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Old 01 April 2010, 03:03   #1
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Twin engines not performing

Quick one for you guys with twins.

While I am rebuilding the merc I thought I try a twin Johnson setup, but I'm just not getting the performanceI was expecting.

I have two Johnsons, perfectly matched, props identical, both tuned to run at the same Vmax. I just cant seem to get the top speed I was expecting. I'll post pics later for analysis.

Help?
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Old 01 April 2010, 04:30   #2
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What size engines on what boat?
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Old 01 April 2010, 04:35   #3
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A couple of Johnson Single cylinders, Mid 70s vintage. old engines, but the were to hand.

Temporarily dropped on the humber while the merc gets rebuilt
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Old 01 April 2010, 04:39   #4
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Single cylinder, can't be much hp? How longs the Humber?
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Old 01 April 2010, 04:49   #5
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remember there were 2-pot 70 and 80 Hps kicking about back then.........

5m.
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Old 01 April 2010, 04:50   #6
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So do you know what hp they are?
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Old 01 April 2010, 04:58   #7
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Here's a pic of the setup:


(sorry, couldn't keep this going 'till 12..........)
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Old 01 April 2010, 05:04   #8
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2hp single cylinders!!! no idea why you cant get on the plane?!?!
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Old 01 April 2010, 05:20   #9
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Happy new April!

To be honest without the main engine on there I'm not sure the props would even touch the water!

Just for the record, I took that as a joke just before I started stripping the transom down and been waiting for 3 months for a suitable day to use it!

This is what was under three layers of "rescue orange", and will be the subject of a "refurb" thread in a few weeks when it's all back together.
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Old 01 April 2010, 10:09   #10
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I know where there is a 3rd one if you need it!
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Old 01 April 2010, 10:43   #11
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,,you could try doel fins ,,most people seem to say they improve performance ,,though there wont be much to bolt too ,,or,,,you could try moving some weight forward that might improve things though i dont think your going to get your eyes streeming with the wind rushing past ,,LOL good one !
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Old 02 April 2010, 03:04   #12
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Quote:
Originally Posted by chewy View Post
I know where there is a 3rd one if you need it!
I could move them to the edges of the cut-out & get my Aux in the middle - double the available Hp!

Quote:
Originally Posted by m chappelow View Post
,,you could try doel fins ,,most people seem to say they improve performance ,,though there wont be much to bolt too ,,or,,,you could try moving some weight forward that might improve things though i dont think your going to get your eyes streeming with the wind rushing past ,,LOL good one !
I think the only way that's going to get my eyes streaming is by crying through boredom!
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