 632..stringers were weak in the front part of the boat so we put it through a tree grinder and blew it into a friends field on his farm..
What kind of Power was that 632 making? Im possibly looking to a 272 single conversion. Also how did it sit in the water? Didi it sit level enough to be set up as a sit down boat? It seams that the twins are pretty sluggish for the total power. 660hp to go only 65. (no offense)
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Old 02-27-2013, 07:04 PM
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I have an '84' 272 and I'm at 57mph at 4000rpm and can't get a single rpm over 4000 with 23p props 3/4 tank of fuel and 3 people motors were rebuilt 2 years ago and sound great!! Just can't get above 4000rpm
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Old 02-27-2013, 07:07 PM
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Just bought the boat in July so lots of tinkering and good ideas to try when the snow melts!! Good luck
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Old 02-27-2013, 07:09 PM
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Originally Posted by 84 Formula 272
I have an '84' 272 and I'm at 57mph at 4000rpm and can't get a single rpm over 4000 with 23p props 3/4 tank of fuel and 3 people motors were rebuilt 2 years ago and sound great!! Just can't get above 4000rpm
I think you are over propped. Try a pair of 21" Mirage Plus...you will break 60 and run closer to 4500. You may also have bad tachometers...it does happen....but 23's are a bit much for stock 260 horse engines....you aren't at peak power which will be at about 4500~4600.
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Old 02-27-2013, 07:29 PM
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That's what I have been hearing !! To much prop! Do you know what they came out with?
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Old 02-27-2013, 07:42 PM
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I've only topped her out a couple of times since I have had her both times she has been almost full of gas!! Mostly she is a cruiser will the 21p hurt my cruising speed and will it hurt to leave the 23p on it?
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Old 02-27-2013, 07:47 PM
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Also tachs go over 4000 if I over trim so I think they are probably ok
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Old 04-21-2013, 01:27 PM
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Originally Posted by Mr Maine
With the 23's, 65mph at a little over 5000 is about 12% slip which is probably accurate for a twin engine boat.

With the 25's, 63mph at 4200 is 4.8% slip. Sorry but old convential hulls arent that good so somethings is off.

Are they worked to 27s or something?? 27s at that speed and rpm would put you back in the 12% slip range.
I guess my readings were off but , yesterday I got 4500 rpm wot at 63 mph w/ 2 on board and 3/4 tank of fuel using my 25 mirage props,would labbing these props give me more speed? Is it worth it?
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Old 04-21-2013, 04:03 PM
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Originally Posted by Diego9040
I guess my readings were off but , yesterday I got 4500 rpm wot at 63 mph w/ 2 on board and 3/4 tank of fuel using my 25 mirage props,would labbing these props give me more speed? Is it worth it?
If you are running 1.5 drives, that is 71 mph at 4500 and 25" pitch. 63 equates to 11% slip which is not bad for a straight bottom heavy deep vee.

Ask about props, I believe labbing them helps them to cut into the water easier allowing you to spin them faster. All the blades are also made the same so they all push the same as opposed to one doing the most work and another the least.

If it allows your motors to unload up to 4800 rpm, that would be 68mph at the same 11%. Big if, call someone that knows what the heck they are talking about if you are really interested. How fast are your 454's supposed to spin? Is 4800 or 5000 within reason?

Brian
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