I just bought another Brison 3.2 and was wondering if the Bisson inverted mufflers take some power away from the Brisons. James at Kange the distributor of Brisons now says yes some power lost will be noticed. Any comments i have always used the standard downdraft mufflers Brison use to sell. They are super loud .

Bruce,

I haven't seen any difference with the wrap around versus the down draft. If you want to make it sound a lot better, without increasing the noise, call Bisson and have them put the same diameter pipes on the 3.2 muffler that they do on the 6.4. The pitch goes waaaay down, even though the db level remains the same.

Pat

I use the standard (Not the pitts style) inverted large volume muffler with the tips cut off. If any thing I gained RPM and have a much quieter engine. The internal diameter of the pipes Bission use on their inverted muffler and the standard Brison exhaust diverter are the same. You just need to cut the rolled tips off of the muffler.

I have used the Bisson inverted and pitts mufflers on 2-2.4ci engines and one 3.2ci engine.
They are by far the quietiest of the mufflers that I have used on these engines.
The only problem that I had is that the mounting flange over time will break.
I assume it is due to repeated heating and cooling but I don't know.
This has happened on all the pitts (2) and one of the side mount (out of 3)

Geistware, do you think a brace like I am using on my modified Bisson muffler would help the problem? It's attached with socket head screws and JB Weld.

Ken

Ken,
Yes, I do think the brace will save your muffler but I don't expect the JB weld to last very long in that application JB weld debond's with heat. That is how I get it off of parts. You may want to weld the bracket to the muffler and make sure it is bolted to the engine and not the firewall. You installation loosk good to me.

Thanks guys for the tips , just for info Kange who markets the Brisons now has 2 or3 left of the 3.2 motors he just got them in yesterday and they are all just about sold allready. I ordered one for my Lanier Giant Stinger, i had the Brison 4.2 on it last year and it was way to much motor for the new arf version stinger. I think the 3.2 will be about right. Thanks again i will cut the pipes off where they are rolled, i have heard that suggestion before. Bruce

Geistware, the plane has about 20 flights on it with the muffler in this configuration with no sign of deterioration of the JB Weld. I didn't use the JB Weld as the primary attachment. I think that the reason that it is holding up is because there is a lot of airflow around the top of the muffler. It is not like being in the direct exhaust. The reason that I installed the brace is that the muffler mounting screws kept loosening up. As far as being attached to the engine, for all practical purposes it is since the screw goes through the bracket, engine mounting plate, and then into the firewall. No movement in the bracket. The bracket idea came from using the bracket on my Bisson Pitts style muffler on my ZDZ80RV.

You are right, welding the bracket would have been the best choice. However, I thought I would try it this way before taking it back to the welding shop and spending another $20 bucks.

Bruce, good luck with your 3.2 and Giant Stinger. I would have probably stayed with the 4.2. As Terry says "Too much power is just about right."

Ken

Ken that sounds good and if it works go with it.
For your bolts, try the red RTV for high temps.
It works great and that is what I use.

Wings is right on this one. Lots more power with the tips cut off. I just used a disc sander to sand the swaged portion off. The light aluminum sands easily. I didn't have a band saw and I can't hacksaw anything straight.

I agree the Bisson muffler is will allow your engine to turn faster with the tips cut off or reamed out. It will be louder. If you don't beleive me then take an "in the air" measurement before and after.

ALSO, I found that JB Weld is good to 600 degrees F. I have new respect for my heat gun

Bruce, FYI, I've been cutting the tips off of the Bisson mufflers for years for that modest rpm gain. Same with the 6.4 mufflers on the new engine. The 6.4 is actually 2 of the 3.2's back to back if you think about it, but I KNOW that the larger diameter pipes on the 6.4 sound a lot quieter than the small diameter pipes on the 3.2 Bisson mufflers. Talking to Gary over a long period of time and I learned that the 3.2 likes a 3/4" diameter pipe for the exhaust. Same pipe that's on the 6.4.

If you have the inclination you might want to talk to James at Bisson about that, since they will do a custom application. I'm going to be doing the same in the near future for the reasons noted above.

Pat

Ok Pat i have the motor and muffler coming allready so i will cut off the ends a little . Its going on a Lanier arf Stinger 84 inch span. I flew it with the 4.2 on it last year , it would fly around on just above idle. I just couldnt get that 4.2 dialed in so it would run right . If i opened up the throttle it would tear the stinger apart HA HA if you know what i mean. I think the 3.2 being a lot lighter will fly it better . Thanks as always for the info Pat and all that responded. Hey Pat are you still doing the moderating on the DOD site. Its a great web site isnt . I kind of feel like a dummy though on it . Most of the guys on that site have mega bucks for the real high priced planes ect. Reference the mufflers on the 6.4 i have Johnson mufflers they are real quiet and nice sounding . I have smoke on the Radiocraft Extra and the mufflers have the coils inside really awesome smoke.

Hello,
I modified my w/a Bisson muffler with 1" pipes.
Check this thread for more info and a photo:
http://www.rcuniverse.com/forum/m_46.../tm.htm#461234
Good Luck!
John

Bruce,

As far as I know I have never been a moderator on the other site. I was over there a few times but the operating system on my computer and the sites programming don't see eye to eye and I have to log back in every time I try to reply. Time consuming.

It's actually a little "up town" for me, too.