boxbeam

My Feedback: (188)

I am building a 1/5 scale T-craft, that has a .91 aspFS in it. There is no room to use the stock exhaust and muffler that comes with the engine. Do you have to run a muffler on a FS, or will that do damage to the engine. If so, what other kinds of set ups could be used to get around an already tight fit inside that cowl, without having the muffler protruding from it.

Thanks,
Ron

TerrellFlyer

shop around, there's a ton of mufflers all size's and shapes,if there's nothing to suit your taste,you may want to build your own.

tdwise

How's the engine mounted, sideways? Upside-down? It seems the aligning of 4-stroke mufflers for minimal cowl interference is fairly easy since they can be rotated and locked into a variety of positions. I've seen many 4S mounted at about 120 degrees from vertical where the muffler would exit through the bottom of the cowl without much fuss. If it's within your budget, get hold of an OS Flexpipe exhaust extension and set it up that way. Check to be sure the threads will fit - OS and Magnum all use the same. FWIW, I have a Magnum 91FS mounted upright in a Bucker Jungmeister and I used a 6" flexpipe with the silencer mounted to the end. The setup kept the entire engine and exhaust inside the round cowl. And I wouldn't run the engine w/o the muffler - you would have no way to pressurize the fuel system and the engine wouldn't run quite right.

Ted

boxbeam

My Feedback: (188)

Hi Ted,

The engine is mounted inverted. All the room is at the bottom of the cow. I even had to cut away for the rocker arm cover clearence. Does OS make smaller flex pipes? How flexible are they?

Ron

tdwise

Ron,

I believe the pipes come in 7-1/2" and 13-1/2" lengths. I got the shorter one. They're not overly flexible which is to say you can't make sharp corners with them nor should you make repeated bends - they eventually can break like bending a paper clip back and forth. On my application, I kinda bent mine to a compound "S" shape but did so very carefully by gradually massaging it in small increments. They also recommend that the muffler and/or mid flex pipe extension be well supported to eliminate excessive vibration. Over time, they can crack which mine has already. I was able to fix it with a piece of brass tubing inside the pipe, then wrapping the joint with fiberglass cloth impregnated with JB Weld. So far, it's held up well.

Ted

TerrellFlyer

Hi boxbeam,I'm sure that you are going to open the cowl so the engine doesn't over heat and quit running.

boxbeam

My Feedback: (188)

Hi John,

Thanks for watching out for me. I was hoping that the two cut outs in the front of the cowl on the T-craft would be enough. There should be enough air flow through those shouldn't there? This is my first time in cowling engine installation. Thanks again for being one step ahead!!!

TerrellFlyer

Hi boxbeam,on a cowled engine I try to have the air outlet at least three times larger than the entry,also I make sure the air flow is going to the engine head. Usually my mufflers or exhaust pipes are dumping out the bottom of the cowl since I've got the bottom open for cooling anyway

althepal

Hi Ron,

Based on my experience this is what I would suggest. If you have to bend the flex pipe on a tight radius, close to the exhaust port of the cylinder, chances are it will crack...I know, it did happen to me, with result a 1,5" hole burned thru the cowling, even after having reinforce with fiberglass, wood and aluminium heat shield. When mentioned to a friend overseas, it did happen to him also... The solution is to use a small header that OS has now marketed, that is stainless steel, and allows to keep the radius very tight...just bolt on the regular header and the muffler...it is clean, and several adjustment are possible...for what it worth, it cost less that the flex pipe