#51
IP: 72.192.247.189
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Quote:
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#52
IP: 71.118.13.238
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Huh
Hanley, your lugging. When I was using trhe prop I sent you I could get 1700 at around 6" of vac and very little more if I cranked it. Now with the Indigo I get 10" and just over 1800 rpm's.
With your 2:1 box I should think you would be around 10" at 2400 and max cruise (7" or so) at 26~2800, these are guesses but should be close if you were proped for around 3,000 at WOT. You will gain a few RPM's when not tied to the dock but not much more than a few percent, say less than 10%. When all is clean and well I cruise at 8" @ 2200 RPM's with the Indigo. Dave Neptune |
#53
IP: 67.78.241.34
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Dave, I think you're right. Maybe too long in the slip or still too much prop. Wish I had data from the trip south. Prop is at 13x11.5, 3 blade power boat prop. What do you think about 13x10 for the prop you sent me?
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#54
IP: 108.23.219.10
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Prop
Hanley, you are lugging with a 13X11.5x3 blade. The 13x10 is it also a 3 blade or is it the cut down 14" with questionable pitch I sent you. Big change 2 to 3 blade! You say you are using a power boat prop, do you have any pics? I most cases the blades are simply wider for absorbing more torque supplied by larger power plants.
I remember you ran the one I sent you and you thought it needed a bit more pitch as it was spinning to fast. Do you remember the vac load at around 2500 RPM's, or anywhere on the rpm curve? Blade area plays a big part of the equasion, you need enough to absorb the torque and any more is just wastin' power for the additional friction. Personally I would run with to little and let it spin a bit but not over-rev the beastie. The insides of the engine will be much happier and the losd off the bearings is a bunch. Dave Neptune |
#55
IP: 67.78.241.34
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Dave , The other prop is the one you sent me. Before sending it out to the shop I am trying to zero in on exactly what I want. Changing the 3 blader from 13x13 to 13x11.5 made a huge improvement for me but the prop you sent me allowed 3000 rpm way to easily...trying to find the sweet spot...
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#56
IP: 108.23.219.10
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Another thought!
As a comparison, when I first installed the Indigo on my boat and started down the fairway I though this thing is to small because I was using a lot more RPM's but the manifold load was staying very light. When I got out to the harbor and started to apply power she spun right up to where she was supposed to. This was such a departure from what I was using and had tried that I really didn't like how it was working, "I" wasn't accustomed to it yet. Well that lasted about 2~3 trips and I started developing my new fuel usage curve with the Indigo spinnig 25% faster than anytyng I had used. The big suprise was it was using far less and the intermediate settings and a bit less at the same a "cruising speed". The engine was much happier and after getting myself accustomed to the broader RPM range I luv it!!!!!!!!!! It works well extracting about everything this ole' A-4 can deliver with the direct drive.
Thought this may eleviate some of your concerns. ave Neptune |
#57
IP: 67.78.241.34
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Brain Wobbling
Dave, Right now I am thinking of having your prop taken to 13x10 or 13x11. What do you think?
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#58
IP: 108.23.219.10
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Decision
Hanley, you need to decide which you want to go with a 2 or 3 blade.
The 3 will give a bit more bite for a headwind and sea if you get the proper RPM's, however it will drag much more when sailing. The correct 2 blade will work almost as well in the headwind if you get the same RPM's at full throttle and be a bit freeer running through the rpm range. The big advantage is sailing you can hide the prop for a considerable decrease in drag and more sailing speed . The 2 blade will require a tiny bit more pitch than a 3 if you stay with the same diameters. Blade area plays a big part and I'm not to sure about your PB prop configuration. Decide where you want the engine to run RPM wise for your cruise and work to it. When you get it you'll be very satisfied with the results. Dave Neptune |
#59
IP: 108.23.219.10
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Check?
Did you evr get the prop I sent measured for pitch? Taking it up 2" from where it is may be about right. I also think the cut down prop like I sent you will work well because the blades are a bit wider that a 13" off the shelf.
Dave Neptune |
#60
IP: 98.85.183.121
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Moving cautiously
Dave - In view of the fact that the 2 blader needs a little more pitch than the 3 blader for the same "bite", I think I'll go to 13x11 with the 2 blader since I only want to pick up 200 rpm or so. I cruise at around 1900 now with decent gas mileage.
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#61
IP: 208.69.133.21
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HC: A few notes from what I have read. A 13x8 or 13x9 three blade are among those suggested for the 2 to 1. A 13x10 or 13x12 two blade also for 2 to 1. By taking 2 " of pitch out of your existing 13x11.5 three blade prop you would be close and should bump your rpm up about 400.
If I remimber correctly when we talked back in NC you said your A-4 was "tired". If you are a little low on compression I think that could explain some of the low but steady vac #s. Dan S/V Marian Claire |
#62
IP: 67.78.241.34
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Quote:
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#63
IP: 71.118.13.238
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Good call!
Hanley, good call not pitching back anymore. In these types of props it is better to pitch up and not back.
That 2 blade I sent should be able to take an increase. I would try it and gather some numbers before pitching mutch. I also think you will need to get accustomed to a free-er reving engine spinning a bit faster albeit under far less load. If you can get 2800~3000 at WOT your cruise range will be around 2200 and almost no manifold load for happy cylinders and bearings and better economy due to efficiency. It took ma a while as I lugged for quite a few years and really had no other experience with the A-4 up to that time. Dave Neptune |
#64
IP: 108.23.219.10
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Do you?
Hanley, do you change out the prop or do you have to get a diver or go to the hard? When I was trying various props I got real quick at getting it off and on in the slip or at the island. If it has not been on to long they come off quite easy. If you can do a run with the 2 blade and post the numbers (vac vs. RPM), we can probably hit this one ritght on the head.
I have a feeling the 2 is not as far off as you may think. Trying it while loaded for cruise is an excellent opportunity to get it right. And then you will have a better sailing mod H-28. One of the guys I would help out on the dyno when building a set of racing engines (12 or more sometimes) it just took a lot of time. Anyway he was a guru of engines and he too sailed a mod H-28. Dave Neptune |
#65
IP: 67.78.241.34
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Slightly Better
Ran another test at the dock:
1000 14.0 1100 14.0 1200 12.6 1300 11.6 1400 10.5 1500 9.5 1600 8.0 1700 5.5 1800 4.5 1900 2.5 |
#66
IP: 67.78.241.34
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Getting Ready to Run
So today I pulled the Dole thermostat out and ran with none like Dan; 155 degrees @ 1000 rpm in gear, more tests to follow. Replaced NGK plugs with Autolite 86. 1 thru 4, left to right.
Last edited by hanleyclifford; 07-13-2016 at 08:32 PM. |
#67
IP: 72.192.247.189
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Quote:
One of the shipwrights at my marina never uses teflon tape, but for a different reason. He says that it is hard to tell when a fitting has been tightened enough. He (and I) have cracked aluminum ports by over tightening. -Steve |
#68
IP: 67.78.241.34
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Manatees
Great to have these guys playing around the boat.
Last edited by hanleyclifford; 07-13-2016 at 08:32 PM. |
02-27-2012, 05:48 PM |
Marian Claire |
This message has been deleted by Marian Claire.
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#69
IP: 138.88.60.5
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Nice Hanley..I am not commenting on your Snake Oil thread!
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) |
#70
IP: 67.78.241.34
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I was sort of hoping to see some other examples from the members. There's a lot of weird stuff out there!
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#71
IP: 173.22.81.163
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What's my mother-in-law doing in the water by your boat, Hanley? Didn't expect her to pop up on an A-4 forum.... I figured she would be at home, watching her soaps.
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#72
IP: 67.78.241.34
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I was wondering who that was shoving me away from that fresh water trickle!
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#73
IP: 67.78.241.34
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The Dave Neptune Prop is now at the prop shop being twisted into a 13x10.
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#74
IP: 71.118.13.238
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Good
Hanley, I'm glad to hear you are tweeking it. Did they check it and give you a guess as to where it was pitch wise. You will need to get use to the engine running under less load at a higher RPM. It took me a while to get use to my Indigo once I installed it. I actually thought I'd made a big mistake the first few times I ran it, however now I can't imagine going back to the lugging and restrictions I experienced with many other props.
I could get about 1900 with the prop you are tweeking with my direct drive. Good luck with it good sir . Dave Neptune |
#75
IP: 96.248.13.91
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From which comment we can presume that you are very confident that your wife does not visit this forum, ever.
__________________
- Bill T. - Richmond, VA Relentless pursuer of lost causes |
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