asherwood

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

Judge Ito

The rotary engine has a totally different design from your regular piston engine, u already know that, but it gets alot more complicated then that. A rotary engine in its true design works totally different from your 4 piston engine. Good topic, I think u should send it over the the Rotary performance part of the Forum, and many of us will be happy to give u our understanding of the pro and cons of a 13B

Maxthe7man

It depends if you go by the two rotations of piston engine to size it or the real amount of crankshaft rotation to realize full displacement in a rotary, by piston definition its 2616cc's, I noticed in sport compact car magazines G-games story, they classified it as 2616, not 1308cc, maybe because of SCCA rules they were using or something...Max

Scott 89t2

the rotary only fires once per RPM. the rotor only spins at 1/3 the crank speed. so it takes 3 rpm to fire all 3 sides. the reason some people call it 2600 is because it does fire once every rpm, where as a piston only fires every 2nd rpm.

Evil Aviator

It's a 1.308cc, just like Mazda says it is. This is based on the generally accepted SAE method of rating an internal combustion engine by the total volume traversed by all pistons (or rotors, etc.), regardless of how often the crank fires. For example, a 2-stroke piston engine fires all of its displacement for each revolution just like a rotary, but it is still rated in the same method as the 4-stroke engine.

Racing is another story. The rotary engine is so much better than a piston engine, the rules had to be changed to allow the piston engines (ie the majority) to compete. Therefore, the rotary's rated displacement is often doubled to make up for the fact that the 4-stroke piston engine can only fire half of its rated displacement per output shaft revolution. This is where you get the 2x factor, which compares the rotary to the other engines by a flow rate as opposed to displacement.

Different racing factions may use different methods to keep the various cars competitive. For example, one car may get a weight penalty, while another gets a displacement penalty, or another may get an equipment limitation, etc.

I don't know of anybody who uses the 3x factor, which would be totally unfair to the rotary engine IMO.