Dave and all; To the best of my knowledge 2 stroke engines have always been
classed by the same bore x bore x .7854 x stroke x number of cylinders. Or
Pi R squared X stroke X number of cylinders. There has never been a standard
based on number of turns V power strokes. Rich Fox
-----Original Message-----
From: Dave Dahlgren <ddahlgren@snet.net>
To: Gary Allen <gallen@relia.net>
Cc: land-speed@autox.team.net <land-speed@autox.team.net>; Dan Warner
<dwarner@electrorent.com>; Lee Kennedy <leekenn@pacbell.net>; Mike Cook
<beauty1@hughes.net>; Mike Manghelli <mmanghel@hughes.net>
Date: Tuesday, December 26, 2000 03:55 PM
Subject: Re: mazda rotary engine factor
>Gary thanks for replying.
>The two strokes I agree on completely no question on that.
>Displacement X 2 as they process twice as much air and fuel
>as a 4 stroke engine of equal displacement in 2 revs. I had
>brought this up with Dan Warner a long while ago on this
>group. But I fail to understand your logic on the rotary.
>From what i can see your logic is not based on facts at all.
>It is based on what it looks like rather than how it works.
>The engine sizes have been historically based on 4 cycle
>piston engines. That infers that it is the amount of air and
>fuel that can be processed in 2 revs as this is typical. had
>you picked the amount of air and fuel that can be processed
>in 1 rev then you would have had cylinders left over over.
>had you picked 3 revs you would have been short cylinders.
>Is an engine that processes 175 cu in of air and fuel in 1
>rev with 4 cylinders not done yet, the same as a 350 cu in
>engine in 2 revs and a 525 that processes all the air and
>fuel in 3 revs? I suspect they are as they are all 350 cu in
>engines using the standard displacement per 2 revs.. It is
>just a matter of how you measure them and the only fair
>yardstick is how much air and fuel in a given # of revs.
>Just like it is miles per hour and feet per minute and
>gallons per hour so is displacement per # of revs. Otherwise
>there is no comparison at all. If you get a fuel pump do you
>as for a 100 gallon pump or do you ask for a 100 gallon PER
>HOUR pump???? Is your car is going 150 miles or is it going
>150 miles per hour.... The relationship of displacement per
>2 revs has always been inferred and not written out. I am
>asking for finish writing it out. No more and no less. It
>all seems very logical to me and ought to to everyone else.
>I think you have to compare things that are dynamic in a
>dynamic situation not a static one. What something seems
>like while stationary has little to do with how it behaves
>dynamically.
>
>In other words.....
>What you are saying is, if I understand correctly, the
>rotary is like a 6 cylinder because it has 6 faces total
>from the 3 rotors. But in only has 2 firings per rev. That
>means it takes 3 revs to fire them all. Well I have a 4
>cylinder engine that has 500 cc per cylinder. In 3 revs it
>fires 6 cylinders... 500 x 6=3000 cc. can I run against the
>F class records too then? If you do not compare engines by
>the amount of air and fuel that is processed per revolution
>then how do you compare them fairly? The simple thing about
>using that type of comparison is that it is all encompassing
>and no new rules have to made no matter what type of engine
>is run. It is the reason that SCCA and FIA use factors of X
>2.1 and X 2.2 because that is a fair way to compare
>engines. It also matches by the way the relative amount of
>power from this type engine also. If I had a 1300 cc piston
>engine and a 1300 cc rotary I would expect the the rotary to
>make about twice as much power as the piston engine. A good
>1300 cc piston engine makes about 220 hp. ask any of the
>bike guys i bet i am pretty close here. if anything a little
>conservative. A 1300 cc rotary makes about 360 hp. I have
>dyno sheets of some of the better ones on hand here. using
>those #'s it puts the rotary at a disadvantage at X2. If the
>rotary was truly twice as good it would make 440 hp. with
>your factor it would be expected to make 660 hp. Does this
>seem realistic? I suspect not! That is because the engine
>only has 2 firings per rev and the only place and time that
>any power came be generated is when there is a firing. The
>rest is a lot of monkey motion with parts going around and
>around but no power being generated. I hope to hear back
>from you on these comparisons.
>Dave Dahlgren
>
>Gary Allen wrote:
>>
>> I diagree with your logic. I consider a 2 rotor, 3 lobe rotary engine
the
>> equivilent to a 6 cylinder engine with 654 cc in each cylinder for the
total
>> displacement of 3924 cc. This is the total swept volume (key term) of
the
>> engine just like piston engines are measured. If your recommended logic
is
>> accepted, then I would expect the 2 stroke engines to be measured as 2
times
>> their actual displacement because they fire on every stroke if one is to
>> only count number of firings per revolution. Engines that run with an
>> intermitant combustion cycle should be measured based on their total
swept
>> volume, not on the number of firings per revolution. Rotary and 2 stroke
>> engines already have an advantage because they get more power strokes per
>> revolution that the 4 stroke engines.
>> Gary Allen
>> ----- Original Message -----
>> From: "Dave Dahlgren" <ddahlgren@snet.net>
>> To: "Gary Allen" <gallen@relia.net>
>> Cc: <land-speed@autox.team.net>
>> Sent: Thursday, December 21, 2000 2:20 PM
>> Subject: Re: mazda rotary engine factor
>>
>> > I did not even mention in my last reply what the issue
>> > really is with the mazda rotary factor. It is currently
>> > engine displacement times 3 for the class it has to run in.
>> > This does not represent how the engine really works. it
>> > takes 3 rev to complete 1 cycle for 1 rotor face. Typical
>> > there are 2 rotors. This gives you 2 firings per rev the
>> > same as a 4 cylinder piston engine. Each rotor face is 654
>> > cc in a mazda 13b for example. That means that it processes
>> > in 2 revs 654 X 2 rotors X 2 revs=2616 cc of air and fuel.
>> > Exactly the same as a 2616 cc piston engine. Currently this
>> > engine has a rating of 1308 X 3=3924 cc. I suspect it had to
>> > do with the 3 faces on the rotors so everyone said just make
>> > it times 3 or that it looks like it ought to be X 3....This
>> > does not seem fair and reasonable to me. SCCA and FIA both
>> > use an engine displacement Factor of just over 2 to adjust
>> > the size of engines built like this when comparing them to
>> > piston engines. In essence treating them the same as every
>> > other 4 stroke engine by sizing them according to how much
>> > air and fuel can be processed in 2 revs.
>> > I would appreciate your thoughts on this matter
>> > Dave Dahlgren
>> >
>> > Gary Allen wrote:
>> > >
>> > > I am not on the landspeed list but did know about the rule change
>> suggestion
>> > > from the rules meetings. It was rejected at the preliminary meeting
>> because
>> > > there was no data supporting the change. I am not sure where the
>> request
>> > > even came from and also not familiar with the current factor history
or
>> > > where it came from. Dan Warner is th best authority on the subject
and
>> its
>> > > history.
>> > >
>> > > What is the issue / question? Gary
>> Allen
>> > > ----- Original Message -----
>> > > From: "Dave Dahlgren" <ddahlgren@snet.net>
>> > > To: <gallen@relia.net>
>> > > Sent: Monday, December 18, 2000 1:33 PM
>> > > Subject: mazda rotary engine factor
>> > >
>> > > > Wes Potter suggested i drop you a line about the current
>> > > > dispalcement factor for Mazda Rotary engines.. Have you been
>> > > > following the land=speed e-mail on this or do i need to
>> > > > forward a bunch of it to you?
>> > > > Dave Dahlgren
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