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-   -   25p vs 23p, same wot rpm? (https://www.offshoreonly.com/forums/prop-talk/326338-25p-vs-23p-same-wot-rpm.html)

Sunrocket24 05-18-2015 07:13 PM

I tried a 26 Bravo once and could only run to 63mph at around 4400rpm and the chine walk was scary due to the stern lift from the 4 blade prop. I have run a best of 67mph with my 23 Mirage plus at 4800-5000rpm with 400 dyno proven HP. How much do the 24 Superboats weigh? I am moving again and weighed the boat and trailer a few days ago (I get paid to move anything the moving company won't move). The boat and trailer weighed 4580lbs full of gear, 1/4 tank of gas and Aluminum Load Rite trailer.

Dave M 05-18-2015 08:18 PM


Originally Posted by Sunrocket24 (Post 4305965)
I tried a 26 Bravo once and could only run to 63mph at around 4400rpm and the chine walk was scary due to the stern lift from the 4 blade prop. I have run a best of 67mph with my 23 Mirage plus at 4800-5000rpm with 400 dyno proven HP. How much do the 24 Superboats weigh? I am moving again and weighed the boat and trailer a few days ago (I get paid to move anything the moving company won't move). The boat and trailer weighed 4580lbs full of gear, 1/4 tank of gas and Aluminum Load Rite trailer.

I never weighed it but I think it was around 3600lbs.

AWOL 05-18-2015 08:33 PM

Load should be comparable. 2 people, same body of water, and around the same fuel. I may try the 25p again, but either prop, my slip % seems high.

I've never weighed the boat but I would certainly hate for it to be a tank.

Heaven forbid its a regular 7.4, it should still run faster speeds.

Edit: for the record, it's an 89 454MAG/bravo 1 drive combo. Research indicates 365hp from the factory, around 350hp at the prop and a 1.5 gear ratio.

Sunrocket24 05-19-2015 06:58 AM

And both props in good shape? I think you should be getting mid 60's out of it and should be able to spin that 23 plus to 4800-5000. Engine running strong?

AWOL 05-19-2015 08:54 AM

Both props appear in good shape. Mirage 23P + looks brand spanking new and has a new hub. Engine seems strong, no knocks, no ticking - but maybe should do a compression check to confirm again.

I may also open the gas tank to check out the pickup tube and make sure its not clogged or something.

Ive got some work ahead of me I guess.

Blueabyss 05-19-2015 11:01 AM

Are you getting enough air to the motor.. Can you run with the hatch propped up 2 inches without fear of it blowing off. If so that will allow plenty of air to see if it is getting enough.

Chris

AWOL 05-19-2015 02:38 PM

I don't think air is the problem, but I can try that.

I'm not sure what the symptoms are of low fuel delivery on a boat, but from what I can tell, it seems fine. I read another thread of a python owner having issues with the fuel pickup, but he doesn't explain symptoms.

Edit: checked serial number : C659348. Comes up 454 mag for sure.

AWOL 05-23-2015 06:07 PM

Had it out today again and gave it some good runs.

I had 3 others in the boat and 3/4 tank and ran 57 mph @ 4500 rpm.

Slip calculates around 13% (improvement) but still doesn't want to get over 4500 rpm. I did end up cleaning some junk from my fuel pickup tube and that may have resulted in the 4mph increase.

Would a lighter load = higher rpm? Or should I look to try just a plain Jane 23p Mirage to get my rpm up

AWOL 05-26-2015 07:15 PM

Update part 2 in case anyone else has these issues.

Was out by myself today for a quick jaunt.

With a little more than half a tank, I had her full tilt, trimmed up and saw 4700 or so rpm. GPS on my phone (same app Ive been using) showed 60.9 mph. It started to chine walk a little, and backed off.

Either cleaning out my fuel pickup tube, or the lighter load, Im seeing some improvements and Im pretty pleased. Slip is right around 10% so I can't complain. With a lighter load, maybe I can get to 4800-4900 and a few more mph.

AWOL 05-28-2015 09:13 PM

Update part 3:

http://img.photobucket.com/albums/v3...psh6ueotnr.png

Still running under 5k rpm, but now in the 4800-4900 range. Being a novice and hauling this speed, Im more focused on not dying.

Life is good, and getting closer to my 65 goal.


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