That statement is completely false.

I suppose a 125cc 2 stroke engine is really a 250cc 4 stroke?

Here's food for thought......How come the 13B (REW) has been rated by mazda and THE SOCIETY OF AUTOMATIVE ENGINEERS as a 1.3 liter engine?

 

He read it in Sports Compact Car - you know, the one about the Rx-7 and displacement about 4 months ago...lol

 

It is? Well hush my mouth!

I was talking about 4-stroke piston engines compared to rotary engines, obviously... I don't know too many people with cars powered by 2 stroke engines. Do you?

Here's food for thought... why wouldn't they? If Mazda says its displacement is rated based on only one complete rotation of the eccentric shaft, I doubt the SAE is going to dispute it. There's no logical point. As long as all rotary engines are rated using the same method, who cares? But I am quite impressed that you know the minds of not only Mazda's engineers, but also everyone who was involved at the SAE... are you clairvoyant? What am I thinking now?

If you want to insist that the rotary only be rated using Mazda's method, that's fine with me. However, I'll then have to ask you why its power per liter is such an overused bragging point when a good sized V8 with less than half as much power per liter can hand the rotary its *** in any measurement of engine performance.

 

Don't quit your day job just yet, your stand-up routine still needs a little work.

 

Each rotor should only be counted as one on a scale of displacement since each of the three sides are not compressing fuel at the same time, only one is.

Haha, you just lost your own argument - You said before that you can't compare a Rx-7 with a Z06...well, don't compare the rotary engine to a normal piston engine...the displacement is measured differently. And I WOULD quit your day job since it seems to be taking away your sense of humour and causing your never ending Rx-7 project to last into the next millenium...just sell it and buy a Viper since that's obviously what you're trying to build...better yet, get a new day job with MOPAR.

 

Did you say something? I'm sorry, you'll have to come back when you're worthy of debating with. I have no interest in wasting my time bandying words with someone whose sole purpose seems to be grinding a personal axe because they can't distinguish between their own personality and that of their car...

 

You have strange hobbies Jim, You spend yoru free time tinkering with a car that you dont particulairly like (at least not the engine) Then you come in here to get your ego boosted by telling us how stupid we all are for not acknoledgeing how superior corvettes are to the RX7?
We are not worthy of debate? What kinda egotistcal trip are you on anyway?

Wife make you take out the trash one to many times or what ??Im just wondering who pissed in your cheerios. If you would be happier with a different crowd then why waste your time in here informing all us us **** ants that the corvette is better bang for the buck. Its a beat story and honeslty who the **** in here even cares except you and a maybe a handful of others. I think I speak for alot of people in here when I say.. We dont care if the corvette is better we like our RX7s!!
If your so inlove with corvettes please visit the appropriate forum. This is the one for RX7 enthusiats. Sorry if we take offence you old coot. Talk about being a mean old man.

Jim----> <------RX7 fans

 

For those who insist that when comparing rotary vs. piston engine displacement 1.3L is the correct number for the 13B:

Every single auto racing sanctioning body on the earth disagrees with you. In race classes that have engine displacement or displacement/minimum weight rules the rotary is always forced to double it's displacement from what Mazda quotes.

This is not the evil anti-rotary conspiracy that everyone purports It's because that's what it takes to make the displacement values of both engine types relative.

IMO anyone who brings up "2 cycle" in any way in any displacement discussion has no idea what they are talking about.

 

the fd is great built 10 years ago and it can still be the topic of discusion and even make certain corvette lovers green with envy,,,,people make cars faster and faster with each passing of year but that the fd can still be even considered agains a brand spanking new z06 for me is great.......btw my fd has e 3rotor with a single turbo in it a turbonetics t76...i dont know `bout you guys but I`LL kick a zo6 *** anyday with half the throttle .........corvettes ........please dont make me laugh since when where they fast never where never will besides instaid of bashing the 7 say thanks to it for given the corvette its current shape

 

Ahmen

 

Please read this link

 

And every motorcycle racing sanctioning body agrees with you. Two-strokes dominated motorcycle racing since the early 1960s (and caused four-strokes to die off in racing) because they were simply a more efficient racing engine (combustion emissions notwithstanding). The motorcycle racing teams and manufacturers racing four-strokes at the time didn't stomp up and down crying about a supposed "relative displacement value"-- they sucked it up, and developed their own two-stroke racing machines.

The only real reason the auto racing sanctioning bodies double the displacement of the rotary is because it's considered an anomaly made by only one manufacturer, versus dozens of others who don't want to market a rotary-powered car (which I can totally understand due to the rotary's many disadvantages for road use; marketing a similar road-going machine is the real reason behind any type of production-based auto racing). The inherent racing advantage of high power output for displacement for the rotary was difficult to overcome with just weight or other handicaps, so the racing organizations took the easiest route.

I find the argument about "relative displacement" just because a four-stroke motor has to go through two complete revolutions of its crankshaft to make power compared to one for the two-stroke (and the Wankel) a bit weak and misguided.

 

I disagree. I think to compare displacements of piston vs rotary you have to look at combustion events per crank revolution; that is why the rotary takes a double hit on its 1.3 liter displacement.

It is also why a 2 stroke would take a double hit; it has twice as many combustion events per crank revolution than a 4 stroke.

It all makes sense to me.

 

sorry teacher brad .....the love for defending the rotary got the best of me.
again, thank you ,since youre link i am a better person.....

 

Not at all to me, because the word "displacement" signifies the amount of combustion volume in a power stroke of an engine. Just because someone built a better mousetrap (yes, I know, debatable in the rotary's case) to make more efficient use of that volume doesn't mean that they should be penalized for it. It's this type of thinking that stunts any development growth in performance vehicles.

 

Then all multicylinder piston engines have their displacement artificially doubled because as you know only half the cylinders are on the power stroke at any given time.

Whether you choose to double the rotary displacement or halve the piston displacement you get the same number that quantifies their relative displacement IMO.

 

Apologies, disregard this post. My mistake in how a rotary housing is actually shaped... I was thinking too much about two-stroke piston engines.

 

No offense taken. I just don't follow you...

I guess this is where we disagree. I don't see it as Wankel and two stroke vs. four stroke piston motor. I just see it as the amount of air/fuel volume ingested and combusted for a given engine RPM. That to me means that rotary volume has to be doubled because Mazda's 1.3 liter figure does not compute displacement that way.

In my line of thought you would also double the displacement of a 2 stroke piston motor if comparing it to a 4 stroke piston motor. We however never do that because we recognize that 2 stroke engines and 4 stroke engines are fundamentally different. A rotary is not fundamentally different however; it is still a 4 stroke motor.

All of this IMO of course.

 

and a better mousetrap indeed, i agree with kento the rotary is far more efficient tahn a piston engine,just the fact that it doesn`t have to convert reciprocating motion into rotating motion, and also that its power stroke is spread over aprox. 270deg of crank rotation already is a testament of the rotary`s supremacy

 

Efficient in what way? It's common knowledge that the rotary has poor combustion efficiency due to its combustion chamber shape and this is proven with it's very high EGT and it's ability to suck fuel.

If the rotary has a 270 degree power stroke than your saying the intake, compression and exhaust strokes added together are only 90 degrees total (360-270=90). I don't follow

 

OK, now that I disagree with. I look at the two-stroke motor as an engine that makes more efficient use of its power stroke displacement, since it's not wasting time with an "exhaust" revolution.

Damon, note that I retracted the previous post...

 

So if someone tells the truth about your car, they're a mean old man? So why isn't Damon a mean old man too?

 

Because Damon isn't as old as you!!

 

No problem! I can see that your sentence structure has improved ten fold! You are an excellent student, I shall nominate you for scholar of the year.

 

Ok how about just old man then. You aint speaking about my car dont worry. I'll stick with my underpowered, unreliable, rotary powered go-kart.
Thanks and enjoy your rx-vette.