Guys, what methods are you using to keep your Aluminum headers fro mcracking or breaking?? I'm on my 3rd set of headers on my 3W 100 SS. They are cracking in the heel of the bend. I have everythign set as straight as I possibly can get. And they still crack!!!

A friend has told me to soft mount the engine?? NA!!!! I'm not going to.

I'm thinking of Stainless Steel headers?? I know 3W makes them! I've seen them for the 240's.

I think I need to pull them out and completely re-vamp the idea of mounting them.

Advice?????

Thanks!

Chris~

Have you contacted Aircraft International or Cactus about it?

Yeah Bob. I talked to Bobby about it last year around July. He told me to re-vamp things in my setup, and see if it makes a difference. It did for about 2 months. Now they've cracked again. I'm almost to wits end here!!! Maybe a new set with some kind of supports welded to the headers??

When I get my new on-board tach, I'll re-vamp the header system in it too!

Thanks!!

Chris~

Headers break because of movement. You have to figure out what is moving and make it stop. Soft mounts on the engine allow the engine to move - very bad for headers. If the engine mounts aren't stiff enough or the engine box isn't stiff enough then the engine can move. Next - figure out if the muffler can move. Mount the muffler with front and rear supports so that it cannot move. Headers break because that big long muffler acts like a lever arm working the header up and down. A steel header will last longer than aluminum because it can resist fatigue better, however if you can fix the problem mechanically (eliminate relative motion between the header, muffler and engine) you will be better off.

I know where you are coming from. I'm on my second header and it just cracked (right at the bend) the end of last year. At $37 a pop, it's not cheap to keep replacing. I'm having someone weld/braise up the crack in the second one. What I plan to do is make sure the header/pipe rests PERFECTLY in the pipe craddles, and I also plan to add a fourth side to my motor box to cut down on motor box flex. It was also suggested to balance the hub of the prop in addition to balancing the tips (Although this didn't help pipe #2)

Good luck............Mark

I do not know if it would work, but how about a high-temp silcone connector between header and muffler. Or flex pipe of some kind? Just an idea! Captinjohn

That is a KILLER thought!!!! Silicon!!! Right now, I have the White Teflon couplers on my 100. And Mark is in the same boat as I am. I'm really leaning on going with the Stainless, but with a silicon coupler? Get rid of the teflon all together. The Stainless header is cheaper to buy than the Alum, per AI's site.

On my motorbox on my Edge, I have it completely consealed. Has all 4 sides. The top is where I have the Ign unit mounted. Pretty neat way I mounted it, I think? I just used a piece of 1/4" lite-ply on the top, and cut out for the Ign unit to sit in there upside down. The unit is Zap-A-Dapped in, so it can come out when I go to the newest Ign unit with tach. Plus the box is glassed per Bobby's recommendation to me personally. Think I used 2oz cloth, cuz I wanted to keep it light up front. What if I used some Carbon cloth around it? That would keep the box from moving??

Oh well. All is a learning curve.

Thanks for the ideas!!!

Chris~

Silicone tubing won't work with a gas engine. Too much heat in the exhaust. That's why they supply you with a teflon connector - it withstands much more heat than silicone. There is no such thing as a high-temperature flexible coupler....sorry. There is a mechanical solution to your problem...not a material's solution.

That is why I said may not work. It works on boats like I had...but the header was water cooled. You would have to have a on board water tank...not to likely! I am surprised that a small ball joint is not used. Works on snowmobiles. Thanks Capt,n

Sorry to drag out such an old post, but I found it when searching for the reason why everyone uses teflon to mount headers/canisters on a gas engine. I found the answer was due to high heat.

I am new to gas engines and have broken my first header mounted on the DLE-30 (great engine by the way). The DLE-30 is soft mounted to the firewall to prevent high vibration. Just looking for thoughts on how to avoid breaking the next header.

The vendor of the header suggest that I cut it into just after the bend and put a second teflon coupler between the two pieces of pipe. Does that sound like it would work?

Courious on how IFLY3W and OnTheEdge solved their problem?

Get rid of the soft mount on the engine and look at the mount of your cans.

As Jake said, the soft mount can be causing a lot of your issues. What I found is that when I originally designed my canister mount I only had a small amount of right thrust in the motor. I ended up needing more so I just shimmed the motor with out changing the canister mount. ANY SLIGHT pressure mixed with vibration will crack a rigid header. I ended up rebending my headers to line up perfectly with the canisters so there was no side to side or up down pressure what so ever. When I lined up my headers to bolt it in the place the holes were perfectly lined up and the gasket was flush all the way around. None of that, "when I tighten it up it'll pull it into place".

Are there flex header available from any suppliers for that motor/canister combo? That may help also but flex headers have been known to fail as well. I've got 500-600 flights on my flex headers (different plane than the one mentioned in my post above) with no issues but I also wrap them every year with a few layers of Teflon tape.

Hope you get it figured out.

.........Mark