Hello everyone,
first I hope I do not bore anyone with my simplistic view of the matter
(if I understand it at all).
It seems to me that there is no ONE way to compare the piston with the
rotor.
Obviously different systems have been applied for different reasons.
Living in Europe I "enjoyed" about all tax-approaches possible
(displacement, horsepower, fuel/gas/diesel, even/odd days off for driving).
I understand Gordons argument of ACTUAL displacement/revolution versus
EQUIVALENT.
However no one seems to have mentioned that a 2.6 litre 4-stroke does
not pump 2.6 litres THROUGH the engine in 1 revolution. It DOES pump it
(as in internal work) however.
If we look at the engines strictly as pumps, a 2.6litre 2-stroke
pump will "inhale" 2.6 litres of gas and "exhale" 2.6 litres in one
revolution. A 4-stroke 2.6 litre pump will "inhale" 2.6 litres and
compress it in 1 revolution, then expand and "exhale" it in another 1
revolution.
So it did some extra work for fun (that is probably why we do not see
any 4-stroke pumps....)
On average a 2.6 litre (displacement) 4-stroke pump would end up being a
1.3litre/rev "put through" pump.
So, to me it really depends on the convention under which the NAME was
given to the device.
In the Automotive (as in cars and motorcycles) world it was obviously
convened that swept cylinder displacement/revolution be used and not
gas-volume inhaled/exhaled per revolution.
Not picking on exact numbers, but Bill Jepson seems to have confirmed this:
The legendary Yamaha RD-series 2-stroke 350 and 500, where still called
a 350cc or 500cc although they put out as much power or more as a 1000cc
4-stroke.
As per the above convention the RD's still where 350s and 500s although
they "pump" the same amount of gas THROUGH the engine as a 700 or 1000
4-stroke.
Based on this convention MAZDA did the trick to keep displacement tax low.
Lucky for the European Tax masters the 2-stroke car engine never became
mainstream, save for the East-German Trabant.....
FOR MY PERSONAL UNDERSTANDING:
As is, the 13B should be called a 2.6 litre as a CAR engine, as it does
pump 2.6 litres in one revolution ("inhale"- compress - expand -
"exhale"), purely to conform with the displacement tax-convention.
As an actual pump, I would call it a 1.3 litre pump because that is what
comes out the exhaust (outlet) in one revolution.
I assume if one would design a real Wankel pump it must have 2 intakes
and 2 outlets to make it work efficiently - then it would be a true
2.6litre/rev PUMP (what comes out per revolution)
I do NOT suggest to go where to contemplate a true 2-stroke Wankel engine!!
Back to the turbo selection:
I assume that tables and spreadsheets are mainly made for 4-stroke
pistons and stated displacements are just to start a reference line. If
one would want to turbocharge a 2-stroke piston, one would have to look
to a X2 displacement reference in the list.
I do not know of any 2-stroke piston out there one might contemplate to
turbocharge (my lawn mower is 4-stroke.....).
If I were to look for a turbo (car application) for a Mazda 13B, I would
start looking under 2.6litre 4-stroke piston engine references (as they
PRODUCE 1.3 litres of exhaust per revolution).
Of course I may be way wrong all the way, but my expenses will be very
much zero, as I am in for the theory only! :)
Best Regards,
Christoph Tomasson
PS:
As a unrelated curiosity:
I subscribed to your newsletter on 22nd of August 2005 with a fresh
gmail account, intended to be used for this newsletter only (keeps
things in order and spam down).
At the time the mailbox size was just under 2700 MB, as of today I have
2843 Mb available, and it keeps growing.
I have used 960 MB (33%) today.
Generally I save about 98% of the posts. I do get about 1 spam mail
every week.
I am curious how long it will take to run out of space, and how much it
will be at this time.....
Thank you for a newsletter at the edge of technology!
I am lost on most of the computer/software based discussions, but I
enjoy reading it anyway. Something new is always to be learnt. I wish I
could contribute to your newsletter, but I am no match to the experts in
this club!
Yours,
sincerely,
Christoph Tomasson
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