so i noticed a drastically changed exhaust note during my last flight of the Fun51 with a ST GS .45 on it this weekend. I landed immediately. inspection revealed that the header broke the front attach lug off where it bolts to the head. the engine was not running lean at the time (it might have gone lean after it broke for the 30 seconds or so it took to get it down). the header is like $11, so no big deal, just curious if anyone has any suggestions why it would break there? It has lots of hours of run time on it as well as the fact that i was dogfighting with an imaginary foe at the time. so what do ya'll think, just metal fatigue due to countless heat cycles? maybe me yanking the plane all over the sky contributed? just looking for some theories.

thanks.

Just fatigue

That failure is not uncommon with Tigres, I had a very old, worn G51 do the same thing. FWIW, when it failed, it was on a H9 Twist, so high G's, vibration or heat, take your pick
Cheers,
Pete

that's what i figured... either that or my invisible foe got off a lucky shot into the engine! thanks... $11 part. problem solved.

Don't bother using a gasket between the header and the engine. It will only last a few minutes

I have one engine that has the gasket, this one didn't. mebbe some high temp silicon to seal it up? dunno if it really matters, it never seemed to leak anyway.

Doesn't really matter

I dress them off flat with a fine file and bolt them together

It wouldn't hurt to blend the interior of the header from the exhaust port shape to the round shape. Use a small riffle file. A dremel might work? The engine is sensitive to this area.

Seems the engine runs better with the muffler as far out on the header as is practical?

I replace the slotted screw in the muffler clamp with a Allen (socket head) screw so I can get it tighter.

sounds like good advice. we call that port matching when building hotrods. can't hurt on an RC engine i am sure. a couple minutes with a set of jewelers files should do the trick.

I also like the allen head fastener idea. as far as how far on or off the header the muffler sits, i guess that would be kinda like changing the dimensions of a tuned pipe. could play with it to see how it affects the power curve.

thanks for the ideas.

I keep an extra exhaust stack for a 40-51 and a 60-90 Tigre in the shop. It is fairly common.

david

troposcuba, Sounds like it was exhausted to me. Tom

har har... pretty good. spit out my soda on the monitor when i read that. hope my nightshift (I'm surfing the net at work alright... ya caught me) doesn't mind the mess.

hi guys

im new in dis model flyin .im 13 years old so dont have that much experience.im lockin at the katana 40 freestyle.do you maybe know if it will fly nicley with a os 46?