displacement again.

You know the Pacer was designed around the RCE that GM never
produced, 2-Rotor, 266 ci, not too far from the 258 of the big
6-in-line AMC engine, just the Wankel was more powerful, at 150 HP,
for 95 HP at 4'300 rpm in the 6-L Pacer; with the 304 ci V8: 125 HP
at 3'600 rpm, so they say.

If the 1987 NA RX-7 13B provides 145 HP at 6'000-6'500 rpm; just
with an axle keeping the engine a bit at higher rpm would be enough,
100-200 lb of difference in engine weight, the Mazda being lighter,
are not that much, and the RCEs taxation is for a single chamber
displacement multiplied by the number of rotors, in this case, 80
ci, 1304 cc, instead of 180 ci, 2608 cc, versus 258 ci for the 6-L
AMC engine. I guess that everything is kept within reasonable
limits, so: what are you so afraid about? Thanks for your attention
and help. Best regards. Salud †

Jose Gros-Aymerich Madrid, Spain

The Mazda Wankel is not 266 ci. It is only 160 ci.

A worth while project is to install a Mazda Wankel in this car.
Probably the lowest drag car on the road. Not necessarily the lowest
drag factor. Certainly the lowest frontal area.

Paul Lamar.

Yes you're right, the GM RCE gave 150 HP from 266 ci, and Mazda RX-7
provides 145 HP from 160 ci, NA, 1987. The frontal area of AMC is
much wider than that of RX-7, and also the AMC drag coefficient
worse, even being among the best of its days and class, but with the
weight reduction from the Mazda versus the AMC engine, both the RX-7
and the AMC Pacer are roughly equivalent in overall weight. I'll let
you know, if the project comes to an end, it's not clear now. Thanks,
best regards. Salud † Jose Gros-Aymerich Madrid, Spain

Jose. I think Paul means that the 13B is like a 160 cu in reciprocal
engine. But it is only 80 cubic inches. All manufactures agree by
their designation proceedure.

Don't let the Spanish government tax you at twice the vehicle engine
   size rate!

I do combustion pressure testing. When tuned ideally the rotary sees
   1200 psi peak pressures. Part of the program's formulas for
horsepower and torque requires actual displacement reference for each
   degree of rotation. I use 0-45 cu in for one rotor (with 9:1
compression we include the 5 cu in rotor pocket). It works out to
500 hp @ 15 psi boost.

If we doubled this displacement as Paul (and the SCCA, FIA, and
others) would have us do it would show 1000 hp @ 15 psi boost.......
   If HP increases could be so easy!

Barry Bordes

No! 2.6 liters!

The rotary is not a two stroke. It is a four stroke.

Lets turn it around. How much air would a 2.6 liter two cylinder TWO
STROKE engine pump and process in one revolution?

The definition of displacement, as far as engines are concerned, is
only valid in context with the type of stroke.

As far as HP is concerned the ONLY thing that matters is how much air
a four stroke engine pumps and processes in ONE REVOLUTION at 100%
VE. Not the physical displacement of x number of chambers.

Here is what Ansdale has to say about that. See the attached jpgs. It
is agreed world wide that Ansdale is the authority on this subject.

13B rotaries are raced in the 2.6 liter class world wide for a very
good reason. The only reason they generate more power than a 2.6
liter four cylinder 4 stroke engine is they turn faster and breath
better. Lately that is less true as the piston engine RPM has been
raised by detail development and the use of high strength to weight
ratio materials like titanium. Also four valves per cylinder has
improved the breathing. It is very rare for any 2 valve cylinder to
have a VE over one. The RX8 engine is just over one and P-ports are
typically 1.2.

Formula One (2.5 liter as I recall) V8 engines are now turning 19,000
RPM. At least four valves per cylinder with a very short stroke so
larger valves can be used for a given physical cylinder displacement.
You will not find the details of a competitive Formula One engine
anywhere. Its a well kept secret. However I would not be surprised if
the VE's were well over one.

Applying the RPM difference to a 2.6L p-port Mazda rotary making 340
HP at 10,000 RPM would make the Formula One engine about
19,000/10,000 times 300 HP or 655 HP which is about right for a
Formula One engine.

Paul Lamar

       Thank you. The taxation for Wankel RCE all over Europe has
     changed, initially, it was the volume of a chamber, multiplied by
     two, multiplied by the number of Rotors, for a 13B, this would
     make 2608 cc, roughly 160 ci.
       If I remember right, the RX-8 is taxed 1304 cc, 80 ci, but this
     was before they expelled it from market because, they said, too
     much CO2 by mile.
       I'd like having an influence in the Spanish government, but
     besides that changing rules just to make it more comfortable to
     you or your interests is not acceptable, this is the kind of
     'conflict of interest' that will put you out of the administration
       forever, the State job positions, are family businesses, specially
       if it have some power of decision that touches money, or can
     disturb the activities of those who pay the highest amount of
     money in taxes (or in briberies), only these paying more
     to the administration will have their interests protected, individual
     taxpayers may vote, but this is lacking any strong power, the
     decisions are made out of public, and the final choice is Coke
     or Pepsi, let's us say, no additional choices.

       A Wankel RCE makes an admission stroke for power
       output shaft turn, but the admission and expansion
       or intake and power strokes, are longer in terms of
       than in a reciprocating engine, and also the volumetric
     efficiency of a RCE is always higher than that of a Reciprocating
     Engine, perhaps with the exception of speeds below 1'500 rpm or so

       American cars' engines tended to be be big, giving low power in
     connection to its displacement, and give all its power from very low
     in the rpm range, while Rotaries are high rev machines, anyway, this
       can be matched through the appropriate axle ratio, making that
for the
       same speed in terms of mph, the RCE turns in a higher rpm regime,
       that is the one these engines are better adapted to, but too
much rpm
     means also a higher wear.
         Thanks for your interest. Be good to yourselves and to the rest of
         mankind. Have a good season. Regards. Salud †
                     Jose Gros-Aymerich; Madrid, Spain

There is no consideration for how the this displacement is used.

"Lets turn it around. How much air would a 2.6 liter two cylinder TWO
STROKE engine pump and process in one revolution?"
Probably about 60% of 2.6 (1,560cc) because only the trapped
displacement above the exhaust is compressed. But it's displacement is
2600 cc.

"13B rotaries are raced in the 2.6 liter class world wide for a very
good reason."
Yes, Porsche could not compete so they had to politic for restrictions
on the Rotary.
Mazda owned Daytona and were still strong at the end of the race.
Porsche not so much!

"As far as HP is concerned the ONLY thing that matters is how much air
a four stroke engine pumps and processes in ONE REVOLUTION at 100%
VE. Not the physical displacement of x number of chambers."

Actually there is a 50/50 chance that it would produce no air because it
needs two full revolutions for it's VE.
( In essence it must double its processing displacement to achieve it's
great VE).

"Lately that is less true as the piston engine RPM has been
raised by detail development and the use of high strength to weight
ratio materials like titanium. Also four valves per cylinder has
improved the breathing."

Four valve/cyl is still like opening your front door about 18 inches and
seeing how many people can run through in a minute.
A rotary in comparison is like opening your Garage Door and watching how
many stream through. The beauty of a peripheral! port!

Barry Bordes

Displacement is as defined by Webster:

the difference between the initial position of something (as a body or
geometric figure) and any later position

the volume displaced by a piston (as in a pump or an engine) in a single
stroke; /also/

the total volume so displaced by all the pistons in an internal
combustion engine (as in an automobile)

Barry Bordes

So how many pistons or equivalent to pistons in a two rotor? Six right?
so each flank is 650 CC. Six times 650 is 3.9 L or 237 cubic inches.
Maybe that is correct and not 1.3 L :)

That would give us a bunch more torque than we are actually getting
and the HP per cubic inch would be piss poor at at less than one.
Particularly since the p-port has no poppet valves in the way when
sucking air.

What does Webster know about rotary engines :)

Ansdale knows. Argument over :)

Paul Lamar

I heard a rumor that the original Ford Mustang (1964?) intended to come
out fitted with a rotary engine installed.. any truth to this rumor?

cheers,

Russ Ward

The engine was built by Curtiss Wright. Here are some pictures.

Paul Lamar

A two rotor engine fires every 180 degrees,the same as a four stroke four cylinder. That is why the Mazda stated displacement is doubled for comparison with four stroke piston engines for engine displacement. Mazda uses one turn of the e-shaft to state displacement for keeping road taxes down.

Dale Davies

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