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Old 16 May 2010, 04:13   #1
Country: UK - England
Town: kingston upon thames
Make: humber
Length: 5m +
Engine: old twin yamaha 40s!
Join Date: Aug 2009
Posts: 2
wot size hp ......

experience advice needed.....currently running mid 80's yamaha twin 40's on a humber attaque 5.5 . the transom was reinforced at some stage with stainless struts so it is solid. but its time for a change. i want to take these of and replace with one engine. but what is the maximum hp i can put on. is the weight the issue,or is it overpowering. if it is weight would you opt for a 2 stroke instead of a 4? obviously too much weight will put the transom to low in the water. and could you explain what is over powering ? is it simply, dont put a v8 in a mini, in dont need it and it wont go any better.... educate me please.

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Old 16 May 2010, 05:19   #2
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Country: UK - England
Town: Fareham
Length: 6m +
Join Date: Sep 2003
Posts: 7,829
Best to speak to Humber to get the max size either in weight or HP this hull can handle. But if you replaced the twin 40's with a 80 hp single engine you would defiantly see a performance increase and a fuel decrease. I would hazard a guess that it could handle 100hp without too much problems, just check with Humber.


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Old 16 May 2010, 05:25   #3
Country: UK - England
Town: Midlands
Make: Nautique
Length: 6m +
Engine: PCM 5.7l
Join Date: Oct 2003
Posts: 1,082
As an'd get similar(ish) performance with a single 60 but a nice match with 90hp and could poss run 100-115 as they are usually the same blocks as the 90hp motors but might have to be a bit careful with the throttle sometimes

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