The little engine that could...

In know that the 13B is a 1308cc engine, but curious to know if this is the total of all 6 swept combustion chambers?

ie. 1308cc/(2 rotors x 3 chambers)=218cc per chamber

Boinger's try and tell me that because the rotary fires 3 times per rotor revolution it should actually be compared to a piston engine with a displacement of about 3.9 liters.

Are they right or just trying to compensate for the size of their boinger

 

What about a 2 stroke 2 liter!
Would that be considered a 4 liter because it's a 2 stroke!

crispeed
87TII
9.202150mph

 

That's the way I end up describing 'em to motorcycle guys... a friend of mine was big into Ducatis around the same time I got my first RX-7, and I was describing peripheral ported engines, and he askd "so how big are these engines?" and I said "just imagine a 1300cc two stroke motorcycle engine". I thought his eyebrows were gonna raise all the way off his head and his eyes were gonna fall out

 

Yeap 1308cc 13b
1146cc 12a

I've heard that agrument brought up by students many times from fellow students automotive engineering major. Rotary makers decided to show the max displacement between two apex seals rotor face.573cc in 12a 654cc in 13b..which makes it correct in a way, since it can't displace more in that particualer cycle. Kinda deceptive though when compared to 4stroke per power pulse vs shaft rotation, one power pulse per rev in rotary compared to 1 power pluse per 4revs in 4stroke.

 

That's what irks me about people who brag "Yeah your 2.2l Honda just got beat by a 1.3l Mazda"... when rotation for rotation, the Mazda actually has a larger engine.

Somewhere I read that NSU convinced everyone to rate Wankels this way so that he could sell larger/more powerful engines while avoiding engine-displacement tax laws The Ro80 for example was rated at less than 1 liter, and was taxed as such, but it made power like a 2-liter.

I'm also told that IMSA (?) uses/used a 1.8 equivalency instead of a straight 2.0 so that Mazda could be competitive... the 12A easily slotted in to (and dominated) the GTU class, which is Under 2.5l, but the 13B would have been demolished if it was required to race in GTO. (Over 2.5l) A slight adjustment and the 13B is legal for GTU...

 

CORRECTION: you get 2 STROKES per revolution 4/2 = 2 Crank Revolutions (NOT 4) for each power stroke for a PISTON engine - also WANKEL ROTARIES ARE 4 STROKE motors.
Since the Rotor moves at 1/3 Crank speed a Two Rotor gets 2 Power pulses for each Crank rotation - The same as a 4cyl piston 4 stroke motor. But each combustion chamber is the same size as a 1.3L 6 cylinder. Rotaries are rated exactly the same as piston engines displacement = the maximum volume of a chamber (cylinder) - the minimum volume x the number of chambers (equal to bore area x stroke x pistons for a piston motor) it is just that 4 stroke Piston motors take 2 crank revolutions to realise their full displacement while it takes a rotary 3 crank revs so the true equivlancy should be 3/2= 1.5. IMSA used 1.8 to account for the improved volumetric efficency possible with the valvless intake/exhaust tract of the rotary In countries with Displacement based Taxation they generaly use the 1.5 equivlancy.

Also I believe the RO-80 motor was BIGGER than the 12a ie around the same size as the 13b but with different geometry, and was taxed as a 2.5L in GERMANY (I knew some NSU owners when we lived there).