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-   Rotary Tech - General Rotary Engine related tech section.. (https://rotarycarclub.com/forumdisplay.php?f=131)
-   -   Actual Rotary Displacement Request (https://rotarycarclub.com/showthread.php?t=14194)

GorillaRE 06-14-2011 05:34 AM
Quote:
Originally Posted by scotty305 (Post 154218)
At one of the Sevenstock tech talks (two or three years ago?), someone from the Mazdaspeed team mentioned that both Mercedes cars were consistently faster than the 787B, but they had engine problems and did not finish the race.

I came across a nice set of photos from that race:
http://www.flickr.com/photos/mendama...57623971081040

Every serious race team tries to exploit their class rules as much as possible in order to win. In my opinion, it would be a great honor to have a new rule written because your team had found and exploited a good loophole in a previous set of rules.
This may be true but I think it only applies due to Mazda keeping a 9000rpm limit during the race, for longevity reasons. The 787B was capible of 150-200 hp more with the tested 10500rpm limit!

-J

Barry Bordes 06-14-2011 04:52 PM
Quote:
Originally Posted by Barry Bordes (Post 150200)
Request to use Actual Rotary Displacement

If someone started talking about a 2.6 liter Rotary would they be referring to a 4 rotor or are we dealing with someone who doubles displacement of a two rotor?

In the interest of clarity I believe that we should describe the displacement of our rotary engines by its actual scientific size.

Some very experienced individuals have doubled and sometimes even tripled its size. This has become confusing to new impressionable members trying to communicate ideas correctly.

One would think that a physical measurement like displacement would be rudimentary but on a rotary it is more complicated than π X radius² X stroke X number of cylinders. Finding max volume from trochoid and peritrochoid shapes is a lot tougher.

I won’t bore you with formulas but all of the manufacturers signing licensing agreements to develop, and those producing Wankel engines including Alfa Romeo, American Motors, Citroen, Ford, General Motors, Mercedes-Benz, Nissan, Porsche, Rolls-Royce, Suzuki, Toyota and of course NSU and Mazda…and motorcycle manufactorers Sachs, DKW/Hercules, Norton and Suzuki… add John Deere, Artic Cat, Curtiss-Wright, also miscellaneous outboard and unmanned arcraft manufactures all agree on way actual displacement is determined and refere to them acordingly.

And yes, some sanctioning bodies use a multiplier which penalizes the Rotary as they do the two-stroke to help even out the competition. Displacement, however is a scientific measurement not up for opinions.

What size would Felix Wankel or Kenichi Yamamoto say that it is?

My Thoughts,
Barry
This would probably be a good time to reiterate my initial request of having us use the Industry Standard in referring to rotary sizing when corresponding with one another.

Interesting side note… I checked the websites of both Rotarygod and Rice.

It was reassuring to note that they both use the requested Industry Standards for clarity. There were no 26B or 39B 2-rotors noted.
Barry

RICE RACING 06-15-2011 02:20 AM
There is no question at all that its a 13B.

There is also no question at all that it displaces 3.9lt when you count the whole engine.

They are two different things, its only when you are talking equivalence to other types of engines you need to know how much it displaces in time (without repetition)... like for your formulas (all based around 2 stroke and 4 stroke) then you just use 1.3 or 2.6 respectively.

It's the common shared chambers that allow all the 3 rotor faces *per rotor* to do their work (Wankel cycle) which confuses many people & to be honest its not really worth debating as we are all really talking about the same thing.

As you well know when you do a health check on the Wankel (two rotor) you will get in most cases 6 different readings as each chamber is different most times (seal wear, tolerances and rotor cavity disparity) ALL of these go to providing work and a health engine overall and ALL need to be counted you will agree to validate that assessment. Otherwise we would only ever need to measure two faces? *stirring pot*...... You and everyone get what I mean here who has anything ever to do with Wankels.

This is why I count all faces and rate the true capacity of the engine as per its cycle, no matter what type it is. And that is the basis of my points on the topic. So its a 13B that displaces 3.9lt over its Wankel cycle.

FC Zach 06-15-2011 05:22 AM
Quote:
Originally Posted by RICE RACING (Post 154537)
This is why I count all faces and rate the true capacity of the engine as per its cycle, no matter what type it is. And that is the basis of my points on the topic. So its a 13B that displaces 3.9lt over its Wankel cycle.
Well said! short, simple, and to the point. That's easy enough for me to comprehend.

Barry Bordes 06-15-2011 07:54 AM
From Webster’s New Collegiate Dictionary… displacement\ c: the volume displaced by a piston (as in a pump or engine) in a single stroke; also: the total displaced by all the pistons in an internal combustion engine.

The key phrase being “ in a single stroke”.

Notice that using the dictionary definition of displacement with your “personal convention of a full cycle” to determine displacement of a 4-stroke... the 720º required for the full cycle would incorrectly doubled its displacement.

Barry

RICE RACING 06-15-2011 04:20 PM
Quote:
Originally Posted by Barry Bordes (Post 154560)
From Webster’s New Collegiate Dictionary… displacement\ c: the volume displaced by a piston (as in a pump or engine) in a single stroke; also: the total displaced by all the pistons in an internal combustion engine.

The key phrase being “ in a single stroke”.

Notice that using the dictionary definition of displacement with your “personal convention of a full cycle” to determine displacement of a 4-stroke... the 720º required for the full cycle would incorrectly doubled its displacement.

Barry
"all pistons" = "all faces" :117: apply that one :Chevy_anim: you then will see that all faces and or otherwise "displace" a volume.

The troubling thing in a Wankel that people don't get (even if they dont understand the cycle) is that is has a common housing that is shared across three faces per rotor :cheers2:

Therein lies your path to understanding, rather than looking for an obscure definition in a dictionary :ack2:

RICE RACING 06-15-2011 04:32 PM
Baz,

Would you only measure 2 pistons in a 6cly 3.9lt for a customer and give it a clean bill of health?

so follows

Would you only measure 2 rotor faces in a 13B and give it a rubber stamp pass BDC style?

You would measure all pistons and report on each.
Mostly everyone inc me and you would measure all rotor faces and report on each.
Why would we do this? if its only using 2 faces and is only 1.3lt in capacity? Surly by Mazda convention and everyone else's then we are mad and we could have saved money by leaving out one apex seal per rotor (potential saving there!) just as we could leave out 4 pistons in the 6cyl and save weight too :)

PROBLEM: Engines function and displace volume over the operating cycle and total sum of working chambers. This is how all internal combustion engines work. 2 stroke, 4 stroke and low and behold the Wankel too :smash:

calculon 06-15-2011 05:19 PM
Out of curiosity, what does everyone think that the displacement of an LS2 is?

Barry Bordes 06-16-2011 10:42 AM
Quote:
Originally Posted by RICE RACING (Post 154723)
"all pistons" = "all faces" :117: apply that one :Chevy_anim: you then will see that all faces and or otherwise "displace" a volume.

The troubling thing in a Wankel that people don't get (even if they dont understand the cycle) is that is has a common housing that is shared across three faces per rotor :cheers2:

Therein lies your path to understanding, rather than looking for an obscure definition in a dictionary :ack2:
Peter,
Maybe it would help if I told you that I agree that a full cycle for the rotor is its complete revolution or three revolutions of the eccentric shaft.
My point is… what does that matter?

In the example of the .357 revolver both views are expressed.
The criminal has two main concerns as he runs from the crime scene.
1- What is the size and velocity of the slug coming at me?
2- How many shots does this guy have before a reload is required?
Both valid concerns… Now let’s say that we add an ammunition belt to supply bullets…. Then the only concern is the size and velocity of the slug. Our engines have continuous belts of ammunition between fuel stops.


Our attempt to make power is done by igniting a specific volume (654cc) which in turn works on a lever. We want to have this happen as often as possible. The best we can do in our case is once each revolution.

Counting in three’s won’t affect anything.

Barry

RICE RACING 06-16-2011 08:40 PM
It has an effect if one chamber (or face) is buggered, Image a S@W 357 mag with a stuffed chamber one will always not work properly, shoot a bad group :dunno: it's why we count all the parts that make up the 6 shots, just like in our donkey engines. :)

All the chambers count to make a whole rig that will work well, faces, pistons does not matter, we dont just look at one alone, we look at all parts of the system :)

We are talking the same things I think :ack2:

My5ABaby 06-17-2011 08:16 AM
Quote:
Originally Posted by RICE RACING (Post 155041)
It has an effect if one chamber (or face) is buggered, Image a S@W 357 mag with a stuffed chamber one will always not work properly, shoot a bad group :dunno: it's why we count all the parts that make up the 6 shots, just like in our donkey engines. :)

All the chambers count to make a whole rig that will work well, faces, pistons does not matter, we dont just look at one alone, we look at all parts of the system :)

We are talking the same things I think :ack2:
The totality of the gun (i.e. whether it works, the total chambers, how well it works, if all the chambers are working, etc.) has nothing to do with it's displacement (i.e. caliber). Unless I'm not understanding it, your argument seems to be referencing the engine as a whole in terms of whether it works or not and how you determine that versus how to determine displacement. When measuring the displacement of a piston engine, do we care if one of the cylinders is screwed up or if a valve isn't working?

Libor 06-17-2011 08:37 AM
I would be interested how we should approach "displacement" of unnusual engines. Like Ilmor "5-stroke" where three cilinders are creating working unit - two outer are regular and middle one is bigger and extracts addition power from still expanding exhaust gasses.

By definition of displacement from above, such engine would be described as sum of displacements of individual cilinders. But only two cilinders have Intake and are doing pumping work of working fluid.

Displacement on its own means nothing without considering working cycle.

RICE RACING 06-17-2011 09:21 AM
Quote:
Originally Posted by Libor (Post 155090)
I would be interested how we should approach "displacement" of unnusual engines. Like Ilmor "5-stroke" where three cilinders are creating working unit - two outer are regular and middle one is bigger and extracts addition power from still expanding exhaust gasses.

By definition of displacement from above, such engine would be described as sum of displacements of individual cilinders. But only two cilinders have Intake and are doing pumping work of working fluid.

Displacement on its own means nothing without considering working cycle.
:iamwithstupid:


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