2 or 4 stroke

[David Molineux]

Hi all,

i am usually an electric only flyer but I'm getting really frustrated by lipo charge vs flight time. The ic guys in the club get 3 or 4 flights to each of mine and longer duration too! I am very seriously considering getting something ic and am wondering about the pros and cons of 2/4 stroke motors. If I can get my head round that ill only have to worry about which plane.......

cheers, Dave.

[Greybeard]

My take on the comparison issue, but I’m biased since I haven’t used a 2 stroke for three decades and I’m just about to take delivery of my 10^th(ish) 4 stroke. I do currently fly 2 electric models but doubt that I will continue with that power mode for the reasons that you give.

2 stroke engines are cheaper and lighter for any given size, but higher revving, harder to silence and I don’t like the noise.

4 stroke dearer to buy, a little heavier but better fuel consumption. The noise is more acceptable being a lower note. About equal usable power as the same size 2 stroke.

Edited By Greybeard on 27/10/2012 19:06:55

[David Molineux]

Cheers Greybeard. I've noticed the noise is less with a 4, and also nicer I think. They do seem a fair bit more expensive though.

Are there any differences, say with setup and operation?

Cheers, Dave

[Dean B]

I have a couple of ic models but I always take my wot 4 foamie in case the engine decides to misbehave which can be often. I have seen chaps at the field spend all afternoon tinkering with a techy engine when they should be flying. After all that is what we go for. Yes ic can be dirty, smelly and a pain sometimes but when they work well something about the smell and the noise just makes you smile. 2 strokes can be noisy but 4 strokes can be worse, just a different note that is more pleasing. Personal preference at the end of the day.

Dean

[Former Member]

[This posting has been removed]

[Dean B]

If mine start to fight I give up and fire up the Wot 4 . Im there to fly not tinker. I can tinker at home.

[Bob Cotsford]

I like 4 strokes but the installation can be more difficult than with a 2 stroke where the carb is out front and easy to access. 2 Strokes also have shorter overall lengths, but they need a humungous silencer hanging out of the side to get the noise down whereas 4 strokes only need a little one. 2 strokes generally drive smaller props which can be better for ground clearance but rev higher which means more noise - see previous point re silencers!

4 strokes can use less fuel, but produce less power per cc.  2 strokes suit high speed models better.

I run both 2 and 4 strokes, both can be brought within my clubs 80dBa limit and both are generally reliable.

The third option is to buy more batteries and charge them at home so you don't need to do so at the field. If I take an electric out I usually have at least 4 batteries of any one size with me.

Edited By Bob Cotsford on 27/10/2012 22:06:38

[Concorde Speedbird]

If you set up and use an IC engine properly then they can be very reliable, especially if it is a good quality brand. 2 strokes are cheaper and more powerful at the same size, but are louder and arguably not as nice sounding. 4 strokes are generally more expensive and less powerful (but modern ones are very good) but they sound fantastic, and can be more satisfying. And look at this!

CS

[Dave Bran]

Posted by Greybeard on 27/10/2012 19:06:19:

4 stroke dearer to buy, a little heavier but better fuel consumption. The noise is more acceptable being a lower note. About equal usable power as the same size 2 stroke.

Engage Tongue in Cheek Mode......................... Well, OK, you did say you were biased, but equal power for size? Thats a big fat No Sireee........

I deliberately did a comparison a couple of years back, had two identical 3D planes (Hangar 9 Tango) apart from the engine and of course recommended prop, one had a budget SC 52 2 Stroke, the other a much more expensive OS 70 4 Stroke.

The 2 Stroke rang rings round the 4 Stroke, would for example prop hang very easily and punch out well, the 4 Stroke struggled to prop hang and the pull out was extremely reluctant.

Fuel consumption?............ who cares.................. (EVIL GRIN) ....in fact it was about the same as with 4 Stroke you had a bigger engine working harder to come near to the same type of flying ability.

Big penalty for a "nicer" noise, I'd say!!

I think if you read a few kit engine size requirements you will find they don't agree with you either, 4 is usually stated as a bigger sized range requirement than a 2.

[Stephen Grigg]

I love my 2 and 4 strokes.My favorite and best looking engine is my newish Saito 40 .It sits proudly in my Red Zephyr and poodles around nice and quietly.My little OS 26 4 strokes moise levels are 71db,so very quiet..But I also like the revvy 2 strokes,my favorite being some SC 52 s that have loads of power and are reasonably priced.They dont suffer so much thrust steer on take off.i struggle with my SC 91 in my Zlin 50 because of the side thrust on take off.Im hoping to get this part of my control improved but not successful as yet.

[Devcon1]

I have some fun electric (smallish) models that give me flexibility re flying sites, but it's 4 stroke all the way for my main stuff.. reasons as follows.

Noise..

Engineering.

Appearance

Consumption

Usable power

Lower prop speed/noise

Gorgeous sound

Hope this helps

[Concorde Speedbird]

Dave, for 3D flying a two stroke will be better like you say, but in other applications a four stroke may come out on top, like a warbird or general aerobatic model (but then again either strokes will do for that)/ I like two strokes too, the MDS 38 in my Funfly is brilliant and with quite a large prop it sounds great, it is quiet and good on fuel, but I do like a nice four stroke a lot! For performance though, a two stroke probably wins but for me overall I prefer a four stroke.

CS

[John Olsen 1]

Well, if either a two stroke of a four stroke is giving you trouble at the field, I would say that you are doing something wrong. Once you have found the right settings, which should usually be mostly done at home, either should be giving you pretty reliable starting. Mind you, in saying that I am assuming that you are using an electric starter. Apart from being too chicken to try to hand start them, I find that the good fast spin over from an electric starter means they will pretty well always start easily, often first try but always within a couple of tries.

The usual rule of thumb seems to be that you go up maybe 30% in capacity when you go to a four stoke, eg replace a .46 with a .60. This does not necessarily carry the weight penalty that you would expect. We (my son and I) have just put an OS .56 four stroke into a Sundowner instead of the Evolution .46 two stroke that it was designed for. According to the published figures, the weight of the OS is the same as the weight of the Evo. Since it will use less fuel we should get a longer flight time for the same take off weight. It has only flown once, maidened yesterday, it certainly goes like a cut cat.

There are pros and cons to both the electric and IC forms of power, and although I rather like the IC, I have a couple of parkflyer size electrics. The ability to fly them on a nearby sportsfield after work is rather nice. The main thing with electrics is to have enough batteries to keep you going. A fast charger and a suitable battery in the flight box lets us charge them at the field. So given say 3 or 4 flight batteries you can get a lot of flying in like that.

John

[David Molineux]

Cheers for all the responses I'll be back up at the field in the morning and will have a chat with the guys there too.

I'm leaning towards an Evolution models Fusion or maybe an Enigma bipe. Sounds like a good 2 stroke might suit better......

I definately wont be ditching electric altogether, especially as my Clean Sweep is nearly finished Maybe I should just get a few more batteries.

Although, If they look as good as that Saito C.S. I may go 4 stroke lol.

Dave.

Edited By David Molineux on 28/10/2012 01:27:55

Edited By David Molineux on 28/10/2012 01:29:27

[buffetslayer]

Whatever you decide, be it 2, 4, or petrol, I can't recommend enough the superb service provided by justengines. I'm sure others here will agree

[Greybeard]

For the sake of clarity. What I wrote was: "About equal usable power as the same size 2 stroke." and I stand by that statement; for when additional silencers are added to a 2 stroke and the revs reduced by over proping to the level usually required to comply with the noise test then that is the practical end result..

 

I remain biased.

 

Edited By Greybeard on 28/10/2012 07:51:14

[Peter Miller]

I use both two strokes and four strokes. I use them in different types of model.

For fast aerobatic types I use two strokes. For slower types I use four strokes..

For example. My CAP 21 and New CAP20L as well as my Zenith Super Acro, Minnow, Dalotel I have used two strokes.

For my Fourniers, Le Grand Simon, Whitman Tailwind and Slingsby I used four strokes. The Van's RV3 also used a four stroke but would have been happy on a two stroke. Also on my Miles Magister and Druine Turbulent. I used four strokes.

Horses for courses.

Harlequin is nice on a 40 to 48 FS. But would be very good on a .35 two stroke.

With regard to operationn. once set up properly there should be no trouble.

99.9% of all engine problems are caused by the fuel system, not the engine.

Edited By Peter Miller on 28/10/2012 08:17:32

[Max50]

I'll just second buffetslayers advise. Bought an ASP 46 2stroke last Monday and received it the following day. Good running-in advise and also bought it with a super quiet exhaust; and it just purrs.

Also they stock all the spares, so you don't have to worry if a bearing goes sometime.( as with my SC).

Edited By Malcolm Williams on 28/10/2012 08:30:44

[David Molineux]

Once again, cheers for all the advice. They way the weather is I can't see the club being an option today.

I have looked at Just Engines and they seem really good. Anyone have any experience of their JEN range? They seem very reasonably priced and I like the black/purple too

Dave

[Mondeoman]

Steer clear of "Jen" engines, they are actually "Vmar" engines and are RUBBISH !!!

[Peter Miller]

I rate SC engines very highly. Apart from my OS 40 and 48 Surpass four strokes almost every engine I have is an SC .I have been using them for nealry 20 years and have had no trouble with them. That includes 2 and 4 strokes.

I did once have a 30FS with a faulty head but that was repalced at once.

Currenlty I have about 6 .32s, 2 .25s .a .12, about three .15s. Then 3 30 FS, two .52 FS. In he past I have used .40s. .46. and a 91 FS. All without any trouble.

[Phil 9]

if you choose a two stroke have a look on ebay and classified adds. used two strokes can be picked up cheep if you a patient

[..]

I use both but prefer the 4 strokers, I have an SC 70 in my ME 109 and it sounds awsome

[buffetslayer]

I'm currently running a couple of sc engines and really happy with them

[Braddock, VC]

I went completely 4 stroke, but do not kid yourself the new generation OS 2 strokes are timed for torque and consequently start to re-establish the difference between them and the 4 strokes.

I can only comment on the ones I have used but if you eradicate the notion of 10 -12" props for 60 size two strokes the OS 55 will amaze you as will the other engines in the AX range, specifically the 95 and 120. These will probably be copied for the Mk4 asps.

For comparison I have several 4 strokes ranging from os 26 (3), os 40, os 52fs, saito 62a, saito 82 (3) saito 125, laser 70 and 80, YS 110 fz the props I use respectively 11x4, 12x4, 13x6, 13x6, 14x6, 16x6, 14x4, 14x8 and 16x8

My two strokes vary from OS10, irvine 20 and 36, OS Fp 20 and 25, YS 45, OS 55, Irvine 46, sc61, os 91 fx, os 160 fx.

Ignoring those up to the ys 45, the 55 I used 13x7 apc, irvine 12x6, sc 15x6, 91 16x6, 160 fx 18x8, 18x10. All these are truly quiet in operation.

It's not true that 2 strokes are lighter than 4 strokes, by the time the OE silencer is fitted they are inevitably heavier.

My opinion is that the 55 ax outperforms the saito 82 which outperforms the irvine 46, the sc 61 is outperformed by the saito 125 which is left for dead by the 91 2 str ( the saito, os 91 and sc 61 all have the same engine mountings and I swapped them about in a H9 pulse 60 xt). I don't have anything to compare the 160 fx to but it's scary, the draught at tickover has to be experienced to be believed.

The lasers are lovely, the 70 is extremely powerful for its size and the 80 has more power than the saito 82 but weighs more than the saito 125.

I run them all on 10% nitro.

The positives for the NEW breed of two strokes is they are simpler than 4 strokes, same or less noise and easier to operate, which is why I've started re-using them.

I'd say try the os 55 ax and gain experience then try a 4 stroke. My view is you get what you pay for in model engines and if longevity is on your mind choose irvine, OS, Enya, saito or laser and you'll have fewer snags. I have a sneaking admiration for sc but have heard some bad reports that couldn't be attributed to operator ability.

Getting a secondhand engine is a good bet if you know the owner though modern lasers don't seem to come on the market that often the one I sold lasted about 20 minutes before it was sold, you do see 75s and 90s from time to time but they are nearly 20 years old by now, speaks volumes for their quality.