X-Mozilla-Keys:                                                                                 
Tracy Crook wrote:

Russell Kent wrote:

OK.  What I don't know about rotary engines would fill a good-sized
stadium, BUT--

Tracy Crook wrote:

The new engine is basically an 89 turbo II engine with non turbo rotors

to

give a compression ratio of 9.7 - 1.

I was under the impression that non-turbo II engines earlier than 93
(i.e. cast
rotor depressions) had a compression ratio of 8.5:1, and that the
CNC-machined
turbo II 93+ rotors were 9.0:1.  Did Tracy make a typo above, or did I
miss
something somewhere?  I'm guessing that the combination of turbo rotor
housings
and non-turbo rotors must do this.  Assuming Tracy's (Bruce's ? :-)
engine is
really 9.7:1, shouldn't that have a measurable improvement in BSFC?

Russell Kent

 Here's the scoop:   86 - 88 13B non turbo compression ratio is 9.4 - 1.
(turbo was 8.5 - 1 I think)
89 - 91 non turbo was 9.7 - 1.  I'm sure the .3 increase over my 88 engine
helped, but not that much.  The significant thing was using the non-turbo
rotors Vs the turbo rotors, a 1.2 point increase.

Using turbo rotor housings does not affect  compression ratio.  They were
chosen for their cleaner exhaust ports.

Tracy Crook    rws@altavista.net
Web site:   http://www.rotaryaviation.com

 
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