The great 2 vs 4 stroke debate

[TBone]

I have read the threads in the past, but while trying to put together the perfect package in my head, I started thinking about a scenario that I haven't seen discussed that often.

Seems to me that a guy could get one of the new better technology 2 strokes for a main engine and a 4 stroke for a kicker for less money than a 4 stroke main engine. What are the thoughts on this?

Seems to me like it's the best of both worlds. Better maintenance / dependability by going 2 stroke on the big engine, nice quiet power for trolling out of the kicker. Plus 2 engines are better than one right? :p

I look forward to everyone's 2 cents.
T

[Beave]

As an engineer who spent 6 years of college studying IC engines, the difference is all about emissions. If it weren't for emissions every small boat motor would be a 2-stroke. Better power-to-weight ratio and cheaper to make. Larger inboard engines have been 4-strokes because it was much cheaper for boat makers to modify an automotive engine than specifically design their own engines in the 100 Hp+ range.

It comes down to what you value. Is less pollution and a bigger engine acceptable to you, or do you value weight and cost?

I wouldnt' be shocked to see all sales of 2-strokes outlawed in the next 10 years for environmental reasons. Even used private sales. A small 3hp push lawnmower produces more pollution in the one day a week you mow your lawn than an entire week of driving a full-sized truck.

[TONGA]

yep the EPA is will put a stop to new 2 sroke engines,and then they will probably start giving pollution credits to large industrial co's for destroying the old ones
this is what they do now for old cars,the large companys go find old cars that just sitting anyway then they have them destroyed then they are alowed to make that much more polution because they have taken that old poluting car off the road
but the thing is the cars they are cruching are not being driven anyway so they are not stopping the car from polluting,and then they are alowed to pollute even more!
not only that they are destoying some real clasics that some people would love to restore!!!
I tell you it is just a big scam to let them get away with $#!+!^& on our planet!!!!!!!!!!!

[Swamp Monster]

After 2006, most 2 strokes will no longer be produced due to the EPA regulations. I say most because not all two strokes are alike. Mercury's Optimax and Yamaha's HPDI (High Pressure Direct Injection) are just two examples of low emission two strokes that already meet the 2006 epa standards and are also legal for sale in California. Standard two strokes will soon be phased out. Now, these low emission two strokes aren't cheap but they are worth it. They cost some money to upgrade when buying new, but the money you save in fuel economy and the increase in resale value is more than worth spending the money up front. I think Evinrudes new E Tec motors are also 2 stroke motors that meet the EPA standards. The only advantage the 4 strokes have on these motors is the noise level, and maybe a very slight increase in fuel economy. We won't have to give up our 2 strokes, we'll just have to pay more money for them!

I'm with Tbone on the motor scenario if I were to buy a deep vee. I'd go with the Optimax or HPDI (Both powerheads are built by yamaha) at the boats rated max and then a small 4 stroke Kicker. I'm leaning towards a fibeglass bass rig so I am not even considering a 4 stroke, just the new era 2 strokes.

To give you an idea of the price difference, one of the boat packages I'm considering is $20,000 with a Mercury 150 XR6 (carburated), $22,000 with the 150 EFI, and $26,000 with the 150 Optimax. The Optimax does come with a longer warranty also. Those differences are also reflected in resale value's also.

[riverman]

All I know is when my brother revs up his twin 125 Hondas 4 stokes and we head for the scumline or some wreck 20 mile out in the Gulf, it sure is nice to have a conversation without shouting! They are also a lot easier on the wallet when it comes time to fill the tanks. Riverman

[Joe_G]

This is just my opinion, but I absolutely despise changing oil. And that's only because I usually spill it all over the place. I here that the 4 stroke motors need oil changes. I'll take the low maintenance 2 stroke over that any day...........

[Swamp Monster]

Riverman, you are correct about the noise. It all depends how you use the boat. I know on a bass boat at anywhere from 60 -80 miles per hour, conversation is hardly an option and even with a quiet motor, wind noise would defeat the purpose anyway. And the gas mileage is excellent for sure, much better than the traditional 2 strokes.

[DEERSLAYER]

Beave,

I have to disagree with you. 2-strokes are not likely to be outlawed. In fact, it would not suprise me to see the 4-strokes market share be considerably reduced since the new oil and fuel injected 2-strokes have even better fuel economy and emissions than some 4-strokes. Plus, you have have a weight saving's. I'm waiting for a 25HP model (for my river boat) to come out in a 2-stroke oil and fuel injected model so I can destroy my old "polluter" (if I sell it, it will still be out there polluting for somebody). ...Then again, maybe I will hold onto it for a back-up. Either way, it will not be out there polluting. Right now they have only made their way down to making a 40HP in this type of motor. Maybe next year.


P.S. Also, How dose a 3HP push mower, which is typically a 4-stroke, (like Briggs& Stratton or Tecumchsy) produce more pollution than a full size truck?

[Swamp Monster]

Deerslayer, I don't think your wait will be to long. I know Merc will be soon offering there optimax technology in a 70 and 90 horse so it won't be long. I can imagine it will be one pricey 25 horse but a standard 6 gallon tank should last 2-3 times longer at least. I think Evinrude/Suzuki/Johnson, all built by Bombardier will be first to offer the smaller motors in this technology.

[MadCatter]

I know california has already outlawed 2 strokes on some lakes ... but I don't think it will happen around here anytime soon.. One big factor for me is that there are an awful lot of 40 year old 2 stokes out there still going strong .. I wonder if we can say that about the 4 strokes in 40 years .. Changing oil is a pain ... I know it don't go in the water, but all oil goes some where unless you take it to be recycled... Small hp motors most of the time mean small boats so weight is a factor.. I am not knocking 4 stokes .. just having a hard time giving up the 2 strokes

[Beave]

Originally posted by DEERSLAYER

P.S. Also, How dose a 3HP push mower, which is typically a 4-stroke, (like Briggs& Stratton or Tecumchsy) produce more pollution than a full size truck?

I'm talking about the older ones. One of the things about an old Briggs or Kohler 2-stroke is they'll last forever since they number of hours they get running is typically very low for a motor. Especially the ones used in lawn equipment and boat motors. Same story with snow blowers and old snowmobiles to a lesser extent where the cold starts usually catch up with them a lot faster than lawn equipment.

The older "standard" two strokes that you'll find in most lawn mowers, rototillers, garden tractors, and such produce HUGE amounts more pollution than a similarly sized "modern" 4-stroke. On the magnitude of 50-100X more pollution. Now they have done a lot to improve on this, but the fact remains that the number of old technology 2-strokes out there probably far outnumber the number of us with an old 70's era car in the garage. I can think of at least 6 old 2-strokes in the family pole barn, and one old 4-stroke. Now imagine that in kind of numbers across the nation.

Why do you think on ozone action days the thing they're most concerned with is mowing the lawn? They'll ticket you for it in California now.

[Beave]

BTW: the combination of burned oil and unburned fuel make up the bulk of the pollution from a 2-stroke. Even when you run them "lean" they're really running at a condition where a good portion of the fuel isn't consumed. That turns into particulate as well as contributing to significant amounts of NOx and Sulfides.

[TONGA]

yea but like you said they don't run very often or for very long
so how much pollution dose a lawn mower make that only runs for 1/2 hour a week,,,as much as your car? I don't think so

[Swamp Monster]

These new two strokes are going to rule the market for the most part anyway, and that technology will be put to use in more than just boat engines. The 2 strokes aren't going to disappear anytime soon.

[Freestone]

The vast majority of tillers,mowers etc. have 4- cycle engines on them. Weed trimmers, back pack blowers and some sidewalk edgers typically have 2- strokes. Lawn mower engines have
no emmission controls on them so it wouldn't suprise me if they
polluted that much. Most have carbs and air filters packed with
dirt (due to lack of maintenance). These two things combined
create alot of pollution.

[Beave]

20 years ago you'd have been correct. Since the mid 70's when we really started to crack down on pollution in the US, we've reduced the pollution rate in newer vehicles by a factor of 100. Seriously.

There are still low levels of NOx and Carbon Monoxide, which are the main pollutants, but those are seriously MUCH lower than before. The advent of electronic fuel injection, variable timing, catalytic converters, and better fuels have it to a point where there really isn't much more we can do to reduce pollution levels on a per gallon of gasoline burned level. The only advances now will be made by reducing fuel consumed. As it is now, the main by-products of running your car engine are carbon dioxide and water.

Figure you spend 6 hours in your car each week if you have an "average" commute and run some errands. You drive a medium sized car with a 3 Liter engine. (3L ~ 180 cubic inches). We'll use imaginary units of pollution and assume your car is producing one unit of pollution per cubic inch per hour of use.

Now figure you spend two hours mowing your lawn each week with a 4hp push mower. Those are usually in the 100-125 CC range. We'll conver to approximately 7.5 cubic inches just to make things easy. Now we'll assume your 2-stroke lawn mower produces 100X the pollution per cubic inch of engine displacement.

For the week, you car would produce 1080 imaginary units of pollution. Your lawn mower would produce 1500 units of pollution. Now if you have a big lawn and an older lawn tractor that still runs a 2-stroke you could really be throwing the equation off balance...

One of the reasons that 2-strokes are such a problem is that so few people believe that such a small engine is capable of producing so much pollution. They don't realize how clean our new 4-strokes burn compared to these old 2-strokes. Think about it though... Your 2-stroke boat motor usually leaves a foul smelling cloud of smoke behind it no matter how well you have it tuned. When warmed up you can't even see anything coming out of your car's exhaust.

I'm not saying you shouldn't use a 2-stroke or you should toss your old ones, but the reality is that they're dirty little things that do a horrible job of converting gasoline into engergy. We've used them for so long because they're incredibly compact for the amount of power they produce, but if you look at it on a molecular level a two-stroke engine is producing a whole lot of NOx, particulate, and carbon monoxide.

[TONGA]

I don't know where you work but I put 45,000 miles on my truck last year,,and on a very good day I spend 2 hours going to and from work,,but it,s usually more like 21/2 to 3 hours on the road
thats not including running around town,,
as for the lawn mower it takes me on my worst day 45 minnutes to cut my lawn
so lets see
lawnmower 45 minnutes a week
truck 12 to 18 hours

?

[DEERSLAYER]

Beave,

Seems like a lot of assumtions that you used in you calculations. Without any hard facts (numbers from a given engine or source), how do you know you are not way off? These small lawnmower engines may pollute many times less than you think. I would imagine these little engines have come a way's too. I know their is definately no smoke that I can see coming from my lawnmower when I'm using it.