2stroke vs 4stroke
 

the 2stroke OS 55AX has 1.75HP and the 4stroke SAITO 82a has 1.5HP... will it be better to get 2stroke as it has more HP? or would the 4stroke be better having more torque? what would be best for 3D and prop hanging later when I am up to it?

RE: 2stroke vs 4stroke
 

4 stroke is better for "3D and prop hanging" and better throttle response. I am done buying 2 strokes (ok except maybe for a piped OS 140RX, but only if the price is right).

Even though there is less top-end power, there is SO much more torque. You can use a higher pitched prop to gain the speed. The high power of 2 strokes only comes at high RPM, so either you're hovering at high throttle settings or you're revving up your engine going into aerobatic maneuvers. Either way you're making a bunch of noise and giving up throttle response, accuracy, and making more noise with a 2 stroke.

I have a large-ish plane that I had a 120AX in, at 3.5HP. I switched to a YS 1.10 with only 2.5HP, but am getting WAY better aerobatic performance out of, due to the amount of torque. As soon as you hit the throttle, the power is there - immediately. I went from a 15x8 and a 16x8 on the 2 stroke to a 15x10 on the 4 stroke, and found that I needed much less throttle to fly the plane - making less noise, leaving more power in reserve for verticals, etc.

Just my experience and opinion. ;)

RE: 2stroke vs 4stroke
 

very nice explanation... would have gone 4stroke even if you said 2stroke... cause just look at this beauty...

http://i531.photobucket.com/albums/d...9/FA-82aGK.jpg

RE: 2stroke vs 4stroke
 

I got one! :)

RE: 2stroke vs 4stroke
 

dammit... thought I had something here, very nice man... I love it!

RE: 2stroke vs 4stroke
 

Mines a 100 though. Youll love the Saito! :D

RE: 2stroke vs 4stroke
 

I have a 65... liked it a lot... gonna sell it and add the rest for this one...

RE: 2stroke vs 4stroke
 

Why not opt for a four stroker that produces MORE than 1.75HP?

e.g a Saito 1.00 instead?

Saitos are great engine btw, my favorite four stroker...

RE: 2stroke vs 4stroke
 

But Laser Engines are good value because of the exchange rate, are easily the match of Saito's and have the valve gear at the back where it's less vulnerable in a prang.

RE: 2stroke vs 4stroke
 

I guess beauty is in the eye of the beholder!

RE: 2stroke vs 4stroke
 

Laser Engines look nice http://www.laserengines.com/ and the Laser 100 costs 235 Brit Pounds or $396 MSRP. Nice V-Twins too.

RE: 2stroke vs 4stroke
 

Never seen the Laser, is it an off shoot of the RCVs?? I liked the RCV but it's another of those engines that didn't take off very well in the states. Maybe it was the added break in time?? Does the Laser have a pump??

RE: 2stroke vs 4stroke
 

I'll Vote for the 82, here's mine
at work.


Bob

RE: 2stroke vs 4stroke
 

depends on what you are flying. i put a 4 stroke in a plane that likes some speed (yak 54), it just didnt work well, put a magnum 52 2 stroke in and boy did the yak come alive.
as for the torque argument, with a 13x4 on a os ax55 it will torque roll my plane faster than i have seen anything ever torque roll. (mojo.40)
yes the throttle response is better with a 4 stroke, and they sound cool. however they cost a lot, and dont save you any money in the fuel area. (most 4 strokes like 15%+ nitro, you can run a 2 stroke on 5% which is much cheaper than 15% and will last longer)

3d, 4 stroke is best, 2 stroke will work fine
pattern, either or
sports flyer, 2 are best, 4 will work fine
speed planes, 2 stroke
big, heavy planes that lumber aroung, 4 bangers.
thats my opinion

RE: 2stroke vs 4stroke
 

cause I wanna get the Extra 300SP and the largest recommended is 82...

RE: 2stroke vs 4stroke
 

You don't necessarily have to stick to the recomended range, that is just a suggestion.

RE: 2stroke vs 4stroke
 

It isn't like the 100 will tear apart your plane with all that extra power and it will slip right into that plane plus it will have a lot more uses down the road. A little extra power is a good thing.;)

RE: 2stroke vs 4stroke
 

dont overpower it. i made that mistake with my pheonix yak 54. i put a .91 4 stroke on it and with the weight of the spinner/prop/ect i added about 3/4 of a pound worth of extra weight (and th lead to balance it). the plane flew and has insane power, but if you slowed down, it flew horrible, it just wanted to fall out of the sky.
keep it light (smaller engine) and your plane will fly sooooo much better

RE: 2stroke vs 4stroke
 

Lasers have been around for absolutely ages in the UK. The proprietor, Niel Tidy, used to be a constant contributor to the modelling magazines with "build it yourself" articles for small diesels and the like. He then began producing 4 stroke engines in about 1986 with CNC machined parts, all from billet. The key feature of the Lasers were high performance due to the intake configuration and the ability to perform well with straight (non-nitro) fuel. Modern lasers use advanced cylinder lining techniques with some aesthetic changes to the machining. the intake and exhaust configurations are unusual and allow some re-orientation of the control link and needle directions.
I have one and it starts a dream (unlike my Enya that needs a starter). I prime by placing my finger over the carb and drawing fuel up by flicking the prop. I then apply a remote glow source and twist the spinner backwards against compression. The engine usually starts immediately, first time and burbles away very quietly. Pick-up is very rapid, I don't think a pump would assist at all and the power of the Laser 90 Mk 1 is excellent. I have run it off straight 20% castor, but I prefer 10% nitro with 18% Klotz Techniplate. After sales service is excellent with spares easily obtained direct from laser or carb spares from Irvine or Super Tigre.
Although Saito GK's look pretty, I think the Lasers are just as nice in a different way and are better looking and better performing than stock Saitos.
RCV engines are a completely different company. Their trick is to use a rotating cylinder liner as the intake and exhaust valve. (Hence Rotary Cylinder Valve). They have engines powering drone aircraft (Predator I think) because the engine is economical and less prone to failure because of the simplicity of the valve arrangement. One aspect of their performance is that the propellor turns at half the rate a conventional 4 stroke would for the same number of cylinder firings. This tends to make them suitable for larger props or multi-blades. the sound is different to a conventional 4 stroke. The in-line versions need a special starter adaptor. I haven't got one of the mor conventional lookig types, so I can't comment on how you start them.

RE: 2stroke vs 4stroke
 

I apologize for hi jacking the thread Switch.

This brought up a question in my mind...

If you are running a four stroke (ASP .71 Four Stroke engine) with 5% fuel - what would be the disadvantages of this?

RE: 2stroke vs 4stroke
 

for 3d YS are the best. Better throttle response and power than any other 4 or 2 cycle, except for a piped 2stroke engine. The only problem is that they drink a lot of expensive fuel. The .63 that I have runs like a champ.

RE: 2stroke vs 4stroke
 

I sure wish people would quit saying YS is a fuel hog, it is no different then any other four stroke and burns 15% just like OS and Saito. Mater of fact my YS 1.10s are better on fuel then my Saito 100s and about the same as my OS .91s. I even run 15% in the 1.40s. I have even tried as low as 5% and the only difference I noticed was the idle was a bit off and needed a tune up.

RE: 2stroke vs 4stroke
 

Switch,

A 4-stroke has a much wider power band than a 2 -stroke. All the "sensible" power from a 2-stroke is at the higher side of the RPM range.

RE: 2stroke vs 4stroke
 

thats good to know... now doubt about going for the 82a is the best option...

RE: 2stroke vs 4stroke
 

Is quite simple, to produce more power more fuel is needed. That´s a fact. And yes, maybe they run ok on 15% but they run a lot better on 20% and 30% becouse they where designed that way. Don´t get me wrong, I love YS engines (I have 3 of them), and in my experience, the higher cost of 20 and 30% fuel more than worth for the preformance you get.
Making comparisions is very subjective. I have the 63. on a profile, and it uses more fuel than 50sx that I had a few years ago in another profile. But the power and torque isn´t the same. I also switched, from my venus II, a 110(non s) for a piped 120ax, and the 120ax use less fuel becouse it can swing a bigger and faster prop.

RE: 2stroke vs 4stroke
 

i dont have a 70 4 stroke.
yes you can run a 4 stroke on 5% nitro, i have done it, it works ok. however your top end takes a hit as well as your idle.
i run my .91 on 10% because i have plenty of 10% and dont want to go buy 15% and lug two jugs around. it works, the idle isnt as great compared to ys20/20 fuel. and i loose 500 rpm on the top end. however i dont care, i bought a bigger engine so i wouldnt have to worry about fuel.
however most people here, and at my field, run 15+ nitro in 4 strokes.

RE: 2stroke vs 4stroke
 

Okay thank you.

I know that my friend, who has this 70 Four Stroke, complains that the plane isn't very fast and I know the plane doesn't idle well. I think I'm going to recommend him to try out 15% fuel then. Perhaps this will solve the problem.

RE: 2stroke vs 4stroke
 

If the fuel is blended for 2 strokes, you may find the excess oil causes the motor to quit at low rpm due to plug fouling and the low nitro content will give you detonation (pre-ignition or pinking) at high rpm, so you'll wind up running rich to avoid that, making your low rpm problems worse.

RE: 2stroke vs 4stroke
 

They are popular at my club in the UK, but their chief proponent has his YS engines serviced regularly every winter because he claims they "go off" due to wear.
The only engine I've ever had serviced was the Laser 90 I bought from an estate sale in 1990 because obviously it had been abused. Maybe I just don't do enough flying.

RE: 2stroke vs 4stroke
 

uhhhhh no. you would have predetonation problems if you are useing higher nitro, not lower. 2 and 4 strokes can and do use the same fuel (and it wount foul your plug). 4 strokes need to be set a little richer than two strokes because they have more moving parts.
if the .70 is new the idle is set wayyyy rich from the factory. if he hasnt messed with it that would be his problem. my .91 would idle reliably on 5% just at a higher rpm than 10-20%

as for the slow plane. if he is useing a 13x6 tell him to try a 12x8
what plane is it on?

RE: 2stroke vs 4stroke
 

Fours produce more useable thrust from tourqe, two strokes produce torque at a higher rpm when you enter the power band curve, but unfortunately, the prop slip will eat thrust when that happens. The most efficent prop is going to be a slower turning high pitch prop over a high speed low pitch prop. As far as the four stroke debate, they all operate in the same principal, the only one's that deviates from this traditional setup is RCV and HP, Hp used a rotary valve for intake and exhaust, called the VT series, and RCV does the same thing, but spinning the cylinder to acomplish it. RCV made a early design that ran off the cylinder or as we americans call it the "camshaft" that runs the valve train, but since the port for intake was the cylinder rotating, there are no camshafts or valve's, just a spinning port. The latest design is the same, but they use the crank as a output like a conventional engine, and I have one in my skybolt, it runs like a top and is very reliable due to the plug being shielded from fuel and oil till it's ready to fire via the port timing of the spinning cylinder. The low profile design is a perk but the weight is a negative, alot heavier than an conventional 4 stroke engine. Adding excess oil to a fourstroke prolongs life, but kills plugs and causes loading-up issues, running too low a nitro will not produce enough heat to keep engine at running temps, nitro adds heat, keeps elements red/white hot and since there is a longer duration between combustion cycles, the more heat the better it will stay lit for the next cycle. Generally low nitro will cause idle issues and loss of rpm, extremely high nitro will cause predetonation and excess heat buildup that the engine can't and wasn't designed to get rid of. Most 4's will run fine on 10% and much better on 15% nitro, only power junkies really see the difference using 20 to 30 % nitro. For most field flying, 10-15% will suffice, another aspect that I'm not looking to start a fire on is oil, I've been running everything with a little castor oil in the fuel or at least 50% castor, I look at it this way, if I have to wipe it off the plane, then it's lubercating the engine, if it vanishes, it was burned off in combustion and provided little or no help to the engine.

RE: 2stroke vs 4stroke
 

I'm sorry, but you have got this completely the wrong way round.
Adding nitro is the glow fuel equivalent of using a higher octane number. Everyone who drives knows that if you use too low an octane number (RON) fuel in your car, it can "pink" or knock because of pre-ignition. Modern engines compensate for this with knock sensors that adjust the mixture and the ignition advance/retard. higher Octane numbers permit higher compression ratios without ignition due to compression heating (pre-ignition).
My own experience of this in my four strokes is that the only engine of the set I have (Enya 60-4C, Enya 40-4C, OS40 surpass, saito 45, saito 90TD, Laser 90) is that the only one that will run on straight fuel is the laser 90. Everything else needs at least 10% to give good behaviour throughout the range and even the Laser runs better on 10% because it runs leaner and therfore has less plug fouling. The "Laser" will knock on straight fuel if it is too lean.
The needle valve isn't used to set the lubrication in the engine, it's used to set the fuel/air ratio so that you get correct ignition. If you think your engines aren't being lubricated enough you should buy a fuel with more oil in it.

RE: 2stroke vs 4stroke
 

While correct on the auto fuel, very wrong on the effect of nitro in model engines. Operation with increased nitro requires lower compression on the engine, not higher compression.

RE: 2stroke vs 4stroke
 

Oh-man, we started the fuel debate again,.......just find a fuel that runs the engine well and fit's your preference and budget. I'll burn a gallon a day running about 8-9 flights on my skybolt or TF P-47, so cost per a gallon is important, on 40 sized planes, performance is more of a factor, so they get the better fuel because I can get twice the number of flights out of a gallon. All my fourstrokes have been treated normally, I forget to put afterrun oil in them every now and then, I try to mix the little bit of old fuel with the new gallon and when I run out of 15% I will run it on 10% for some of my other planes, I just realize that it's not going to run the same as the other fuel and tune it accordingly. I'm more interested in flying on the wing rather than the prop so that is where I stand on tweaking engines to get every last drop of power out of them. The wear of an engine can be offset by running a lower nitro, if compression decreases the lower nitro will make the engine run cooler, this will keep the interfearence fit between the piston and cylinder tighter, hence extending the usable life out of a worn engine, also adding castor will help seal the fit at top dead center. So with that bit of knowledge, if you normally run your engine on 15-20% nitro and decide to run on 10%, imeaditaly, plan on breaking it in again because the fit will be tighter due to the lack of thermal expansion.

RE: 2stroke vs 4stroke
 

Aint this pretty! :)

RE: 2stroke vs 4stroke
 

4stroker in a drag car!!!... yours???

RE: 2stroke vs 4stroke
 

awww i love my lil 2 strokes! super tigre G90 makes me smile! but 4 strokes are Very nice!!

RE: 2stroke vs 4stroke
 

Naw, I think its iin Austrailia. Somebody posted it on my site awhile back.

Notice the blower?