Hi guys

I'm getting sometimes a little extreme...but while looking at conrad´s site, I've found the following muffler:

And since I've lost the muffler of my Thunder Tiger F-75s during flight...I was wondering using this one...just fix it to the fuse and put a silicone tube between the manifold and the muffler... Since 4 Strokes are not so sensitive to mufflers...and since a new muffler cost more than the double of it...I was wondering..... What do you think?

www.thundertiger4u.com have the replacement mufflers for US$20 and $10 for the manifold if you lost that too.

Their postage is very reasonable and takes about a week.

Thanks custom PC...

Here in Germany it cost about 30€ plus shipping(Price I'm not willing to pay)...and I just lost the muffler, manifold is still there... If it is not a good idea at all..I'll may have a friend make a muffler for me (he has a lathe shop) or buy a ASP muffler instead =(...
In my plane (Black horse su-31 with engine at 225°), I have the problem that I have to use an exhaust deflector, and they don't last there...the silicone deflectors are after a couple of flights just not there anymore, and there are 2 reasons: High exhaust temperature...the silicone deflectors break just where the muffler sting ends....or because there is not enough space to attach the deflector...

With this car muffler I won't hae the problem of the deflector because the sting is already deflected

Four stroke exhaust is much hotter than two stroke exhaust. The silicone may not hold up

That is one thing, another matter is that car mufflers are really tuned pipes designed to push gasses back into the sylinder to "supercharge" a twostroke. It might work, but chanses are that this muffler will give too much back pressure so you will loose power or run too hot.

OS and Magnum .70-.91 exhausts fit the F-75S.

Greg

Pattern flyers ran two stroke airplane pipes on YS four strokes for years untill they made purpose built pipes for them. The tuned pipe on a two stroke is nothing more than a muffler on the four stroke. Forget the silocone and use a piece of teflon tubing which is also used by pattern fliers and sold by central hobbies.

Do you still have the swept manifold? Some people prefer to fly with just that. I've seen manifolds tapped for a vent line to the tank.

Yes I still have the manifold

I actually run the engine without the muffler after I lost it....I would say it delivers a bit more power...or maybe it was just the sound..which is about the same that with muffler....but the engine didn't work well at the transitions...and I saw lot of bubbles in the line, so I think it relies on muffler pressure to workt well and not just by suction... Another thing is that it is too short for the plane...the plane has a real fat fuse.

I thought it would be a good Idea to try this muffler since it's just 9EUR.... an ASP muffler would cost about 20 I think..and the original about 30...so I do my math hehe!...

How many times have you seen that the rear cap of the muffler...where is the gas exit...begin to turn???

Now I have 2 4 strokes and in both of them the rear cap turns and gets oily and black =(.

I have had it happen to Magnum .91's and the good ol Saito old style muffler's. I tig welded all of them.