We got the plane up in the air again, there was gobs of power,
the temps stayed low, no higher than 160 for oil and coolant,
but CO in the cockpit reached 300 PPM so it was only one circuit
of the traffic pattern and a smooth landing. That SS flex
exhaust tube is getting replaced tomorrow with the inconel. Also
going to make sure the firewall is well caulked.


At full throttle the engine is missing a bit, I think it's too
rich. The pilot was going to play around with it a bit but due
to imminent danger of CO poisoning he decided to land it. I'll
take it up on the next flight after some Van's familiarization
flights and exhaust refit.

I'm using the stock 13BREW O2 sensor, Tracy- is that the one
recommended for the EM2? It seems that the EM2 mixture graph
shows about 3/4 rich, so I lean it out slooooowly, and it
doesn't have a sweet spot- it just goes to about 1/3 scale.
There seems to be no in-between.


But, the plane flies nicely, like an RV should.

Next flights will be in a few days.

Brian Trubee

I don't think it is the flex tube. I just installed some
in the race car.

I think you have a low pressure in the cockpit.

Paul Lamar


     One of the connections to where the tube connected to the muffler showed a lot of leakage. I'm going with either inconel, or 321. Still, I don't like the thought of the thin gauge of metal used for the flex tube, given the exhaust heat.  I have some Inconel bends, I'll see if I have enough to fit it up, or I will cover the flex tubes in fiberglass to fix it's unique shape and positioning, and them use them as a model for a muffler shop to create some new ones out of 321 stainless.

So, the exhaust problem and the tuning issues are the only real squawks at this point. The engine cools just fine.

Brian Trubee

Check out JC Whitney or Warshawsky.
I just bougth some SS braided exhaust flex tube  10" long for the race
car muffler for $30. Works great and is widely used on
transverse engine front drive cars.

The exhaust comes out under the wing root which is a high
pressure area. If there is any leakage into the cockpit
that is how the CO can get there. Most RV have open areas
there to get the fuel lines and spars inside the cockpit.

Paul Lamar