Prechamber Combustion

[luv2spd]

I have been wondering for years now about the engine of the AMG F1 car, when the car first started racing in 2014 it had more power than any other car and was more fuel efficient as well. Which makes no sense. Anyways, a year went by and in 2015 there were rumours going around that they are using a prechamber combustion engine. I have been searching for 2 years now to see what this is with no luck. Fortunately the March issue of Car And Driver explained where the technology comes from and how it works. So I thought I put it up here in case others are interested as well. In F1 racing, the only restriction on fuel is that the car can only use 105kg per race, so there are millions of dollars invested in adding additives into the fuel to maximize the energy extracted.

Turbulent Jet Ignition

“Exactly what goes on under carbon-fiber shell of a Formula 1 car is a matter of guesswork for observers, but they should know that it’s all about saving fuel. For a while last season, rumors persisted that Mercedes AMG Petronas, among others, was using homogeneous-charge compression ignition, or, essentially, combusting gasoline as if it were diesel under certain conditions and as a spark-ignited engine the rest of the time. Then it emerged that the team was actually onto something new, called Turbulent Jet Ignition, which extracts more energy from fuel similar to Honda’s old Compound Vortex Controlled Combustion from the 1970s. For now, this is racing-only tech, since at the much lower speeds and power loads that road cars run, the combustion isn’t stable. “

MAHLE Powertrain Jet Ignition


1 TJI engines have a small prechamber above the combustion chamber where both an injector and a small spark plug are nestled together.

2 A conventional injector sprays most of the fuel during the intake stroke. The remaining 5 percent or so is sprayed into the prechamber by the secondary injector, yielding a super-rich mixture that’s easily ignited by the spark plug.

3 Burning fuel exiting the prechamber through four to eight tiny orifices initiates combustion of the main fuel-air charge. The resulting flame front spreads quickly through the combustion chamber, allowing a much leaner overall mixture and improved fuel efficiency.” March/2017 Car And Driver

The cat is out of the bag.

[Desy151]

Thanks for the info. Good review!

[R.I.D.E.]

Precisely what Honda did with their CVCC (Compound Vortex Controlled Combustion) engines in the Civics and the first Accord in 1977. The HF CRX that came out in 1984 did 73.5 MPG in one car mag road test on a single tank of fuel, all highway driving. So we are talking 40 year old technology, just upgraded with computers and precision engine monitoring. Some of the current formula 1 engines are approaching 50% thermal efficiency in racing environments.

Prechambers are ancient tech. Mercedes had them in every diesel they made up until the advent of ultra high pressure (30,000 PSI) direct systems in recent years.

The Honda Civic VX used the valve lift technology to use one intake valve to provide turbulence under light loads, with air-fuel ratios as high as 25-1 versus the normal 14-1 required by emissions.

Mazdas sky-activ engines uses multiple injections DURING COMBUSTION to change the pressure wave properties of the combustion stroke giving higher pressure later in the downward movement of the piston, further improving the efficiency.

Last I heard Mazda is bringing a practical HCCI engine into the market, with thermal efficiencies approaching the best diesels. While not quite at the level of the super large container ship engines of 100,000 horsepower with 56% thermal efficiency, we may actually see that level in future passenger car engines.

While many agenda driven advocates of pure electric propulsion would want to see the IC engine die quickly, I think they may be in for a surprise, with the competition continuing for quite some time. The real trasformational moment would be if the often predicted "miracle" battery becomes reality, with low cost production combined with the transition of power generation more based on extracting the most available solar-gravitational resource which is evaporation.