On the discussion of the displacement, perhaps we should look at a
certain shaft speed and see how much volume is being displaced at 100% VE.

If we take 1000 rpm of the output shaft and calculate the throughput in
l/s we have 1000 / 60 = 16.67 rps. (revolutions per second)
For 6000 rpm it will be 6 times more.
The RX7/8 have a chamber volume of 654 cc = 39.95 cuin. roughly 40.
Per shaft rotation we have two rotors = 2 * 654 cc = 1308 cc, and at
1000 rpm its 1308 /1000 * 16.67 rps = 21.8 l/s
At 6000 rpm it is 130.8 l/s displacement at 100% VE.

If we compare that with a four-stroke engine it would need 2.6 Liter
displacement as it need two rotations for all cylinders to fire once.
Say 1000 rpm = 16.67 rps * 2.6 l  / 2 rev for all cylinders to fire =
21.8 l/s. So both displace the same volume of air per same rotational
speed.

For the calculation of a booster, the base volume of the engine at 6000
rpm is 130 l/s. That is the air flow at 100% VE. If VE is higher, say
1.1 we would have 143 l/s air flow. Hope that helps.

If you want 15 psi boost, it is the equivalent of the same volume 130
l/s. If 10 psi is your aim use 10/14.7 *130 = 88.5 l/s in boost volume
for 6000 rpm engine speed.

Rolf Pfeiffer



The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.