Author Topic: Are you running Autoprop on your H46?  (Read 164 times)

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Re: Are you running Autoprop on your H46?
« Reply #3 on: July 19, 2024, 04:37:48 AM »
Honestly I don't know what size our Autoprop is on our H46, but I ran through this today while underway for you and hope it's helpful. I was a bit surprised by the results comparative to yours.

1.  Bruntons Autoprop H6 - fully rebuilt less than 4 months ago
2.  Rated max output at crankshaft of Yanmar 4JH3-TE (75HP) is 3800 RPM (continuous 3700 RPM)
3.  Neutral RPM (WOT) - 4000+
4.  Reverse RPM (WOT) - 4000+
5.  Forward RPM (WOT) - 3900
6.  Idle RPM - 700

Transmission is Kanzaki KM4A-2 (new Aug 2021) with gear ratio 2.14.

SV Beleza - H46 #44


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Re: Are you running Autoprop on your H46?
« Reply #2 on: July 10, 2024, 01:07:40 PM »
Hi Peter,

H44 with same motor and similar results.  I have a max prop though.  I think my issue is more related to fuel starvation though.  Does yours blow black smoke at full throttle?  If not, mine doesnt either, than its probably not the pitch or anything else mechanical restricting max power.  Black smoke is un burnt fuel apparent when the motor doesn?t have the power to consume what is provided.  Check your tanks, pickup tubes, filters, etc.  Let me know how you make out too.



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Are you running Autoprop on your H46?
« Reply #1 on: July 09, 2024, 03:23:22 PM »
I would like to collect some comp data.  I think our prop is over-pitched.  On H46 Nepenthe, we have

1.  Bruntons Autoprop H-6 (21 inch) just greased
2.  Wide Open Throttle rating of our Yanmar 4JH2-TE is 3600 RPM
3.  Neutral RPM (WOT) - 3600
4.  Reverse RPM (WOT) - 3600
5.  Forward RPM (WOT) - 2850
6.  Idle RPM - 800

We can not reach the rated RPM at WOT and she slams into Forward with a newly rebuilt transmission (Kanzaki KBW-20, 2.63:1 gear ratio)

Please list your data if you know it, per 1-6 above.  I'm in touch with the Autoprop rep as well, but trying to do a bit of research myself.  Thank you!


Pete and Edie Neidhardt
Boothbay Harbor, Maine
Hylas 46 #16  Nepenthe


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