2 stroke vs. 4 stroke

[rangerbassman]

I was looking at some new 15hp motors. The salesman said the 4 stroke was not as fast in an empty boat but just as fast or faster with a loaded down boat, 14' jon boat with 2 or 3 people in it. Any truth to that?

 

[ob]

Re: 2 stroke vs. 4 stroke

Probably get more replies in the outboard non repair forums rangerbassman.

 

[phatmanmike]

Re: 2 stroke vs. 4 stroke

he is gonna tell you whatever you want to hear, or whatever youll hear thatll get him more commision.<br /><br />he is a salesman.

 

[JB]

Re: 2 stroke vs. 4 stroke

Gone to Outboard Non-repair

 

[Silvertip]

Re: 2 stroke vs. 4 stroke

Put the same diameter and pitch prop on both engines, and provided they have the same lower unit gear ration and WOT rpm are the same the boats will have the same speed. Variables would obviously be the gear ratio. But a 1.85:1 would need to run less pitch than a motor with a 2.33:1 for example. WOT RPM is another variable. Go to Yamaha or Alumacraft web sites and click on Performance Tests. Alumacraft uses various engines for testing and you will see that two strokes typically outperform equivalent four-strokes on any size boat although in some cases they are quite close.

 

[MajBach]

Re: 2 stroke vs. 4 stroke

The salesman doesn't know what he's talking about. That's why he's a salesman.

 

[marinemech1]

Re: 2 stroke vs. 4 stroke

salesman lied 4 stroke outboards should be banned they suck

 

[WillyBWright]

Re: 2 stroke vs. 4 stroke

It's the power curve. 2-strokes keep getting stronger as RPMs rise. 4-strokes reach a plateau and level off. Conversely, 4-strokes are stronger at lower RPMs than 2-strokes. So if you can plane it, the 2-stroke will do better. If not, the 4-stroke will do better.

 

[JRJ]

Re: 2 stroke vs. 4 stroke

The 2-stroke will probably stink

 

[MajBach]

Re: 2 stroke vs. 4 stroke

LOL! <br />Care to rephrase, Willy?

 

[CFronzek]

Re: 2 stroke vs. 4 stroke

Oh, Willy!<br />If motors are of the same displacement the 2-stoke will make more torque. Why? Because it fires twice as often as the 4-stroke. <br />If you want maximum HP it's 2 strokes again. Why? Because the ports on a 2-stroke are far bigger and flow more air/fuel than you would ever get with a comparable 4-stroke. Flow thru' a 2-stroke is so good that raw fuel slops out the exhaust port before it's burned. That's why 2-stroke are so dirty. <br />And 2-strokes do all this with only about ¼ of the moving parts of it's competition. <br />4-strokes are just dandy when they are brand new. But, overhauling one that's 35 years old, like we do with old 2-strokes, will depend on how big your bank account is.