2 stroke vs 4 stroke outboards

[Andrew Leigh]

Hi,

I have done a search on the forum but can't seem to get the answers.

Could someone help me with the relative advantages / disadvantages of each. I was speaking to the boat salesman and he tells me that there is a big lag on pulloff?

I would have thought that the 4 strokes have better fuel efficiency?
Also that four strokes would be quieter as they would be lower revving?
4 strokes also should have a wider torque band?
4 strokes are more expensive as an initial buy but are more expensive to run ober a long period?
You don't need to pre-mix fuel
4 strokes are more environmentally friendly?
I would also think that being lower revving that 4 strokes are longer lasting?

Have I got it wrong? Help

Cheers
Andrew

 

[jimmbo]

Re: 2 stroke vs 4 stroke outboards

pros of 2 strokes
2 strokes will out accellerate the four strokes
the new designs like e-tec and optimax usually have better economy than 4 strokes
same goes for emissions
fewer moving parts to break
very low oil consumption. cost of oil burnt often is equal to, sometimes cheaper than the cost of the prefered 4 stroke oil, oil filter and cost of labour to change oil.
smaller and lighter than comparible 4 strokes

cons of 2 strokes
electronics are getting very complicated

Pros of 4 strokes
I'm thinking....

Cons of 4 strokes
more parts to break or wear
much less get up and go
electronics are getting very complicated
messy to do oil and filter changes, not easy/safe to do unless boat is out of the water
larger and heavier than comparible 2 strokes
Often rev as high or higher than 2 strokes to make power, dragging all the valve train along



there that ought to pi** someone off

 

[Rancherlee]

Re: 2 stroke vs 4 stroke outboards

Depends on which size engines you are talking about. I only have experiance with a 70hp carbed 2 stroke johnson VS. a 70hp 4stroke Johnson on the same boat.

2 stroke

pros
Lighter wieght (though the new DFI are closer to 4 stroke weight then 2 stroke carbed wieght)
Easy maintance

Cons
Sucks gas like there is no tomarrow (New dfi's are on par with 4 strokes)
Still burns oil (though 4 strokes will also if not broken in properly)
Emissions higher than 2 stroke (dfi is pretty clean but don't believe people that say the Etec is WAY cleaner than 4 strokes, if it was as clean as some people I have seen claim then that would have a 4 star sticker on the back)

4 stroke
Pros
Easy starting (EFI, carbed ones are a bit fussy)
Easier pushing a heavy load, getting on plane (in my experiance, the 4 stroke is a bit slower with just one person getting on plane but with 3 people, gear, and a full live well the 4 stroke jumps on plane and runs faster on the top end compared to the 2 stroke)
Low fuel useage 5.5gph WOT Vs. 7.5pgh DFI get good mileage)
I can troll 8 hours on less than 2 gallons of gas

Cons
Heavy
Need to change oil (one a year in the fall for most people, NO biggie)
........... nothing else I can think of

Personally here is how I rate engines from TOP to Bottom

DFI 2 stroke>EFI 4 stroke> Carb 4 stroke>EFI 2 stroke>Carb 2 stroke

 

[studlymandingo]

Re: 2 stroke vs 4 stroke outboards

If you are buying new, go with a DFI 2-stroke. In my opinion a hands-down winner!​

 

[steelespike]

Re: 2 stroke vs 4 stroke outboards

Both the 4 stroke and 2 stroke are quality motors. The problem with the 4 stroke is moving parts.Many many more than the 2 stroke.Lets say you take your car every saturday and sunday and run it full, bore out of the hole and around a track at 5,000 rpm for several hours as you might for a skiing afternoon on the water.I don't think it would be long before major work would be rerquired or at least frequent oil changes and valve train maintenance.
The Etec is approved for all emissions requirements, including California.
My opinion Etec type outboards will be the norm in the future.

 

[Rancherlee]

Re: 2 stroke vs 4 stroke outboards

Both the 4 stroke and 2 stroke are quality motors. The problem with the 4 stroke is moving parts.Many many more than the 2 stroke.Lets say you take your car every saturday and sunday and run it full, bore out of the hole and around a track at 5,000 rpm for several hours as you might for a skiing afternoon on the water.I don't think it would be long before major work would be rerquired or at least frequent oil changes and valve train maintenance.
The Etec is approved for all emissions requirements, including California.
My opinion Etec type outboards will be the norm in the future.

I know of several Gas Car engines that are also used in construction equipment which means full throttle for hours on end and 5000hours is reached easy with no issues (I have a Bobcat skidsteer that has a 1.3L ford engine that has 7000 hours on it and its never been touched except for oil changes and it just started using oil in the last 500 hours). Only difference between the car and industrial engine is usually a 4th oil ring and forged crank .

 

[Bigjohn1]

Re: 2 stroke vs 4 stroke outboards

Andrew - A couple of things to consider. If your salesman is selling/pushing either the E-tec or Optimax, it follows then that he may be emphasizing the downside of 4-strokes. Truth be told, ALL of the DFI 2-strokes and 4-strokes these days are rock solid reliable bar none.

There is some truth to the fact that overall, the 4-strokes are heavier (overall as a technology) and they are not (in general) as strong on the bottom end in the power band. That said, if you need more low-end out of a four stroke, its not really a big deal as you can install an appropriate prop to make up much of the low-end lag relative to a 2-stroke.

Its true that you do have a little more maintenance to perform with a 4-stroke such as 100 hour oil changes, checking timing belts, and checking valve adjustment. If you're operating your boat for the average 100 hours per season though, its not a big deal. What I mean by that is....if you have to change the oil once per year, so what, its a 20-minute job.

If you put hundreds of hours on your engine per year and/or do alot of low speed trolling, the 4-stroke oil changes will be more often so this is a case where you may want to lean toward 2-stroke DFI (E-tec or Optimax).

 

[steelespike]

Re: 2 stroke vs 4 stroke outboards

Most construction equipment is Governed probably to not exceed 3,600 rpm gas and probably 1,000 to 2,000 rpm diesel.And some equipment,welders for instance go back to idle if an ark is not struck for a certain length of time.
Sure the throttle goes to full bore under load but they don't exceed the gouvener speed.Some diesels are 2 stroke.
I never said the a 4 stroke won't run 1,000s of hours.But they do require more expensive maintenance more often especially in marine applications.
There is no doubt a 2 stroke can develope more hp than the same size 4 stroke. Carbed outboards were developing over 1 hp per cubic inch all the way back in 1955 on stock Merc outboards not high performance.By 1961 a number of manufacturers were routinely building stock motors developing signifigantly more than 1 hp per cu. in.
Sure there were a few 4 strokes motors in the 50s developing 1 hp per cu. in. but they were without a doubt not stock and most difficult to maintain and prone to breaking pretty easily.

 

[byacey]

Re: 2 stroke vs 4 stroke outboards

4 stroke sink to the bottom faster if they fall off the transom...

 

[deejaycee_2000]

Re: 2 stroke vs 4 stroke outboards

4 stroke sink to the bottom faster if they fall off the transom...

hahahaha, and it is also easier to swim with a 2-stroke under the arm when it fell off the transom ........

 

[kenmyfam]

Re: 2 stroke vs 4 stroke outboards

4 stroke sink to the bottom faster if they fall off the transom...

Good One.
I have no experience of a 4 stroke outboard, but if someone would like to send me one to "test" then I will give an unbiased opinion !! LOL

 

[John_S]

Re: 2 stroke vs 4 stroke outboards

It is a fishing tradition, the smell of a 2-stroke in the morning. I'll keep my ole carbed 2 strokes as long as I can. Someday, I'll probably have to convert, but it is not today!

 

[jimmbo]

Re: 2 stroke vs 4 stroke outboards

Ahh, the aroma of the burnt oil from a 2 stroke after a boat has cruised past. That brings back memories

 

[byacey]

Re: 2 stroke vs 4 stroke outboards

Ahh, the aroma of the burnt oil from a 2 stroke after a boat has cruised past. That brings back memories

It sure beats the fresh smell of diesel exhaust first thing in the morning with an empty stomach; enough to just make one wretch the guts out.

 

[kenmyfam]

Re: 2 stroke vs 4 stroke outboards

It is a fishing tradition, the smell of a 2-stroke in the morning. I'll keep my ole carbed 2 strokes as long as I can. Someday, I'll probably have to convert, but it is not today!

Yes , the delightful fragrance of a freshly started 2 stroke outboard in the morning is like your boats cologne !!! You would sure miss it if it was not there.

 

[JB]

Re: 2 stroke vs 4 stroke outboards

Well, in spite of the bashing scare tactics of BRP about 4 stroke engines there is no evidence that any of that carp is valid.

I have used an Optimax (not mine) a Ficht (not mine either), more carbed 2 strokes than I can count and 2 different 4 strokes. I have not used an E-tec.

My Suzuki DF70 EFI 4 stroke was hands down the best outboard I have ever used.

I will not buy a Brunswick product because of their monopolistic marketing policies and I will not buy a BRP product because of their misleading 4 stroke bashing advertising (even when they were still selling 4 strokes!). That pretty much leaves HondYamhaHatsuZuki. All fine engines that will last a loooooong time.

Differences in price, weight, emissions, performance, reliability and economy are trivial and well blown out of proportion by the sales people. In the real world they don't matter as much as user friendliness.

 

[studlymandingo]

Re: 2 stroke vs 4 stroke outboards

I know of several Gas Car engines that are also used in construction equipment which means full throttle for hours on end and 5000hours is reached easy with no issues (I have a Bobcat skidsteer that has a 1.3L ford engine that has 7000 hours on it and its never been touched except for oil changes and it just started using oil in the last 500 hours). Only difference between the car and industrial engine is usually a 4th oil ring and forged crank .

Don't forget forged industrial sleeves in the cylinders.​

 

[jimmbo]

Re: 2 stroke vs 4 stroke outboards

It sure beats the fresh smell of diesel exhaust first thing in the morning with an empty stomach; enough to just make one wretch the guts out.

An overflowing outhouse beats the smell of diesel exhaust.

 

[Rancherlee]

Re: 2 stroke vs 4 stroke outboards

Don't forget forged industrial sleeves in the cylinders.​

ya, the ones with sleeves for 20,000+ hours (diesel) I've never worked on a industrial gas engine with sleeves. My truck at work (Komatsu 730E 200ton haul truck) just went in for its first rebuild at 38,000 hours.

 

[croSSed]

Re: 2 stroke vs 4 stroke outboards

The only reason 4-stroke outboards exist is because of tightening EPA restrictions. The 2-stoke engine is perfectly suited to the marine environment as an outboard: Lots of power in a compact, light-weight package, with ease of maintenence thrown in. Outboard manufacturers had to come up with a new paradigm because of the emissions regulations to get a 4-stroke motor to fit a small package, and make comparable h.p. to a 2-stroke of the same displacement. The super clean 2-stroke technologies came later. I'm all for 2-stroke outboard motors.

Re. BRP's "4-stroke scare tactics", keep in mind that for their product to compete, they had to get the message out that 2-stroke engines CAN be clean. By the time BRP came out with their big ETEC engines, it had been planted firmly in the minds of the general public - by the manufacturers of 4-stroke outboards, mind you - that 2-strokes were "dirty". I don't fault BRP AT ALL for their marketing; it was in RESPONSE to Suzuki's/Yamaha's/etc. (and even their own marketing of their 4-stroke outboards) to obtain a piece of the market share. They HAD to show that 2-strokes can be made to, not only run AS clean as a 4-stroke, but even CLEANER, and be easier to maintain.

Re. Brunswick's "monopolization" - This is the only American company in JB's list. I'll go with an American product first, all things being equal, thank you.

The only 4-stroke outboard I would buy would be a kicker/trolling motor. At idle speeds little 4-strokers can't be beat - very quiet, virtually no exhaust fumes.

Go with a 2-stroke.
There's my 2 cents.

TG