2 stroke versus 4 stroke

[2004 Voyager]

This is really more of a historical question rather than present day. Seems most of outboard motors from early times to recent were all 2 stroke. Was 2 stroke more reliable, maybe lighter, less complicated? We know they were not cleaner burning, or quieter, that's for sure! Modern 4 stroke are fuel efficient, quiet, reliable, maybe a little heavier than their 2 stroke counterparts I believe, maybe more expensive also? Just curious what others out there might know (or believe)!

 

[glenn property of pam]

Re: 2 stroke versus 4 stroke

theres a lot of reasons

weight
combustions per cycle (2 cylinders 2 strokes have the same combustion's per revolution as a 4 cylinder 4 stroke)
old 4 strokes were still flatheads
lubricating a 4 stroke is a major design headache on a vertical motor
the list goes on and on.

 

[GA_Boater]

Re: 2 stroke versus 4 stroke

EPA or environmental concerns - It's really that simple, in my opinion. 2 strokes have the smoky image to overcome, even though there are modern 2 strokes that are as clean or cleaner than 4 strokes.

 

[Peter Eikenberry]

Re: 2 stroke versus 4 stroke

2 strokes were lighter, more HP per pound, higher revving and simple construction. No valves, no complex parts. But they were cranky and had to be carefully maintained. They spewed oil into the environment and were loud.

That's how they were. Contrary to popular belief Mercury, Evinrude, Nissan and Yamaha still make 2 strokes (as well as 4 strokes) But they are nothing like the old 2 strokes. They are far quieter, more fuel efficient, do not pollute (they meet all EPA and CARB requirement) and lighter than 4-strokes. They are much more reliable. But they are more complex than they used to be. Everything is computer controlled, the fuel systems are High Pressure Direct Injection which is far more complex than the old carburetors, but much more efficient.

Anyway, there are good reviews of this at Two-stroke versus four-stroke outboard motors and 4-Stroke Outboard Motor vs 2-Stroke Outboards

By the way, just this week I bought a Merc 4 HP (it's a four stroke) and the man who sold it to me said no one makes 2 strokes any more. I didn't set him straight. But if you believe it then check out their web sites.

Outboard Engines | Mercury Marine The Opti-max are 2 strokes
Two Stroke HPDI? | Yamaha Outboards The HPDI are two strokes
Nissan Marine Outboards - Authorized Distributor Offering Boat Motor Products, Technical Information, & Dealer Locations for the U.S. & Canada." The TLDI are 2 strokes.
Evinrude Outboards: Evinrude Johnson Outboard Engines | BRP USA E-TEC 2 strokes

 

[Texasmark]

Re: 2 stroke versus 4 stroke

Merc Optimax is in production and a 2 stroke fuel injected 150 for one. Agree with all the comments above. Only 4 stroke I know of in the old days was built by Homelite, the chain saw company....who built 2 stroke chain saws. It was 4 cyl 55 hp. Rumor has it that it used the engine from the Crosley automobile...friend had one of those, a station wagon; one of the first compact cars here. Later on they changed the name, sold out or whatever to Bearcat and hp went up to 85. Don't know what engine that was.

A friend had a 55 on a 15' glass semi-V of the day which were easy to plane and light and it was a real nice combination. Power was adequate and engine was real quiet and smooth.

Mark

 

[Peter Eikenberry]

Re: 2 stroke versus 4 stroke

Crosley automobile...friend had one of those

Same here. It was so unreliable and prone to rust that he tore it down to the frame and made a trailer out of it. Don't remember what he did with the engine.

 

[Dave1027]

Re: 2 stroke versus 4 stroke

My 25 year old 2 stroke is like a hot rod out on the water. I don't think an equivalent 4 stroke has the grunt to haul my butt out of the water on a slalom ski.

 

[Jim Cash]

Re: 2 stroke versus 4 stroke

The Evinrude 15hp 2 stroke is/was a very powerful 2 stroke motor and to this day will outrun 4 strokes as large as 20hp. I personally know that they can take three 200lb men up on plane in a 16' aluminum boat! Unlike 4 strokes they fire every revolution and can rev up quickly and much lighter. 2 stroke technology is advancing rapidly again and we should see even small 2 strokes in abundance soon. I am an ex Yamaha Dealer and believe me there is no 4 stroke dirt racer motorcycle ever been built that will out perform a CR500 Honda 2 stroke!
Depends on what you are using the motor for to determine which type of motor for you to choose!

Anyone who has been on iBoats forums for many years: I am RA Chief!

Chief, AMA #6 Arizona M/X

 

[2004 Voyager]

Re: 2 stroke versus 4 stroke

Thanks for the interest/replies everyone. Not really biased one way or the other, bur most outboards have been 2 strokes forever! Must be some reason for this preference, seems it must be of a mechanical nature, nothing else would have led it in this direction otherwise.

 

[wired247]

Re: 2 stroke versus 4 stroke

Thanks for the interest/replies everyone. Not really biased one way or the other, bur most outboards have been 2 strokes forever! Must be some reason for this preference, seems it must be of a mechanical nature, nothing else would have led it in this direction otherwise.

They are cheaper to build and they run at high rpms for long periods without self destructing. They get relatively decent gas mileage and can build high levels of power in a compact and lightweight package compared to what you'd find in a 4 stroke. You can build a 4 cycle package that will do what 2 cycle will . It will just be more complicated , heavier and it will cost more.