changing gear ratio's in a evinrude 3 cylinder 1995

[phillnjack2]

Ok first off I have the 1995 model 3 cylinder evinrude
gear ratio is 2.42 to 1.
the engine is longshaft with the newer multi spline main shaft from engine to gearbox and that will NOT be altered .
I know some of the older model came with a 4 spline shaft,but this is the later version.

My question is this.
can I change the gear ratio to 2 to 1 by using gears from the v4 engine ?
I have the gearbox that looks almost identical to the v4 crossflow as in size etc, and the thru hub exhaust is around the same diameter.

I am wondering if the actual gear set (F-R) could be changed to give me a 2 to 1 ratio.
this would allow me to have a faster spinning propeller and thus allow me to run smaller diameter props.

would the actual gear shaft allow for the different gears..

 

[racerone]

Re: changing gear ratio's in a evinrude 3 cylinder 1995

Gears in outboards are precision fitted.-Has to do with mounting dimensions.------Doubt that this will work.-------Let us know how this works out if you want to give it a try.

 

[steelespike]

Re: changing gear ratio's in a evinrude 3 cylinder 1995

Why are you looking for a smaller diameter?

 

[steelespike]

Re: changing gear ratio's in a evinrude 3 cylinder 1995

Why are you looking for a smaller diameter? It appears a V4 115 uses the same diameter prop as the 3 cylinder 65.
At 5500 rpm a 23" prop will do about 43 mph figuring 12% slip.

 

[phillnjack2]

Re: changing gear ratio's in a evinrude 3 cylinder 1995

the older omc v4 uses a different gear ratio to a 3 cylinder omc. But yes the older v4 has the same spline and same clearance for prop.
a lot of the early 1970,s race boats with 3 cylinder engines used the 23 prop, but had a different gear ratio to mine.
the early triple that was used for racing was short shaft engine with a 1.83 gear ratio from what I gather.
the v4 is 2-1 ratio and the 3 cylinder is 2.42 to 1 so there is a fair amount of difference in gear ratio's.

By using a 2-1 ratio I might be able to get more advantage using a smaller diameter prop than I have now.
my prop is a original 13 3/4 x 23 omc silver streak, now known as the srx prop from omc .
the only difference being a silver streak was painted silver metallic and the srx being polish stainless.

I am hoping to get nearer the 50mph mark once I get everything how I want it.
the 2 - 1 ratio would I think give me more top end ,as I think with the prop riding high it will be hitting the rev limiter of 6300 rpm.

hope ive explained it right

.