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| 21 pitch volvo 4 blade prop on a h180 3.0? https://www.smwebhead.com/phpBB3/viewtopic.php?f=3&t=8385 |
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| Author: | ric [ Mon Sep 12, 2011 10:50 am ] |
| Post subject: | 21 pitch volvo 4 blade prop on a h180 3.0? |
My local dealer will sell me a new 4 bladed volvo 14x21 pitch aluminum prop for $150. I'm in the market for a 21 pitch propeller, the current 19 pitch WOT is too high (5000) and I would like to raise my cruise mph. Is there any benefit to a 4 bladed prop in my application instead of just getting the standard 3 (just general cruising, no towing). |
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| Author: | boater [ Tue Sep 13, 2011 5:46 am ] |
| Post subject: | Re: 21 pitch volvo 4 blade prop on a h180 3.0? |
It will handle better at slow speeds. How fast is that thing if you're getting 5000 rpm out of a 19" ? See if he'll let you test it. |
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| Author: | chrisvs [ Tue Sep 13, 2011 5:59 am ] |
| Post subject: | Re: 21 pitch volvo 4 blade prop on a h180 3.0? |
From what I understand ric, that 4 blade should do just what you are looking for. It might not be as fast as a 3 blade for top speed, but mid range cruising should be a bit faster and more efficient. |
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| Author: | ric [ Tue Sep 13, 2011 7:11 am ] |
| Post subject: | Re: 21 pitch volvo 4 blade prop on a h180 3.0? |
Right now I GPS 39-40mph at top speed with the 19. I'm not looking for more top end (I never take my motor above 4k usually), I just want faster cruise at 3200. Doing the math the 21 should give me 5-6mph faster, as if I was at 3800 with the 19. |
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| Author: | Walt [ Sat Sep 17, 2011 9:15 am ] |
| Post subject: | Re: 21 pitch volvo 4 blade prop on a h180 3.0? |
The issue with changing #blades, and large pitch changes is as blade count goes up, prop diameter goes down. Case in point, my 3 blade 19P is about 15 3/8" dia and gives me 51 MPH at 5200 RPM. My HiFive (5 blade 21P) is 13 5/8" dia and gives me 50 MPH at 5200 RPM. The 5 gives much improved hole shot, and better throttle response in the low-mid range for my Prefect Pass cruise control, but is definately not for top-end or cruising. I agree that you 4 blade option should be a good prop for your set-up as far as speed and RPM, and at a fair price. You will feel in improvement in the bottom end, but don't think you will increase your cruise speed, or top end. I believe you would see your most desired performance (no tubing, skiing, etc) from a 3blade 21P, or even 23P. But keep in mind, even going from the 19P to a 23P you are only going to change top end by about 5 mph. IMO, if you ain't over-revving it and getting the otherwise desired performance, leave it alone! It soulds like you have already used a prop slip calc. hope that helps! |
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