Interesting upgrades
Nope, he doesn't understand the basic principles of the rotary.
Regarding his first idea.
Mazda placed the trailing plug hole (the big lower one) so that it is at the point where the intake pressure above the apex seal and the exhaust pressure below the apex seal is equal.
Intake charge will not push into the exhaust and exhaust will not push into the intake. The larger sparkplug hole allows the sparkplug electrode to have as much reach as possible for stable ignition and less "pocket" volume for less chance of fouling.
This is clearly illustrated/documented in the book "The Wankel Engine" 1971 Chapter "Toyo Kogyo" (that is Mazda), page 252, illustration #2 titled "Gas pressure differences between the three working chambers, measured in pounds per square inch (psi)."
This concept is discussed in detail on page 271.
--------------
Regarding his second idea.
Mada experimented with different shapes depression in the rotor.
First off, the rotor he shows is crap because it does not have a depression at all in the center of the rotor.
This depression doesn't just dictate the compression ratio on a rotary, but also it allows the compressed air and fuel to travel from the trailing side of the minor axis (the pinch in the rotor housing) to the leading side of the rotor housing.
If that gas cannot travel to the leading side through the slot in the rotor it WILL push backward against the trailing side of the rotor just as he is describing he is trying to avoid.
What is possible is to alter the shape of the depression in the rotor so it is deeper on one side and shallower on the other.
Mazda did experiment with this as well.
Page 259 illustration 1 through 3 of the same book shows the results.
What Mazda called a Trailing Deep Recess (his idea, but with a slot still in the middle for gas to travel to the leading side) creates a more uniform gas transfer (through the slot) velocity with a peak velocity before the spark plugs fire (ie, more gas is trapped above the minor axis pushing backwards on the rotor).
What Mazda used for maximum power was called Medium Deep Recess (symmetrical rotor depression) and it creates a peak velocity on the trailing side later so more gas shoots into the leading side as it can overcome the velocity of the gas expanding from being ignited on the leading side by the spark plug better.
Mazda used the MDR rotors for production and racing and also used the opposite of what he says, Leading Deep Recess rotors for the 1978-1980 12A for emissions.
This LDR rotor engine employed a thermal reactor (to reduce hydrocarbons instead of a catalytic converter) and using only the leading spark at low load to dump more air/fuel into the thermal reactor to light it off (emissions strategy). The LDR rotor has a very late trailing side high velocity to push the trailing side intake charge over to the leading side even faster as the trailing spark was no longer expanding the trailing side intake charge in this single plug operation (to keep the thermal reactor hot).
Basically, the guy in the video needs to "read a book" to quote Leslie Chow (The Hangover).
Edit- MDR needed to be LDR 4 text lines up.
Regarding his first idea.
Mazda placed the trailing plug hole (the big lower one) so that it is at the point where the intake pressure above the apex seal and the exhaust pressure below the apex seal is equal.
Intake charge will not push into the exhaust and exhaust will not push into the intake. The larger sparkplug hole allows the sparkplug electrode to have as much reach as possible for stable ignition and less "pocket" volume for less chance of fouling.
This is clearly illustrated/documented in the book "The Wankel Engine" 1971 Chapter "Toyo Kogyo" (that is Mazda), page 252, illustration #2 titled "Gas pressure differences between the three working chambers, measured in pounds per square inch (psi)."
This concept is discussed in detail on page 271.
--------------
Regarding his second idea.
Mada experimented with different shapes depression in the rotor.
First off, the rotor he shows is crap because it does not have a depression at all in the center of the rotor.
This depression doesn't just dictate the compression ratio on a rotary, but also it allows the compressed air and fuel to travel from the trailing side of the minor axis (the pinch in the rotor housing) to the leading side of the rotor housing.
If that gas cannot travel to the leading side through the slot in the rotor it WILL push backward against the trailing side of the rotor just as he is describing he is trying to avoid.
What is possible is to alter the shape of the depression in the rotor so it is deeper on one side and shallower on the other.
Mazda did experiment with this as well.
Page 259 illustration 1 through 3 of the same book shows the results.
What Mazda called a Trailing Deep Recess (his idea, but with a slot still in the middle for gas to travel to the leading side) creates a more uniform gas transfer (through the slot) velocity with a peak velocity before the spark plugs fire (ie, more gas is trapped above the minor axis pushing backwards on the rotor).
What Mazda used for maximum power was called Medium Deep Recess (symmetrical rotor depression) and it creates a peak velocity on the trailing side later so more gas shoots into the leading side as it can overcome the velocity of the gas expanding from being ignited on the leading side by the spark plug better.
Mazda used the MDR rotors for production and racing and also used the opposite of what he says, Leading Deep Recess rotors for the 1978-1980 12A for emissions.
This LDR rotor engine employed a thermal reactor (to reduce hydrocarbons instead of a catalytic converter) and using only the leading spark at low load to dump more air/fuel into the thermal reactor to light it off (emissions strategy). The LDR rotor has a very late trailing side high velocity to push the trailing side intake charge over to the leading side even faster as the trailing spark was no longer expanding the trailing side intake charge in this single plug operation (to keep the thermal reactor hot).
Basically, the guy in the video needs to "read a book" to quote Leslie Chow (The Hangover).
Edit- MDR needed to be LDR 4 text lines up.
Last edited by BLUE TII; Dec 5, 2015 at 04:14 PM.
i don't wanna bash on the guy anymore, let's just say this video is rather old.
the only truth to his statements is that the spark plug depressions are a major cause of the losses in a rotary engine, but overcoming that isn't as easy as shrouding the spark plug.
the only truth to his statements is that the spark plug depressions are a major cause of the losses in a rotary engine, but overcoming that isn't as easy as shrouding the spark plug.
Last edited by RotaryEvolution; Dec 5, 2015 at 08:28 AM.
Joined: Mar 2001
Posts: 31,833
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From: https://www2.mazda.com/en/100th/
Mazda used the MDR rotors for production and racing and also used the opposite of what he says, Leading Deep Recess rotors for the 1978-1980 12A for emissions.
This MDR rotor engine employed a thermal reactor (to reduce hydrocarbons instead of a catalytic converter) and using only the leading spark at low load to dump more air/fuel into the thermal reactor to light it off (emissions strategy). The LDR rotor has a very late trailing side high velocity to push the trailing side intake charge over to the leading side even faster as the trailing spark was no longer expanding the trailing side intake charge in this single plug operation (to keep the thermal reactor hot).
This MDR rotor engine employed a thermal reactor (to reduce hydrocarbons instead of a catalytic converter) and using only the leading spark at low load to dump more air/fuel into the thermal reactor to light it off (emissions strategy). The LDR rotor has a very late trailing side high velocity to push the trailing side intake charge over to the leading side even faster as the trailing spark was no longer expanding the trailing side intake charge in this single plug operation (to keep the thermal reactor hot).
the thermal reactor system lives up to its name, it works with heat. i had a 79, with the reactor and i had my smog guy pre test it, because i had no experience with the system, and it passed, easily. he shut it off, for about a minute to go through the menus in the computer to start the test, restarted the car, ran the test and it almost failed.
the system to shut the trailing ignition off is to dump extra fuel in the exhaust to get the reactor hot, and there is more to the strategy than just partial load, it doesn't always do it.
in 1981, Mazda revised the engine to use a catalyst. they switched to the corner seal with the rubber plug, and the apex seal corner got moved more to the corner to improve engine sealing*. they also moved the spark plug closer to the trochoid surface. the emissions controls also got revised, the exhaust sleeves distribute air pump air better. all of this allowed them to run a leaner mixture, and then run a catalyst. they claim a 20% increase in fuel efficiency, which is NOT MPG, the EPA mileage was up by 1-2.
the 13B was always MDR
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