A little bit of history on the Lister cold starting Diesels:
There's not a great deal of information available on these, despite how common they are throughout the British Commonwealth. Perhaps "familiarity breeds contempt"? This is basically what I've been able to put together through snippets from enthusiasts' sites on the Web, discussions on the Stationary Engine Lists (both on the atis.net and oldengine.org servers), data from my good friend Peter Forbes, David Edgington's books on the Lister petrol engines and stationary engines in general, and from a couple of old books on Diesel engines that mention Lister briefly. Oh, and from the Lister 3/1, 5/1, and 10/2 owner's manual. :-)
Like the well-known Oldsmobile 350 V8 and Volkswagen Rabbit Diesels of the 1970s, the Lister CS series of Diesels were converted from an existing petrol (gasoline) engine. The Lister L, built since 1909, was a side-valve, low-compression, spark-ignition engine. It was made in many variations with different combustion chamber designs, speed ratings, etc., and produced anywhere from 4 to 6 1/2 BHP. It had a bore and stroke of 5 1/2" x 5 1/2". During the late 1920s many manufacturers were developing small, solid-injection Diesel engines, either from new designs or by converting existing ones. Lister chose to base a new Diesel engine on the proven "L" design. Though this might be regarded as a "kludge" by some, the CS engines that resulted were highly successful. Introduced in 1930, they continued in production by Lister until 1987! And several companies in India are still producing unauthorized copies to this day!
Sir Harry Ricardo had served as a consultant to Listers for some time, designing combustion chambers for the petrol engines that greatly improved their power output and efficiency. Ricardo was well known for Diesel combustion chamber design as well, particularly for his "Comet" combustion chamber. This can be seen well in a cross-section of the Waukesha Comet truck Diesel. The piston came very close to the underside of the head, forcing nearly all of the air into a small passage that opened tangentially into a small spherical turbulence chamber. This produced a violent swirling turbulence. The injector nozzle was centrally located in the top of the chamber, with a single orifice aimed straight down to the floor. Swirling air broke up this relatively coarse spray and mixed it with air, the heavy droplets that hit the floor mostly bouncing back as a fine mist into the raging cyclone, the heat of the chamber walls rapidly vaporizing fuel that wet the surface. As the fuel ignited and burned, the hot gases were forced back through the passage into the cylinder, entering at about a 35 degree angle to the cylinder axis and from one side, resulting in a highly turbulent mixing action with the air still present in the cylinder. This sort of combustion chamber is known generically as a "turbulence chamber," and differs from a "precombustion chamber," "prechamber," or "antechamber" in that most of the air drawn into the cylinder is forced into this small chamber, and most of the combustion occurs within this space. In a prechamber design, only a little of the air is forced into the prechamber, where partial combustion prepares the fuel as a hot gaseous mix that's forced into the main chamber to mix with the rest of the air for complete burning. The terms are often used interchangeably, however.
It is not known to what extent Ricardo may have participated in the planning and design of the Lister cold starting Diesels. The engine's design is generally attributed to Arthur Freeman-Sanders, a Lister designer of the period who became their chief designer, and to whom the Lister "D" design is also credited. I have mentioned the Ricardo Comet combustion chamber design in some detail because I believe it may have been the basis for the somewhat modified, yet strikingly similar, chamber of the CS engines.
In converting the petrol "L" to a Diesel, Freeman-Sanders faced major engineering challenges. A new head had to be designed with overhead valves, as a sidevalve layout is highly inefficient at the high compression ratios necessary for autoignition of Diesel fuel. An injection pump and nozzle system had to be selected (a Bosch unit was chosen) and adapted to the engine. The governing mechanism would have to be modified to control the pump rather than a carburetor's throttle. Perhaps most problematic, the bottom end of the engine would be subjected to far higher stresses at Diesel compression ratios than at the existing petrol engine compression ratios of 5:1 or less. And combustion in Diesels is notoriously "rough," as anyone who's sat next to an idling truck at a traffic light can attest!
To make the bottom end stresses manageable, Freeman-Sanders did two things: 1) He reduced the bore diameter from the 5 1/2" of the "L" to 4 1/2" in the 5/1 (5 HP, 1 cylinder) CS Diesel, and to 3 3/4" in the 3/1 version. This greatly reduced the piston area over which the higher pressures would act. 2) Recognizing that the peak forces were still risky for the crankshaft and bottom end bearings when the compression was high enough for cold starting (that is, without using a torch to heat a hot bulb, plate or glow plug, and without a burning punk inserted into the cylinder), he came up with an ingenious idea: Start the engine at a compression ratio high enough to ensure good starting, then switch the running engine to a lower compression ratio to reduce the strain! The method he invented to accomplish this was unique and elegantly simple. The spherical turbulence chamber was tilted up from its slanted position at the edge of the cylinder (in the Comet design) to an upright, nearly central location to make room in the head for a second, smaller spherical auxiliary combustion chamber or air cell. Passing through this auxiliary chamber is a threaded plunger with a handwheel attached, just like the valve in an ordinary faucet. When it is screwed all the way in, this plunger seals off the narrow passage between the main combustion chamber and the auxiliary one, giving high compression for efficient starting and running on light loads. When screwed all the way out, the plunger seals against the outer wall of the auxiliary chamber, the passageway is open between the two chambers and the compression ratio is lower for minimizing the strain on the engine while running under heavy load. (In between the two positions, the compression changeover valve leaks air to the outside and the engine has no compression.) This arrangement can easily be seen on the cutaway on the right side of this picture of an early Lister Diesel. (This engine is not a CS. It is a JP or 9/1, which was introduced slightly ahead of the CS and is actually Lister's first Diesel engine. It has the same handwheel compression changeover used on the CS.) Here's another picture, of the head of a CS showing the compression changeover apparatus. Mechanical compression ratios for the 5/1, 6/1, 10/2 and 12/2 engines using this system were 19:1 starting, 15:1 running. For the smaller 3/1 and 3 1/2/1 engines, the ratios were 22:1 starting, 18:1 running. (Smaller engines have more surface area for the combustion chamber volume, cooling the compressed air more rapidly, thus requiring a higher ratio to ensure that the air will get hot enough during cranking to reliably ignite the fuel. Some older books stated that a Diesel could never be built with less than a 6" bore!) ;-)
Despite the two precautions of de-boring the engine and reducing the running compression ratio, the old "L" bottom end developed problems when used in a Diesel. In the early '30s the crankshaft diameter was increased from the original 1 3/4" to 2". (The same change was made to the petrol "L-31," which was run at higher speeds and was rated at 7, 8, 9 or 10 HP depending on speed, usually 9 HP.)
An innovation introduced in the mid-30s was the "Listard" coating on the cylinder bore, which greatly reduced wear. Reportedly the secret to its success was that after this hard chrome plating was applied, the polarity of the current was briefly reversed. This produced microscopic cracking and pitting in the chromium, which held oil and provided far better lubrication than would be the case with a plain mirror-polished chrome surface!
Sometime during the 1950s the 3/1, 5/1, and 10/2 engines were slightly uprated in speed (from 600 to 650 RPM) and rerated to 3 1/2, 6 and 12 HP. The 3 1/2/1 was discontinued in 1952. The official renaming of the uprated 6/1 and 12/2 was in 1962, when the 800 RPM 8/1 and 16/2 were introduced. The 6/1 continued to be manufactured until 1974, the 12/2 to 1975. The 8/1 was made until 1987.
In addition to the higher speed rating, the 8/1 and 16/2 dispensed with the compression changeover system. Apparently Lister's engineers figured that with a slightly lower compression ratio than the original starting ratio, the engine would start reliably and could run continuously at this ratio without the complication of changing compression ratios. The removable auxiliary chamber inserts and changeover valve were replaced with a simple plug. The compression ratio was fixed at 17.5:1. This was done without altering the volume of the combustion chamber, by shimming the cylinder at the base to produce .030" more clearance between the piston crown and head, leaving a little more air in the cylinder space at TDC. Thus, the cylinders, pistons and heads remained interchangeable between the older and newer engines.
While these venerable engines had become unprofitable for Lister to build and market by the '80s, there remains a considerable demand for these durable, simple, economical engines in many of the less-developed nations where they are used widely for jobs such as pumping water to irrigate fields. Several firms in India had begun to produce replacement parts for Lister Diesel engines, and some firms began to assemble entire engines from replacement parts! (Just as has been done in the United States with PC clones and clones of Harley-Davidson motorcycles.) Many of these are faithful replicas of Lister engines, with all parts being interchangeable. Several interesting local innovations have been developed, including models with tapered roller main bearings and pure splash lubrication without an oil pump, bored-out, higher-speed 10/1 and 20/2 variants, "Mini-Listers" with smaller outside dimensions, and "Maxi-Listers" up to a 16/1! There are many sites on the Web for companies offering these engines, and far more for companies cloning the small, high-speed Petter Diesels. While it seems likely that the Environmental Protection Agency will stymie the future importation of these engines into the United States, I expect that they will continue to be built and used in India for a long time to come. Perhaps the Lister CS will be the first engine design to remain in continuous production for 100 years?