The backward EVO of small outboards

[MOTION LINE]

I have been thinking, how is it possible that my 5,5 hp. Johnson from 1957 runs much nicer (like a ROLEX) than any of the modern outboards today, even my friends 6 hp. Johnson from 79 which is basicly the same engine runs much rougher.<br />How can it be? Is it so that the smart engineers have left the business to more profitable jobs or what? And another question about the weight;<br />If you build outboards for 40 years wouldn´t it be natural to shave some weight especially with the newer technology?

 

[Silvertip]

Re: The backward EVO of small outboards

Engine design and casting techniques have resulted in weight savings however technology is added on so its added weight. ECM's fuel injectors, air pumps, electric pumps, superchargers, added sensors all add significant weight. As for running quality, I'll take a new engine thank you.

 

[JB]

Re: The backward EVO of small outboards

Some of it is state-of-tune, Bolaget. Engines running at a low state-of-tune simply are smoother at low speeds.<br /><br />Boost hp/cu.in. by altering port timing and ignition timing, raising compression ratios, enlarging the mixture flow path and you get a less smooth engine at low speed, where it is most noticable.<br /><br />The mass of the assembly can also affect how smooth the engine seems to be, because it will vibrate less than a lighter engine with the same state-of-tune.<br /><br />Your CD-14 Johnny is one of the two best small outboards ever built, by anyone. Count your blessings.

 

[Chinewalker]

Re: The backward EVO of small outboards

There have been some weight savings, but it's been measured in ounces, not pounds. Fiberglass hoods replaced cast aluminum hoods. Plastic knobs replaced aluminum ones. Small spiral recoils replaced larger full top recoils.<br /><br />There's really only so far you can go and still maintain reliability and power. Some of the lighter weight motors tend to not be able to take the abuse of similarly powered but more substantially built motors. You can make castings thinner, but then they're not as strong. If you make it out of a more exotic and stronger material, cost goes up. Or, in the case of some plastic knobs and linkages, they often have a less than admirable longevity record.<br /><br />As for running quality, a lot of that has to do with the motor itself, not the design. You're comparing a 50-year old motor with a 25-year old motor of similar design. Maybe the 50-year old motor has been better taken care of than the "newer" one. Maybe the '79 is due for a tune-up. I know I've worked on quite a few motors from the 1970s and 1980s that ran absolutely beautifully when they were done. Can't really say they ran "better" or "worse" than an older motor.<br /><br />- Scott

 

[R.Johnson]

Re: The backward EVO of small outboards

Most newer engine's pick up there weight from a much heavier mounting, exhaust housing, and gearcase assembly. The older engine's were lighter in this respect, but they could not stand much impact damage, and on a boat, this is a very likely occurance. The older small engine's had both a high, and low speed needle valve in the carb, you could adjust this for the running condition. Nobody want's too, or has too, do this today. Like every thing, It's a trade-off. The engine is basically the same, just engineered for the common sense impaired.

 

[BoatBuoy]

Re: The backward EVO of small outboards

Originally posted by Bolaget:<br />If you build outboards for 40 years wouldn´t it be natural to shave some weight especially with the newer technology?

That's absolutely correct if you build them the same way. My '56 30hp weighs 128 lbs. My '77 35hp is 11 lb. lighter. Essentially the same engine. Then comes the emission issue. Add lots of doo-dads like Upinsmoke says and the weight goes up.

 

[R.Johnson]

Re: The backward EVO of small outboards

BoatBuoy: A mid 90's 40 hp. is a 190 #. Would that be alot for a 5 HP gain?

 

[BoatBuoy]

Re: The backward EVO of small outboards

And current Evinrude takes 40hp to a new level at 240 lb. Course it's an E-TEC which is a lot different, but still 2-stroke.

 

[rodbolt]

Re: The backward EVO of small outboards

give us both the same hull and weight and 6 gallons of gas and lets see if the mid sixties 40 will run as far as fast as a mid 90's 40.<br /> I have an old 33 twin, runs my 14 ft jonboat well, drinks fuel like its still 15 cents a gallon. the 85 35 is just as fast and sips fuel in comparison.<br /> its a difference in design.

 

[MOTION LINE]

Re: The backward EVO of small outboards

The difference between the 2 old motors interested me so much that I asked my fried if I could rebuild his engine and at the same time compare it to the older, Indeed the older has a heavier flywheel lighter conrods and seems like even the compression is lower some bearings have improved during the years(probably tho get it running on less oil?). The older bearing are of a different type and also contributes to the nice running. My conclusion low compression moderate timing, heavy flywheel, small carb and you got a nice running motor. I thing I will give my favorite the old 5,5 a paintjob so it will look like right from the box.