Lynn,
This gives me a lot info for the proposed external exhaust/muffler system for my "Dyke Delta"
and for any other of the Rotary group needing such a system............One question......You show
the straight run noted "As long as possible"...........Will there be a down side if the total primary
header length is longer than 22-24 inches ?..........I have more space under the "Delta" cowl than
average and may be able to add more primary length before the collector.........What would be
the next primary length that "Tunes" ??..............Really appreciate your knowledge and the effort
you go to helping myself and the group out...............
Thanks Again,
--
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold
Our engine builder said that 2 exhaust pulses before the collector was abouit it for tuning. Racing Beat says 22" to 24" for Nonported or street ported engines. That is the short system length to the collector.
The long system would be 120" to 125". That would have the muffler under the rear bumper. The primary length is designed to pump up the dismal torque at the lower end of the power band. So think about 7,000RPM to 7,500RPM. So airplanes (assuming 5,000RPM to 6,500RPM cruise) would do fine with about 30" to 36" which is about the length of a street header. And 36" was what I used on the piston 4 cylinder engines I raced. The major interest is the equal length primaries and long collector. I wasted a year of tuning with a header that had one tube longer than the other. When I redid that to get equal lengths the engine came alive.
The intake tuned length would more likely have a bigger effect on torque peak And best power. So, I would put the most efffort into the intake lengths.
Lynn E. Hanover
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