Exhaust system

This thing is simple but has its challenges too.

 
You start out by straightening and grinding the flanges because
you must get the best mating surfaces you possibly can. 

If you don't get a good mating surface you'll end up with leaks in the joints and prematurely blowing exhaust gaskets possibly spitting sparks from the joint and burning hoses, fuel tanks and etc.  Whatever is in line with the joints will be susceptible to burning so take care here.

When that's done you have to make a decision on whether or not to go with ceramic coating or the wrap RotorWay gives you for the pipes.  We chose to go with the wrap due to finances but some have reported great results with the new ceramic coating available with cooler temps emitted from the pipes.  One great thing about ceramic coatings in my opinion would be that there isn't any wrap to soak up oil and antifreeze and start burning. If it did catch fire my opinion is there isn't a way in Hades you could extinguish it. Another would be not having to replace it periodically as it hardens and begins to flake off in large chunks I'm told it will and then there's not having that fiber the wrap is made of burrowing into your skin like fiberglass as you work around it.

Should you go with the wrap you must paint it so it won't have as much potential to absorb oil and antifreeze. RotorWay gives you one can of paint to accomplish this and believe it or not it's enough.

If you continue to apply paint as we did the wrap will absorb all you throw at it, we stopped at five spray cans and it never once offered to reject more.

My thoughts were if I completely saturated the wrap it couldn't possibly absorb any more substances thus avoiding the fire thing all together, Wrong!!  About all I accomplished is making the wrap weigh four times more than it would have if I just used the one can of paint so don't get overzealous because you can't out smart this wrap lol.  I should mention I had a conversation with Stretch at RotorWay and he told me it wasn't necessary to over do it but I wanted to anyway so he told me it was ok and to go for it so I did.

  What they don't tell you is your supposed to bake high temp paint in within a certain amount of time or it won't do its job. 

In the time frame you build your ship there really isn't any possible way to do this short of baking it in some sort of a large oven which we didn't have one large enough nor did we want to take a chance of the shape of the pipes changing shape and not being able to install them without going through a major refitting job.  All you can do is bull the pipes into place once the wrap is on and I don't think you could heat the pipe to allow it to bend to get it fitted so we didn't take any chances and went with what we had.

Tom Smith told me that once the engine is ran and heats the pipes up they will relieve themselves
and will no longer have the stress on them they did when we bulled them into place.  Personally I think before the pipes left RotorWay they should have been properly fitted as there really isn't an easy way to do this in the field and I'm pretty sure all the engines coming out of RotorWay have the same flange clearances and positions. The flanges of the pipes should be thicker and machined to fit the heads since this is a known problem area of the ship and accredited to starting more then one fire, something I'm sure RotorWay is aware of.

The bolts only go in the heads about 5/8 of an inch

so watch your washers and torque here and don't over do it, I don't think it would take much to tear the threads from the heads if too short a bolt were used or too much torque were put on the bolts.

First time startup of a engine with exhaust wrap installed

needs to be monitored carefully to avoid the risk of fire.  As the paint on the wrap begins to heat up it will begin to smoke and whether or not you've over done the paint it will ignite into flames so start the ship and monitor the pipes and when they begin to smoke on the outside shut the engine down for a bit until it cools and repeat as necessary until it stops smoking all together.

Be sure to have plenty of fire extinguishers handy because if it does ignite it would be difficult to put out.

The Muffler

No biggies here to speak of, everything went by the book.

One thing you may want to work out is a safety catch of some sort at the front of the muffler

because it has been reported that the muffler can break off where the ball is welded to the four header pipes.  I've not done this yet but plan to because if it does come down it will at the very least mess up your paint job as the end of the hot tail pipe comes slamming up into your tailboom and rear cowl panels, worst case scenario is it could cause you trouble landing since it will be hanging down possibly holding you off the ground, it's a long shot but it could happen.  Imagine loosing the pipe, the engine getting a lot loader all of a sudden and having to deal with that when you touch down in an auto!. :o)

When I took our ship to John Spurling's for its final check

one of the things John did was to run the ship up until it was light on the skids then he would let the ship come to an idle and I would tighten one of the flange bolts. He would run it up again, bring it back to an idle and I would tighten down another bolt. We repeated this process twice until we had them all as tight as they would go. To date I've never had a seal leak so I would highly recommend this method.

In the past there have been several people that blamed the gaskets RotorWay provides for being inadaquet but from what I learned from John, if you use this method you'll have much better luck with them .

END