Easy question, lazy questioner.
What is the minimum radius of exhaust bend that won't effect tuning?
Decker, Michael
Good question. I don't know the answer. Most people using tubing
bends which are about 2.5 inch center line radius minimum as I recall.
http://www.burnsstainless.com/321tubing/Ubends321/ubends321.html
The stock manifolds are sharper bends. Particularly the turbo manifolds.
--
Paul Lamar ...No rotor no motor.
STRAIGHT. Anything resistance whatsoever in the exhaust flow will
affect tuning. In fact, putting even a straight tube will affect tuning,
compared to just letting it blast out unconfined.
However, the Wankel gives a much smoother exhaust flow in the first
place, so there's room to play. You might make a water stack and try
some flex tubing and see where you start getting some back pressure.
I think the reason for the 2.5 bends is that the benders most people use
were made for thicker steel pipe, and 2.5 is about as small as those are
bent. If they need a tighter bend, they just use an elbow.
Keith W
I agree that straight headers would be the ideal, but I don't know that
I agree that, "blast out" is better. My understanding is that for ideal
tuning you are trying to set up a situation where the exhaust reaches
ambient air just slightly before the valve opens to give another exhaust
pulse. This creates a pull that helps the exhaust stroke out.
For 5400 RPM at 3 pulses/shaft rotation? 16200 pulses/min=270/sec
Speed of sound @ 1080fps/270pps=4ft. Answer is ft./pulse.
So if I have my pulses/RPM right then ideally one would need just short
of 4 feet to set up the tune.
Be gentle folks.
Decker, Michael
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