Has anybody used the Slimline 4-Stroke Muffler for an OS FS-91 II Surpass?

This one:



I am thinking of using one to mount the engine horizontal in a Y/A Extra.

Do these increase the noise significantly? Do they cause problems with not enough back pressure to supply fuel to the engine?

Any other tips?

Maverick- thanks for asking about that muffler.

I have a couple .91's and have considered using it.

So nobody has had any experience with this thing?

Haven't used one for a .91, but I have used basically the same product for the O.S. 1.20. Worked fine, and met our field's 98Db at 3-meter rule..... came out at like 96-97Db with an APC 16x8 prop.

BJH

Mav- Take a look at the Bisson version as well to make a fair comparison.

Why not use the stock muffler? Certainly you can reposition it
to effectively be out of the way?

I just received mine yesterday with my new OS .91 4 stroke for my GP Lancaire.

I assembled the engine and muffler last night to see what it looks like. I like it so much that I will be buying another and replacing the stock muffler on my World Models Midget Mustang.

Sorry, it's brand new. I can't give you a flight report.

Don

I didn't know Bisson made a muffler for a 4-Stroke. I thought their mufflers were all Pitts style for 2-strokes.

I guess I could, but as the engine will be on it's side rather than inverted, I just feel the muffler will be hard to position and need more of the cowl cut away.

If I go with this Slimline muffler, it exhausts straight down behind the engine and should not require much cowl cutting and also make it easier to replace and remove the cowl after it is mounted.

I always hated having to remove the muffler from my OS FS-70 II in my WM P-51 whenever I wanted to remove the cowl.

Let us know how it goes when you get to run the engine. I am mainly concerned about having enough back pressure to push the fuel into the engine, as I have heard some Pitts mufflers have problems with this.

I have Bisson Pitts mufflers on a variety of my 2 stroke motors (ST .51, .90 and OS .46) and don't have any problems with fuel draw.

Are you talking about 4 strokes?

Don

Actually the only engine I have heard having this problem when using a Pitts muffler is the OS 1.60FX. It maybe a problem only with larger engines that require a much higher fuel flow rate.

I just wanted to make sure there weren't other engines with the same problem.

I have this muffler on a Saito 180 mounted in a H9 quarter scale Cap (The blue and white one). It had the stock muffler in it originally. I love it. It's seems slightly quieter than the stock muffler. Also, I have not had any fuel flow problems, seems to provide plenty of back pressure. I have the smoke version, but have not yet run smoke through it.

I did have to cut a notch out of the cowl to accomodate the can part of the muffler. The Cap cowl easily accomodated the Saito on its side, but the cowl narrows below the cylinder head location and that's where this muffler sticks out.

Jason

Thanks! This is the type of information I was after.