Wankel's Rotary Engine


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Here is a simple and very good clip to understand how Wankel's Rotary Engine works. Then have a look on the history behind it.





Felix Wankel was in born 1902 in Lahr Schwarzwald in what is today the south west Germany.
His Family was neither poor or rich they where just doing okay.

As a kid the young Felix wasn't good at school in particular in physics and mathematics.
Felix left high school before passing his degree.

But Felix Wankel still had a very good imagination especially for when it was about mechanical stuffs.
Some may say he was a genius.

One night in 1919 he dreamed about a pistonless engine with no rods and he was only 17 years old.
This dream will never be forgotten.

In 1920 Germany is literally falling apart around Felix :

- 15% of the Germans men died in WW1 (including Felix Wankel's dad).
- The economy was destroyed.
- Germany owed 132 Billions Gold marks for war damages ( 269 Billions Dollars in today's money).
- The money used for the war effort was borrowed.
- All this led to massive quantitative easing which created a massive inflation (by Nov 1923, 1 USD cent was exchanged for 42 Billions Marks).




The very same year, Felix Wankel helped by his mother, opened a machine shop behind his house.

The simplest way to pursue his dream was to go to the academia to become an engineer.
This wasn't an option since he left high school without his degree.

In 1929 Felix Wankel patented his Rotary Engine design.
In 1932 he was broke and came back to live at his mom's house in Lahr.

So her mom helped him to set up a new shop space behind the family house : a place he could work on his designs.

His first car was a 3 wheels design called the "Devil Beetle".

At first it was powered with a 1 cylinder engine which was very weak and could barely move the "Devil Beetle".

Then he swaped the 1 cylinder engine for a two cylinder designed by Felix Wankel himself that was making 7hp for a 50 mp/h top speed.

All these researches were very unprofessional.
And during WW2 Felix Wankel went to Austria to start researching seriously on the Rotary Engine.

Felix's idea was great but more than two decades after his dream the engine still wasn't in production.
In 1945 the allied won the war and came at Felix's shop, seized the machines and dismantled the shop.


NSU - Audi's Rotary Engine.


NSU "Spider".


In 1951 NSU bought the license to use the Rotary Engine in their own cars.
NSU was the brand that will become one day Audi.
Felix went to work with NSU, aiming to refine the design and finally put the rotary into production.

The rotary engine performances were very good in particular due to low amount of moving parts that allows an insane amount of RPM and to reach it fast.

On the other hand the rotary engine wasn't reliable yet, Felix had neglected to create oil passages on his engine.
The result was that the rotor and the Apex seals were subject to extreme friction wear specially at the tips of the rotor.

In 1964 the NSU "Spider" came out, it was the first ever production car equipped with a Rotary Engine.

But as we saw in this article, innovations are rarely reliable.
The rotary engine was plagued with Apex Seal's problems.

NSU hopped their engines could last at least 50k miles but it just didn't happen.

Many cars had engines problems while still covered by the guarantee.
This meant that NSU had to rebuild hundreds of engines.
With this, the profitability of the "Spider" was gone.

The redline was then set at 6k rpm in an effort to make the rotary engine reliable.
But this is well before the rev range where the rotary engine gets fun and comfortable.

NSU still thought that those issues could be fixed and they were right.



JDM rotary clothing rx-7 rx-8



THE NSU "RO-80".


NSU RO-80 rotary engine


In 1967, the "Spider" was discontinued an was replaced by the "NSU RO-80."
A car that would be awarded "European car of the Year".

Still this car shared many problem with the "Spider".
In particular the Apex Seal's problem was still there.
The earlier versions of the car could not go beyond 30k miles even with regular maintenance.

From this point the motor had to be rebuilt.
This was a catastrophic news : like for the "Spider" the RO-80 profitability was overshadowed by the guaranteed engines that had to be repair at NSU's expenses.

Rotary engine damaged rotor

Considering that the gas mileage wasn't that good either, the car didn't sold very well.
All this combined led to a very bad reputation for NSU and the rotary engine.

A reputation so bad that the competition was selling conversion kits to swap NSU's twin rotary for a four cylinder engine.

Even with all this the RO-80 was a very desirable car and by 1970 the Apex Seal's problem was solved.

But too late, NSU didn't make enough profits due to it's reputation and was bought by the Volkswagen Group in 1969.

The Brand became "Audi NSU Auto-Union SG".

In 1977 the "RO-80" was discontinued and in 1985 the brand finally became "Audi AG".





Trough the years many companies (23 in total) tried to license the rotary engine From Wankel and NSU to power a car of their own including GM, FORD, ROLLS ROYCE, MERCEDES and CITROEN...
But none of them reached the holy grail of the reliable, practical, efficient and mass produced Rotary engine... Only Mazda made it.




In the 60's a company that will someday become known as Mazda got the license to sell it's own variation of the rotary engine.

At this point an army of 47 engineers start to work to improve the design.
"From this point, wherever you are, night or day, asleep or awaken, the rotary engine must be on your minds at all times and at all costs !" Is what the legendary team was told.

Mazda's engineers tried everything possible to solve the Apex Seal's problem.
They even tried to replace it with Gold, Silver, or horses and cows bones (yes).

After all these efforts it seemed like this problem had no solutions.
Soon the rotary engine was viewed like a waste of efforts and money from within the company.
This atmosphere led the 47 dedicated engineers to work even harder.

In 1963 the first major breakthrough was made : vibrations were damaging the Apex Seal's.
So Mazda's engineering team guessed that modify the Apex Seals shape would change the frequency of the vibrations... And they were right!


MAZDA "COSMO" and "RX-3".

 Mazda Cosmo Rotary engine

The next year in 1964 the Mazda "Cosmo" was presented at the Tokyo Motor Show, the exact same year the the NSU "Spider" was released.


Mazda RX3 Savanna Rotary engine

In 1968 Mazda tried to reach a large public launching the "Savanna" aka the "808" or the "RX-3".
But the same year in the US the first "Clean Air Act" came out, and it was a massive obstacle to this little car,
The rotary engine is particularly bad in terms of emission at this point since a lot of gas are unburnt when going out of the motor.

It seemed like there was only one solution : de-tune the engine.
The problem was that if Mazda de-tuned the Rotary it will soon ceased functioning.

But Mazda was no stranger to big challenges and soldiered on.
The company wanted to improve the rotary's efficiency and sell the RX-3 to the US market.

So Mazda simply introduced a thermal reactor to their exhausts.
It increased production costs and smashed the fuel efficiency but the car was authorized to be sold on the american soil.

A thermal reactor is a chamber where the unburnt Carbon Monoxide is burnt again turning it into Carbon Dioxide which is less dangerous.

We know that an innovation is generally not reliable. So some problems started to raise but nothing big enough to stop the Japanese car maker.

In 1973 the rotary passed the emission test and even had a preferential tax treatment due to low emissions.
The same year the oil crisis stroke hard and Mazda destroyed the gas mileage of the rotary engine to comply with emissions standard.

The 47 engineers had to tackle another ambitious obstacle  : "OPERATION PHOENIX" was launched.
It was an ambitious operation aiming to decrease the rotary engine fuel consumption by 40% within 5 years.
After only 2 years of hard work a 20% improvement was achieved.
Shortly after a breakthrough pushed it to 50% ! Exceeding the original target by 10%!

Finally Wankel's rotary engine, improved by Mazda was reliable and ready to be a success.



Mazda RX7 rotary engine FC

In 1979 the Mazda "RX-7" premiered at the "Las Vegas Motor Show".
"RX-7" Stood for Rotary Experiment Seven.

With a style inspired by Lotus was supposed to compete against the Datsun/Nissan 280Z, Toyota Celica and other Japaneses sports cars.

The rotary was placed behind the front axle in the RX-7, making it a "front mid-ship rear drive".

This gave the RX-7 a great weight distribution and a low center of gravity.

When it came out Mazda recommended to its customers to "shift at the redline" which was 7k rpm.
Doing this will burn get rid of the carbon deposit in the rotary and will make it reliable.

The RX-7 was selling well on the Japanese Domestic Market too since it was less taxed due to it's small displacement, making it cheaper while outperforming the competition.

Low, light, cheap, competitive, powerful and looking great... The Mazda "RX-7" sounds like the perfect recipe to many sports cars enthusiasts.

Mazda RX7 FD Rotary Wankel

In 1991 the last version of the RX-7 : the FD came out, for many this is the pinnacle, the best Rotary powered car you could ever see.
It was powered by the 13B, a 1.3l rotary engine with the first mass produced sequential turbos ever.

This JDM dream has marked it's era and beyond, in video games, anime's, racing events and much more.
It was sadly discontinued in 2002 after two economic crisis in Japan.



Redsuns RX-7 JDM canvas and stickers






IMSA-GTU Mazda RX7 rotary jdm


 In 1979 the RX-7 was often on the podiums of the IMSA GTU Series, and place 1st and 2nd at the "24h of Daytona".

In 1980 the RX-7 won every race it competed in the IMSA GTU series that season.

In 1981 the decision was taken at Mazda's headquarters that the RX-7 proved it's performances and a factory team wasn't needed anymore.
So from this point independent teams raced it and won every IMSA GTU Series Championship from 1981 to 1988.

Rx7 Mazda IMSA GTO quad rotor racing

In 1990, to reach the IMSA GTO class Mazda had to raise the displacement of the rotary.
So the RX-7 was equipped with a four-rotor engine producing more than 600 horsepower and 529 Nm of torque!

The same year it finished 3rd at this championship.
But Mazda came back the next year (in 1991) and won the championship.

1991 was also the year that the mighty Mazda 787B entered the competition at "Le Mans"... and won.



Mazda 787B Racing JDM Rotary


Mazda rx8 rotary jdm


In 2003 Mazda launched the RX-8, had no turbos, was less sporty and the weight balance had been messed up.
On top of that it had reliability issues and in general it was a disappointment to the rotary community.
It was discontinued in 2012.

Then Mazda used the a compact rotary as a range extender on it's Mazda 2 EV and this was the last rotary to ever been used in a production car.

In 2019 rumors said that the Rotary engine may be revived, the community around then was expecting a lot or hoping at least.
But in 2020 Mazda announced that it may be used in the MX-30, a SUV, as a range extender.

Sadly it seems like the rotary equipped sports car that we are all waiting for, may never come...



JDM RX-8 Canvas drift


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