operating revs of Johnson

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BigwayNZ

Seaman
Joined
Jan 9, 2009
Messages
56
My johnson 175 hp 2 stroke 1988, I am told that it has a rev limiter on it set at 5800 revs.
at WOT i get about 4800 revs out of it, on a good day and with nice water it gets up to 5200rpm.
I have the right tach on it now.

Anyway, what is the operating speed of these motors? What is the range for this motor to provide full horse power at? What should the limit be at and what could the limit be at and what is the revs i shoud have it at WOT?

Appreciate any replies.

Thanks.
 
james williams

james williams

Petty Officer 2nd Class
Joined
Jul 22, 2006
Messages
105
Re: operating revs of Johnson

It needs to be set-up so it will get at least 5500rpm maybe a little more.I believe the limiter 5700-5800.If it don`t reach at least 5500,you`ve got some work to do.
 
tashasdaddy

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: operating revs of Johnson

you may need to change props. post that question in the prop forum.
 
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BigwayNZ

Seaman
Joined
Jan 9, 2009
Messages
56
Re: operating revs of Johnson

james williams said:
It needs to be set-up so it will get at least 5500rpm maybe a little more.I believe the limiter 5700-5800.If it don`t reach at least 5500,you`ve got some work to do.
Click to expand...


What sort of work if you would not mind elaborating.

It is spinning a 22p prop. If it is spinning a smaller prop would it not then be slower or should it get some more speed out of it?

Yesterday in the calm i was hitting 60mph gps. it usually sits around 55mph at 5200 rpm.
 
tashasdaddy

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: operating revs of Johnson

usually you pick up 200 rpms, with a 1" drop in pitch, changing to a 21 inch pitch would possibly put you at 5400, 20" 5600. you may loose a couple of MPH, at wot, but will be turning the proper rpms for the motor. dropping the pitch will improve the getting out of the hole performance, you will get on plane quicker.
 
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BigwayNZ

Seaman
Joined
Jan 9, 2009
Messages
56
Re: operating revs of Johnson

I appreciate that, however my timing advance had seized and is now working and i find that getting out of the hole is super fast, i mean it really is super fast in my little sidewinder. Would it make much more of a difference? I feel i get out of it faster and would not want to give up top speed for getting out of the hole quicker as i am very happy with that area, unless it was a much bigger difference that outweighs the MPH i would lose.

People in the sidewinder forums have been telling me to try a higher prop with my motor, i am guessing that would be the wrong move?
 
tashasdaddy

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: operating revs of Johnson

you are not bad at present with your rpms, but for longevity of the motors life, you want to turn the proper wot RPMs. when you have your motor set up this way, you are not "lugging (over working) the motor at lower rpms and speed".
 
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Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: operating revs of Johnson

Look on the packs and see if there's any numbers on them. Look for something like 58L or similar. That'll be the limiter if there is one.

I'd work the set up to gain rpm & performance rather than drop pitch. That's a fun little boat. It'll respond well to rpm to a point.

Have you done anything to the hull?
 
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ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: operating revs of Johnson

I believe that the V6 1988 175HP engines all came with PP #583114 which did not have a rev limit.
 
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