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[quote=Matra et Alpine;886525]ht, the ACTUAL displacement of the engine by traditional means is 1.3
THe "combustion chamber maximum size".
Having to talk about swept voume and it's relevance makes it confusing for some.[/quote]
You are missing an important part of the definition of engine displacement... its combustion chamber maximum size times number of combustion chambers...
There are 3 combustion chambers for each rotor... and a total of 6 combustion chambers for a two rotor wankel engine. Swept volume is just total displacement minus combustion chamber volume for a normal piston engine but wankel engines sweep their entire displacement and therefore swept displacement = total displacement for wankel engines (generally, there is a small volume around the spark plugs that isn't swept).
[quote=Matra]The actual "displacement" is the SMALLEST of the figures ht.
When it goes "bang" that is the power pulse and thus SHOULD be the only one of interest. ... or to borrow one of your analogies, shuold a single cylinder engine be compared the same as a rotary IF it spins 3 times faster ? :)[/quote] Ok but what about the other two sides of the rotor? are they working in a vacuum? So far the only reason I have heard as to why they shouldn't be included is because of the fact that there is only cycle that fully completes per revolution of the crankshaft (eccentric shaft if you will). But that is not a part of the equation for total displacement at all?
take a look at this animation: [URL="http://www.rotaryengineillustrated.com/wankel-engine-animations/chamber-centric-848k-swf.html"]Here[/URL]
This animation shows what happens in one chamber of the wankel engine.
Then take a look at this animation: [URL="http://www.rotaryengineillustrated.com/wankel-engine-animations/2x3-working-chamber-1mb-quic.html"]here[/URL]
clearly there are 6 working chambers just like say a 6 cylinder engine which also has 6 working chambers. The fact that it takes 2 revolutions of the crankshaft to fully complete a 4 stroke cycle in each cylinder of the 6 cylinder engine as compared to the neccessary 3 revolutions of the eccentric shaft to fully complete a 4 stroke cycle in each working chamber of the wankel engine is a question for equivalency factors, it has nothing to do with actual displacement.
[quote=fpv-gtho]HT, forget about the displacement, swept volume and all that crap and just concentrate on the power pulses. Just like a 2 stroke, a wankel rotary produces a pulse for each RPM. 4 strokes produce a pulse for every 2 RPM. That is why x2 is the most common equivalency for both. Your scenario has the factor applied the wrong way; a 250cc 2 stroke is equivalent to a 500cc 4 stroke.[/quote] ??? again I am only talking about displacement... I know all about the different equivalency factors that are used for the wankel rotary engine but I am not arguing about equivalency factors. Forget about equivalency factors!
A wankel engine is a 4 stroke engine regardless of the number of times a power pulse is produced per eccentric shaft revolution. whether an engine is a two-stroke or a four-stroke is defined by the number of "strokes" needed to complete the combustion cycle for a single working chamber.
You misunderstood my scenario... I was talking about the physical displacement of the engine. Let me ask you a question: If you had a 250cc two-stroke engine what is the combustion chamber maximum size???
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Sorry ht, I'm not getting in to opinion with you.
You're 3 combustion chambers is pish.
There is only ONE combustion CHAMBER and that is the one that occurs as the rotor face comes to the spark plug(s) in the housing.
The rest are NOT comb ustion chambers until they come to the spark plugs.
So please, don't spread mis-truths about the wankel capacity.
As in the past you bring logic to an area where established principles exist.
Thus it is accepted principls that a 2-stroker is 2*bore*stroke.
BUT the same is NOT accepted for the Wankel because it is "different" :)
So by all means we can debate 1.3 or 2.6 but let's take 7.4 off the table !!
PS: I own and race/rally/hillclimb a Prodrive Mazda RX-8 PZ :):) and spent time at last years Le Mans 24h in the Mazda 757 pit garage :)
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[quote=Matra et Alpine;886609]
There is only ONE combustion CHAMBER and that is the one that occurs as the rotor face comes to the spark plug(s) in the housing.[/quote]
Ok and because each rotor has 3 faces that means that we can count them all for total displacement.
[quote=Matra]The rest are NOT comb ustion chambers until they come to the spark plugs.[/quote]
OK but all three faces do at some point come to the sparkplugs...
[quote=Matra]As in the past you bring logic to an area where established principles exist.
Thus it is accepted principls that a 2-stroker is 2*bore*stroke.
BUT the same is NOT accepted for the Wankel because it is "different" :)[/quote] OK but I am not trying to change the established principles... I am simply stating that in reality wankel engines are much larger displacement engines then they are classified. I am not trying to get a petition signed at all, I couldn't care less what countries recognize the wankel engine as displacement wise for tax purposes. I am discussing this from a specific engineering viewpoint. Did you look at the animations?
[quote=Matra]So by all means we can debate 1.3 or 2.6 but let's take 7.4 off the table !![/quote] Not paying too much attention are you ;)... I said the 13B is really 3924cc (3.9L if you will). The R26B is actually a 7848cc engine (7.8L if you will). Although when I talk about wankel engines with anyone who I don't really know well or who I don't consider especially car-literate then I have no problems calling the 13B a 1.3L engine and the R26B a 2.6L engine... Just FYI.
[quote=Matra]PS: I own and race/rally/hillclimb a Prodrive Mazda RX-8 PZ :):) and spent time at last years Le Mans 24h in the Mazda 757 pit garage :)[/quote]
Haha I know you have that car you lucky b**tard! it is a very nice car and you can consider me jealous...
Did you get any pictures of the 757 engine bay? is it turbocharged? I thought it wasn't but others have said it was...
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2 Attachment(s)
ht .... let me repeat NOBODY counts all the chambers for cpacity of a Wankel !
Find me ONE source to validate your opinion ?
Oh and you KNOW the point made about the differing capacities.
It's WRONG to count them all and let me repeat .. NOBODY DOES.
Yes it's NA, not only pics, but crawled all over it :)
Discussed it with the mechanics, the driver and even his wife !!
the car details [url=http://www.groupcracing.com/cars/38]New article[/url]
and Jim [url=http://www.groupcracing.com/drivers/26]New article[/url] a really nice guy.
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Was the turbo rotor they speak of in the [URL="http://www.groupcracing.com/cars/38"]article[/URL] run a inlet restrictor ?
heres another article of how well the rotors have done in road racing
[url]http://media.ford.com/pdf/rotary6_e.pdf[/url]
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[quote=Matra et Alpine;886627]ht .... let me repeat NOBODY counts all the chambers for cpacity of a Wankel !
Find me ONE source to validate your opinion ?
Oh and you KNOW the point made about the differing capacities.
It's WRONG to count them all and let me repeat .. NOBODY DOES.[/quote]
Try reading: [ame="http://fdowners.com/showthread.php?t=2159"]this[/ame]
and [URL="http://www.hemmings.com/hsx/stories/2008/04/01/hmn_feature11.html"]this[/URL] and [URL="http://www.enginesandgearboxes.co.uk/pages/home/engine-sizes-displacements.php"]this[/URL]
you get three for one!
BTW it isn't my opinion it is simple logic. Not my fault Mazda marketing was able to fool governments into agreeing with the 1.3L figure...
Thanks for the pictures! Yeah positive confirmation of N/A!
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CLassic links..
THe first one is an expert pronouncing how he has always advocated the larger size ... he mentions DISCUSSING it with Wankel ... I woudl suggest that if Wankel agreed with him he'd have called that loud from the mountain tops. So we make an inference.
The forum link ( usually not to be trusted ) does have a comment which will help explain your confusion... "3.9L displacement, 6-stroke cycle" ... so IF you use the "big number" then you accept you're citing for a SIX cycle and thus is incomparable to an otto piston banger :) It would be like trying to compare a jet engine with a piston engine based on the size of the "combustion chamber" of the jet engine :) :)
Finally the third link didin't work :(
Your "logic" is flawed. You are tyring to quote capacity so it can be compared with a piston engine. by firing at 1080 degree repeat then the wankel is NOT the same. Again, it'd be like comparing the cylinder size instead of the swept volume of a 4 stroker :)
Please don't sperad the confusion. Compare apples with apples or if you insist on comparing them with oranges then at least adopt the accepted "standard" ratios.
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[quote=charged;886632]Was the turbo rotor they speak of in the [URL="http://www.groupcracing.com/cars/38"]article[/URL] run a inlet restrictor ?
heres another article of how well the rotors have done in road racing
[url]http://media.ford.com/pdf/rotary6_e.pdf[/url][/quote]
there's a sticker on the rear quarter window of my rx-7 commemorating the 1980 IMSA/GTU manufacturer championship.
[url]http://www.ultimatecarpage.com/forum/attachments/users-rides/257891d1193866250-pokeys-rex-07oct20-102-resize.jpg[/url]
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No offence Hightower, but i just think you are way to set in the traditional mindset of a piston engine. I think thats were we fail at understanding each other. That they are so vastly different engines.
I think it's cool however that you stand by your belives and don't budge. I won't agree with you one bit tho.
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[url]http://shell.deru.com/~sgn1/AW11/images/4age20v.jpg[/url]
4A-GE 20V or a Group A spec Honda B16A like the one in this video.
[url=http://japanesenostalgiccar.com/blog/2007/11/02/group-a-division-1-racing-the-shopping-trolleys/]Japanese Nostalgic Car - Blog Blog Archive Group A Division 1: Racing the Shopping Trolleys[/url]
The sounds; they are awesome. :D
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[quote=Matra et Alpine;886651]
THe first one is an expert pronouncing how he has always advocated the larger size ... he mentions DISCUSSING it with Wankel ... I woudl suggest that if Wankel agreed with him he'd have called that loud from the mountain tops. So we make an inference.[/quote] Actually it is the second article posted that is the made by a professional journalist by the name of Karl Ludvigsen you should read the wikipedia article about him: [ame="http://en.wikipedia.org/wiki/Karl_Ludvigsen"]here.[/ame] He doesn't directly say he discussed the actual displacement problem with Felix only that he did have corresspondance with him. Maybe you should also read alittle about Felix too he was not the type of man who could succede alone at championing anything.
[quote=Matra]The forum link ( usually not to be trusted ) does have a comment which will help explain your confusion... "3.9L displacement, 6-stroke cycle" ... so IF you use the "big number" then you accept you're citing for a SIX cycle and thus is incomparable to an otto piston banger :)[/quote] You misunderstood what he meant by 6 stroke cycle Matra. He wasn't talking about the thermodynamic cycle he was talking about the fact that the eccentric shaft performs 6 "strokes" (i.e. 3 revolutions of the eccentric shaft) to get one face of a rotor through all 4 phases of the Otto cycle. Try reading the article again it is actually quite good.
Here is the third link: [url]http://www.enginesandgearboxes.co.uk/engine-sizes-displacements.aspx[/url]
Hopefully if copy-paste doesn't work for you then you can navigate from the main page to the article, it is also a relatively good article.
It is rather odd that you are trying to somehow discredit my links but as I recall you only asked for one single refference to somebody else counting all the working chambers in the displacement of wankel rotary engines. As if you thought that I was the only one who ever thought to do that? The second article clearly states that in SAE J1220, approved in 1978 that the "large" displacement I am putting forward (including all chambers) is listed as the Thermodynamic Displacement of Wankel rotary engine.
[quote=Matra]You are tyring to quote capacity so it can be compared with a piston engine.[/quote] No I am not even considering piston engines at all. That quite simply doesn't come into it. Again, I am only stating the total displacement of a wankel rotary engine should include all working chambers. (full stop)
[quote=Matra]by firing at 1080 degree repeat then the wankel is NOT the same.[/quote] I have never stated that a wankel engine is the same as a 4-stroke piston engine. I fully agree that they are different but again the relation to piston engines is of no consequence. I am perfectly capable of comparing a 250cc 2-stroke with a 250cc 4-stroke engine because I know they are different I don't need an equivalency factor.
[quote=Matra]Please don't sperad the confusion. Compare apples with apples or if you insist on comparing them with oranges then at least adopt the accepted "standard" ratios.[/quote]Well one of the articles I posted states that the displacement I consider the "true" total displacement is infact an accepted "standard" value!
Matra: I don't want to convince you or anyone else to start referring to wankel engines by the full large displacement. At best I am hoping that you and others can see the logic of the point of view and accept it as valid as the rest of the scientific community has.
I mean hey I still talk about the 13B as a 1.3L engine too eh.
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Fully understood 6-stroke.
AND that's the point.
Nic eto see you now call it "Thermodynamic displacment" .... wondered WHY terms liek that are necessary ? Because capacity as a simple multiplication doesn't convey the correct interpretation.
Thus why all use other numjbers.
The "logic" of your point I do accept. It's a mathematical calculation.
But does it tell ANYTHING useful about the engine ? NO.
You'd be as well comparing piston engines by the volume of the crankcase :)
"Rest of scientific community" rofl ....
and sorry for "discrediting" some fo the links .. but if not then we end up with nonsense like the reagan website cross-posts from a few years back. Just because it's written does not make it right :) So if we do not critique all inputs we use then they are all pointless :( and yes I *DO* that myself, every word !
WHICH led me to try to find J1220.
No luck. Anyone access to the SAE online database able to do a search please ?
Woudl liek to see the details and especially if still valid or updated/replaced ??
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[quote=Matra et Alpine;886784]
Nic eto see you now call it "Thermodynamic displacment" .... wondered WHY terms liek that are necessary ? Because capacity as a simple multiplication doesn't convey the correct interpretation.
Thus why all use other numjbers.[/quote] Thats just what it was called in the SAE paper. The smallest displacement is called Geometric displacement and the middle displacement is called Equivalent displacement.
[quote=Matra]But does it tell ANYTHING useful about the engine ? NO.
You'd be as well comparing piston engines by the volume of the crankcase :)[/quote]It tells the actual displacement of the engine which can be used for proper tuning, correct calculation of BMEP and other statistics. Try doing that with the other displacements and you have to do alot of weird things to get the values to fit!
[quote=Matra]"Rest of scientific community" rofl ....[/quote] So being accepted by the SAE means nothing?
[quote=Matra]and sorry for "discrediting" some fo the links ..[/quote]I said you tried... and failed, because there is absolutely nothing wrong with any of them.
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EXCEPT they describe the "wrong" information.
You brought this up by saying "displacement" and I'm pleased to see that you now recognise and accept there are actually three DIFFERENT displacements with regard to a rotary.
ANY ONE OF THE THREE are valid.
Q-E-D
Just the counting all chambers all rotors doesn't take into account that because the rotor moves within an eptrochoid makes it different.
AND why EVERY comparison on the planet NEVER uses the thermo displacement :)
If you'd made it clear at the start which displacement you MEANT we'd not have ahd to ahve this conversation to correct any misconception others may take from the comment.
Oh and to "close" ... you asked whether the fuel consumption of my '8 was more like a 1.3 or a 3.9 ? though the obvious more like a performance 2.6 might be my asnwer :) I have rallied in a Mini with a 1275 which dropped to 10mph on events and followe by a Mark 1 Escort 1600 rally car that did 7-8 when pushed. The RX-8 gets less than 10 on track ... so .... by the logic then it's closer to a 1.3 than a 3.9 :)
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[quote=Matra et Alpine;886830]EXCEPT they describe the "wrong" information.
You brought this up by saying "displacement" and I'm pleased to see that you now recognise and accept there are actually three DIFFERENT displacements with regard to a rotary.
ANY ONE OF THE THREE are valid.[/quote] What? you are not making sense with all the flip-flops! First you state that the sources I gave are faulty solely because they describe the "wrong" information, then you act like it was me who was having trouble accepting anything! I have always excepted the three rated displacements of rotary engines for their own merits and uses. My whole point was to get you to see the third one as valid and important in it's own specific way!!! Each displacement rating has its specific use. The smallest is for classification of rotary engines (thats why the 13B is called the 13B) the second medium displacement is used as an equivalency factor so that wankel rotary engines can race together with piston engined vehicles on a somewhat fair grounds, and the third large value is the true full displacement value which should be used for calculations like BMEP, specific output, and other displacement based calculations to do with the actual thermodynamics of the engine.
That is what I am trying to get people to understand!
[quote=Matra]If you'd made it clear at the start which displacement you MEANT we'd not have ahd to ahve this conversation to correct any misconception others may take from the comment.[/quote] Which misconception could others possibly take from what I have said???
[quote=Matra]Oh and to "close" ... you asked whether the fuel consumption of my '8 was more like a 1.3 or a 3.9 ? though the obvious more like a performance 2.6 might be my asnwer :) I have rallied in a Mini with a 1275 which dropped to 10mph on events and followe by a Mark 1 Escort 1600 rally car that did 7-8 when pushed. The RX-8 gets less than 10 on track ... so .... by the logic then it's closer to a 1.3 than a 3.9 :)[/quote]
What? Your "logical" comparison compares your modern RX-8 against an ancient mini (from the '60s I imagine) which uses an ancient carburetted 1950s engine (the BMC A-series 1275 right?) and a 1970s rally car? and you are comparing track mileage??? Unless you are basing the mileage from racing on the same track the mileage achieved cannot be compared.
Compared to modern cars you get about the same mpg as a 2008 BMW 550i (thats 4.8L V8 in a much heavier car) and a 2008 Chevrolet Impala with a 3.9L V6 and 4 spee dautomatic transmission can get better mileage. Anything with an engine even approching 1.3L is getting 50% + more mileage!