Paul,

During my combustion testing on rotary engines I kept finding an anomaly of autoignition.  Usually about 6 to 8 cycles on a normal 8000 RPM sweep. It seemed to be caused by exhaust reversion continuing to the next intake cycle and causing the auto ignition. Very scary to have an uncontrolled ignition source.... but the good news was that the burn rate on those cycles improved!

After a little study I discovered a Honda experiment that concluded with a race bike for the Dakar rally that had a two-stroke engine running without ignition and getting 20% better fuel economy. But the details were very sketchy.

Fast forward to Formula 1 today. They are using what is known as Turbulent Jet Ignition. This process is not new, it was discovered by Ricardo and published in his papers from 1911. The latest version of this process by Mahle uses a direct injector and spark plug in a very small pocket that injects active radicals into the main combustion chamber. The engine can then be operated almost like a diesel and the burning process is spread throughout the combustion chamber by quenched active radicals causing a very fast burn rate. Lean burns have been demonstrated to lambda 2 or 30:1 AFR gasoline and throttling losses greatly reduced.

This is why Formula One is now  producing the same horsepower but is using 40% less fuel.
Mahle  is reportedly working with Ferrari but Mercedes seems to be way ahead of them.

This ignition process seems to be a perfect fit for the rotary engine... especially on aircraft where BSFC is so important.

Barry Bordes


How are you doing the combustion testing on rotary engines?
References for the Honda experiment?

http://papers.sae.org/2010-01-1457/

The reason Formula One engines are burning less fuel is because they are turbo compound
hybrids. A formula 1 engine is either on full throttle or on the brakes. The power recovery
from braking is  a large part of that.

http://www.rotaryeng.net/Oxford-TC-talk.mp4

We have known for years that leaning the rotary up to 18:1 improves the BSFC at the expense
of power.

If you have a leaking apex seal hot exhaust gases from the leading chamber can
pre ignite the following chamber.

Paul Lamar

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