Mr. Bagle,


I also used a deflector on my MVVS 1.60 glow, with the MVVS #3266 tuned pipe.

It pulls like an ox! I cannot tell you the exact RPM difference, if there is any, but the deflector is the same i/d as the pipe's stinger, so it essentially both extends it and bends it...

It is the .35-.90 size extension, but it does not seem to choke the engine down, like it did on the MVVS .49.

I think Dar has hit on something here. It's probably going to come down to a try it and see how it works for your particular application. From the posts so far it appears some are getting losses and some are getting small gains depending on the particular engine and exhaust combo.

I can't quote the numbers, but I had a deflector on my OS 46AX, and I gained a few hundred RPM's by taking it off.

It wasn't huge, but it was enough difference to convince me I didn't want it on!

I gained RPMs on two engines... bumped my old thread.

somegeek

I was breaking in my O.S. .91 4 stroke engine when the exhaust deflector fell off. Lost several hundred rpm. While the engine was running, I temporarily replaced the deflector. Rpm went back up to previous value. This engine seems to like the deflector. I will drill/tap the muffler for a 2-56 screw to provide a knob for the deflector so it won't slide off.

Chuck.

This is getting interesting. There must be some common thread to all this.

I have had a similar increase to (Ken6PPC OS46AX) on my OS55AX with the Deflector off.

I believe there is a slight increase in power now.

I had already taken the baffle out of the muffler and will continue to run it without a deflector for now.

Unfortunatley I do not have any quantifiable figures as to RPM or power increase. It just seems slightly better.

So far the OS 91 4C-
SuperTigre 51-gasoline -
Webra 55 and Jett muffler- Have slight reported gains in RPM.

OS46AX
OS55AX Slight decrease in RPM.

When running a tuned pipe, the deflector does not make much difference, it may tend to increase the RPM.
On a stock pipe, it lowers the RPM. I have seen this on many of the engines I run. All of these are two strokes.
From the posts in the thread, it would seem that this deflector increases RPM on a 4 stroke.

I agree Jez. At our field, I have noticed that some win and some lose, depending on the engine and muffler setup. A non flexible extension (rather than a flexi plastic tube) seems to have the best shot at improving performance.

A flying bud got 300 more rpm (repeatable tests) out of his GMS .47 by adding a 3 inch carbon fibre extension to his Tower muffler stinger.

Harry,

Interesting point.

I havnt tried a straight pipe extension, only the bent silicone extension.

I will look out for a suitable straight pipe and try, as i would prefer to port the exhaust further away from the Fuse and tail.

Ive also wondered what effect an extension pipe with a larger diammeter hole. What effect would a pipe two times the diameter of the muffler exhaust have.



Wheres the flying site in AKL.

I was told (by a non model flyer) it was around here.

I need to try that. I have a Tower Muffler that I can put on my plane and see how it works out.