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Purdue team developing pre-chamber technology for cars for ultra-lean combustion

Purdue University researchers are developing pre-chamber technology for automobiles to replace conventional spark plugs and enable more reliable ultra-lean combustion. In the pre-chamber approach, a tiny chamber—a pre-chamber—is filled with a mixture of fuel and air. The mixture ignites, producing combustion, and specialized nozzles in the bottom of the chamber release the hot combustion products in the form of powerful jets, which penetrate into the main chamber and cause ignition.

Compared with traditional spark ignition, this method provides a large surface for multiple-site ignition and fast flame propagation and enhances the overall combustion efficiency. Both passive and active pre-chambers are being considered.

For the former, the main-chamber mixture is pushed into the pre-chamber by compression stroke through the tiny holes; and for the latter, additional fueling is supplied to the pre-chamber to facilitate leaner operation of the main combustion chamber.

Ultra-lean combustion technologies are seen as a potential solution to meet stringent emission regulations including NOx. However, ultra-lean combustion has serious challenges, including misfires as a result of poor ignition. Such misfires and difficulties in ignition can lead to cycle-to-cycle variability, rough operation, reduction in efficiency, and increase in unburned hydrocarbon emissions.

The Purdue pre-chamber technology looks to ignite ultra-lean fuel/air mixtures, which may not be able to ignite using current pre-chamber technologies.


Sequences of images showing the jet (produced from pre-chamber on the top) penetrating into the main chamber and igniting the main-chamber mixture.

Li Qiao, an associate professor of aeronautics and astronautics in Purdue’s College of Engineering, said the technology her team is working with already has been used in large bore natural gas engines and in some F1 racing cars because of its superior performance, but it is new to passenger car gasoline engines.

The auto industry is feeling the pressure to optimize these engines because of the competition from electric vehicles. Several automotive engine companies have started exploring pre-chamber technology for passage cars.

—Li Qiao

Qiao is currently collaborating with industry on design and optimization of passive and active pre-chambers for gasoline engines.

Qiao and her team have performed tests at Purdue’s Herrick Laboratories and Maurice J. Zucrow Laboratories, the largest academic propulsion lab in the world.

Qiao and the team are working with the Purdue Research Foundation Office of Technology Commercialization to patent their technology. They are looking for additional partners.




Not a lot of information here ...
How about - how much more efficient it will make engines.
How long it might take.
How much extra it would cost.

Some kind of ICE range extender would be a boon to humanity, you could drive mostly battery cars, without fear of running out of charge.
Thus, you could have 10 KwH EVs (PHEV or range extender), rather than 60-100 KwH monsters as we are trending towards currently.


It is... interesting how the research and promotion seems to be directed at the least-effective replacement for vanilla ICEVs, isn't it?


Large marine methane-fuelled engines have used this technology for ages. It makes sense in that case since the spark plug is very small compared to the combustion chamber. Igniting a very lean charge in such engines is challenging. Scaling spark gap and voltage according to the size of the engine is simply not possible. Recent F1 technology is, per definition, very much confidential but they also seem to find advantages with a pre-chamber. I suppose the researchers, in this case, aim to stretch lean-burn technology as far as they possibly can also on passenger car engines. Why not? With a few exceptions, there has been relatively little research in this field so far. It would be interesting to see the potential of this concept.

I could add that urea-SCR aftertreatment technology borrowed from diesel engines could be used to cut NOx under conditions where engine-out NOx would be too high for NOx storage catalysts. SCR aftertreatment is also tested in some EU projects on lean-burn gasoline engines. Cost and complexity are issues but we know today that SCR aftertreatment on diesel engines can be very effective, so of course, it could be used on other types of engines as well. Note that high NOx has been a prohibitive problem for many lean-burn concepts in the past. Conventional TWC is so much easier and cheaper but it can only be used on lean-burn engines when they run stoichiometrically or with fuel enrichment.

Mahonj must learn to distinguish between research projects and a commercial product. This study must be very far from commercialization and it might be difficult to assess the full potential.

Account Deleted

Any thoughts on how this is different or more efficient than the MAHLE Jet Ignition®
which is used in some form by all Formula 1 engines and achieves 50% BTE.

Roger Pham

Why bother? Just use hydrogen, which can burn very lean without misfire.


Maybe because H2 requires high pressure tanks.


It looks similar.

Account Deleted

Good reference SJC, thanks.

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