GT-R32

Martin it's a somewhat pointless cause as some individuals are unlikely, or unable to for various personality, belief and morality based reasons, accept that they are wrong (although in this case, part right) and learn something. You would be flat out insane to look at the rotors, that's like looking at piston speed to determine RPM. Except just because it rotates, it confuses the casual observer. You have to look at the shaft to determine RPM. How does the engine sound at 9,000RPM? Listen to that Mikac 20B in the video I posted a few pages back. The only technically correct way to rate the engine's displacement is by looking at the shaft. Anything else is wrong and is not something you would learn anywhere, in any mechanical engineering degree, but I guess here you can on the internet if it serves your agenda. This applies to all engines and from there you have the ability to 'equalise' them as many motorsport bodies have done.

Why would he need to read so many posts from someone who thinks a rotary is a two stroke and fails to understand that displacement for any engine is measured using the crankshaft? All that will serve to do is fill someone's mind with misinformation.

I agree. A 13B should be known as a 3.9L Wankel. Where you are wrong is in drawing equivalents. You somehow think the engine is a 2 stroke? A two stroke completes its Otto cycle in 360 degrees. How much air does a 13B inhale per 360 degree revolution of the crank?

A rotary is not a two stroke. Okay, I see where you are getting mistaken here. Every single engine in the world's displacement is measured using crank degrees. It's just that they are all mostly 4 strokes so you don't need to have that understanding and hence your comment above. The rotary is not excluded from this. It is this ensures it is accurate and further that it's the relative measure. A two stroke completes its Otto cycle in two distinct 'strokes' and does this in 360 degrees. A four stroke completes its Otto cycle in four distinct 'strokes' and does this in 720 degrees. A Wankel completes its Otto cycle for all rotor faces (which also have 4 distinct 'stokes') in 1080 degrees. For every 360 revolution a 13B Wankel inhales 654cc x 2 = 1308cc. You then apply this volume for whatever 'equivalent' you require above. That's what was trying to show you with regard to the 2/4 stroke comparison (250cc 2 stroke = 500cc 4 stroke). It's all about volume of air per shaft revolution for relative comparisons. I encourage you to do some reading on this. Errrr... That's been my point all along. I'm just trying to ensure that crank degrees are used as the measure as that is the only accurate way to measure displacement. You can then run equivalents off this.

You honestly believe a 13B is like a 6.8L V8? (even then his maths is astoudingly bad) You better call CAMS and FIA and let them know you have discovered something amazing that they don't know! What a conspiracy! How much air does a 13B ingest per 360 degree revolution? Look at the e-shaft mate. Then think. Then think again. And again if you need to. 720 degrees? 1080 degrees? It's not rocket science and this is starting to get embarrassing for you Gary.

Remember to pull excess apex seals out if you are going off 360 degrees.

This bloke understands it. 720 degrees for a 4 stroke TDC to BDC.

http://www.answers.com/topic/engine-displacement The above is a 720 degree, 4 stroke engine. The rotary is the exception to the rule. A 13B is a 3-revolution (1080 degree) 3.9 litre engine. The displacement figure is where I agree with Gary. He does not standardise it by revolution, this then makes comparisons impossible (and incorrectly refers to it as a two stroke which is impossible). Thankfully the motorsport bodies out there understand the idea of relatives. Standardise the 13B to a (4 stroke) 720 degree (2 revolution) rotation and you end up with 2.616L - where each rotor displaces .654 litres of air. 2 stroke? 1 revolution? It's a 1.3L.

There's no point. Gary has already said he doesn't do comparisons in that fashion (using an equaliser). This will never end. Best to agree to disagree. Let's just call the 13B a 80ci engine (and ignore the fact it uses that air like a 2 stroke) and move on.

It appears you can't get past your beef with Mazda quoting the 13B as 1308cc. I'll repeat once again, in order to accurately compare the Wankel to the 4/2 stroke piston, it has to be done on a displacement per shaft revolution basis.

The engine takes 1080 degrees to complete a full Otto cycle, displacing 3.9L. This is not 2 stroke by any stretch, if you believe it so, you must call it 1308cc. You are again, forgetting displacement per (crank/e) shaft revolution. To accurately and fairly compare engine, this must be done on a displacement per shaft revolution basis. How do you rate it in a comparative sense then, Gary? For instance, if you raced 2 stroke 250cc bikes again 4 strokes, what would the 4 stroke engine size be?

Gary, it does the Otto cycle in different chambers, which result in a power stroke per crank revolution (how it the comparison needs to be made) somewhat equivalent to a 2 stroke piston engine. Which means the 1308cc combustion chamber volume needs to be doubled to compare to a 4 stroke. Due to rotary engine inefficiencies, some racing bodies don't do a straight doubling of this. FIA does approximately x1.795 based on these basic engineering FACTS. The gif above accurately demonstrates what happens in one, to help you understand it: http://www.animatedengines.com/wankel.shtml You can then apply it to this: http://www.animatedengines.com/twostroke.shtml Then you will see that due to the arrangement of the rotary, it's arguably a 4 stroke (really, it's a Wankel) as the elements of the Otto cycle takes place in separate chambers by design, which results in a power stroke equivalent to a piston engine 2 stroke. I can see why some racing bodies just ban them altogether. Sometimes people just cannot understand in relative terms.

Rotor tip speed/rotor 'revolution' has nothing to do with engine revolutions, it is akin to measuring piston speed. To accurately and fairly compare engine, this must be done on a displacement per shaft revolution basis. This will not result in a 3.9L equivalent capacity on a 2 or 4 stroke reciporacating basis (1.3L and 2.6L respectively). Some people have somewhat two dimensional minds and find it hard to relate all of this information together at once.

I'm honestly baffled Gary. You seem to have a basic understand how the engine works, a bit here and a bit there, but fail to see how it all comes together as a power unit for comparisons in relative terms to the reciporacating piston counterpart. 3.9L 6 stroke (Wankel 1080°), 2.6L 4 stroke (720°) and 1.3l 2 stroke (360°) are its piston relatives. I guess the closest when you look at this gif (going on power stroke/crank revolution), is the 2 stroke - the only issue is that it doesn't count all chambers (the things that allow the separate parts of the cycle to occur in different locations - that's all they do!), perhaps why Mazda ran with 654cc x 2 for the 13B I think you are confused by the fact that each part of the Otto cycle takes place in a different location, which is what makes them suitable to Hydrogen... but I digress. Remember, it is still a 4 cycle engine! Not 2!

They are unique! You can draw comparisons and rate them in relative terms, but for it to really make sense seeing them in terms of a piston engine need to stop.

Why is there all this talk of a rotary being closest to a two stroke? It's a 3.9L Wankel Cycle. There are six rotor faces that are measured in a compression test. The 4 Otto cycles you refer last 1080 degrees, rather than 720 degrees in a 4 stroke piston. And when compared in this manner a 13B be is directly comparable to a 2.6L piston engine (where the the extra strokes should not be ignored, as a 4-stroke cylinder produces a power stroke only every other rotation of the crankshaft which doubles the volume for the four stroke piston and the demand of displacement). CAMS lower this (normal parity as combustion chamber rotor face volume x2) as the engine is not as efficient as a 4-stroke piston for various reasons. Racing and rego bodies run between 1.5-2 times rotor face volume for the Wankel as a 4-stroke equivalent - Mazda quote 1308cc (654x2) for a 13B which is equivalent to a 2 stroke piston. I don't get why it's so hard to understand?

I've owned rotaries for 9 years and still do. The figure I quoted is from my 'real world' experience, where around town a FD with an average speed of about 30km/h, will see 350kms before the fuel light goes on and ~62L of fuel goes in again. An exceptionally tuned 13B bridgeport in a light RX3 or something can get closeish to the stock FD figures! Most people run them as absolute cops and way too rich, which makes for sweet flames, LOL. This will make them use like 22L/100km. My 20B Cosmo would do the same thing except it would only do 300km and need more fuel. Most of those figures to me are fairly acceptable for modified performance cars. The Cosmo being the exception, LOL.

It's actually 30% greater capacity, comparatively (as the 200SX is a 4 stroke). Oh, did I go there again?

marty I don't care what they say there, I've owned both and a FD RX7 will use 17/18L/100kms around town. While a GTR will use 10-15% less in the same situation. Highway is comparable, however.

Great post rxnomore. And thanks for taking me back. However I was 10-12 years later than you to rotaries, but even then they were something of an oddity. And in my import engine 13B turbo Series 2 RX7 it was $30,000 R33 GTSTs that I loved to beat so much! There was nothing like that surprise on people's faces. Now the reputation of a rotary is that it is fast, it's the mainstream magazines and in drag racing they have made that mark.

For all those saying rotaries sound shit: Entertaining video: http://www.youtube.com/watch?v=yXjzLaVvhjU...feature=related Mazda Furai: http://www.youtube.com/watch?v=vtbjye3JABs...feature=related 787B: It's the twin rotors that people don't like noise wise (I love them though).

They are sick, but nothing beats Toyo Cork Kogyo 's K360: and the Toyo Kogyo K360 SP:

And we all know that Bush was the worst American President ever, but could any one tell him that?

Mate, with all due respect, go back to AusRotary. I go there when I want to read that kind of superiority-complex attitude. It grates on everyone, even people who might have otherwised agreed. Right now back on AR, they are lapping up your attitude as this time it isn't against them. Enjoy it for what it is. Hell, you might have even had people agree with your valid points with regard to the Wankel cycle if they were posted in a different manner. If the RX7 SP is so brilliant, why modify it so extensively? If you are honest with yourself, you will recognise that all my previous points with regard to the Wankel's successes and issues, that are yet to be addressed, have come from you. Quit the disrespect and quit the bashing, for your own sake. It looks weak.

Shouting at us LOL. That car isn't even worth $23k then.