Four-stroke diesels have long been the norm. Two-strokes? Sure, we all remember the “Screamin’ Jimmys” of years past… sometimes even fondly… and those legendary Uniflow GM diesels pretty much define the American memory of the two-stroke diesel. Few remember another two-stroke diesel that mounted a challenge in the American market.

Europe embraced the diesel engine much earlier than North America. Because of high fuel taxes, Europeans demanded higher fuel economy and developed diesel technology for their commercial fleets and passenger cars. One of the more important figures in that process was Professor Doctor Hans List (1896-1996), an Austrian engineer, scientist and internal combustion engine theorist.


A storage-worn NOS Waukesha-built Model 3 3-cylinder with a 1969 manufacture date. The application is unclear but it was likely military. The basic features are the same for all engines, though injection pump and blower mounts mountings varied a little. The three cylinders had four main bearings supporting a nodular iron crankshaft with 3.5-inch diameter main and 2.87- inch rod journals. In this application, a Roosa-Master DB series pump was used and the pintle-type injectors opened at 1,750 psi. The engine weighed 605 pounds even with its aluminum block (SAE#4 bellhousing). Note the very early application of flat belts, driving both the accessory drives and blower. We could not find a boost pressure specification but the information indicates the blower was tuned to supply only a little more than atmospheric pressure. Turbocharging was envisioned as a future power enhancer.

In 1948, Dr. List started the Institute for Combustion Engines in Graz, Austria, the Austrian acronym being “AVL.” They are still in business and responsible for many high-tech advances in combustion engine technology. In the early days, List was a proponent of loop scavenging, a method whereby the engine breathed through ports and didn’t have valves at all. The father of this idea was Adolph Schnuerle, who conceived it in 1926. Loop scavenged engines can be designed for any fuel and many of the best gasoline two-strokes are loop-scavenged. They are high revvers and were considered very efficient in their day because they don’t have the major internal frictional horsepower losses of an engine with a conventional valve train.



The M-Series Jeep Forward Control FC-170 4x4s were built for the United States Marine Corps in 1963 and were the most notable vehicular application for the Cerlist. As many as 400 are known to have been built. This is the M-677 four-door crew cab variant, the most numerous of the M-Series produced, but there was also an M-676 standard cab pickup, M-678 carryall and M-679 ambulance built on the same chassis. They were fairly standard Jeep FCs but militarized to suit USMC requirements.


The FC-170 was normally powered by a 226ci flathead six that made 105 hp at 3,600 rpm and 190 lb-ft at 1,400 rpm (gross ratings, deduct about 15 percent to approximate the net power). The two engines were approximately the same weight, with the Cerlist about 40 pounds heavier than the six. As you can see, the diesel fit well under the doghouse and was a relatively easy conversion. In tests, at an 8,000 lbs GVW, the gasser delivered 8 mpg while the Cerlist powered truck made over 16 mpg. Testers said performance was comparable, especially in hilly country.


The Cerlist in the M-Series was backed up by a Warner Gear T90 3-speed and a Spicer Model 18 transfer case. Axles were a front Spicer 44 and a rear Spicer 53, both equipped with Spicer Powr-Lok limited-slip differentials. They came wearing 7.50-16 commercial mud and snows, but most were soon converted to military non-directional tires. This M-677 belongs to Dan DeVries and has been restored to USMC splendor wearing its original registration markings.

List’s loop-scavenged diesels were first used by the Austrian car and truck maker Graf & Stift in 1948. From 1952 to 1960, AVL licensed loop-scavenged diesels to Alfa-Romeo (Italy), Janbacher (Germany), Ford Motor Company (Germany), Turner Manufacturing (England), Landini (Italy), Krupp and Mannesmann (Germany) to build engines for automotive, marine and stationary use. Each company had a slightly different variation on the theme and there would be other licensees later.

The Cerlist Model 2 cranked out 54 hp at ,3000 and 107 lb-ft at 1,900 rpm from 113 ci. This engine weighed in at 530 pounds and saw the most use as a stationary or marine engine.

In the heyday of that mid-1950s movement, along comes an American named Peter Cerf. How and exactly when he connected with AVL is unclear, but by the end of 1956 he had formed the Cerlist Diesel Company in North Carolina to build List diesels under license. In case you haven’t figured it out yet, the name “Cerlist” blended “Cerf” and “List.” Cerlist engines used the design features found in the European List engines but were updated for the American market by AVL with Cerf’s input. That process took 18 months and the result was a five-engine Cerlist family that shared the same basic 4-inch bore and 4.5-inch stroke. A 4.18-inch bore was also envisioned as a future power upgrade option, as was a turbocharger, but neither were implemented in production.

Loop scavenging is a simple concept. Piston position uncovers the inlet (white arrows) and the exhaust ports (black arrows). The blower supplies constant airflow. After ignition, the piston moves down and uncovers the three exhaust ports first and much of the combustion pressure exits. Next, the six intake ports are uncovered and the inlet flow both pushes out the remaining exhaust and fills the cylinder, with the fresh air moving in a loop. The piston rises, covering the ports and compressing the air (22:1 CR). The injection system pops, the cylinder fires, and the cycle begins again. The size, shape and location of the ports represent the job a camshaft and valves do. The biggest problem with the loo- scavenged diesels was oil consumption control and that’s why the pistons had six sets of rings, four compression (keystone type on top) and two oil control. The oil control rings were at the bottom of the piston and stayed just below the intake ports at the top of the stroke.

The lineup included a 2-cylinder inline (113 ci, 54 hp, 107 lb-ft), 3-cylinder inline (170 ci, 85 hp, 170 lb-ft), V-4 (224 ci,100 hp, 220 lb-ft), V6 (336 ci,150 hp, 340 lb-ft) and V8 (448 ci, 200 hp). All the engines were rated for a 3,000rpm intermittent maximum and 2,600 rpm continuous, plus they had a broad, fl at torque band right up to redline. They all shared the same liners, pistons, rings, heads, Tri-Metal bearings and a beltdriven Roots blower.


The block was cast from aluminum with four-bolt mains and a nodular iron crankshaft. The inline engines used a balance shaft. The pistons were Hypereutectic with six rings. Cerf and List toyed with both direct and indirect injection and either worked well with the basic design, but lower noise levels favored indirect injection. A major side benefit was multi-fuel capability. The Cerlist could run on #1 or #2 diesel, JP-4 jet fuel or gasoline with no tuning changes. In a 1959 SAE White Paper, Cerf presented a dyno graph that showed power dropped only 4 percent from #2 diesel compared to gasoline. The injection pumps on production Cerlist engines most often had hardened internals to run on fuels with no lubricity, like gasoline, kerosene or JP-4.

Because Cerlist was a small company with little capital, it took a while to get up to speed. When orders came, the 3-cylinder proved the most popular engine, followed by the 2-cylinders and the V4. Few V6s were sold and, as far as can be determined, no production V8s were built. In the late ‘50s, Cerlist experimented with repowering a Jeep FC-170 1-ton with a 3-cylinder and tested that truck extensively over hill and dale, likely with full cooperation from Jeep. The Cerlist closely matched the package size needed to fit in the Jeep engine doghouse and it wasn’t far off the original 226ci flathead six for net power. When Jeep needed diesels for its military XM-676 program, the Cerlist was chosen. This became the militarized Jeep Forward Control 4×4 truck designed for the United States Marine Corps and came in four variants. Production records also show a small number of civilian FC-170s built in 1963 with Cerlist diesels.

A Cerlist was tested in a Checker cab and delivered fantastic fuel economy and power comparable to the stock six. A Studebaker postal Zip Van was given a Cerlist diesel swap for tests. Beyond the M-series FCs, the USMC swapped Cerlist diesels into M-38A1 Jeeps for tests. According to some sources, a supplemental order came from the Marines for 3,000 engines and that may have been the straw that broke Cerlist’s back. The company had capitalization issues that became acute as the Jeep project was being finished up and could not meet the supplemental order.


The Cerlist V4 was very compact for its output. It was only 30.7 inches long, 33.12 inches wide and 35.12 inches tall but weighed a hefty 770 lbs. The blower mounted in the valley between the cylinders and so did the injection pump. The intermittent rating was a respectable 100+ hp but look at that torque line! All the Cerlist engines had a similarly flat torque line from 1,000 to 3,000 rpm. In this case it only dropped 10 lb-ft from the peak at 1,900 to the redline at 3,000. The governor cut in at 3,150 revs.

Waukesha Engine came in to buy the company, completing that deal in June of 1963, keeping Cerf on the payroll as Sales Manager but moving production to Clinton, Iowa. During the Waukesha era, Cerlist diesels were sold mostly for stationary use. One interesting military application was a Vietnam-era portable aviation fuel dump for remote airfields. The Air Logistic Corporation used Cerlist diesels in its Boondocks Air Transportation Fuel System. The Cerlist pumped JP-4 from fuel bladders and ran off the JP-4 fuel it was pumping.

Production continued on the 2 and 3-cyl inlines and the V4 through July of 1973, when Waukesha discontinued them. The remaining spare parts were sold off in 1980 and today Cerlist parts stocks have dwindled. The exact production number of Cerlist engines has been hard to track down, but some sources list as many as 8,000 of the 3-cylinders and a combined 2,000 2-cylinders, V4s and V6s.

Loop-scavenged engines had an era but even had Cerlist survived as a company, emissions regulations would likely have doomed them, as they did the Uniflow GM engines. DW


Another possibility of a road application for the Cerlist came from Studebaker or the U.S. Postal Service. At the end of 1963, Studebaker won a contract to produce a postal van. It was called the Zip Van, appropriately named since the postal Zip Codes were just being introduced at the time.


Production Zip Vans were powered by Studebaker’s 110 hp/156 lb-ft (gross rating) OHV 170ci gasoline six, but Cerlist repowered at least one with a Model 3C diesel. It isn’t clear exactly when this occurred but it was in the ’64-65 timeframe. It’s also not clear if it was instigated by the USPS or Studebaker. This might have gone farther but Studebaker went out of business as the Zip Van was being built. In a strange twist of fate, when the last of the ordered 4,328 Zip Vans were being built in April of 1964, Studebaker was already officially out of business in the U.S. and the Zip Van was likely the last vehicle built in the U.S. under the Studebaker nameplate.



In another odd quirk of fate, that single prototype has survived. It was built January 9, 1964, and delivered to the government on January 17. It is unclear when the conversion was done, but the engine production date was February 19, 1964. We located it in the extensive Ron Hackenberg collection and Ron was kind enough to let us photograph it. The vintage photo shows Peter Cerf, then the Sales Manager for the Cerlist Engine Division of Waukesha Motors, with the newly converted van. The other images show it today in a corner the storage facility where it has lived for many years, still wearing the original postal colors and still containing various postal accoutrements within. This vehicle will be up for sale on July 15, 2017, when Hackenberg’s 750-vehicle collection of cars and trucks will be auctioned off in Norwalk, Ohio.






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