2ManyHobbiesWI

I have found that the exhaust deflector that I am using will not stay attached to the muffler on my Magnum .91 at full throttle. The nub on the end of the muffler is not long enough for a secure attachment! Without it, the exhaust sprays directly into my wheel bay for my retracts. Oil in new wing= not good! How do I keep the deflector attached? Are there any other options on the market that work well? Thanks!

Razor-RCU

My Feedback: (50)

Rough up the area use some slow Zap and zip ties--- other than that I dunno...

WorldTraveler

I've seen others use a bit or wire twisted around the area that does slip over the exhaust outlet, then run it over and secure it to the engine mount or head somewhere. Another idea is to use a cable tie and secure the wire to it, this would prevent the wire from cutting the rubber on the deflector.

Clint

DarZeelon

Travis,


I have seen the mere installation of a Hobbico exhaust deflector, reduced the RPM of a muffler equipped MVVS .49, by over 1,000.

I cannot guess what it would do to your engine...


Using 1-2 zip ties on the channeled end, tightened firmly around the muffler outlet stack, will keep it from being blown off.

coralcape

My Feedback: (4)

Drill and place a #2 self tapping screw on the end of the outlet pipe, force the deflector over this screw and put a small tiewrap tightly upstream of it. The screw head bump is what does the job. Good luck, red

richrd

Dar
Are you saying the deflector increases back pressure. If some one mounts the tank to low would this be an easy way to increase pressure �verse baffle� . Easy fix for lean running Tower engines. Just lose some RPM instead of fishing line sinker.
Rich

wcmorrison

My Feedback: (2)

I have a fellow flyer who is plumber, he uses old copper pipe to make his extensions. He force fits it on the muffler stubb. You might try Home Depot or Loews for some copper pipe to make you extensions and make an interference fit on the muffler.

Muffler extensions can and do cause some loss of performance, but in this case one needs the exhaust to clear the wheel bays. In that case I would open up the muffler and remove the internal baffle. Sort of a trade, gain some performance back but the net loss is probably the out come. But if it flies well who cares.

Cheers,

Chip

DarZeelon

Rich,


It could be the specific lengths used by the muffler and deflector components did increase back-pressure, but I am more inclined to believe they were 'inadvertently tuned', to decrease VE in the RPM range the engine was spinning.

I cannot be sure, since I do not recall if I had to close the needles, to compensate for excessive fuel pressure, or not.

...My engine sure wouldn't mind forgetting those few all up-hill flights...

richrd

It would be odd if this is why some people get totally different results from same engine and it's they just put on deflectors. I myself put them on all my sport planes an begin thinking now this is why I've never had lean problems and also explains why I’ am a thousand off most people’s tach.
Again thanks for reply it make things clearer now to me.
Rich

Deadeye

I've got the Dubro extension on my Magnum 91 on my TF 182. The muffler sits pretty close to the firewall, and the cable ties bump up against it to keep it on. I tried wire once, and it gets too hot and burns through the silcone. Lasted less than 30 seconds before it burned through. As mentioned above, try a small screw to give the extension something to grab.

Also, there is no performance loss using an extension on a 4 stroke motor. The 4 stroke makers make up to 10 inch extensions for their motors.

Sport_Pilot

I assume the muffler is lower than the wing, if so I would simply trade in the muffler for a tuned pipe.

Ladyflyer

My Feedback: (2)

While a 2 stroke may be sensitive to back pressure and reverse waves etc, the four strokes are nearly immune to reasonable changes in the exhaust system. I doubt the power loss here is cause for concern. We usually use the wire trick already mentioned above.Pretty simple and no modifications are required. Two or three turns around the extension then a twisted section going forward, usually to the muffler front. Wrap a turn or two around the front and finish with another short twist. ....... A dash of Horseradish and a sprig of..... Ooooops a different recipe
Edited corrections thanks to my personal proof reader, general fault-finder and pretty much perfect person, Dar. Thank you Dar for being there!
My fault for trying to squeeze in a comment at break time

Ernie Misner

Clean the muffler and deflector really well to get all oil and grease off. Then rough up the muffler a bit with sandpaper or steel wool. Apply a dab of high temp silicone before pushing the deflector on and using 2 zip ties to secure it.

Also the little sheetmetal screw head will do a good job of keeping them on. Another approach is to put a little bead of JB Weld around the end of the stinger. That will keep the zip ties from getting past it.

Our hobby shop owner says that 4 strokes get too hot for an exhaust deflector, but I sure see a lot of them at the field.

Ernie

2ManyHobbiesWI

Wow, a lot of good ideas! I need to test my latest engineering feat: I took a small aviation hose clamp and tightend the deflector onto the end of the muffler. It sure holds better than the zip strips! It is just about time to fire up the engine and test it. I will let you know...

Ernie Misner

Hey, what does an avation hose clamp look like????

Thanks,

Ernie

William Robison

My Feedback: (3)

Ernie:

I think he means an odinary automotive screw clamp. Many call them "Aviation" clamps, but if the FAA inspector saw one on a plane he'd go looking for the mech that signed off on the installation.

Bill.

William Robison

My Feedback: (3)

TooMany:

Some engines will not run well at all with anything added to the exhaust, others don’t seem to notice it at all. One of my old tricks is to stick a length of silicone hose on the muffler stinger, and tie the other end to the landing gear strut. All the oil blows away underneath, the plane stays clean.

The fanciest exhaust extensions I’ve cobbled up are on my Tiggerkitty, with its twin AMD engines. They run fine with them. The muffler outlets blow into the forward end of AeroTrend blue silicone hose, the hoses come out near the tail end of the nacelles.

First picture shows the outlet, second shows the hose inside the nacelle, and the fuel tank.

Bill.>>EDIT: Loaded the wrong picture. And that's why the second should be the first. wr.

Ladyflyer

My Feedback: (2)

QUOTE:

Sport_Pilot
Super Contributor
Posts: 4882
Joined: 1/21/2002
From: Acworth, GA, USA
Status: online
"I assume the muffler is lower than the wing, if so I would simply trade in the muffler for a tuned pipe. "

2ManyHobbiesWI

Well, the screw clamp did not work. Off to round 2.

Deadeye

Bill, on that second picture, is that a spring strut? Homemade dealy? Please share more.

William Robison

My Feedback: (3)

Randy:

It is indeed a spring strut, home designed and home made. It uses the hairpin spring, with the forward ends bent across to act as the scissors for the strut, and it also holds the assembly together.

Here’s a picture of the nose strut, it’s made a little differently but still the same idea. Because of the ½ yoke for the nose wheel I didn’t have enough room to make it the same way, the pivot axle for steering is mounted behind the suspension cylinder.

Also a picture of the lower part of the main strut, should give you a pretty good idea of how they are made.

If you would like a complete copy of the post I made a long time ago, including illustrations and the way to make the flush hubs, send me your email address, I’ll send it to you.

Bill.

Ladyflyer

My Feedback: (2)

The reason many people call them "aviation clamps" is due tothe manufacturers use of that term on their packaging.

doubledee

My Feedback: (4)

What the heck do the manufacturers know anyway? Especially when it comes to setting up and breaking in a new engine.
Regards,
doubledee

Gringo Flyer

My Feedback: (18)

On my extensions I use a zip tie tightened down but not overly tight and then RTV. A bead of RTV on the muffler and over the first rib of the deflector and the twist tie seems to hold the extension pretty tight. I have this on my ST90 bc the exhaust goes straight back and there is no way to rotate it. I havent noticed any RPM losses.

carrellh

Drill a 1/16 hole through the deflector and the muffler outlet, run stainless steel safety wire through the hole and twist the ends. I think my wire is .043" but I'm not sure. This is a TT-61 Pro muffler and a Hobbico deflector.