think about change from mecrury to a johnson

josh_2562

Seaman
Joined
Jun 7, 2007
Messages
60
well right now i have a 92 mercury 100hp on my 17 foot flats boat. i was told the engine is about 320lbs. with this engne the boat does about 40 wot. my ? is i have a 1992 70hp johnson that i was told is about 250lbs. do you guys think that the 70hp would push the boat good.if so about how fast will it still go.one of the reason i want to change it is that i put on a jack plate and when i left the engine all the way up it hit my poleing plat form. also becuse of the wight.thanks for any help
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: think about change from mecrury to a johnson

you may lose 5 mhp. but instead of burning 10 gallons and hour you will burn 7 ghp. proper propping and engine height to get the best performance. you can turn 5500 wot.
 

josh_2562

Seaman
Joined
Jun 7, 2007
Messages
60
Re: think about change from mecrury to a johnson

what is a safe cruise rpm for both of these motors
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: think about change from mecrury to a johnson

they both can run all day at 5500. they reach there optimum around 5000.
 
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