RONIN FC

It all depends on what is more important, port timing, or velocity. And what compramises your willing to make to each to get a satisfactory result. If you need large timing, small runners would keep up velocity by inertia. If you can afford small timing on your application, large runners reduce restriction while the small port keeps velocity.



Unfortunately for us shmoes, we need to experiment on actual engines to actually see the results.

ColinRX7

Rhetorically speaking anyways, it's easier to grasp the dynamics using a peripheral intake port as an example. Picturing pressure wave action on a side port is a bit harder than a straightforward peripheral port, and they also generally (not having the intricate sweeping face of a side port) maintain the runner shape so understanding the velocity and pulses is MUCH easier.



If anyone wants to get started learning about velocity and pressure wave tuning, Paul Yaw's articles are perfect to touch base on all the essentials. The articles are very well done, but there is still plenty of reading out there on tuning. Good stuff though.



(you have to read them all in order)

http://www.yawpower.com/techindx.html

Lynn E. Hanover

The big runner/small runner comparison only works if both are NA, or both are turbo.



If you can adjust the input pressure to anything you want, then, a bigger runner is better from several viewpoints.



More mass per second without additional heat of compression. Ratio of bowl volume to runner volume is lower so less velocity change at the port.



Two smaller fast spooling turbos come on soon after idle and make the two rotor appear to be much bigger engine in the heavy Cosmo. This also means that the engine is working a bit harder all of the time. You would need cruise boost numbers to determine some of their thinking.



Like our experts that look at Eastern Block aircraft to determine how and why they do things this way or that.



Not at all happy all of the time, and poof! A three rotor Cosmo.



None of this applies to a NA engine, where all of the boost is less than one bar (14.7 pounds at sea level).



So the runner size vice velocity becomes a great big deal. Bowl volume vice runner volume and port opening area same same and so on.



The different shapes and runner sizes between primary and secondary inlet tracts are used to expand smooth transition from idle to full power.



When you do the all out port job all around, then jump in and floor it, the runner velocity right off idle drops to zero or near zero, and tunning for zero flow mixtures is tough for even experts. Same for Bridge porting all of the irons. That 110 degree open point will generate zero vacuum right off idle.



So, you end up with a 2,000 RPM idle, just so you can get it to roll away from a standstill.



The Japanese ended WWII without two sticks to rub together. And they deserved it. Perhaps not the wemon and children, but they were the products of a very violent past that did not fit into the century.



General MacArthur ordered the staff to write them a constitution that included no forign military involvements. Only defensive forces. He gave the order to his male staff, who gave it to two secretaries. "Female" secretaries. So the constitution only included those things the General ordered, All of the US Constitution and all of the things the two secretaries thought would be good for the women of Japan.



These were two very smart women these secretaries. Look them up.



The "Japs" all seem to think the same way about everything, same as before the war. They do things as organized platoons, or commitees. Very little individual thinking is used without very much experimentation,

and full scale modeling. Lest they loose face should something not work in public and embarass the leadership and family. Dont agree? try a brainstorming session with a bunch of them. Just silence. They all fear that they may say something that is incorrect, and cause the group to be embarressed. They would rather die (literally).



(Brainstorming is a bunch of people sitting around just spouting the silliiest things they can think of about a loosely describbed problem or function). Then you make a list of all of the dumb *** ideas that have been spouted, and discuss each of those in about the same way. Then you turn over those ideas to other groups to do the same thing, and you take their ideas and start over. If you start with a diverse group of people, and do it long enough, you will be generating ideas by the thousands, and exposing them to people trained in all kinds of engineering disciplines. If you do this often enough in the same organization, you develope a team that can fix anything with a chainsaw and a pair of pliers. You can also develop a new product or service in a few hours. And amazingly, develop answers to problems other than the one you started off to fix.



Try it. Write down a problem that you have with a product or service. Write down the first 50 things about that problem that come into your mind. Don't cheat yourself. If it is a color write down that color.



Go through that list and write down the first 5 things about each answer item on you first list. There you go. More thinking than you have done in years and it was all you doing it. Now apply each of those scondary items to the original problem. Of course 99% will have nothing to do with the problem, but now your mind is spooling up like a turbo, So put turbo down. And on it goes.





So, Japs on crack?



Very unlikely. Anything you see in public has been worn out and evaluated hundreds of times in private before publication. These people are expected to commit suicide in the face of embarasment, and do it. The product we see was developed to perform a very specific function, and do it at a level determined by extensive reasearch.



http://tkdtutor.com/05Instructors/TQM.htm



Why did the Japanese take to Dr. Edward Demmings TQM like fish to water, when we in the west discarded it out of hand?





If we are unhappy with that level of performance, it is we who must educate ourselves to the possibilities made available to us.



If you don't know, then you don't know!





Lynn E. Hanover

j9fd3s

it seems like sometimes we dont know what or whom some of this stuff is built for. like the cosmo exhaust sleeves, we're all looking at em going WTF? and maxt seems to have read the bulletin on em.



back to the motor, all of the REW (Rotary Engine tWin turbos) run off of a smaller primary turbo under a certain rpm (around 4500rpms, 20b is lower), and then a second turbo comes online. in practise, if you've ever driven a healthy one, boost is instant, the boost needle will follow your foot, from nearly idle to nearly redline. they are actually a lot of fun on the street, power everywhere, plus it pulls, pauses, and then starts pulling harder, where most cars are falling off.



it also is complex (they redid it in 98, it went from 70+ vacuum hoses to 8, why they didnt do that earlier...), and adds TONS of heat load.