If you use locking nuts like Jet nuts that grip the stud, you just back out the stud on removal. Use the stock nuts or stainless nuts and safety wire them in the tightening direction. They never come loose and can be removed without drama. On my NA engines I use no exhaust gasket. Just a bead of GE 100% silicone tub and tile calk. Keep it well away from the ports. Never had a leak, but I had no back pressure from a turbo hot section either. Might be worth a try.  

 

Lynn E. Hanover

 

 

 

I believe Mazda uses some Inconel hardware on the 93+ 13Brew engines…………found this out the hard and expensive way.

Marc

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of David Leonard
Sent: Saturday, January 25, 2014 8:14 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Exhaust Leak at Turbo Outlet Flange

 

Bummer!  Glad you are safe.

 

I use the stock steel nuts.  Locknuts might be an improvement but not if there is any non-steel component.  I did loose one of those nuts once without to-do.  Not sure how long it was gone.  The other 2 held everything together.

 

Be very careful with what gaskets you choose.  I found some nice-looking aftermarket turbo manifold gaskets for about $20 while the stock versions are about $90 each, so I installed one.  It lasted about 30 hours until it disintegrated.  The resulting exhaust leak burned through a coolant line and I dead sticked onto a local airport (departing from a formation routine at an airshow!..  complete with a cloud of steam).

 

Sigh, the stock ones are nothing but stainless steel layer, not some sort of fiber stuff in the after market ones. 

 

On another occasion I was using some very nice and expensive exhaust clamps that were steel but I didnt notice that part of the block holding the nuts was aluminum.  About 50 hrs in something caused the alumimum to get too hot, which created an exhaust leak, which accelerated the process.  It burned a hole in the cowl and splatered molten aluminum everywhere - some of it is still around.

 

Another time I was using some fancy exhaust wrap.  It slowly disintigrated over the course of 100+ hours and was generally an annoyance.

 

I tried a flowmaster hushpower muffler but melted most of the stuffing out of it on the first flight. Luckily it melted pretty cleanly and didnt clog the exhaust.

 

Moral of the story..  as if it didn't take me long enough to beat this through my skull..  NOTHING that is not made of steel or better goes into any part of the exhaust system.  Particularly gaskets and nuts.

 

Guess I should have passed that one along sooner.  Glad you got back safely.  Good job.

 

Dave Leonard

On Sat, Jan 25, 2014 at 5:14 PM, <downing.j@sbcglobal.net> wrote:

 

I had the nuts come loose on my turbo manifold on the block, I'm using with out the turbo, so I drilled the nuts and secured them with wire.  JohnD

 

Thanks for keeping us all informed , helps us all to make sure we look for often simple overlooked areas.

 

Cheers

Christian 

Renises 13 b rv7

Sent from my iPad

On 26/01/2014, at 3:17 AM, shipchief@aol.com wrote:

During the 8th flight of my RV8 with 13B Turbo, I experienced an exhaust leak at the turbo exhaust flange. I mistakenly used brass exhaust nuts  which are twice as tall as regular nuts. They work great on most engines. I should have know better, as the temperature at the turbo outlet, under the insulation is much higher.

The brass nuts softened and deformed into a flange face at the washer! Once the tension was gone, the heat & vibration did the rest.

The exhaust gasket blew where the gap was widest, at the top.

The escaping heat burned thru the insulating jacket and the stick on reflective aluminum. Then the fiberglass cowl charred, I smelled that!

I was close to my destination, and high, so I was able to pull off the power, put down the nosed and get on the ground without incident.

I'm disassembling it now, looks like I need 4 high temperature lock nuts and a TO-4 exhaust flange gasket. I should review and improve the insulation over the turbine housing. Also I need to repair the charred area of the cowl, which might be in the form of an aluminum access hatch.