Massachusetts, June, 2007. Improving the fuel efficiency, emissions and power of IC engines, while maintaining their simplicity and low-cost, has been a major challenge for CEI. Michael Ward, Harvard, Ph.D., worked for 30 years addressing these issues, and began to succeed in the last 12 years. Advances were made in emissions and efficiency through patents issued between 2000 and 2007 on spark ignition and the 2-valve, 2-plug, squish-flow engine. Advances were made in three areas of concerns: 1) burning of leaner mixtures, i.e. a higher ratio of air-to-fuel (AFR); 2) having a faster burn; and 3) using a homogeneous mixture. More important, the cost savings that can be made with modern, 2-valve engines, operating with lean mixtures for best efficiency and emissions, went against views long-held by the auto industry.

The main factor to a successful lean burn engine is the reliability with which the burning occurs in the lean air-fuel mixture in the engine. Stated otherwise, the engine’s success depends on how tolerant it is to dilution by excess air, i.e. lean burn, or dilution of exhaust gas, EGR. The advantage of dilution by air is fuel economy; and dilution by EGR is low NOx. EGR is only 60% as effective for efficiency as lean burn, i.e. excess air, but is more effective in NOx reduction since EGR operates at a 15:1 AFR and can use the 3-way cat for NOx reduction. As can be seen, a very lean AFR of 24:1 is required for NOx to meet Emission Standards. Note that the level of Hydrocarbons (HC) is low for the entire lean burn range because of the presence of an oxidizing atmosphere. HC can become high if flame speed becomes too low. We can obtain efficiency gains of 15% > 30% > 45% as a function of three major advances made in lean burn by CEI.

It turns out that CEI made the first two of the three stages in lean burn a success by:1) developing a breakthrough ignition; and 2) developing a breakthrough engine. The ignition was demonstrated in collaboration with Champion/FM, and the engine was designed and built by CEI as a low-cost, single cylinder, 2-valve, 2-plug, squish-flow engine. Compared to today’s 4-valve, 4-cylinder gasoline engine, it has a cost advantage of $400, and $1,000 against the diesel. In the form of the 2-valve engine it gives a 15% gain in efficiency by using the CEI ignition as a simple retrofit; in the form of a 2-valve, 2-plug cylinder head using the CEI ignition, it gives a 30% gain in efficiency; and a gain of 45% when the technologies are used in combination. According to the table on page 2, the total cost can be as low as $200, or 1/5 – 1/2 the cost of current, low efficiency systems. It is unfathomable how the industry can claim a large increase in cost for fuel efficiency when CEI will show an actual decrease to be the case.

The first stage uses CEI’s high energy ignition to increase the air-fuel ratio capability of the engine to operate as either a lean burn engine or an EGR engine for better fuel economy with acceptable emissions. The efficiency is raised to 15%. The second stage uses CEI’s low-cost, 2-valve engine with squish-flow and twin-plugs. It increases the AFR to over 25 to 1; it speeds up the burn; and it increases the CR from 9:1 to 10.5:1, as in the 2-valve, 2-plug Honda FIT, for an efficiency gain of 30%. At this AFR, it can meet emission standards and get full advantage of lean burn. The requirement for the third stage is to implement a variable compression ratio (VCR) system in the low-cost, 2-valve engine, which can have its compression ratio raised to about 14 to 1 CR at light loads and lean burn conditions for a maximum efficiency gain of 45%. The VCR works to give the highest power and efficiency of the engine at high loads.

CEI has made the first two stages a success, and is well along the third stage. The first phase involved using CEI’s patented ignition which gave 5 times the energy for the same size coil, and easily provided extension of the engine’s lean limit. Tested by Champion on a 2005 Ford Focus, the ignition gave a higher EGR with 5% better fuel economy than the state-of-the-art, double-spark ignition by Visteon. Assuming the Visteon ignition gives a 4% fuel economy gain due to limited gain in EGR, the CEI ignition gives the remainder 5% (remembering that EGR is only 60% as effective for efficiency as lean burn). For a car averaging 25 miles/gallon and traveling 10,000 miles/year, it uses 400 gallons/year, and a 5% improvement means 20 gallons/year saving. At $2.50/gallon, it gives a saving of $50/year. This is only about half the additional maximum cost the CEI ignition.

The second phase involved building a single cylinder engine which CEI did in 2000, with the cylinder head shown on the right. The engine is a strongly patented 2-valve, 2-plug, squish-flow, homogeneous charge engine with a simple and low-cost design (see table below). The engine, enhanced by the CEI dual-ignition, set records in lean burn and fuel economy. It achieved a breakthrough in the lean limit of over 30 to 1 AFR, twice as lean as normal, with a fuel economy gain of 30%, similar to a diesel, without the high cost, weight, emissions and other disadvantages of the diesel. In 2001, CEI presented an SAE paper (2001-01-0548) on the engine and showed that lean burn had been solved despite reservations by the industry. Recently, Chrysler and Honda built a 2-valve, 2-plug, high efficiency engine, similar to CEI’s, but without CEI’s patented benefits of squish-flow and CEI ignition.

Following the previous analysis, a 30% gain in fuel economy gives a saving of $300/year, while the additional manufacturing cost of the engine, designated for short as 2-2-4-LB Engine, is seen to be only $100, with a payback time of only 1/3 year. Note that the additional cost is 1/10 of the diesel, with similar fuel economy, and with many other advantages over the diesel.

The third phase is to implement a design developed by us on our 2-2-4-LB Engine which uses pistons with steel or titanium disc springs to provide the variable compression ratio at a low cost of $100 to $200 above the cost of the CEI 2-2-4-LB Engine. Adding this simple form of VCR to the CEI engine can raise its efficiency gain from 30% to 45% at light loads and high CR, leading to an unheard of high engine efficiency. The engine leanness is higher at a higher CR, with a lean limit of 36 to 1 at 14 to 1 CR. See a GPC paper Volume 29, 2004. Note that the saving per year is $450, and the payback time, or return-on-investment, is only about 1/2 a year.

The cost saving of the CEI 2-2-4-LB VCR Engine cannot be given since there is no engine to compare it with. Its fuel economy and lean burn ability are far ahead of any engine, whether an advanced Diesel, or a hypothetical engine as a HCCI and Fuel Cell. It is remarkable that a 2-valve engine, with a simple, low-cost design promises to be the most forward looking engine and to be the lean burn engine of the future to alleviate problems of fuel efficiency & global warming.