40 size OS engine
 

What can I do to get more power out of my 40 size OS engine?

Thanks for your input.
Rick

RE: 40 size OS engine
 

More nitro but that will give you a couple of hundred RPMs only ... move up to a 46 perhaps? :)

RE: 40 size OS engine
 

Get a Diesel Head for it

RE: 40 size OS engine
 

Retime the crank, retime the ports on the sleeve....add a tuned exhaust system. Add nitro.

I would personally go out and buy a .46

If you can afford an OS 46 AX...that is a terrific engine. Also, an Italian made Super Tigre .45 ABC is really one of the best .46s out there.

RE: 40 size OS engine
 

put a good muffler on it.

RE: 40 size OS engine
 

46 ax is a great engine. Sell yours and pick one up used.

If not, check and see if the tower hobbies .40 size muffler will fit your engine. They are said to give a little boost in performance.

RE: 40 size OS engine
 

If your muffler has a baffle in it, take it out. Or put a tuned pipe on it.

A guy in our club had a 40 size engine on a sig couger with a tuned pipe and it would go over 100 mph.

RE: 40 size OS engine
 

Lots of beginners ask the same question, "how can I get more power", about engines.

First thing to do is try a couple of different props. More times than not, beginners bolt on the prop somebody said was the best for the engine and done nothing since. Seldom is somebody else's opinion better than the opinion of the engine on your airplane. And more times than not, you'll find better performance if you test a few props.

As for boosting the power of most engines, beginners won't come close to being able to do anything of the sort. Higher nitro is about it, unless there is a muffler made for the purpose. There used to be a "tuned pipe" muffler for that size engines. It wasn't actually a tuned pipe but it looked sorta like one and it actually did up the power a bit.

Simply running the engine with a prop that'll let it turn higher rpm gets more horsepower, but unless the engine/airplane combo like the new pitch you won't gain a thing other than louder noise.

RE: 40 size OS engine
 

Upgrade to a .46 AX if you can.

RE: 40 size OS engine
 

At last, a great reply!!!!!!!!!!!!!! Just changing the prop can make it run a lot better!!!!!!!!!!!! Basic Prop rule of thumb. Shorter prop with more pitch=Faster plane. Also means more roll out needed for take off and the plane doesn't slow as much for landing. Longer Prop and less pitch=more torque but a slower plane, uses less runway for take off and slows for landing better. Much better vertical pull. That is just the basics though and you never know what the plane/engine combo is going to make the pilot happy. If prop testing doesn't make you happy then get a bigger engine. I have never tried a diesel???? Read about the heads though, sounds good.

RE: 40 size OS engine
 

What makes you believe that your 0.40 is not doing its best, Rick?

RE: 40 size OS engine
 

Iwould like to see some tach readings to see if your engine really is low on power or just over propped or something.

RE: 40 size OS engine
 

Wow.. Rock and Gray Beard.. a sensible answer.

I keep saying "more noise does not equate to more power". All the gimmics have been tried several times over and none work. If the plane/engine/prop combination is working, and is the right combination to take off, fly, maneuver, and land safely, then you have the right combination. If you really want to increase the power well, a bigger engine more than likely your best bet.

If you prop down and get more RPM, well, you lose on the thrust and make more noise.. again.. more noise. Changing fuel mixture will only give you a small percentage of increase in power, and probably nothing that the flyer will notice to make it worth while.

As said, play with different props around the recommended size and go for the best combination. Then if you are still not satisfied, well, that OS .46 AX will do wonders.

CGr.

RE: 40 size OS engine
 

You could use a Magnum .46. It's a great engine, and it's on sale now for 49.99.

http://www.hobbypeople.net/gallery/210756.asp

RE: 40 size OS engine
 

Ihave seen a member try to fly a heavy trainer with a .40 and a 10X8 Top Flite prop. A 10X8 is bad enough but a Top Flite prop has a much higher loading than most. Ibarely flew. He simply switched back to a 10X6 Master Airscrew black and it flew correctly. Still it was a bit under powered for the weight of the plane.
2 stroke glow engines are like any other engine and respond to mods just fine.

RE: 40 size OS engine
 

Put a 9-6 on it.

Super Tigre recommends these props for their 40 size engines.

Recommended Props: 9x5, 9x6, 9x7, 9x8, 10x5, 10x6, 10x7, 11x4, 11x5

http://www.supertigre.com/engines/supg0122.html

O.S. always recommends larger size props on their engines to reduce noise levels over there.

Check any of these ST engines below for prop sizes and compare to OS engine props if you'd like.

http://www.supertigre.com/engines/index.html

big dan

RE: 40 size OS engine
 

Wow, so a good exhaust that can give 15% more power is a gimmick? The OP doesn't say what engine however, if its an OS LA don't bother with a tuned muffler but an supertigre 40 or similar will respond nicely. Taking the baffle out if there is one usually gives a few extra rpm's (more power and noise) and doesn't cost anything.

RE: 40 size OS engine
 

Not if it actually gives more power, any amount.

Unfortunately, there aren't many of them around. Do you know of one?

RE: 40 size OS engine
 

Unfortunately there aren't many around, Jett makes the jettstream tuned exhaust. They are expensive at around $60 however but perform very well and are less expensive than a new engine. I don't know if performance specialties is still making the ultathrust pipes.

RE: 40 size OS engine
 

OK, for the hot rodders. In our racing class one of the engines required was the OS .46 FX. By milling down the head with a wet dry sand paper on top of a glass sheet then taking tach readings over and over until the RPMs raise then start to drop you can gain a little. By using the burrs on my dental hand piece I could smooth out the ports and do the same thing and get a little more. Is it worth the time and trouble?? No. You could also destory an engine doing this or just make it worse then it was. A MACs Exhaust system will add some more beans but at the cost of over 40 bucks. A hand full of good APC props and doing some flight testing is a lot cheaper and teach people what the correct prop on any given plane will do. If all out speed and power are required then there are a few good engines like the Jett to start looking at. The price of some props or a bigger engine is just a good idea unless you plan on going racing. RPMs don't always equate to power, in drag racing we shifted at the peak power band, not the top RPM.

RE: 40 size OS engine
 

"Is it worth the time and trouble?? No."

That is rather subjective isnt it? Igo through all the time and trouble to port and polish some of my engines and I like the results.

RE: 40 size OS engine
 

Not when you consider that you could have boubht the larger engine in the first place with the cost offset already priced in.

Note, that he said that there is a downside to this. The person could ruin the engine <if not done right> . So, where's the savings there? Consider that this is a beginners forum, and most posters asking questions like this are, by definition, beginners, and may not have the necessary experience or, for that matter, the knowhow to do this sort of modification.

CGr.

RE: 40 size OS engine
 

Iapologize. My remark wasa aimed at Graybeard and not at the original poster.
If the original posters only concern is that his trainer is not going well enough for some unkown reason Ithink the has been addressed already.
However if the original poster has advanced to a level to which his 40 size engine is not fast enough I would be happy to teach him a few simple methods for extracting more power from the inexpensive engine he already owns rather than spending a bunch of money on a bigger engine. He is welcome to PM me if this becomes too controversial.

RE: 40 size OS engine
 

I'd like to know which OS 40 size engine he has.

I once had an OS 40 LA and switched to an OS 40 FX and never looked back.

The difference in power was amazing!

big dan

RE: 40 size OS engine
 

Hi!
Use a tuned pipe!

For what airplane do you want more power??
In a high winged trainer a 11x6 or 12x4 APC or RAM propeller MA prop if you fly at sea level.

But if you have a low winged sport plane, a 10x6 or 10x7 APC or RAM prop might be a better choice.