OS 46 SF baffle vs. no baffle

A short run of this engine first with the muffler baffle installed and then without. It had a 1500 RPM increase without the baffle installed.

[@michaelmatus4005]

I fly nothing but glow engines and I always remove the baffle. Good to know that I get a performance increase. Also, so far at my field no one has complained to me about the noise. I have a muffler on the engine.

[@vincentrobinette1507]

With the affinity laws of a propeller, that 1,500 RPM increase is a significant increase in horsepower. Every time you double the speed of a fan/prop/impeller, the torque needed to run it goes up on the square, X the increase in speed. That means the power goes up on the CUBE of increase of RPM. I haven't done the math, but you're increasing horsepower by at least, 40~50%, by removing the baffle. I actually gained power, taking the spark arrestor screen out of my 2 cycle leaf blower. Anything that reduces exhaust restriction, allows an engine to take on more air, (and fuel) and produce more torque. it seems to make a much bigger difference for any 2 stroke engine, than for a 4 stroke, although the 4 cycles engines also benefit, but to a lesser degree. 2 stroke engines rely on exhaust scavenging, which requires the exhaust to maintain a high port velocity, which is severely dampened by the restriction of the baffle.

[@davelowets]

Removing the baffle will increase the engines power, but it will also make the engines tune more finicky as the fuel level in the tank changes. Removing the baffle makes the pressure going to the tank, from the muffler, less consistent and affects the tune throughout the tank. If you remove it, just test to make darn sure that your engine doesn't run lean as the tank runs out. Also, the baffle being gone also increases the effects of the fuel ratio change from nose up, and nose down, compared to level on the aircraft. Test all of this before you call it good when you remove the baffle.

[@MURDOCK1500]

We did something similar. Me and my mate had similar models. Mine had a Magnum 40 which was an OS40 copy. My mate had a stock OS40. My model performed much better but was noisier. So anyway we did a thrust comparison test on his plane using a spring balance. Long story short, when we fitted my unbaffled Magnum exhaust on his engine it produced an extra 1 pound of thrust more and performed very well after that with a Magnum exhaust fitted. Another thing we found is that those silicon pipe extensions you can fit also sap a lot of power. Your better off with an oily model

[@vykdp]

Você complementos com propriedade, parabéns valeu.

[@midwestsirens]

Holy cow, that thing ran forever after you ripped off the fuel line!

[@davelowets]

Yea, seemed rich to me.

[@125saito]

Ha! "It's a little warm" Finger prints burned off. I think it's great when you put up the changes you are making when tuning the motors. Very helpful.

[@dmrcflyr2]

Yeah, LOL, I remember that one too. Now I use the ove glove to handle all hot parts.

[@125saito]

Yep, live and learn. Good vid Dave.

[@dmrcflyr2]

No, I don't learn...... Burned my hands hundreds of times in this hobby alone let alone other endeavors.

[@petergoodwin2465]

@@dmrcflyr2 i never learn either, was cutting out rocker panels on an old Mopar, i knew the steel was sharp and still grabbed it without gloves . Cut all the way across my fingers . I never learn .

[@halleffect1]

helpful video, thanks. i like how the prop straitened up under high rpm.

[@craigvanderborgh4324]

I just tried this out on my new OS MAX 75 AX. I removed the baffle from the PowerBox muffler (#4040) and it made almost no difference.. about a 50 RPM increase. Wonder why that could be. I am at 5300' altitude.

[@davelowets]

The current state of tune will affect the power difference of baffle Vs. no baffle. The closer it is tuned to perfection, the bigger difference it will make.

[@rscarawa]

I would also say it sounded real rich on the high end for the first run with the baffle. Needle sounded closer to correct without the baffle. I guess you got more tank pressure with the baffle in. Just a guess. I like your video series'. I am thinking of doing the same for some classic motors.

[@JackieAudio]

So do I think - with baffle was too rich so the differenc in rpm was so big. Try to regulate engine to the highest rpm with and without baffle.

[@dmrcflyr2]

It is doubtful that I will run this experiment again. I have many other projects that take a higher priority over this one.

[@rudyprikosovich8113]

Thank you enjoyed it

[@pokiou]

new to nitro planes, quck question... do all exhausts have a baffle in them and are they removable? for example an ASP 52 4stroke ?

[@dmrcflyr2]

No, four stroke mufflers are not designed to be disassembled. Any 2 stroke muffler that has a screw running the length to keep the 2 pieces together most likely has a baffle of some sort inside that can be removed. Why would you even want to mess with a 4 stroke muffler to begin with?

[@davelowets]

No and no.

[@driverman8615]

Would love to see how you made your test bench!

[@tylercurtis441]

my os 46 ax 2 max will die at WOT randomly causing me to land not in the best of places, what am i doin wrong???

[@midwestsirens]

Probably the tune.

[@cymaz100]

Over heating, running too lean, I would guess

[@Jswizzle8r6161]

Can you please tell me whats the difference between the O.S. .46 fx , .46 fs, .46 AX ,...? Thanks , also which engine has more power? Thanks

[@user-fm5ni1yp9k]

Hello how many revolutions of the main needle did you have when starting the engine?

[@needmoreboost6369]

If Exhaust tuning carburettor tuning is essential!

[@rscarawa]

One question. Is that screw threaded into the rear part of the muffler? I have an FP with a similar muffler and the two units are seized together and I cannot get that screw to move either. If that screw is not threaded into the rear part, then I will consider pounding it out once the nut is off. Trying to figure out how to disassemble so I can redirect the exhaust where I want it. Thx

[@dmrcflyr2]

It is thread into the rear of the muffler. Just use 3 in 1 oil and heat to loosen it up. Very easy. Just beware that the screw head is very soft and will easily strip out. Remove the nut on the end first.

[@extra330sc]

Did you peak the needle before and after you removed the baffle? Before and after noise readings would be helpful also.

[@dmrcflyr2]

You realize that you are responding to a video that is 4 years old right? What you think would be helpful is irrelevant at this point.

[@RodrigoSotoCastro]

I have a dumb question. Why fuel line looks empty? Transparent line shouldn't take the color of the fuel?

[@dmrcflyr2]

The line is not transparent/clear. It has a blue tint to it that makes it difficult to see the fuel in it unless you are very close. The fuel is a light pink color as seen in the tank. The tank is not colored not clear, yet you can see the fuel in it. So compare the color of the tank to the fuel line. Not the same are they?

[@RodrigoSotoCastro]

@@dmrcflyr2 Yes I can see now. Thanks for the answer!

[@scotty1004]

Does removing the silencer from a 4 stroke engine cause power loss?i have a gas saito fg14 i want to remove just the silencer and have just a 4" bit of pipe coming from the head

[@davelowets]

Not nearly as much as a 2 stroke.

[@davidharrison1572]

How about drilling a few holes in the baffle

[@petermaidment1175]

Hi David, i know this is an old video but how come the engine ran on so long when you removed the fuel line? Thanks Peter

[@dmrcflyr2]

I only counted 3 seconds from pulling the line to the engine dying. That does not seem excessive to me.

[@petermaidment1175]

Ok thanks

[@markcummings150]

I noticed that too. I’m guessing there must be a small amount of fuel in the needle valve inlet.

[@davelowets]

@@dmrcflyr2 Huh? 🤔 Watch the video again... 12 seconds went by, with an engine rev in there, before it died. The engine was hella rich, and had a TON of fuel built up in the crankcase.

[@jmaclaren4147]

Miss ye videos Dave

[@guitarcleveland]

If you remove the baffle does it mess with the back pressure and reduce fuel flow, to the carburetor making the engine too lean?

[@dmrcflyr2]

I don't recall if I readjusted the HSN during this or not. So long ago. But anytime you change something on an engine, glow plug, fuel, exhaust, there is always the chance that an adjustment will need to be made. Tuning an engine is just part of owning an operating glow engines.

[@guitarcleveland]

@@dmrcflyr2 Thanks for the response

[@georgichochev8418]

what kind of fuel are you using? asking for my Os Max 25 Fx,thanks

[@dmrcflyr2]

That is a very old video and I do not recall what fuel I used. But what difference does it make? Any glow engine fuel between 5%-10% is fine to run that that engine. Or you could also look up the manual. Glow engines are not that particular regarding fuel requirements. I also have numerous videos showing the types of fuels I use, so explore my channel a bit.

[@rscarawa]

that is a huge rpm difference just for a baffle. What glow plug is that?

[@dmrcflyr2]

It looks like an Enya #3. I know I was experimenting with using them on 2 stroke engines for awhile.

[@rcfred_689]

Did you run it with a tuned pipe?

[@dmrcflyr2]

No, I do not use tuned pipes.

[@manolocordovez9323]

Thanks for the video!

[@cetGT3]

It was more responsive as well! So where goes what the experts say about the scavenging effect of muffler then if this test proves it achieved higher revs and more responsiveness without the baffle !

[@davelowets]

No expert has ever disagreed that an exhaust change won't affect power.

[@user-fm5ni1yp9k]

Hello to your glow for a candle what battery? 3000mA?

[@dmrcflyr2]

I do not recall. Just buy a glow driver for a glow engine, you do not need to worry about the battery as it comes with it.

[@user-fm5ni1yp9k]

@@dmrcflyr2 I have 5% methanol fuel and the engine does not work from the glow of the candle... 1700 mA battery....

[@dmrcflyr2]

@@user-fm5ni1yp9k well then I guess you have some trouble shooting to do then.

[@blakjack3053]

Real late to the party lol but very informative yo! I'm gonna have to try that out on my OS.40sf

[@dmrcflyr2]

You might want to watch the revised video on this same topic. kzbin.info/www/bejne/bKbYnqeceKh0p6c

[@looneytunes47]

But will it blow up and take away life from the motor???

[@dmrcflyr2]

Is that a serious question? Yes this will absolutely cause the engine to explode, do not try this at all..... LOL

[@Aviator111167]

good stuff

[@edgarguzman7895]

Would you sell me two of those engines completely set up ready for install with the propellars and all

[@dmrcflyr2]

Wow really? First you assume that I would have 2 of these engines. Then you assume that I would do such a thing for a faceless stranger on the internet. Get real and get some etiquette.

[@thebug4046]

much better with out!

[@tristanruel]

Does the baffle help with then?

[@dmrcflyr2]

Define help? The baffle is in place to reduce the noise of the engine. It also reduces the peak RPM of the engine.

[@tristanruel]

So it reduces the noise. I suppose if your testing in the city you want the baffle but when you go flying you should remove it.

[@dmrcflyr2]

That depends on WHERE you fly and if the field is an AMA sanctioned field. They have noise restrictions as do most clubs in urban areas.

[@davelowets]

The baffle is NOT "just for noise". It also helps to make the engine less finicky tuning wise because it helps to keep the pressure going from the muffler to the fuel tank more consistent, hence less variation in air/fuel ratio as the tank goes from full to empty. If you have a perfect tune, and then remove your baffle, you WILL be lean as your tank runs low. Also, the tune will NOT be as stable when the aircraft transitions to nose up, and nose down, from level. You will NEED to test all of this after you remove your baffle, and set your tune accordingly. Some racing clubs do not allow competitors to run without a baffle in competition because it's seen as an "unfair advantage" to the guys that don't want to deal with or risk the exaggerated effects on the tune as the fuel level varies in the tank. One CAN damage an engine by removing the baffle if he doesn't compensate on the tune for the varying fuel pressure that results from removing it. It's not just a "free horsepower tip" that doesn't have consequences. Tread carefully.

[@redbearrc6706]

Just bought a used 46 SF. I will remove it.

[@driverman8615]

A video on how to make a test bench would be cool. Just saying is all.

[@davelowets]

Use your imagination, its fairly simple.

[@mayamaya2068]

Nitro engines are for real men