Engine Shop
09-19-2006, 03:32 PM
#21
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Re: Engine Shop
Originally Posted by RJBBC
Dyno sheet says 461HP at 5100rpms and 514lbs at 3700rpms. The speed of the boat went from 65.0mph (GPS) at 5100rpm spinning a 23 Mirage Plus to 72.3mph (same handhelf GPS) at 5000rpm spinning a 26 labbed. I am very impressed with the speed increase (feels like a different boat at all speeds), but the dyno numbers seem a little soft to produce such an increase in speed. Any thoughts?
Congrats on the speed numbers. I think you might be able to find a few more MPH with some prop testing. That speed sound close to what others have said with similiar HP numbers. Enjoy!
09-19-2006, 03:39 PM
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Re: Engine Shop
Rob,
When you are calculating theoretical speed with a Bravo 1 prop, you must deduct 1 1/2" of pitch. For some reason, Bravo 1 props are measured at their maximum pitch, where as other props are measured at average pitch. There is a 3" pitch progression from the leading edge of the blade to the trailing edge. The formula is calculted at average pitch. So, to use the formula correctly, you have to deduct 1/2 of the pitch progression on those props, or 1 1/2".
As I said, I am not knocking or doubting your speed at all. I am just one who likes and believes in numbers.
Good luck and be safe.
Vinny
When you are calculating theoretical speed with a Bravo 1 prop, you must deduct 1 1/2" of pitch. For some reason, Bravo 1 props are measured at their maximum pitch, where as other props are measured at average pitch. There is a 3" pitch progression from the leading edge of the blade to the trailing edge. The formula is calculted at average pitch. So, to use the formula correctly, you have to deduct 1/2 of the pitch progression on those props, or 1 1/2".
As I said, I am not knocking or doubting your speed at all. I am just one who likes and believes in numbers.
Good luck and be safe.
Vinny
09-24-2006, 06:55 AM
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Re: Engine Shop
Originally Posted by checkmate454mag
Rob,
When you are calculating theoretical speed with a Bravo 1 prop, you must deduct 1 1/2" of pitch. For some reason, Bravo 1 props are measured at their maximum pitch, where as other props are measured at average pitch. There is a 3" pitch progression from the leading edge of the blade to the trailing edge. The formula is calculted at average pitch. So, to use the formula correctly, you have to deduct 1/2 of the pitch progression on those props, or 1 1/2".
As I said, I am not knocking or doubting your speed at all. I am just one who likes and believes in numbers.
Good luck and be safe.
Vinny
When you are calculating theoretical speed with a Bravo 1 prop, you must deduct 1 1/2" of pitch. For some reason, Bravo 1 props are measured at their maximum pitch, where as other props are measured at average pitch. There is a 3" pitch progression from the leading edge of the blade to the trailing edge. The formula is calculted at average pitch. So, to use the formula correctly, you have to deduct 1/2 of the pitch progression on those props, or 1 1/2".
As I said, I am not knocking or doubting your speed at all. I am just one who likes and believes in numbers.
Good luck and be safe.
Vinny
I agree trusted formulas are important in predicting accurate results. I ran the boat yesterday and achieved more realistic speeds but I am puzzled nevertheless. The first GPS run hit 71.8mph((5000rpm)7%slip) with just myself on the boat. I was convinced at that point we have a 72mph boat and couldn't wait for some friends to come down so I could show them. The boat pulled two more runs each with a passenger now resulting in 67.8 and 68.2mph both at 5000rpm and 12% slip. Certainly these numbers make more sense. I do have a theory on the higher GPS speeds. The max speed reading of 72.3 and 71.8mph was when we had a light load on the boat and rough water resulting in a significant amount of air time. The boat can achieve these higher speeds for few seconds out of the water but can not sustain these speeds for any length of time while moving in the water. I have concluded with this new data hydraulic steering can wait until the boat has more power.
Rob
09-24-2006, 06:44 PM
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Re: Engine Shop
Rob,
Your right about the water conditions and load. I experience the same situtation. I can run 80 any day, regardless of load or water. However, an a good day, lighter load, right amount of chop, I'll get 84 mph. Thats just the way it is.
Get the steering anyway. You wont be sorry. Your wallet will be, but you will be smiling.
Your right about the water conditions and load. I experience the same situtation. I can run 80 any day, regardless of load or water. However, an a good day, lighter load, right amount of chop, I'll get 84 mph. Thats just the way it is.
Get the steering anyway. You wont be sorry. Your wallet will be, but you will be smiling.
09-25-2006, 06:02 PM
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Re: Engine Shop
Originally Posted by checkmate454mag
Rob,
Your right about the water conditions and load. I experience the same situtation. I can run 80 any day, regardless of load or water. However, an a good day, lighter load, right amount of chop, I'll get 84 mph. Thats just the way it is.
Get the steering anyway. You wont be sorry. Your wallet will be, but you will be smiling.
Your right about the water conditions and load. I experience the same situtation. I can run 80 any day, regardless of load or water. However, an a good day, lighter load, right amount of chop, I'll get 84 mph. Thats just the way it is.
Get the steering anyway. You wont be sorry. Your wallet will be, but you will be smiling.
I agree steering is king!. I don't even think your wallet will mind that much, maybe the wife.
I think you can run those top speeds alot safer with more confidence with steering.
09-26-2006, 05:52 PM
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Re: Engine Shop
Originally Posted by RJBBC
OK, hydraulic steering it is.
09-26-2006, 07:48 PM
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Re: Engine Shop
Rob,
Our boats are identical. I used Imco's tilt helm. Fit like a glove. Take a look at the picture. Their hydraulic unit fit perfect also. I got it in through the wiring access panel in the cabin behind the dash. If you want to see, I can take a picture this weekend for you.
Vinny
Our boats are identical. I used Imco's tilt helm. Fit like a glove. Take a look at the picture. Their hydraulic unit fit perfect also. I got it in through the wiring access panel in the cabin behind the dash. If you want to see, I can take a picture this weekend for you.
Vinny
09-26-2006, 08:30 PM
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Re: Engine Shop
Originally Posted by checkmate454mag
Rob,
Our boats are identical. I used Imco's tilt helm. Fit like a glove. Take a look at the picture. Their hydraulic unit fit perfect also. I got it in through the wiring access panel in the cabin behind the dash. If you want to see, I can take a picture this weekend for you.
Vinny
Our boats are identical. I used Imco's tilt helm. Fit like a glove. Take a look at the picture. Their hydraulic unit fit perfect also. I got it in through the wiring access panel in the cabin behind the dash. If you want to see, I can take a picture this weekend for you.
Vinny
I ordered the Imco product you suggested the SA-2. I was under the impression they did not have a tilt helm. The stem angles would be fixed at straight out or 15 degrees. Pictures would be appreciated.
Rob
09-26-2006, 09:54 PM
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Re: Engine Shop
Thats weird... I just checked their site, they dont list the tilt helm. Maybe they stopped making it ?? try to call them
