horsepower, old vs. new

[ssschoeni]

I'm running an old 1966 slickcraft with a 1975 evinrude 115. I am thinking about repowering with a newer engine, possibly with fuel injection as i change elevation a bit.The boat is in really good shape for the age and is a good size for the local lake. I know that the power rating in 1975 was taken in a different way than the propshaft power they rate at now. How much different is it. The boat is rated at 100 but came with the 115. I'm looking at maybe an Evinrude e-tec 90 or a merc optimax 90. Even though the power is rated 25 horse different, should i expect comparable or beter performance?

 

[walleyehed]

Re: horsepower, old vs. new

Comparable would be a good explanation if going with a new 90, maybe a "tad" better performance, but I think you will see that in the mid-range.

 

[ssschoeni]

Re: horsepower, old vs. new

should the 90 still have enough torque for sking like the 115?

 

[Navigator]

Re: horsepower, old vs. new

The change from crankshaft to prop shaft horsepower rating was the equivalent to a 12-15 percent drop in stated horsepower. Each engine is different, 12-15 is about the norm. You old 115 computes out to about 100 +/- horsepower after the spec change. As walleye saig, you performance should be comparable. I'm not sure of the weight of the old versus new, but if the new is lighter, that could make up for the slight horsepower change.<br /><br />Nav