gwilson40

IREAD RECENTLY IN A MAGAZINE THAT ALL 13B MOTORS ARE ACTUALLY 2.6 LITERS NOT 1.3 BUT EVEN THE MAZDA DEALERSHIPS IVE TALKED TO HAVE SAID THAT THE ENGINE IS 1.3 LITERS. I JUST WANTED TO KNOW FOR SURE THANKS

BicuspiD

...look out behind you.... theres a BEES Nest...

Im not touching this one - I love my rotary regardless of what anyone think the displacement is

Kevin

I dunno - From my understanding, it seems that people who are jealous of the rotary engine's efficiency like to tell themselves that "oh, it's really a 2.6 liter."

paw140

This thread explains it all https://www.rx7club.com/forum/showth...5&pagenumber=1

The 13B is basically equivalent to a 2.6L piston motor. Anyone who says otherwise doesn't understand the 13B very well.

KevinK2

There is no official SAE 'displacement' standard AFAIK, but most commonly used definition is "total swept volume per engine cycle" .... and an engine cycle is one rev for piston 2-stroke, 2 revs for piston 4-stroke, and 3 revs (crank) for rotary. The 'swept volume' is related to the amount of intake air pumped thru a NA engine at 100% VE in one engine cycle.

For a 2L 4-stroke boinger, the 2L is 'air swept' in 2 revs. For 2L 2-stroke piston eng, that air is swept in one rev, so it injests about twice the air, per rev, of the 4-stroke with same bore, stroke, and number of cyl's. So there was inconsistent displacement vs power ratings before rotaries.

The 1.3L rotary 'sweeps' 1.3L per rev, and will pass charge air thru all 6 chambers in 3 revs, displacing 3.9L in one engine cycle, which takes 3 revs. So by the old convention, 3.9L displacement rating.

Mazda has it's own unique rating system, rates it's rx engine's 'swept volume' displacement for just one CRANK rev ( vs engine total cycle).

Race equiv's rules are most clear when grouping equivelant engines, the 1.3 mazda = 1.3L 2 stroke boinger = 2.6L 4 stroke boinger ....... all will ideally pump the same air per crank rev at 100% VE.

Historic practice is to normalize to the most popular engine, the 4 stroke piston engine, with 2 revs to exercise it's rated displacement of charge air. The 1.3L mazda rated rotary becomes a 2.6L engine, and a 500cc 2 stroke piston engine runs against 1000cc 4 strokes.

regarding stroke, the piston stoke is linear, and exactly 2x crank offset. The wankel stoke is not linear, as the active rotor face chases the eccentric offset. Knowing the rotor face displacement, and it's projected area, the actual effective stroke is 1.5 times the eccentric shaft offset.

piston muncher

I agree with Kevin!

madaz07

i dont think RICE RACING would agree with ya on that

ERAUMAZDA

its a 1.3 period the end

jgrts20

i dont AGREE WITH THAT, its a 2.6L, PEACE!!

ERAUMAZDA

tell it to sae.....not every thing u hear is a fact.

Street King

1.3 liter PERIOD!

Who are you going to trust SAE or some yup on a forum board?

paw140

Well, you an either understand the reasoning behind SAE's and Mazda's designation, or you can accept on blind faith everything that people tell you.

Wargasm

The way I see it the displacement is how much volume difference there is between maximum and minimum chamber volumes. In a piston engine this yields area of the bore x the stroke and that's your displacement.

For the rotary, it's actually calculated the same way and it ends up being the maximum chamber volume - minimum volume (0).

The rotary just makes better use of the displacement so everyone gets all bent.

Who cares anyhow, they're fun to drive

Brian

The_Ego

Are they not 80 cubic inch?! I think it's just the 2 stroke type cycle and the wicked power output that makes sad people say they're really 2.6L, but in reality, 2 stroke or not, they are 80ci, correct me if I'm wrong here.

Funny thing is, I never hear anyone say that a 500cc 2 stroke bike is actually 1000cc just because it's a 2 stroke! At the end of the day, the cubic capacity is still 500cc so yeah.... That's it right there I think.

Just the anti rotor brigade get there knickers in a twist coz rotors go hard for their size. Who really gives a toss if they are 2 stroke, they're still 1.3L regardless, not me.

paw140

I'm not saying it's a 2.6L!! I NEVER said that. Yes, it's a 1.3L. Just like you would never compare a 500cc two-stroke to a 500cc four-stroke, you would not compare a 1.3L rotary to a 1.3L four-stroke piston. That's my point.