Scott,
That is EXACTLY what I did, and you are right on all counts. Exhaust would get in the fresh air vent if you went out the left side, but it is possible to go straight down and out with acctptable noise (about the same volume as a C182 with an obviously higher pitch sound that grabs the attention of a bystander). It would subjectively sound louder than a lyc powered RV, but objective measurements showed it was really about the same volume.
I then installed the extra pipe to hang the "hushpower bomb" underneath me. Now I am clearly more quiet than the other RV's.
There is nothing like that cast iron turbo manifold and turbo to tame the exhaust of the rotary. The extra weight there is a drop in the bucket compared to the piece of mind.
Picture of original exhaust outlet:
On Sun, Jun 8, 2008 at 9:27 AM, < SHIPCHIEF@aol.com> wrote:
I'm just starting my ground running phase, but I elected to use the turbo for a 'muffler'. I decided the weight would be offset by the power, somewhat.
I decided not to dump the down pipe out the left cowl cheek because the RV-8 fresh air intake for the pilot is right aft of the turbo. Carbon monoxide is a real problem in aircraft, so I decided it was best to avoid having any engine compartment air or exhaust on the left side of the cockpit.
My exhaust downpipe comes straight aft off the turbo, turns 90 degrees and aims down to the lower cowl exit where it's directed aft at the angle of the exit ramp. If I discover a problem with heat, I'll ad a 15 degree turn down. If too much noise, I have a stainless Hush Power that I could add, hanging like a bomb under my seat.
Running the engine on the ground, the noise level did not seem offensive, but the highest RPM so far was 3500, or just about half take off power. My YouTube video shows the engine running (search flyrotary) taken about 20 feet away by my wife with a FUji F650 digital camera. I think it is acceptable.
Scott E
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