Can you tel an 85 hp from a 115 hp?

[Tacklewasher]

Strange question, but I'm thinking about things again.

I have a motor that, according to the cowling that came with it, is a 115hp.

There is no tag on the transom bracket and the freeze plug has been "altered". Obviously this motor went for a walk at some point in it's history.

It looks to be an early 80's motor and everything on it is the same as what my Johnson 1981 V4 manual shows. So I know it's around an 1981 motor.

I'm curious because, even though everything seems to be running well and I have it running at 5,500 rpm with a 15p prop, I'm thinking I should be able to push a 1977 Starcraft faster than 38 mph with a 115 hp.

I'm thinking maybe it's an 85 hp, that came with a 115 cowling.

So, is there anyway to tell an 85 hp from a 115?

 

[ezeke]

Re: Can you tel an 85 hp from a 115 hp?

They stopped making the recreational 85HP in 1980 and went to the 90HP models. The 85HP recreational motors don't come back until 1991.

You could tell by the high speed carburetor jets and the size of the carburetor throats. You would not notice much difference in performance until you reach greater than 5000 RPM.

BTW, The theoretical maximum speed that your motor could move a boat with a 15 pitch prop is based on the 15" for each complete revolution of the propeller which requires 2 complete revolutions of the engine. So the fastest your boat could go is 39.06 MPH at 5500 RPM if everything were perfect, which does not happen.