What limits the size of the prop?
07-28-2003 | 09:01 PM
#1
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From: IL
What limits the size of the prop?
I'm running upwards of 640+ HP, actually 540 HP at 4000 RPM to 648 HP at 5300 RPM, yet I am only able to turn a 28P Bravo1 prop 4650 RPM.
It actually seems like as I push the throttle to the max, my HP drops off! Engine has less than 10 hours on it. I've taken it easy for break in, but want to run a little now!
Last year before the rebuild, I was able to spin a 29 at over 5000 RPM.
What limits the size of the prop I can turn, shouldn't it be the HP and torque? I should have enough of both to spin a 28P faster shouldn't I?
Just curious. . . and a little disappointed
It actually seems like as I push the throttle to the max, my HP drops off! Engine has less than 10 hours on it. I've taken it easy for break in, but want to run a little now!
Last year before the rebuild, I was able to spin a 29 at over 5000 RPM.
What limits the size of the prop I can turn, shouldn't it be the HP and torque? I should have enough of both to spin a 28P faster shouldn't I?
Just curious. . . and a little disappointed
Last edited by Elite Marine; 09-06-2003 at 08:50 AM.
07-28-2003 | 09:21 PM
#3
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From: IL
4000 - 542 HP, 711 Ft-Lbs
4250 - 580 HP, 716 Ft-Lbs
4500 - 604 HP, 706 Ft-Lbs
4750 - 623 HP, 693 Ft-Lbs
5000 - 628 HP, 661 Ft-Lbs
Peak Torque is around 4650, but the HP is still going up.
With a 4500# boat, Deep V whats the recommended prop. Darin at Houston recommends a 26 Bravo 1 repitched to a 27, cupped and labbed. I agree at this point, but just like to get several opinions/ideas.
Thanks
4250 - 580 HP, 716 Ft-Lbs
4500 - 604 HP, 706 Ft-Lbs
4750 - 623 HP, 693 Ft-Lbs
5000 - 628 HP, 661 Ft-Lbs
Peak Torque is around 4650, but the HP is still going up.
With a 4500# boat, Deep V whats the recommended prop. Darin at Houston recommends a 26 Bravo 1 repitched to a 27, cupped and labbed. I agree at this point, but just like to get several opinions/ideas.
Thanks
07-28-2003 | 09:36 PM
#4
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Joined: Jan 2001
Posts: 1,461
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From: PA and MD
What speed are you running at WOT with the 28"?
I would try a stock 26" and get the numbers and then talk to Darin.
Before I labbed or cupped a prop I would test the 1 and 2" shorter lowers. Maybe trying different lower units (shorter) might help more.
I would try a stock 26" and get the numbers and then talk to Darin.
Before I labbed or cupped a prop I would test the 1 and 2" shorter lowers. Maybe trying different lower units (shorter) might help more.
07-29-2003 | 08:24 PM
#8
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From: IL
What could be wrong? Engine is strong, boat seems smooth and good. This is a stock prop no modifications.
Should still be getting the RPMs up. I'll try a 26P and see what happens.
High Tide - I ran the dyno. Did 15 - 20 pulls all the same.
Should still be getting the RPMs up. I'll try a 26P and see what happens.
High Tide - I ran the dyno. Did 15 - 20 pulls all the same.
