George Lendich wrote:

Lynn,
I found TDC as you suggested and marked it, put in the rotor and had a

play around ( no degree wheel yet).

Had a guess-da -mate on your IO ( looks similar to the Leeman) and your

IC which (looks to be a good 5 degrees after the Leeman)  - 5 degrees before
90

degrees ABDC.

Question !!
As 90 degrees ABDC is the max volume have you elected to have the 5

degree safety margin so as to not have a problem with compressing the
mixture and having

some forced back into the intake tube???

Another question!!
The overlap with a PP is much greater - with a greater volume of

exhaust gas mixing with the intake, there is a greater chance of decreased
volume efficiency

( rough idle etc.)

OR

does the greater volume of intake compensate for the mixture of intake

and exhaust ( maintaining volume efficiency) ? with the nearby butterfly
giving only a

better degree of control at low RPM?

Now given all this wouldn't it be better to have a late IC ( such as

yours) and a later IO ( even later than Jerry's) to minimize mixing and have
a better

volume efficiency.

The more I read the more I'm confused!
George (down under))

--Bryan wrote:

If there is greater overlap in port timing, would it not be feasible to use
an expansion chamber (i.e. two stroke) tuned to the correct rpm band to
force the fuel air mixture and exhaust to work together nicely.  In two
stroke racing engines it not only pushes the fuel air mixture back where it
belongs, it also helps to get the intake flowing with negative pressure on
port opening.  Since aircraft only use a very narrow rpm range this could
work very good.  Then again I am by no means an engineer, just did a lot of
Kart racing in the past.

Bryan

 
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