Oh, one more interesting thing. Some people, me included, pretended
that you could improve the rotary's BSFC by going to aggressively lean
mixtures (some spoke of 21:1 air/fuel ratio...) Well, tests show
clearly that BSFC decreases as you lean the mixture until you hit an
optimum, then it increases again as you lean further. This optimum is
not too bad as we are down to 0.455 lb/hp.hr at 75% cruise power and
believe we still have a few percent to gain. Of course, fuel
consumption decreases as you continue leaning but, past this optimum,
power drops faster. I want to do a few more tests before I release the
optimum A/F ratio. Let's say that it is definitely on the lean side
of peak, but much less lean than I personally anticipated. I'll
elaborate an other time on the two combustion phenomena (well.. at
least two...) that seem to be at work.
Best regards, Francois
Excellent!! Excellent!! EXCELLENT!! You were right I was fooled by the
plot. Next question. What are the ID's of the runners?
We will then have the last piece of the puzzle.
First good data we have ever seen on a simple tuned side port engine. We
owe a huge debt of gratitude to you Francois for sharing this
crucial data with us.
Thank you very very much.
BTW are the ports 2nd gen turbo four port or third gen turbo four port?
If second gen 200 HP is well within your grasp by switching to third gen
porting. I know the original Mecanair engine was 2nd gen.
It has always been known if you slow down MPG increases greatly as HP
required also decrease much more greatly. The vaunted Thielert diesel
Diamond twin crossed the Atlantic at 40% power :) Diesels have much much
better BSFC as percentage of power is reduced. Cagey of them to cross
the Atlantic at 40% power. You might as well go in a boat or a hot air
balloon :)
Paul Lamar
Matt Prather wrote:
Maybe the lean mixture limit is being driven by inadequate/not optimised
spark. More spark energy, bigger gap, multiple discharge, better fuel
atomization are things that could be looked at. 0.455 isn't bad, however.
Regards,
Matt-
Maybe. We'll try, we ave a system which can adjust spark energy.
Thanks for the suggestion.
Francois
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/
Copyright 1998-2004 All world wide rights reserved.