-------------- Original message from Lynn Hanover <lehanover@gmail.com>: --------------

Lynn,

   I realize that the Drummond dyno exhaust system is sized to get maximum power at much

higher rpm (9000+) than we use but can you give us approximate tubing diameters and lengths

of both the primaries and collector of the Drummond system then pulling from your many years

of "Real World Experience" recommend  tubing diameters and lengths sized for our aircraft

systems (perhaps one for the 2.17 re-drive that spends most of the time at 5000 to 5500 rpm

then one for the 2.85 re-drive typically used at 6000 to 6500 rpm)..............

 

Thanks,

--
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold

 

The goal will be the scavenge effect and not actually pumping up torque at lower RPM. So any system that does not screw up the scavenge effect should be a huge improvement. So one system design should work fine for either reduction ratio.

 

This all conjecture since I no longer have a dyno. But, I would use 1/7/8" ID primaries of 18" to 22"  into a long collector maybe 8" ending at 2 1/4". Then a smooth transition to a flex pipe (to allow for engine moving in the mounts) then to the end of a fixed down tube of 2 3/4" clamped to an engine mount tube with Dutch clamps. 

 

A streamlining cuff over the down tube with air holes for cooling. Then into a Bomb style muffler with the cooling tube through the center as seen here on the news group. I would use crossed fish tails so as to look like ordnance. With air along the outside and through the centerline, plus the distance from the engine, muffler failures would be reduced. Plus there would be less heat inside the cowl. No dripping liquids would be set alight. More room for other items to fit. 

 

If it does fall apart the worst that could happen is that it falls off, never to be seen again. Just don't put your tail number on it. I would have the cooling center tube turned through the centerline to disconnect the cooling tube from the exhaust note.  

 

The important part of the build is to get the primary pipes exactly the same length to the collector.

 

I can do drawings if you like.

 

Lynn E. Hanover

 

 

Lynn,

   I would like to see a drawing and I am sure others of the group would also !!.............I

know this is splitting hairs but I am planning on splitting my exhaust after the collector to two

mufflers (no good reason other than the Dyke Delta bottom skin has a "Keel" shape (V)

and I want to keep the bottom symmetrical with a muffler (recessed with cooling air) on each

side of the "V" ) and I wonder what size you would use from the 2.75" to branch off to the mufflers ??......... 

 

Again Thanks,

 

Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold