Nihilanthic

Ive already explained this. Repeatedly. It sucks in air at the same rate as a 2.6 liter engine. This *DOES* matter if youre trying to tune an aftermarket ECM for it, size a carburator, or pick a turbocharger.

Why does it suck in air at the same rate as a 2.6 liter engine? It goes through that "1.3 liter displacement" every 360 degrees. Piston engines are rated every 720. A rotary engine doesnt go through a complete cycle until 1080 degrees, however - but 3.9 liters 50% slower than a piston engine is... 2.6 liters at the same rate a piston engine goes at.

Or, more directly, a .65 liter combustion chamber fills in air and ignites the fuel/air charge every 180 degrees. Given the STANDARD RATE OF 720 DEGREES, .65 * 4 = 2.6, exactly the same as a 2.6 liter, 4 piston engine, even down to the tach signal.

And, if youre doing a pro/con contrast and compare between this and a piston engine, it does matter... that is exactly how you compare it so it makes sense.

Dont like it? Well, sorry, you cant play the displacement/liter card (as if it matters ) and it CAN be compared apples to apples to piston engines, if you understand how it works.

gerbraldy

rotary +1

v8 -1,000,000

mark57

Total volumetric (swept combustion) capacity of the rotary cannot be considered as it is for the four-stroke in this "comparison"?

MaxDuo

Eh, I didn't really play a card. I just said I'd call it 1.3 liters but never act like it was the godly 1.3 that beat everything over it. That's what I meant when I said: "Give up the 1.3L beat them" thing. I meant you have to give up your bragging rights of "It's smaller but wins!"

Nihilanthic

It should be readily apparent that a rotary doesnt have "STROKES". You dont need to use them to compare rates anyway, because revolutions of the crank or e-shaft work nicely. Thats where the whole thing about how it behaves like a 4 cylinder 2.6 liter piston engine... or a 3.9 liter 6 combustion chamber engine thats moving 50% slower than a 6 cyl piston engine, so is the same as a 2.6 liter 4 piston engine going at the standard (full combustion cycles of all the chambers in the engine every 720 degrees).

How fast it moves air over time is directly related how much power the engine makes. If you double the ability to move power at a given rpm, more than likely you double POWER at that rpm, assuming the AFR and spark and volumetric efficiencies are the same. Thats why bigger engines can make more power. Thats why turbochargers help engines make more power. This is basic engine theory.

Just because its a different kind of engine doesnt mean all the ingredients arent there. Its just set up differently. The rate at which it can take in air and go through the full combustion cycle matters a lot, becuase thats exactly how you can tell what kind of engine it is and its capable of. Piston engines take two revolutions to go through all the cycles of combustion (intake compression combustion and exhaust) for all of their chambers, and rotaries take THREE.

Everyone KNOWS the rotor goes at 1/3rd the speed of the e-shaft, right? There ya go.

Also, mark57, Im not quite sure what you meant by that statement. Could you reiterate it? And MaxDuo, HOW is it a 1.3 liter engine? If you measure by one revolution of the engine? Then all the piston engines should have their rated displacement halved, and *ALL* the equations out there need their constants changed to go with it.

YELLOWGSLSE

iTrader: (7)

The "R" may not "stand" for Rotary, but it surely "represents" the Rotary. I don't need verification from Mazda to see the clear pattern in the naming. Think of all the Mazda cars with "X" in the name. Some begin with "M" (Mx-3, Mx-5, Mx-6), now the ones that begin with "R",(R100, Rx-2, Rx-3, Rx-4, etc.) What do the ALL have in common??? It's just common sense really. Just my $.02 on the issue. as for the V8 thing, I just prefer the Rotary. I don't see a need to go any further than that.

mark57

What I mean is the only correct displacement measurement of the rotary is to measure its entire capacity of all its rotor faces even if it means spinning the flywheel three times. That the four-stroke must travel through 720 degrees to account for its entire thermaodynamic cycle is fine that engine.

DrunkenGimp

iTrader: (3)

Someone get a rich bastard to make two FD's, one with a rotary, one with a ls1, with equal peak power output and weight, and do a time attack with the same driver and we can all stop bitching...


And no, the v8 shouldnt be reduced to 2.6 litres. The argument is rotary vs v8, remember that the 13b is turboed and the v8 is NA. Two different approaches to making power...

RX-Heven

iTrader: (1)

LOL
I knew once this was posted some of the v8 RX owners out there would come in to defend themselves and the same old bs would happen.

Don't you numbskulls ever get tired of this?

Outkast

The 2 rotor 13B engine always was, always will be 1.3 liters. 80 cubic inches, 1308 cubic centimeters. Just because it breathes more and makes more power than it's piston counterparts, you cannot change the rules. When you go to the Mazda dealer, it is classified as a 1.3. In racing, they put it in a higher class and put restricitions on it, because IT HAS AN ANDVANTAGE. JUST BECAUSE IT HAS AN ADVANTAGE, IT DOESN'T MAKE IT BIGGER!!!. We like the rotary engine because it is compact, powerful, and allows for a low overall weight and center of gravity, and nice bodywork. Now someone please provide a downloadable version of this video (600+ hp V8 supercar getting slapped around by 1.2 liter rotary).

Outkast

And the next time you guys pick up a 3.9 liter 6 cylinder engine, and put it on a scale and it weights <250 lbs, and you can put your arms around it, PLEASE LET ME KNOW!

SmogSUX

iTrader: (12)

Heh the point behind v8 vs rotary is the engine in the car it was made for...Take a stock 93 FD vs a stock 93 corvette Too many people trying to compare a NEW technology V8 vs an OLD rotary...and no don't even say "Okay take the renesis against it then" because Mazda took a huge break from rotary..now if they had been working on the rotary making it lighter and having a higher power output...then we can talk. Rotary 1 V8 - NADA

Nihilanthic

Hey braniac, displacement has exactly zip.**** to do with weight or size of the engine. Furthermore, I said its a 3.9 liter engine that goes slower than a piston engine, making it equivilant to a 2.6 liter engine.

You *DO* Know the rotor in there moves at 1/3rd speed of the e-shaft, right? This has been gone over repeatedly, and a lot of the rotards love the fact that its going slower in there for longjevity reasons. Heeeeeeeres your sign.

Um. YOU cant change the rules, neither can Mazda! My arguement is to measure things by the same standard that makes SENSE. Math and physics doesnt lie or work differently because you dont understand what Im saying, or because mazda is getting off on specific output and measuring displacement in some nonsensical way.

Mazda says its 1.3 liters because they measured ONE rotor face's combustion chamber's displacement, and then did it times two for the numbers of rotors. Thats not the whole engine, now is it?

However, WTF are the other two rotor faces? Chopped liver? do they do nothing? Are they useless? No. They suck in air, compress it, burn it and exhaust it too. However, the rotary has to spin 3 times, or 1080 degrees to go through all three of them. A piston engine takes 2, or 720 degrees.

Do you actually understand that? Or are you simply ignoring it and regurtitating what mazda rated the displacement as wihtout even opening your mind to the explanation of it.

Oh, and finally, go read up on what BMEP is and why a rotary engine cant possibly be a 1.3 liter engine - besdies the fact that going by the rate used in the equations that were previously developed with piston engines in mind (two crank or e-shaft revolutions, aka 720 degrees, which is exactly 2/3rd of a rotary cycle...) two rotor faces x 2 rotors (or 4 x .65 liters, go open up windows calculator to figure it out for ya) a 13b is moving 2.6 liters of air, the KNOWN inefficiences of the rotary engine due to the geometry of the combustion chamber (its surface area is too high and it loses heat) plus the geometry not allowing it to as efficiencly use thermal expansion to move the rotor, PLUS the fact that it cant burn the whole fuel/air charge in the engine, which contribues to its higher BSFC than a piston engine, all mean that if its a 1.3 liter engine its somehow sucking in two atmospheres of air into each rotor face.

Well, hey, it doesnt make sense. Just becuase you dont feel the need to read and understand this, or are unable to, and thus mentally lock up and regurtiate mazda brochures and marketing instead of actually comprehend my arguement and issue a counterarguement to it, doesnt mean what you have to say is right.

First go and understand WHAT im saying, and then try to argue against that and prove me wrong. EVERYTHING Ive just said Ive said before, and other people have said before. For it to be a 1.3 liter engine it would have to be using some exotic fuel or somehow having a VE% between 140 and 200%! A rotary engine does NOT have a VE% of that without forced induction. The math doesnt add up!

Also, to reiterate again, SPECIFIC OUTPUT DOESNT MATTER. DISPLACMEENT AND WEIGHT AND OR SIZE OF THE ENGINE ARE NOT DIRECTLY RELATED. A 5.3 liter 5300 and a 7liter 427 LS1 are... *gasp* THE SAME SIZE. The 5300 just uses an iron block becuase its a truck engine, but otherwise the block and heads are the same.

One of the strengths of the rotary is packing displacement into a small size, but the marketing and import mentality that displacement is 'bad' is driving you to argue its a 1.3 liter without even understanding what youre talking about. Specific output doesnt make one engine beat another in a race, its POWER to WEIGHT.

Specific output CAN be a measure of an engines efficiency, if you do it by TORQUE output instead of power. Even an inefficient engine can rev up to make a high specific power output, but torque per displacement is more equal, a engine that never sees north of 6.5K can have a higher specific output of one that spends its days revving to 8K. But Im sure youd think the 8K rpm engine is better because it revs higher .

So yeah. Happy thanksgiving, and go understand what youre talking about before you ignore everything I've said and just stubbornly re-iterate the marketing and misinformation, because if you continue to do so I will continue to tell you to do your homework and learn what the variables are.

P.S. - 12as are 2.4 liter engines. Id love to see you prove me wrong, but you obviously cant grasp how a 3.9 liter engine going 50% slower than a piston engine can be the same as a 2.6 liter piston engine in terms of its ability to move air, so I dont see how you could.

particleeffect

where are you getting the "50%" slower? 1/3 speed does not equal 50%...

maybe you should just stick to measuring displacement based on crank rotations. it takes 2 rotations for a 4 stroke piston engine to move it's displacement, so 2 crank rotations for a "1.3" rotary would be more like 2.6... just like sanctioning bodies do for motoX with 4-vs-2 stroke engines.

Nihilanthic

particleeffect - all 3 rotor faces dont go through a complete cycle unless the rotary engine spins 3 times. 3 x 1.3 is... what? Also, if a piston engine takes TWO revolutions.. and a rotary has one extra rotation... its 50% more. A piston takes 33% less than a piston. You know the old brain teaser about... you have a dollar, you get 10% to it (1.10) and I take 10% away (11 cents) how much do you have left? 99 cents.

My point is that if you want everything to be apples to apples with all variables accounted for, a piston engine is (whatever) liters with a 720 degree cycle. a 13b is 3.9 with a 1080 degree cycle. If you go by the same cycle, 720, a rotary is 2.6 liters. Now, if the rotary takes an extra revolution to go through all of its chambers, but its also 50% bigger, so it cancels out, sure, call it a 2.6 liter engine... but its really not. Its a 2.6 liter engine when compared to the 720 degree world of piston engines.

Besides, part of the marketing of Rotaries is that the rotor goes slower than the e-shaft, helping with reliability vs piston engines.. but suddenly that factoid evaporates because it makes them look 'bad' becuase displacement is a bad thing in their mind .

It IS a 3.9 liter engine, but it doesnt go through all of it as fast as a piston engine does, so its really a 2.6 liter engine with an extra rotation to confuse everyone :P

mark57

Let's go the other way: What is a four-stroke piston engine when compared to the 1080 degree world of rotaries?

When did Mazda take this "big break" from rotaries that SUX claims?

Outkast

When the RX-7 was discontinued in the U.S. in '95, it continued to be produced and slightly improved in Japan until '02. However, the 13B-rew motor it had was an entirely different animal from the RENESIS in ther RX-8. Ford has a controlling share in Mazda, and research and development of the RENESIS was not authorized. A handful of dedicated rotorheads made it on their own time without any financial support and presented the finished product to Ford, and they were so impressed they made the car. The RX-8 is the second best selling sportscar in the world behind the MX-5, (18 months to reach 100,000 units vs. 17 months) according to Guiness records, and beat the 333 hp 8000 rpm BMW M3 for Engine of the Year in 2003. I don't think it needs to be defended, just maybe put in a lighter car and blown to annihilate all once again like in '93.

And the rest of you need to go suck on a piston, we don't care what displacement has to do with size, we care what fits under our tiny hoods and how much it weights. The 9000+ rpm redline allows us to take advantage of gearing (4.44 stock RX-8, 4.10 stock RX-7) and the rotary is unbeatable in all forms of motorsports it hasn't been banned from. Have a nice day

Outkast

Published: 10/19/04

David S, AutoWorld.com
Copyright 2004 Vehicle Information Services, Inc.
Mazda Motor Corporation’s four-door, four-seat sports car—the RX-8—has reached a significant production milestone: number 100,000 rolled off the Ujina No.1 final assembly line near Mazda’s corporate headquarters on September 29, 2004. This important milestone was achieved 18 months after production began in April 2003.

Reaching 100,000 units in 18 months compares favorably with Mazda’s other famous sports car, the open-top, two-seat Roadster/MX-5/MX-5 Miata. With the Roadster, which has been recognized by the book of Guinness World Records as the world’s best-selling convertible sports car, only 17 months were required to reach number 100,000.

As an entirely new type of sports car that features distinctive sports car styling and excellent performance, the Mazda RX-8 was launched in Japan in April 2003 and is now sold in over 20 countries around the globe. Cumulative sales volume as of the end of August 2004 was over 23,000 units in Japan, over 29,000 units in the US and in excess of 18,000 units in Europe.

Mazda’s RX-8 is powered by the award-winning, naturally aspirated RENESIS engine. The compact, high performance rotary engine is without a doubt Mazda’s spiritual soul and shortly after being launched in 2003 was named "2003 International Engine of The Year."

In total, the RX-8 and its RENESIS engine have won more than 37 important automotive awards around the globe to date, including Japan’s "2004 RJC Car of The Year","2003-2004 Most Excellent Developer Award," presented by the Japan Automobile Hall of Fame, the 2003-2004 Japan Car of the Year ''Most Fun'' special award",10 Best Cars 2004" by US’s CAR AND DRIVER magazine and in Australia, "2003 Car of The Year" by Wheels magazine.

Outkast

Did I mention that it's still a 1.3?

mark57

It isn't 1.3L. Do I still have to suck a piston even though some of your rotary buddy proponents, like Smog SUX, are stoopid ee-dee-otts?

academytim

Tiny hoods? So tiny that a small block V8 slides right in like it was designed for it? lol Try again dude...the 13b doesn't have a whole lot of displacement, but the block and accessories aren't exactly "tiny". As far as weight is concerned...go search for the corner weights and tell me that the addition of 20lbs the LS1 adds makes it a "nose heavy" car. Then I want to go see you post in every thread in the "audio" section where someone has a stereo in their FD and tell them about how they destroyed their handling by adding 50lbs of subs and amps in the back. Get real.


btw Mark...you need to get another ride in my dad's car. He just changed the plugs out and they were fouled to hell and back. The butt dyno says it has about 30whp more than it did when you rode in it. You can't even roll easy into second without the whole rear end stepping out at about 3k rpm.

Outkast

Wrong again. The LS1 is only a little bit heavier than a 13B + the twin turbocharger assembly. The turbos on a 93-95 RX-7 weight around 100lbs as a unit. As you have just stated, the rotary weights less than the LS1 even with the turbo setup, and is much much lighter and smaller when comparing ENGINE to ENGINE. And yes, adding 50+ lbs to an ultra lightweight car with near perfect 50-50 weight balance that was designed on a "gram strategy" diet WILL compromise weight balance and handling precision ( which is why I ripped $2000 worth of stereo out of my '94 when it started running mid 11s on 15 psi boost - on a 1.3 liter street engine BTW ), although it may help with launching. Just because you put a motor in a car that weights "only an little more than the original" and "fits pretty well", doesn't mean that motor is better suited for that vehicle or superior in any way. Please tell me what the big deal is about V8 RX-7s running 11s and 9s occasionally when the 2 rotor does it all day with some added boost. And the day an LS1 - swapped FD outhandles a stock Spirit R or mildly modded 93 on ANY road course I will shove a piston up my own ***. Take your flowmasters and your torque and go drink some beer and comb your mullet.....

academytim

haha...guess you should search for the autox results that Damonb posted in regards the comparison between his prepped 13b Rx7 and an LS1...I'll save you the effort, the LS1 was faster. And what is so nice about running 11s and some occasional 9s? Doing it in an engine that will last longer than 30k miles without requiring an engine rebuild. Also getting 25+ miles per gallon is a nice added bonus.

Outkast

Here is a little FACT from history for my 900th post as a reminder to all rotary driving and mullet wearing creatures alike:

A base model 1993 5-speed RX-7 completely STOCK and perfectly driven:

220 rear wheel horsepower
4.9 seconds 0-60 mph
13.5 @ 100 mph 1/4 mile
2700 lbs on the scales

Give me a V8 that can lay down those numbers with such little power and let's not forget that the motor is capable of 500 hp without pushing too hard and a 2.0 liter 3 rotor can do it on single digit boost with a weight penalty of only 100 extra pounds. Power to Weight ratio goes through the roof into outer space........

academytim

Are we comparing a total car or an engine? You're comparing a 2800lb rotary to a production V8 car that weighs what? 3400+ pounds? I'll show you a video of Hinson's prototype with a bone stock LS1 running an 11.9 on drag radials. 500hp, you think thats not easily attainable with an LS1? I'm completely with you on the performance of the 3rd gen Rx7. Hell, I used to be the one bashing the V8 swaps. I just recently pulled my full bolt on motor out of the car while it was still running. All it took was for me to open my mind up a little bit and actually ride in/drive a converted car. The rest is history. No one is arguing that the 3rd gen Rx7 isn't a fantastic chassis. It's a scorching performer no matter what engine is in it. Whether its a properly built 13b, 20b, or LS1. Any of them make a great performer. You don't have to like it, it may not be your cup of tea...but you have to at least respect it. Anything less, is just having blinders on and being close minded.


PS-I don't have 900 posts, but look at my join date. I'm not some newbie man. I've owned this car since early '02, and have only been a "swap" guy for about 6 months now. No ones trying to start an argument, just trying to get people to see the facts and look past all the BS.