MikeC

LOL! Pot kettle black. Don't you see the irony in the fact that you are uptight + that you're coming in here telling people to stop throwing insults when your posts are full of insults. If you don't want to involve yourself in the thread then **** off somewhere else and let those who do continue.

quicksilver_rx7

This IS pointless. Fact is, Mazda owns the engine so they get to determine the specs. Even if people disagree, the fact still remains that Mazda OWNS it. It's their ball, and if they don't want you to play with it....too bad. Get it? Please lock this Evil!

13btnos

iTrader: (1)

HA! I got to you. G-day mate. And when did I insult you. I don't insult anyone, atleast not on a forum I'd do it to your face, and if it was taken that way I apologize.

MikeC

That's the whole point, MAZDA ARE LYING!!!

MikeC

I replied before your edit ...

I took this as an insult, my apologies if it was not meant that way. "Man you guys just like to show off how smart you are. Cracks me up."

sar

iTrader: (1)

http://rx7.com/techarticles_displacement.html

RX7.com publishes this and shows displacement to be 2.6L based on degrees of rotation even though they show that the 3.9L is calculated just by the engine faces and chambers stuff.

maxcooper

I own a blue shirt, but I decided that anyone referring to the color of my shirt should say that it is red. I own the shirt, so I get to make the rules.

This argument doesn't make any sense.

-Max

t-von

iTrader: (8)

Ok how about this?

1.3L in one rotation of the e-shaft.

2.6L in two rotations of the e-shaft.

3.9L in three rotations of the e-shaft.

5.2L in four rotations of the e-shaft.

6.5L in five rotation of the e-shaft.

7.8L in six rotations of the e-shaft.

Notice how redundant this is getting?

MikeC

That article started off well but they didn't make any explanation of why they chose 2 revs to measure displacement over. There explanation was "The best way is to study 720° of rotation of the two-rotor engine." which really just says "we're going to use 2 revs". Then they wrote "720° will have a total of four faces completing their cycle." which isn't true. In 720 degrees none of the chambers will have completed a cycle, it takes 1080 degrees for any chamber to complete the full otto cycle.

The reason 2 revs is used with piston 4 stroke piston motors is because that's how long it takes them to complete the full otto cycle. For the rotary it takes 3 revs and the displacement should be measured over 3 revs. A rotary is *much* more like a 6 cylinder motor than it is a 4. It has 6 chambers, it has the same overlap between the chambers/pistons, it has the same torque flutuation graph as a 6 cylinder (different from the torque curve), the volumes follow the same curve etc etc. Measuring the rotary as 4x654cc is ignoring 2 of the chambers.

quicksilver_rx7

It does if you made the color red

I never said that I agreed or disagreed with the proposed theories of displacement. Just stated the fact that it's Mazda's baby and they got to name it. Understand?

GentlemenVII

Ok the 13B, 13BT, 13B-REW are all 1.3 liters!!!! The Laws of physics, the people who designed it, and the educated that own them all KNOW THIS!!!!!! Ever since Dave Coleman want on a "I think I am an engineer that works for a stupid magazine". who wrote mulitple articles on this topic all stating that a 13B is 2.6L with his half assed math and false theories!!!!!(which is way I have never bought a SCC in about 2 years)

So Dave Coleman and all you others that think a 13B is a 2.6L are wrong unless you can prove that your IQ is higher then some of the best minds in the Engineering feild or mastered physics on a new level!!!!!!!

MikeC

But they didn't make it red, they made it blue and just said it was red.

No, it doesn't make sense. Mazda have so much to gain from rating the engine lower than it really is they should be the last people anyone believes. If you look back through the last page or 2 of this thread this "mazda say it's 1.3 so it must be so" has been repeated over and over. Anyone who believes that doesn't have an understanding of the topic. The whole point is to work out whether mazda is telling the truth or not, you can't say mazda are telling the truth because mazda are telling the truth.

MikeC

LOL! Another one!! FYI, not all the masters in the field think it's 1.3L, co-incidentally it's only the masters in the field who have something to gain eg mazda engineers. All of the SAE engineers from other countries wanted it rated at 3.9L.

maxcooper

This mindwalk (past many who bark "1.3L" at the end of their mind-leashes) started long before Dave Coleman's article.

The International Engine Award folks (or whatever that award was that the RENESIS won) also decided that 1.3L was not the proper rating. They picked 2.6L.

I don't get why people are so upset at the prospect of considering ratings other than 1.3L.

-Max

MikeC

Long before that even. Mazda themselves originally called the 10A a 3 litre but changed their mind once they realised they could get away with 1.0 litre. Many of the members of the SAE wanted it rated at 3.0 litre also. Both of these would have been back in the 60s.

mark57

1.3L figure doesn't account for all the swept volume capability of the rotary engine. 2.6L best accounts for swept volume relative to a four-stroke; it's a comparison figure. The 3.9L accounts for all the swept volume of the two-rotor rotary and justifies the wildly high HP numbers coming out of this midget-sized box. A four-stroke size figure accounts for all the swept area.....and this shoud apply to the rotary. 13B = 3.9L.

Evil Aviator

LOL, I actually discussed that subject with Graham Johnson. He said that the Renesis was entered in the 2.5 to 3-liter category because "in more countries than not it is taxed as a 2.6-liter, the idea being that a 1.3-liter couldn't possibly hope to have 230bhp."

Apparently, the press places tax codes and pre-conceived power limitations over engineering standards and physics. This leads me to believe that part of the current glut in engineering jobs is due to the fact that these media rags refuse to staff any engineers, regardless of how much they are obviously needed.

I have no problem with personal opinions or differing viewpoints. What bothers me is when trolls posing as engineers unleash incorrect information on the unsuspecting public. I find this nearly equitable to posing as a police officer or a doctor. Simple good Samaritans can help others by simply doing the best they can do, without the pretense of a title that misrepresents their level of competence.

Aviator 902S

Just to be a ****-disturber:

A 500cc two-stroke boinger fires twice as often at a given rpm as a 4-stroke. So it must be a 1000cc, right?

Evil Aviator

I'm way ahead of you on that one. Last year I also asked Graham Johnson that question, and he said that he probably WOULD double the displacement of a 2-stroke engine if one were ever included in the International Engine of the Year Awards.

So how do you like them apples?

Doesn't it make you glad to know that you received a good education when you hear things like that?

quicksilver_rx7

Hell, I'm jsut gald to konw taht I'm not teh olny jeanous left in tihs wlord

BLKTOPTRVL

https://www.rx7club.com/showthread.p...light=argument

MikeC

Another beautiful post evil. Full of all your usual insults and total lack of any real information. FYI, I am an engineer. I studied mechanical engineering at swinburne university in Melbourne Australia. I can't say I passed with flying colors but I did pass and I can assure you that I know 100 times more about this topic than you. Some of things I don't think I could even explain to you, it's nothing overly complex, high school math and physics stuff but I don't think you'd get it. You probably know a lot more of the mechanic side than me, such as how to rebuild a rotary, but the engineering side you don't have a clue. Ironically you think you are so right and ask others to consider that they might be wrong while never entertaining the thought yourself.

MikeC

No, because you measure an engine on the amount of air it would theoretically induct at 100% volumetric efficiency over the number of revs it takes to complete the full otto cycle. A 2 stroke completes the otto cycle in 1 rev, a 4 stroke in 2 and a rotary in 3. Over 3 revs the rotary inducts 3.9L of air.

mark57

Well put, but the rotary inducts 3.9L at not more three turns of the crank.

tmiked

MikeC, you are, of course, technically correct.

The displacement of a rotary is confusing because of the difference in rotor speed and shaft speed. This gives and effect like a gearset between the crank and the output shaft of the engine.