2 stroke versus 4 stroke

[Latestarter]

Hello all,

 

I'm very new to recreational aviation and wondered the pluses and minuses of 2 stroke versus 4 stroke. I would expect two stroke are lighter, more powerful, less economical, messier and more sensitive to tuning and the four stroke heavier, cleaner, more expensive and more economical. As two strokes can be sensitive to tune and the safety aspect is so important I would thing they are run rich to be sure but is that right in practice?

 

I'm getting my head around the RAA aircraft specs and the importance of light weight overall and liked the idea of fours stroke more but if the weight aspect is so important is it worth considering two stroke?

 

All thoughts gratefully accepted.

 

thanks

 

 

[fly_tornado]

have you had a look @ the RAAs market place to get some idea what stuff people are flying?

 

 

[facthunter]

IF you are buiding and flying a lightweight plane, the 2 stroke engine has all the advantages you have listed. If you start with a low hours engine and keep the mixtures right and mix your fuel fresh with a good lube oil you will get about 400 hours of reliable engine performance. Look after your battery and the fuel pump. Some people get a lot more hours but the assurance of reliability diminishes.. Some people have got over 800 hours out of a Rotax 582 . This cannot be guaranteed. Nev

 

 

[Guest davidh10]

Two stroke has more frequent routine maintenance and less range due to fuel consumption.

 

Bottom line is most aircraft come with one or the other, but not the option to choose. On that basis, choose your aircraft on the basis of its specifications meeting your needs. The engine choice will be made by the aircraft choice.

 

 

[Latestarter]

Thanks everyone.

 

That summary looks spot on David, just the direction needed.

 

Great details, thanks Facthunter.

 

FTornado, I'd been told some people register RAA but are only able to fly by themselves because of limits and the flying school I'm looking at has a Jab 230 with only 2 seats so I'm not sure if looking at the list will help absolutely but I expect the common types are probably the better fit for the limits. I've seen a Spacewalker 2 for sale here in SA and that's really nice but I'm not sure it will fit carrying 2. I suppose I'll just contact the seller (trying to hold off talking to sellers as I might get too excited!).

 

thanks all

 

 

[fly_tornado]

the spacewalker2 is a 2 seater and awesome looking plane when fitted with a ***** engine.

 

In RAA sphere, the most common 2stroke is a rotax 582 which is 65HP, the most common 4 stroke is a jabiru 2200 which is 85hp.

 

 

[Latestarter]

G'day FT, What is a ***** engine?

 

How long does the four strokes last before needing overhaul?

 

I do like the Spacewalker 2 but the open cockpits maybe a minus.

 

thanks

 

 

[sleemanj]

If you're thinking Spacewalker 2, you'd have to seriously consider finding the money for a ***** Radial, who cares about the practicalities!

 

Hmm, it appears that ***** is a banned word. Odd. Google for radial engine Australia and you'll find them.

 

One day. When I'm rich and famous.

 

 

 

[Thirsty]

LS - the four strokes commonly available here are the Jabiru 2.2 (4 cyl) or 3.3 (6 cyl) and the Rotax 912 in 80 or 100hp guise. The Jab engines have a rep for unreliablity while the Rotax has the opposite rep. Parts for the Jabs are pretty reasonable while the Rotax bits are quite dear (so I believe).

 

I quite like the Jab engines and believe the rep they have isn't 100% warranted. I think it's all about how they are treated and maintained so I personally would buy one but others may have different opinions.

 

There are also VW, Subaru and other auto conversions around.

 

If you buy a Jabiru plane you will almost certainly get a Jab engine. The 230 has 2 seats because that's the max allowed in RA. It can be registered VH with 4 seats as well.

 

 

[facthunter]

If we are going to be comprehensive you would HAVE to include the Lycoming 0-233 and the continental 0-200D. These two engines would definately have the highest genuine TBO's and proven reliability. If you are building/buying a single seater you have lots more choices, because you could get down to 30 HP and can even have multi-engines under older rules ( very light build). You can forget the spacewalker with the ***** radial as it is pretty heavy two up. (I don't like the U/C much either). Don't forget that you can fly experimental GA if you can get a PPL. The Hornet from Australian Aircraft Kits usually flys that way (look up their site) as do practically all warbirds (I believe). Do MORE flying and talking and be patient. Everyday things change and more possibilities emerg. Nev

 

 

[sleemanj]

If we are going to be comprehensive you would HAVE to include the Lycoming 0-233 and the continental 0-200D. These two engines would definately have the highest genuine TBO's and proven reliability.

Well if we are being comprehensive, better throw in wankels too. Best of both worlds, simple, higher power to weight, high reliability and good failure modes, and of course everybody knows when you're coming --- Baaaaaaaarrrppppp!

 

 

[sseeker]

If you're thinking Spacewalker 2, you'd have to seriously consider finding the money for a ***** Radial, who cares about the practicalities!Hmm, it appears that ***** is a banned word. Odd. Google for radial engine Australia and you'll find them.

 

One day. When I'm rich and famous.

It's banned because of some problems Ian had with them. No content to do with them is allowed to be posted.

 

All I can say is 2 strokes have a better power to weight ratio (weight being engine weight), use more fuel, I don't hear a lot of good things about them and are commonly associated with a whipper snipper

 

Andrew

 

 

[facthunter]

I think a wankel design is ideal for sportplane application. They have been successful in racing outboards for a while now. A Norton manufactured aero engine (air cooled) was made years ago. I believe they should be liquid cooled, purpose-built. Potentially greater reliability... Nev

 

 

[Guest Maj Millard]

David 10, Fuel consumption is not bad on the 582, not a lot different to the 4 stroke 912 really. Range depends on what aircraft it is in, and the fuel capacity that the aircraft could carry. I regularly used to do 4 hour + legs in my 582 Drifter when I had it, with 75 Lts on board.

 

fly tornado, I would definitly question you suggestion that the Jab 2200 is the most common four -stroke in use. The 912s should easily outnumber them, and are without a doubt less failure prone also.................................................Maj...

 

 

[GDL]

Hi Latestarter. I would like to put my 2 cents worth in a Canadian perspective. I fly on the west coast where the terrain is not often very good, I prefer 4-strokes. Having owned and flown Rans S6, one with 2-stroke 582 and 1 with 4 stroke 912 (my current machine), the conditions under which we fly often dictate the type of engine we use. I like the 582 but it really only is good for ~300 hrs, uses more fuel, and is prone to seizing (had this happen in the mountains). Never had a problem with the 912 in more than 1000 hrs. I just feel more comfortable on long trips. 2-strokes have their place, and Rotax makes good ones. On the other hand, 912 engines are very expensive.

 

 

[Guest Maj Millard]

GDL, It sounds like I'm preaching to the converted anyway, but in respect to Rotaxs being expensive...what price do you really put on your life and aircraft anyway ? By the sound of it you know the feeling of being reasonably comfortable over mongrel country...............Maj...

 

 

[GDL]

Hi Maj. You are absolutely right about how much price does one put on one's life when flying. Still, the cost is so expensive here ($20,000 and Bombardier is a Canadian company) that all of us have looked at alternatives. Lots of car conversions (especially the Suzuki and I continue to explore them), Smart engine, Mid-West rotary, 2-strokes, diesel, and so on. And each time, have come back to 912. Yes, I trust my 912. Ran it out of coolant once (overflow failed because of my stupidity), and it made it back to base (~10 minutes) with no problems. Had the cylinders tested for hardness after that and they were fine.

 

When I fly from my home base into the the Interior, I have to cross the Coast Mountains (up to 4000m). In some spots, no place to set down easily or at all. Have done that trip on several occasions with a decent sense of comfort behind the 912. It is a trip with a 582 I wouldn't have the same joy.

 

Do you find the same thing in Australia as I see in Canada? Some of the hard core conventional guys here are (seriously) suggesting that I replace my engine with a real engine like an O-200 or a C-85. They have zero comfort level with any Rotax. Geoff

 

 

[Student Pilot]

Do you find the same thing in Australia as I see in Canada? Some of the hard core conventional guys here are (seriously) suggesting that I replace my engine with a real engine like an O-200 or a C-85. They have zero comfort level with any Rotax. Geoff

I would rather a new 912 Rotax than a forty or fifty year old Continental that's been rebuilt 5 or 6 times. A Rotax (Two or four stroke) treated like an Aircraft engine and serviced regularly is very reliable. With the two strokes and to lesser extent the four strokes, people do all sorts of things to them that they wouldn't do to a certified aircraft engine and reliability suffers. More Aircraft are powered by Rotax than any other engine.

 

 

[facthunter]

reliability. aircraft power plants.

 

There is the design, the condition the usage and the servicing. Its not just the engine either. The ancillaries can let you down. eg exhaust systen mounting (cracks etc) the rubber carb hoses on the 912 can deteriorate. I would rate the 80 HP rotax as the most bulletproof with the 100 close behind.

 

NO engine will last forever despite the loyalty and affection that some feel for their favourite brand.

 

IF you get an auto engine it may have lots of Kms on it and have been overheated and abused. Metal fatigues, distorts and cracks. Sometimes it goes soft (where heat is involved.)

 

Similarly any old Lyc or Continental should not be rebuilt indefinately. Like retreaded tyres they can be a poor prospect especially if you want reliability. Not even value for money. The new engine can be not much more expensive, and can be a better variant with better engine mounts improved parts,more parts availability etc.

 

I suppose it can be done but I've never seen a rebuild (where it has run it's first life, at least),that went quieter and smoother and longer than a brand new one., and I have seen plenty that were put together by the most qualified firms that have had multiple failures, because they were not assembled correctly even though (for the most part) they are essentially simple engines design-wise . You could "blueprint" a brand new one and if I was going to fly an RV or such around the world, I would do that, but that is a one-off situation where the extra expense would be justified An engine would also be more reliable statistically with 100 hours behind it than when brand new. Nev

 

 

[Guest Maj Millard]

There is nothing wrong with the Rotaxs, both the 582s and 912s are very reliable, if set up properly and left alone. Basically the proof is in the pudding. I personally, and many other pilots in this country fly 912s regulary over suspect country, without too much worry. I have flown behind probabily a dozen different 912s now, and trust them without question. I have yet to experience any failure with one.

 

Pilots in the bush who often use their aircraft for up to six hours a day, everyday, prefer the 912 especially in the daytime excessive heat and dust of our extreme summers.

 

Three Slepcev Storches that I help maintain in the bush, are all now on their second or third 912. They'll do around 2000 or more hours on them, and put in a new one. It is simply a buisness expense for them, and by the time they do the change, the engine has probabily paid for itself many times over. In no way, shape or form would they entertain the idea of using another type engine.

 

The 912s now have the numbers to back them up, and I don't mean numbers of failures.................................................Maj...

 

 

[dazza 38]

There was a story i read back in American Kitplanes magazine in the mid Nineties.This blokes name was Tracy Something.Anyway he put a 13B rotary in a RV4 he built.Back then every body told him not too.It was out of a Mazda with a alot of miles on it.Anyway he tried to find a mechanic to rebuild it.No luck there they all said its a black art.The reason he wanted a rebuild was because it blow out smoke and burned alot of oil on ground runs.He decided it couldnt be that hard and he rebuilt it himself.There isnt much internaly in the engine.He replaced the seals inside.Problem fixed.The problem was from memory, is that being a realy short crank, the harmonic balance was a problem high frequency or something. These engines have destroyed a few dyno's in the past.Anyway he found a company in the states who made a excellent reduction drive for his engine.He flew happily ever after.Well he did whist the Magazine came out.

 

 

[HEON]

Read an interesting article from USA some time ago that tracked the expected costs of Rotax 2 and 4 stroke engines in the same aircraft. Something like a Drifter from memery.

 

The 4 stroke was much cheaper over time.

 

Break even was around 1000-1500 hrs I think. Thus if you are not going to fly much...go 2 stroke: otherwise 4 stroke. This excludes potential ban on 2 strokes due to polution

 

 

[GDL]

Hi Student. My sentiments exactly as to new 912 vs old rebuilt old Continental. Servicing is the key. I had a friend (a mechanic) take the Rotax course (Canadian dealer is 150 km away) and then rebuild my engine. When he pulled it apart, he was amazed at how new it was (1000 hrs at that point) and how strong and tight it was. But the Continental guys don't like gearboxes, water cooling, electronic ignition, high rpm. I tell then, why don't they drive a Ford Model T car. Basically the same engine as theirs. They say that is different. You are right. Servicing is the key. And the engine should be treated as an aircraft engine. It is, and our lives depend on it. But I have supreme faith in my 912. As much as any engine out there.

 

 

[GDL]

Hi Dazza. I remember the Tracy you are talking about. I am not sure if he is still around but he was very popular in the 90s and early 2000s in the US. According to what I have read there are 2 main problems with the RX-7 rotary engines (the 13B). It burns a lot of fuel (nearly double a 912) and the exhaust runs extremely hot, so placement of components is critical. In the last few years, some people have experimented with the RX-8 engine but I know very little about their success. In North America the 2 most popular car engines are the Suzuki 3 & 4 cylinders and the Subarus. I may build a plane around a Suzuki G13 (the 4 cylinder - the G10 is the 3 cylinder). I have been in one and they have reputation for good reliability, are very smooth (far more than a 912), and burn about 2 imp gals/hr. A fellow I know in Quebec (Airtrikes) sells them for about $7000 rebuilt and ready to go into your aircraft.

 

 

[GDL]

Hi Heon. The 2-stroke cost vs 4-stroke is a big point where I fly. Having had similar Rans S6 (at the same time) - one with 582, one with 912, I can agree completely with you on the costs of operation between both. My 912 buys (by my records) just less than 3 imp gals/hr. The 582 burned around 5. Rebuild on 912 is now 2000 hrs, 582 is raised to 500 I hear. Add in cost of plugs and how often, oil in fuel for 582, and costs start to even out. Although the 912 is a huge expense to start with. Now $20,000can for the 80 hp (gulp!). The 582 is about $8000. I think better to buy an airplane with it in it. Get a better deal.