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
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.
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" <firstname.lastname@example.org>
> To: "Gary Allen" <email@example.com>
> Cc: <firstname.lastname@example.org>
> 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
> > > from the rules meetings. It was rejected at the preliminary meeting
> > > there was no data supporting the change. I am not sure where the
> > > 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
> > > history.
> > >
> > > What is the issue / question? Gary
> > > ----- Original Message -----
> > > From: "Dave Dahlgren" <email@example.com>
> > > To: <firstname.lastname@example.org>
> > > 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