Give your opinions on attached 2 vs. 4 stroke article

[Frank Martin]

Re: Give your opinions on attached 2 vs. 4 stroke article

Ralf wow what a earfull .all this but what about the consumer ? why are they jumping on the 4 stroke band wagon ? well i have been a diesiel machienist for 27.5 years in the steel industry every sumer i would get laid off well because of my own personel love of fishing boats i would work for a old man with a johnson shop after 17 years he sold me the shop have been omc master tech since 1986 been burning the candle at both ends seen alot of things in the mill and in the boat shop , but when i first heard a fitch motor run in the test tank in waukeegan years ago it had a not so funny knock when acelerating from idle i told the instructor that noise was not good he agreed and said they where working on it i told him then that the root cause needed to be adresed they didnt want to listen to me or the obviusly frustrated instructor . i have changed many fitch powerheads since then . everone of these people i canot blame for jumping on the 4 stoke band wagon . the honda v6 has been in the cars and the minivans since 1991 . these people also have good reason to be on the 4 stroke band wagon . the big dealers will have very little trouble seling the new quota of 16 motors from bomb./ johny/rude there new mechanics will now be trained from a interactive cd rom ,there customers who have to have there motors worked on by cd rom mechanics i fear will also have good reason to jump on the 4 stroke band wagon .bomb wants to make the DETICATED dealers more profitable by tacking the small frachises away giving more area to the big dealers more area the real question is what are they bomb / big dealers realy deditcated to when the responce on the dealer tech line is we will not be suporting any product built before 2000 the ones that need the help the most these people are not asking for free help just help . another reason to jump on the 4 stroke band wagon . i have seen alot of big dealers come and go the little guys just hang in there by tacking care of there customers well the little guys made the motor manufacturers big guys now they all want to be harley like companys well when i see pictures of two stroke outboard motors tatooed on some ones arm and a groop of customers all wearing the same color leather jackets then they can be like harley dealers ,until then when my districk sales manager comes in and says i have to paint and put in new floor tile sell 16 motors i will have to jump on the four stroke band wagon too . get real the customer that has fun on the water DRIVES OUR BUISNESS NOT THE WIEGHT OR TECHNOLOGY

 

[rwise]

Re: Give your opinions on attached 2 vs. 4 stroke article

FlyBoyMark<br />You got it!<br />Richard

 

[Forktail]

Re: Give your opinions on attached 2 vs. 4 stroke article

Well, not really rwise. FBM is missing much of the other side. <br /><br />First, almost all 2-strokes will have a "tuned" exhaust. But this is very inefficient. "Tuned" exhaust systems are tuned for maximum power at only one particular rpm value, usually where max hp occurs. The 2-stroke engine isn't really operating effectively throughout the rest of the rpm range. It's merely a compromise.<br /><br />2-strokes actually use the resonance of the exhaust gasses escaping to produce additional power. It is a complex type of backpressure. It's extremely important.<br /><br />The only true way a 2-stroke can capitalize on efficiency, is by using a variable exhaust system (not a tuned exhaust system). A variable exhaust automatically changes the dimension of the exhaust outlet in order to match rpm resonance and backpressure. At low rpm the exhaust chamber is slightly closed, and at high rpm or WOT the exhaust chamber is fully open. This maximizes efficiency throughout the entire rpm range. Bombardier has used variable exhaust technology on Ski-doo's and Sea-doo's since the mid '80's. Now others are using it too. For some reason it hasn't reached outboards. I assume its difficult to find a place to put it on an outboard.<br /><br />Regardless, 4-strokes don't need this variable exhaust. They have mechanical exhaust valves. And without a variable exhaust, 2-strokes miss out on maximizing efficiency at low and midrange rpm. This leads me to my second point ....<br /><br />A comment was made that 2-strokes produce more power and torque than a similar 4-stroke. This is an ambiguous view. A view that probably is only assumed at one particular rpm stage. Of course engine design is a major factor here. For example an inline 4 cylinder will have different performance characteristics than a V-4 design. But aside from that, the inherent design of the 2-stroke doesn't allow it to make good low end, midrange, and high end power all in one package. It's the exhaust/intake and fuel scavaging thing again. So when looking at torque and horsepower, one must look at the entire rpm range, and the entire power curve. The area under the rpm/torque/power curve will be the work done. And the 4-stroke outboard will have more area, produce more work, and be more efficient. This is why we all drive 4-stroke automobiles instead of 2-strokes. On a bass boat in a fishing tourney give me a light-weight 2-stroke that I can run WOT from point A to B. But in a fishing boat where I'm busting waves and riding swells, I'll take the grunt of the 4-stroke and awesome power throughout the rpm range.<br /><br />FlyBoyMark mentioned the 2- stroke Detroit Diesels as an example. I assume these are the Detroit series 53, 71, 92, and 149. Although these engines had an oil sump and pressurized lubrication system, they did not have direct fuel injection. These engines are history....no longer made. The reason according to Detroit? Because the 4-stroke offered lower fuel consumption, reduced emissions, and better performance. These engines were high revving, short-lived, and had peaky power. They simply wouldn't work in a dozer, because they wouldn't lug. They certainly couldn't keep up with the 4-stroke diesel technology of today.<br /><br />The camless engines are already here. International/Navistar has a 530 that has already made several coast to coast test runs. It's scheduled for consumer production within a couple of years. The engine works. Hydraulic-electronic valves work. We're only going to see more of this.<br /><br />FBM's comments about using oars and sails is off. Where I live we have 30 foot tides and huge rivers that run 20 mph. Navigation can only be done safely with power. Lead in batteries is recycled these days. So is crankcase oil. But the oil expelled into the water and air from a 2-stroke will always be a problem. Ever wonder where all that injection oil goes? It's an inherent design issue with a 2-stroke. Implying that a 4-stroke is less environmentally friendly than a 2-stroke is wrong.<br /><br />You find older long lived 2-stroke motors, because that's what there was back then. I don't think a 4-stroke was introduced until the late 70's early 80's. If 4-stroke outboards were used in the 50's, you'd find them too...just like thousands of original automobiles still running. Again, the lubrication system of a 2-stroke outboard does not lend itself to a longer life than a pressurized oil sump 4-stroke system. Period. <br /><br />And since when is "cost and weight" the "purpose" of an outboard? Not for me. I find the purpose is the fact that the outdrive and the engine are one unit (no outdrive to mess with). The entire unit can be lifted (tilted) out of the water when not used. No bellows to breach. Trim is built in. Interchangability and upgrades are easy. You can maintain and work on the engine standing up rather than on your belly. No engine covers to trip over while fishing. No flame arresters, engine hold explosions, and blowers. Etc, etc.<br /><br />I love 2-strokes and own many. They have some great technology going on. But I will never buy another one for my boats. Not with the 4-stroke technology available. My snowmobile?....give me a 2-stoke please. Weight is an issue here.<br /><br />

 

[clanton]

Re: Give your opinions on attached 2 vs. 4 stroke article

The Detroit injects fuel directly into the cylinder, how could it not be a direct injected engine, fires the fuel from the heat of compression.

 

[JS2]

Re: Give your opinions on attached 2 vs. 4 stroke article

To say that a 2 stroke O/B will not last as long as a 4 stroke O/B is incorrect. A 4 stroke engine has far more moving INTERNAL components to break, wear out, etc. A FICHT engine is still less complicated than a 4 stroke. A 2 stroke engine is much less costly to rebuild. As for pollution, where does the exhaust residue from a 4 stroke O/B end up? Where do you "dispose of" the used motor oil? What happens when a 4 stroke O/B starts leaking motor oil into the water (just like auto engines leak oil)?

 

[RJS]

Re: Give your opinions on attached 2 vs. 4 stroke article

Enough already, let's compromise and split the difference..........3 strokes rule!!!!!!!!!!!

 

[RJS]

Re: Give your opinions on attached 2 vs. 4 stroke article

Forktail.<br />all kidding aside, your post are probably the most thoughtful and insightful posts that I have read. Area under the curve = work. I take it your an engineer or scientist.

 

[JS2]

Re: Give your opinions on attached 2 vs. 4 stroke article

Why don't we all buy electric O/Bs? We can really have some fun with those enviro-nazis when it comes time to dispose of all those big rechargeable batteries.

 

[Forktail]

Re: Give your opinions on attached 2 vs. 4 stroke article

Good point clanton. I didn't mean to say the Detroit isn't direct injected, only that it is not direct injected with technology similar to the current 2-stroke outboards that we were comparing. The 2-stroke Detroits used conventional direct injection by means of injection pumps and lower injection pressures. New 2-stroke technology uses piezo-electric or high pressure direct injection. Conventional direct injection pressures rarely exceeded 200 psi. New technologies in outboards pressurize the injection process 4 times that. This is what's equating to better emission, economy, and power....better fuel atomization.<br /><br />JS2, the number of moving parts has nothing to do with when an engine wears out. An engine with only two moving parts can wear out instantly if lubrication is inadequate. A 4-stroke engine is designed to pump oil throughout the valve train. And a "complicated" engine doesn't necessarily wear out sooner either. Take your FICHT example. You say it's a simpler engine design. Do you think there has been more failures of FICHT outboards or similar 4-strokes?<br /><br />There are engine failures due to "wearing out" and then there are failures related to other problems like gaskets, maintenance, gears, etc. But "wearing out" an engine usually means rings and bearings. And there is no way a 2-stroke's rings and bearings will outlive a 4-stroke. The inherent oil lubrication system in the 2-stroke doesn't allow it.<br /><br />I'll give you credit that a 2-stroke is cheaper to rebuild. But I will add that they will need to be rebuilt more often. Call Yamaha and ask them for "hours to rebuild" on their 2-stroke vs. 4-stroke outboards. You'll be surprised.<br /><br />I'm not buying the pollution argument though . Yes, maybe our exhaust residue ends up in the same place, but 2-stroke exhaust residue contains oil (mostly burned but some unburned). The 4-stroke does not. Yamaha recommends I change my 4-stroke oil every 100 hours. My high-power 115 takes a little more than a gallon when I change it. I bring the old oil to the recycle center. How much injection oil will a 2-stroke use in 100 hours? Way more than a gallon. Even at a low 5 gal per hour fuel consumption, after 100 hours you would burn 500 gallons of gas. At a common 50:1 oil ratio, you would use 10 gallons of injection oil.....never to be seen again.....gone to the water and air.....only to be recycled by mother nature in 10 million years. And if my 4-stroke is leaking oil into the water, it needs a repair.<br /><br />I do love the 2-strokes. I do love the 4-strokes. Both have their place and disadvantages/advantages.<br /><br />Good idea on the 3-strokes RJS!

 

[rwise]

Re: Give your opinions on attached 2 vs. 4 stroke article

Forktail<br />You are right, I just did not want to argue with FBM. It would use up all my reading time!<br /><br />Richard

 

[JS2]

Re: Give your opinions on attached 2 vs. 4 stroke article

The complexity of an engine has no bearing on it's life? That's a new one for me. Then why don't Formula 1 car engines go the entire race season with little or no maintenance? Just because something is supposedly designed "right" doesn't mean much in terms of long term durability. As a former owner of a Honda lemon auto, I can speak to that firsthand.<br /><br />Why don't you ask your Yamaha dealer the cost of a 2 stroke vs. 4 stroke powerhead rebuild? Check out the latest issue of "Powerboat Reports". The Honda 225 4 stroke is an interference engine. That means when your timing belt (instead of more durable chain) snaps, your engine is toast. 2 strokes don't have to worry about this. Nor do 2 strokes have to worry about valve adjustments, oil pump failures, cam wear, etc.<br /><br />If 2 strokes have such a short lifespan, why are there so many 20+ year old versions still running around the Great Lakes?<br /><br />Maybe you can explain why a 2-stroke powered snowmobile won the emissions portion of the Society of Automotive Engineers clean snowmobile contest? That's right - a 2-stroke engine had lower emissions than any of the 4 strokes.

 

[Forktail]

Re: Give your opinions on attached 2 vs. 4 stroke article

Sure JS2, I'll answer your questions the best I can. But I didn't really want this to become a debate, or pull off subject which would distract from the kudos that the 2-stroke technology deserves.<br /><br />But lets please be honest....<br /><br />The Clean Snowmobile Contest was won by a 4-stroke engine....again. In fact, it was a tie between multiple 4-strokes. The University of Idaho and Kettering University tied for 1st place. There were about 20 categories for this contest. "Best emissions" was only one of them. The 2-stroke did win this category...very respectable. But unfortunately the 2- stroke that won the "emissions" category scored zero (0) in fuel economy, 0 in noise, 0 in accelleration, and was not eligible for best performance points, best design points, best fuel economy pionts, quietest points, and only scored a measly 2 points in the hill climb. It also took 25 points in penalties. Obviously the 2-stoke was designed to win only the emissions category, which sacraficed the overall, and combined functions, required of a real world snowmobile.<br /><br />One thing to remember is that the 4-strokes that were beat out on the emissions category were of much bigger displacement, and designed to win the overall contest. Bigger displacement generally means more air and fuel towards emissions. Idaho used a 659 cc Yamaha/Daihatsu turbocharged EFI 4-stroke. Kettering used a 750 cc Arctic Cat/BMW EFI. The 2-stroke "emissions" winner used a 594 cc Suzuki with direct injection and a catalyst (catalytic converter).<br /><br />Had the 2-stroke combined all aspects of the contest rather than just emissions, it may have won. Maybe some day soon I hope. It certainly has the potential to win.<br /><br />Formula 1 car engines can hardly be compared to outboard engines, or the complexity and durability of most engines for that matter. It's a bad example JS2. Here's why....<br /><br />Formula 1's use pneumatic operated exhaust valves. This is extremely high pressure air used to close the valves. Opening of the valves is still done by a cam. The extreme high rpm of a Formula 1 engine exceeds the physicall properties of mechanical valve springs (they don't return fast enough). We're talking about 12,000 rpm here, not the 5-6000 that your outboard makes. Keep in mind that these are 10 cylinder engines and only about 3 liters in displacement. They produce 3 times the hp similar displacement outboards produce. They have very little torque, lots of rpm, and small crankshafts. They run on different fuel and cost hundreds of thousands of dollars to manufacture.<br /><br />You may want to pose your question to the Formula 1 outboard racing engines (boats). 325 hp in 2 liter 2-strokes. 10,000 rpm. 0-60 mph in under 2 seconds. Talk about high maintenance!<br /><br />As a more realistic engine example, I have a Subaru that is nearing the 250,000 mile mark on the original 4-stroke engine. It redlines at half the rpm a 2-stroke would, so chances are a similarily built 2-stroke would wear out the rings and moving parts twice as fast, especially given 2-stroke lubrication methods. Sorry to hear about your Honda. <br /><br />JS2, I already agreed with you about the cost of rebuilding a 2-stroke vs. a 4-stroke. Yamaha agrees with you too, but they also agree that the 2-stroke will need more frequent rebuilds. Twice the rpm and no pressurized lubrication system equates to faster wear. I'm not aware of timing belts being an engine failure issue. It's surely not a common occurrence. Injection oil pump failures are more common than 4-stroke sump pump problems. How about sucking one of those broken intake reed pedals into the cylinder? The 2-stroke has more to worry about than moving parts. Like fuel scavenging, critical air/fuel mixtures, and consistant exhaust resonence. The durability of 4-stokes is proven. Lets not forget that most million mile diesels are 4-strokes. <br /><br />By the way, did you know that Yanmar makes a 27 and 36 hp direct injection diesel outboard? I didn't!<br /><br />Again, you see older 2-strokes running around because that's all there was back then. 4-stroke technology in outboards is relatively new.<br /><br />Maybe you can explain why my 2-stroke Yamaha's come with 2-year warranties and the 4-strokes come with 3-year warranties? Warranties deal with repairs and durablility, don't they?<br /><br />I love 2-strokes. But don't knock the 4-stroke on a boat until you've tried one.<br /><br />It's been fun guys.

 

[evin300]

Re: Give your opinions on attached 2 vs. 4 stroke article

Oh gee, I must add this. Are the four strokes using roller bearings yet? For each and every moving part? Will you ever achieve 250,000 miles in AUTO engine if you are climbing a hill for each and every mile? Thats what a MARINE engine has to do. Please do not compare cars to boats, there is NO comparison. <br /><br />Listen to a Inboard 4-Stroke or Outboard 2-Stroke next time you are on the water. What you will hear is the sound of an engine that is working very hard, almost all of the time. Now listen to your car engine on flat roadway, now go climb a steep long hill, the noise will be very familiar to what you hear on the water.<br /><br />Now, I do believe that 4-Stroke I&O's were very popular 20 years ago, doesnt it seem kinda funny that we dont see many on this board from that era?<br /><br />Just more food for thought.

 

[ODDD1]

Re: Give your opinions on attached 2 vs. 4 stroke article

Ya know, I have to stick my nose in this longevity issue..the less moving parts vs. a closed lube system can be beat all day with no clear winner..conditions of use always favor one or the other.....the one thing I do see that I have to throw on the table is the fact that most outboards dont wear out...something always gets them in the first ten or twelve years....bad gas, forgotten oil, submersion, corroision, and dont forget plain old neglect...idiot proof for these conditions and we can talk about durability....

 

[FlyBoyMark]

Re: Give your opinions on attached 2 vs. 4 stroke article

Like I said...Outboards were originaly for low cost and low weght but that is not the case at all anymore....A nice stern drive unit is less...If you use a cost of living index calculator the smaller 2 cycle outboards are rite on in price today(discounted). But as a comparison the 4 cycles are not. But then again they did not really exist 25 years ago. The larger outboards did not exist 25 to 30 years ago so its hard to estimate if their cost is justifiable. I do know that I can put together a 3.4 liter 350 HP aluminum engine(200 lbs) thats reliable for about $5,000.00 + outdrive. In view of the cost of living index and the prices of engines being rite on I have to disagree with part of the index value. The engines today are also produced in greater numbers and with less labor and use less parts in some cases. I would think that they should actually be cheaper than they are priced now. I own a KIA Rio automobile that cost me 9 grand LOADED......How do we arrive at a 150 Hp outboard that cost $10,000.00?<br /> 2 cycle, 4 cycle, shmoore cycle...........they are all ok and very good engines, jus' too expensive for what your getting.......I jus' bought a Merc 40 HP 3 cylinder short shaft last year, cost me $2,500.00 new in box @ Outdoor World (BassPro Shops). If I buy this motor in a 4 cyle it would cost me$4,000.00. They also sell Mako 15' flats boats here for $18,000.00 with a 40 HP on it!!! Ok, so the motor cost $2,500.00 and the trailer cost $500.00, rigging ;$1,000.00(and thats high!) $14,000.00 for 15' plain jane flats boat with no options??????????? Again...I thnk the boating industry pricing is getting out of hand and the consumers jus' go along without questioning............<br />By the way they have jus' cut the price to $16,000.00 then to $14,000.00 and they are still not selling...........

 

[Forktail]

Re: Give your opinions on attached 2 vs. 4 stroke article

Good point ODD1. Many outboards out live operator error or the life of the boat itself.<br /><br />Evin300, 2-stroke and 4-stroke crank bearings are much different. <br /><br />The 4-stroke allows pressurized oil from the sump pump to form a layer between the two metal surfaces as the crank rotates. These bearing surfaces are wide in order to distribute stress, wear, and oil. Oil is squirted or forced directly between them, constantly and plentiful. Under normal operating conditions the oil layer restricts the two metal surfaces from contacting each other, or wearing.<br /><br />A 2-stroke uses roller bearings. The many rollers are constantly moving. The rollers cause the stresses to be directed to one small point of contact (they are round). The rollers are not lubricated by pressurized oil, only by oil that happens to be distributed there from what was unburned in the cylinder. It is not uncommon for crank roller bearings on a 2-stroke to have some metal to metal contact. <br /><br />I don't agree with the marine engine climbing constant hills and being under constant stresses. This may be true in an overloaded boat in a sea of huge swells. But for most normal operation a marine engine can be run at cruise rpm. A marine engine certainly doesn't have to deal with the stresses of rpm drop due to clutches engaging in and out, transmissions shifting, constant fluxuating throttle, passing lanes, and stop and go traffic. Normal marine use on the water and sea is much like the wind and road that most 4-strokes see.<br /><br />Automobile and marine 4-strokes can be compared. At least Honda thinks so. Where do you think 4-stroke marine technology came from? Automobiles, that's where.<br /><br />FBM, add the outdrive to your cost. Then add the cost of trim tabs, which an outboard has built in. Since you can't take your inboard or I/O out of the water during non-use, add the cost of a boat hoist. Outboards simply lift out of the water at the press of the tilt button. Figure in the cost of engine compartment blowers, flame arresters, and Halon systems. Lets not forget the bellows or shaft maintenance costs. Add hydraulic steering costs, not necessarily required on an outboard. Need dual engines?....better have a big boat for two inboards. Add that cost. And if you happen to need an engine upgrade or replacement figure in the added labor costs for removing the engine from your hull rather than the transom. How about the friendly rigging, wiring, and controls, included with an outboard. Built in speedo peto tubes, tach and fuel management. Add that to your inboard.<br /><br />While you're punching the calculator, don't trip over your engine cover.

 

[Beernutz]

Re: Give your opinions on attached 2 vs. 4 stroke article

Hey, just discovered this battleground! Where's it been? Guess it just looked like too much reading.<br /><br />Couple of thoughts:<br /><br />Call me old fashioned, but I'm sticking with my 2-strokes til the 4's have had time to prove themselves.<br /><br />I can just see a 2-stroke deisel outboard with a big ol' Roots supercharger sitting on it!<br /><br />In the 4-stroke corner, the high-speed valve train problem could be solved with a desmodromic configuration. Ducati used it years ago. Those things would rev til they melted! But there we go again with the complexity.<br /><br />Porsche was using Hirth roller bearing cranks in the 50's. Worked good, as long as you kept it on the pipe, but galled and self-destructed in city use.<br /><br />I/O's? Don't like thinking about that rubber boot below the waterline while I'm 30 miles offshore.<br /><br />So I'm the one mucking up the planet?????????<br />Hmmmmmmm.......

 

[Forktail]

Re: Give your opinions on attached 2 vs. 4 stroke article

4-stroke outboards proven? I owned a Honda 4-stroke kicker nearly 25 years ago. My neighbor bought it and still uses it. It's the old blue and white one.<br /><br />Its things like 2-stroke FICHT, direct injection, etc, that I consider not proven or perfected yet.

 

[DJ]

Re: Give your opinions on attached 2 vs. 4 stroke article

FlyBoyMark,<br /><br />It all boils down to economies of scale. O/B manufacturers really do not build that many engines. Add on to that that their total production may be spread out over 20 different models per producer. That further dilutes the economies.<br /><br />Even BEFORE litigation drove the small airplane business to the brink of extinction, they were still rather pricey as compared to automobiles and were one heck of a lot simpler-older engine technology, etc.<br /><br />The only thing that keeps the cost of I/O's down relative to O/B's is the engine. The engine is just about the same price as the transom section and the outdrive. In some cases cheaper. The marine producers are goosing everyone on the I/O package also when you consider what they want for their proprietary parts. Again, it's economies of scale. Like your Kia. There may not have been that many of the sold in the US but you can bet there were PLENTY sold worldwide. Not to mention Kia is discounting to get a foothold on marketshare.

 

[FlyBoyMark]

Re: Give your opinions on attached 2 vs. 4 stroke article

Ok Fork Here goes, 1st; lets compare engine to engine setup. Lets reduce the horse power setup to about... hmmmm... 150 Hp since there are no 350 hp outboards. Cost on the engine is reduced to $2,500.00 using stock heads and all stock parts except for pistons and cam and intake and the disp. will be reduced 2.8L on the same block. The engine will still produce over 180 hp but we will detune it further for the sake of this argument. The entire engine package is about 18-20" high so this would fit under MOST decks without tripping. Next most all of the newer outdrives come with trim. So tabs are not an issue. Second is the price of lets say a Merc Alpha drive......Hmmmmm on monday I'll get you a price from my suppplier to balance this out Monday. Vent ducts and fans comeplete cost about 50 bucks, unless you by gold plated stuff. And for bellows, there are several outdrives that do not use these anymore. And later I will post pics of them. Hydraulic stearing is a non issue to most lower hp stern drive units, they use the same stuff outboards do. Next, Tilt; the newer outdrives tilt enough to tip the entire unit out of the water unless you have some transom heavy boat. Now...I live here in South Florida and very few people with outboards OR sterndrives leave thier boats in the water full time. We do not have a boating season...It's year round. Outboards are great and I own a bunch of them but they are just too much $$$$ for what your getting.