Two Stroke Versus Four

[rsbeck]

Which is the better engine? I have noticed that some areas, like Lake Tahoe, have banned two stroke engines. Is this a trend? If I buy a boat with a two-stroke engine, am I going to find it outlawed in a few years? Who makes the best four stroke engines? Are two stroke engines that much louder, pollute that much more than four stroke? Any other major differences?

 

[seahorse5]

Re: Two Stroke Versus Four

Lake Tahoe did not ban 2 stroke motors. The regulations say that a motor above 10hp has to meet CARB one star, same as EPA 2006 emission levels, to be legal on the lake. To appease the sailors, they do allow the under 10hp old style carbureted oil dripping motors on their boats.<br /><br />The Lake Tahoe patrol boats are powered by Evinrude direct injected 2-stroke motors that replaced 4-stroke Hondas because the Evinrudes have fewer total emissions.<br /><br />The new E-TEC V-6 Evinrudes (direct injected 2-stroke) have less than half the total emissions as a Yamaha F225 4-stroke outboard.

 

[imported_JD__]

Re: Two Stroke Versus Four

From what I read, some of the new two-strokes are more fuel efficient and have less emmissions than the 4-strokes. Are the 4-strokes better? I think that is a matter of personal preference. 2-strokes have one major disadvantage in my opinion. Oil has to be mixed with the gas at some point, either in the tank, at the carburetors or injectors. Some are "hybrids" with a mini oil sump. If an injector fails or gets stopped up, that cylinder doesn't get lubricated. I know of a few individuals and have read about many more that have had this happen. Four-strokes are heavier by design with a head, valve train, etc. I bought an EFI 4-stroke back in February. It started as quickly, ran as smooth and quiet in 30 degree temps as it does today. I don't worry about adding oil, just check it occasionally and change it every 100 hours, similar to my car engine. There's no smoke and no odor. I personally wouldn't go back to 2-strokes even if there wasn't an evironmental issue.<br />JD

 

[swist]

Re: Two Stroke Versus Four

On the reliability, IMHO, there isn't enough data. DFI 2-strokes are completely new designs. Some (Ficht) had horrendous teething problems.<br /><br />4-strokes are mostly based on auto technology, but show me an auto that consistently runs over 4000 rpm in a saltwater environment....<br /><br />The carbed 2-stroke is the only design we really understand where the long term reliability problems are. Note the number of posts in the specific engine forums that give advice like changing the foobar every 3 years - this is based on years of accumulated knowledge that foobars older than 3 years can become unreliable. I think we need a few more years before the wrenches will have the body of knowledge that can only come from observing lots of 2000 hr engines.

 

[Forktail]

Re: Two Stroke Versus Four

The Lake Tahoe patrol boats are powered by Evinrude direct injected 2-stroke motors that replaced 4-stroke Hondas because the Evinrudes have fewer total emissions.

There's a little bit more to it than that.<br /><br />First, there are several patrol boats on Lake Tahoe. It is only the Tahoe Regional Planning Authority that uses the DFI's on their patrol boats. And I think they only have one or two boats with these DFI's.<br /><br />The fact the TRPA re-powered with Bombardier DFI's because they have "fewer total emissions" is only one reason. After all, the Honda's exceed the emission requirements too. Bombardier's Boats and Outboard Engines Division simply approached the TRPA with an offer they couldn't refuse, and they teamed up. <br /><br />Most patrol boats on lake Tahoe use 4-stroke engines. <br /><br /><br />

The new E-TEC V-6 Evinrudes (direct injected 2-stroke) have less than half the total emissions as a Yamaha F225 4-stroke outboard.

Unlike the new E-Tec V-6's, the Yamaha F225 has years of proven reliable performance under its belt. And it meets all emission requirements.<br /><br />Lake Tahoe can be some big water. In answer to the original question, there is much more to look at in an outboard than emissions. I would suggest a proven and reliable 4-stroke. Over all, you will find it a much more enjoyable outboard to own. Some people make a big deal about the DFI's emissions, but the 4-strokes have been meeting or exceeding emission standards for decades.

 

[BoatBuoy]

Re: Two Stroke Versus Four

And just imagine. Someday you might be able to get a radical Isky cam and M/T headers for it. Just think of the possibilities. Roller tappets, rockers, Granatelli power chips......

 

[zj-jeepster]

Re: Two Stroke Versus Four

My 74 Evinrude runs great but I don't think it has any CARB rating at all. It starts in a cloud of 2 cycle blue smoke, smells real bad. For now it'll get me around.<br /><br />My 2 cents.<br /><br />.

 

[UpstNYer]

Re: Two Stroke Versus Four

zj- your comment says a lot. 30 year old 'rude that runs great. From what I see on the forums, that's not uncommon. Will it be as common in 2034 with today's 4-strokes?<br /><br />On thing's strange though. My '04 Merc Classic starts in a cloud of blue smoke and smells great....it makes me nostalgic for what used to be the land of the free. Black powder smoke from the muzzleloader has the same effect.<br /><br />I know, it's much better now that we have bureaucrats telling us what's good and what isn't.

 

[Forktail]

Re: Two Stroke Versus Four

Will it be as common in 2034 with today's 4-strokes?

Why sure it will. Why wouldn't it?

 

[WillyBWright]

Re: Two Stroke Versus Four

Which is better? Each has it's advantages and disadvantages.<br />Is there a trend to ban 2-strokes? Carbed and EFI's, yes.<br />Are 2-strokes going to be banned in the future? Many places yes and some places already are, but again the carbed and EFI versions.<br />Who makes the best 4-strokes? Yamaha. Suzukis are nice too. I'm not a big Honda fan, car motors adapted to outboard legs. The others use powerheads engineered specifically for boat motors.<br />Are 2-strokes louder and do they pollute more than 4-strokes? Carbed and EFIs, yes. The DFIs are incredibly quiet (except fot the Optis). I hear the little Briggs & Stratton 4-strokes are terribly loud.

 

[swist]

Re: Two Stroke Versus Four

There are 3 times as many moving parts in a 4 stroke - I am not at all convinced that when we look back on this 10 years from now we will say the 4-stroke was a model of reliability. Maybe we will, but car engines loaf on the highway at 2200 RPM with occasional bursts to 3000. What will be the effect of running all those parts constantly in salt at 4000-5000 with the occasional burst to 6000 as normal operating procedure? We shall see.<br /><br />And the technical descriptions of the DFI engines show some pretty sophisticated stuff - the injection pressure on a Yam HPDI is incredibly high. Can this last for 10 years without beating something up?<br /><br />The simplicity of the Carb 2-stroke is I know a dead issue in 2006, but they are damn reliable with good preventive maintenance.<br /><br />Like I said in a previous post, maybe it is too early to know which components in a DFI or 4-stroke are the weak links and need pro-active maintenance.<br /><br />And what will be the price? 2-stroke carb proactive replacements include thermostats, relief valves, impellers, carb rebuilds, adjustments and<br />throttle setup. Most of these things are doable by the home mechanic, and the parts prices of all the above are not excessive. And what if we find out that for reliability the DFI pump should be replaced every 3 years on an HPDI, that could be a serious chunk of change. Just a timing belt on a 4-stroke can be very expensive, if cars are any indication. Hope you see my point.

 

[jim dozier]

Re: Two Stroke Versus Four

First let me say I own a 2-stroke outboard (Suzuki). I also own a Honda (Acura Integra GSR)car. I can rememeber hearing and reading knowledgeable people say and print that foreign cars wouldn't last. That overhead cam engines were too complicated. That 4-valves per cylinder would cost a fortune to have valve jobs every 80,000 miles. That removing lead from gas would doom all engines. That electronic fuel injection would be nothing but trouble and would be the end of the backyard mechanic. That high reving engines would not last. That you could never put a high horsepower engine on a front wheel drive car. That aluminum block engines would never last. Etc. Etc. Etc. <br /><br />Well I would put the reliability and longevity of my 8,100 rpm redline, double overhead cam, 4 valves per cylinder, variable valve timed (VTEC), dual intake manifold, electronic fuel injected engine right up there with the best.<br /><br />I am sure there will be teething problems with new designs, but the overlall reliability isn't going to be a question. Every time somebody designs a new engine block there are always unforseen problems whether its 2-stroke, 4-stroke or whatever. <br /><br />The marine environment is harsh but nobody is going to argue that we should go back to points and condenser ignitions because CDI electronics don't like salt.<br /><br />Me I'm just waiting for a E-tec direct injection multi-rotor Rotary.

 

[Forktail]

Re: Two Stroke Versus Four

Yea, I think the reasoning of, "wait and see if the 4-strokes will last" is getting old.<br /><br />The best way to tell if an outboard will last is to use it. You don't need to wait 30 years.<br /><br />My commercial operation can wear out an outboard in 3-5 years. I don't need to wait 30 years to tell you that the 4-strokes live longer. The engineers at the factory will tell you the same thing....if you want longevity, get a 4-stroke. Day in and day out in hard salt water use, the 4-strokes are simply a more durable engine. I attribute this mostly to the cooler cylinder operating temperatures and the pressurized lubrication system. 4-strokes aren't the fastest growing segment with the happiest ownership (per J.D. Power) for no reason. If 2-strokes had more advantages, we'd see them in autos and airplanes.

 

[jim dozier]

Re: Two Stroke Versus Four

Just to second what Forktail alluded to. The primary reason that we have 2 stroke outboards as a standard is that back in Evinrudes day you could not hang a 4-stroke of equivalent power off the back of a runabout without pulling the transom off while sitting at the dock. While modern 2-strokes are way better than they were back in the early part of the century, I would say that 4-strokes have come a lot further. Now at least we can have a forum where people can argue that they are approximately equal. There are high points and low points for each and I won't fault a person who prefers one over the other.<br /><br />Now does anybody know how to reprogram the E-tec computer for a Wankel engine? I want to put direct injection on a Mazda RX-7 and turn it up sideways.

 

[Guest]

Re: Two Stroke Versus Four

I just put a 50 e-tec on my boat. <br /><br />My brother has a yammi 4 stroke. I really like it except for one thing: it won't troll down as slowly as I wanted. That's why I chose the Evinrude. The RPM can be dialed down to almost nothing and still run like a champ. With a fairly narrow boat, I can troll to 0.9 mph. <br /><br />I just learned some of the new Yamaha 4 strokes can also be set to idle lower. I just didn't know that a few weeks ago when I made the purchase. I may have bought one. <br /><br />Anyway, I'm very happy with the e-tec. I guess only time will tell if it will hold up after many years of use. All the theories really don't matter. The only thing that matters is actual experience over time. It's good to hear from users who put a lot of hours on motors (like the commercail operater who posted earlier). If anyone should know about long-term reliability, it's them. <br /><br />By the way, my previous motor was a 2003 Merc carbed 2 stroke. I was not very happy with it--at all! They may last a long time-- but maybe that's what I was afraid of!<br /><br />Trout

 

[tym42ply]

Re: Two Stroke Versus Four

ForkTail, why do you hate the Evinrude E-Tec's soooo much? Have you ever used one? Nobody's saying your beloved Yamaha makes a bad engine, in fact they are quite good engines. I just keep seeing time and time again how you try to slam the E-Tec whenever you get the chance. <br /><br />Shouldn't you at least run one of these engines before discounting it as a relative alternative to 4-Stroke technology. <br /><br />If the E-Tec's do all the things the Evinrude claims shouldn't people at least give it some consideration when deciding what engine to purchase? I mean to me better fuel economy, more power, lower emissions, and better sound and idle all seem reasons to look hard at an E-Tec <br /><br />BTW, E-Tec's have been out in the marketplace for over a year now without ANY of the problems that plagued Ficht. How much longer do these engines have to prove themselves before the diehard 4-Stroker’s start giving the E-Tec some credit.<br /><br />I’m not saying you should go out today and get new engines for your Fleet (although you would probably save money), just make sure you have all the facts and actually run the engine before slamming it again. <br /><br />Once you know all the facts the only reason I can see for your continued hatred of 2-Strokes (mainly E-Tecs) is that you in fact work for Yamaha. You don’t do you?

 

[Forktail]

Re: Two Stroke Versus Four

tym42ply, I wasn't aware that I've ever "slammed" the E-Tec. <br /><br />I take a very conservative approach to them since they are very new. Not just entirely new models, but entirely new technology with roots from the troublesome Ficht. To top it off, Bombardier is an entirely new manufacturer to the outboard industry. New dealer network, new service techniques, new parts system, etc. <br /><br />Surely you understand that I simply can't afford to have Bombardier use me as part of their learning curve. When they've been around for several years and boast a reputation for durability, reliability, and longevity that exceeds the outboards I currently use, then I will run them. I guarantee it.<br /><br />On top of that, the E-Tec has not been available in bigger horsepower models. Their new higher HP releases will again be totally new. Their smaller models have a tiller handle that does not appeal to my use. The "no maintenance" thing only applies to minimal recreational use, not me. Additional or future maintenance costs are unknown. Fuel savings are yet to be seen, and not a big importance to me over dependability, etc. Emissions are of no concern to me, as my 4-strokes exceed the requirements. And adding oil to an injection oil tank still does not appeal to me over just adding gas.<br /><br />Finally, I am not convinced that Bombardier is being honest with their product. As many members here remember, I found exaggerated data in their performance reports which was impossible to achieve. Bombardier's explanation on the issue was lacking. I also found out that their story of Tommy Kriska on the Yukon River had more to it, as Tommy was a little bit more than a "local" guy just running an E-Tec. He had previously been sponsored by Ski-doo (Bombardier) and his dealer for snowmobile racing. He also received much promotional incentive for his E-Tec story, which I know is exaggerated as well. Then we have the fact that these outboards were introduced as "light-weight technology", which really isn't the case. As we've seen here, most of their current models are heavier than similar HP 4-strokes, and they're certainly heavier than traditional 2-strokes. Then there is the fine print within the "no maintenance" thing. Doesn't do me much good. Plus there's been some posts here about using more oil than promised. Oh yea, they're not exactly cheaper either. And the dealers that shadow this site pushing how great it is make me nauseous.<br /><br />Again, I've never "slammed" the E-Tec and I have no "hatred" toward it. My brand loyalty lies with whatever is best. I will give the E-Tec all the credit in the world. But it has to earn that credit. All the hype going on and 1 year on the market isn't quite enough to earn me. Not to mention my dealer hasn't even sold one.<br /><br />BTW, I love 2-strokes. I own 2-stroke Bombardier snowmobiles, PWC, ATV's, motorcycles and believe it or not, even outboards.<br /><br />And no, unfortunately I'm not a Yamaha dealer. But I own enough of them to own stock in their company. Instead I have stock in Bombardier. So what's that tell you.

 

[lark2004]

Re: Two Stroke Versus Four

I am not sure whether this adds anything to the debate, but the ability of ANY engine to operate at a certain RPM, is how it was manufactured. If it was designed to operate at high revs all day, then it will. Passenger car engines are designed to redline (generally) at 6000 rpm. My friends 4-stroke motorbike revs to 12500 rpm, The raceing versions (1000cc superbikes) can rev higher than that (about 18000). Then look at F1 or Indy/Cart racing, 4-strokes that rev high, because they were designed to. <br />Now to the 2-strokes, They are easier to make for high reving (from a manufacturers point of view) due to less moving parts (less cost). My whipper snipper only revs to 4000, but my model car (same size engine, yes, it's a BIG toy) revs to 18000. <br />So really, the sustained RPM of any outboard, is what the manufacturer says it is at WOT. That is what that motor was designed to do. <br /><br />BTW, It is a bit hard to compare the 4-stroke technology used in cars to that of 4-stroke outboards. They are 4-stroke and that is where the simalarities end.

 

[jim dozier]

Re: Two Stroke Versus Four

Lark2004 I agree with what you said except I would take issue with the concept that outboards are hugely different than car engines. It depends on which car engines you are comparing them against. Chevrolets maybe, but others are more similar.<br />Compare the Suzuki and new Honda outboards to what Honda/Acura, Toyota/Lexus, Suzuki has on the road.<br />They have EFI (electronic fuel injection)<br />They have variable valve timing electronically controlled (VTEC)<br />They have dual phase tuned intake manifolds<br />They have tuned exhuaust manifolds<br />They (some of the cars not all) have DOHC (double overhead camshafts)<br />They have aluminum blocks and cylinder heads<br />They have 4 valves per cylinder<br /><br />So how are they so different outside of the fact that they are standing on their ends. I believe (someone will correct me if I'm wrong) that the larger Honda outboards are based on the Honda Accord block.<br /><br />Certainly they have to modify them for marine use and to mate to an outboard. But I think the technology is more similar than you might believe. Most of the outboard manufacturers aren't just grabbing car engines and standing them up but the technology that allows my car to make 170 hp out of 1800cc stock is what allows us to have a 4-stroke that won't rip off the transom while its tied up at the dock.

 

[TOHATSU GURU]

Re: Two Stroke Versus Four

The Honda 90 outboard uses the Civic car engine.