LC10 was the original name given to a series of very small three-cylinder, two-stroke engines built by Suzuki Motor Corporation in the 1960s and 1970s. They were used in a number of kei class automobiles and light trucks. The LC10 and its derivatives did not completely replace the FE and L50 two-cylinders, which continued to be used mainly for light commercials. The LC10 engine was developed together with the Suzuki B100 engine, a single-cylinder motorcycle engine which shared the same bore and stroke. For longevity and convenience, the LC10 received Suzuki's new "Posi-Force" auto-lubrication system, eliminating the need for pre-mixed fuel.
LC10
The engine was first seen in air-cooled form, equipped with three Mikuni VM carburettors, in the 1967 LC10 Suzuki Fronte 360. Displacement was , from a bore and stroke of .Ozeki, Suzuki Story, p. 28 Originally developing , a SS version soon appeared, with a stunning .Ozeki, Suzuki Story, pp. 34-35 For the conventionally laid out Fronte Van, Estate, and Custom a single carburettor version was used. Combined with a lower compression ratio of 6.8:1, this meant a max power of . For 1971, the LC10 engine received Suzuki's new self-lubricating "CCIS" system (Cylinder Crank Injection and Selmix).
In 1969, Japanese racing car manufacturer Nialco built a single-seater called the RQ which utilized the triple-carb LC10 engine and competed in the RQ ("Racing Quarterly") Minicar Racing Tournament.Ozeki, Suzuki Story, pp. 48–50 Their best result was a fourth in the 1969 meet at Fuji, with Kikuo Kaira (future co-founder of Tommy Kaira) at the wheel.
Applications: 1967.04–1970.11 Suzuki Fronte 360 1970.11–1973.07 Suzuki Fronte LC10 II ("Sting Ray" Fronte) 1969.01–1972.03 Suzuki Fronte Van/Estate/Custom LS10/11, 1970.08–1971 Suzuki Fronte Hi-Custom LS11,
LC10W
In May 1971, as kei cars were becoming more and more sophisticated, a water-cooled version was presented.Nippon Kei Car Memorial, p. 79 The air-cooled versions were soon relegated to use only in the cheapest versions,Suzuki New Fronte (catalog), Suzuki Motor Corporation: 1972, p. 4 and disappeared entirely after 1973 as emissions standards became more stringent. The watercooled versions also had slightly better weight distribution (38/62 versus 37.5/62.5), due to the radiator being mounted up front.Ozeki, Suzuki Story, p. 56 This, the LC10W, was the only engine ever to be installed in the iconic Suzuki Fronte Coupé, whether in domestic or export market cars. The new 1973-1976 "oval shell" Fronte received the new LC20 chassis code but retained the LC10W engine code. In May/June 1974, power outputs dropped as the engine received additional emissions cleaning equipment. A version using Suzuki's Twin Catalyst ("TC") system was announced on the Fronte LC20 in May 1976 but only 61 examples were built.
From 1973 the LC10W engines also received Suzuki's SRIS (Suzuki Recycle Injection System), a method for lowering visible exhaust smoke by collecting and burning residual oil/gas lying in the bottom of the crank chambers. This was first seen on the Suzuki GT750, GT550, and GT380 motorcycles. In an effort to reduce CO, HC, and NOx emissions, the EPIC (Exhaust Port Ignition Cleaner) system was also installed.Ozeki, Suzuki Story, pp. 58–59
Applications: 1971.05–1973.07 Suzuki Fronte LC10 W 1971.09–1976 Suzuki Fronte Coupé 1973–1976.05 Suzuki Fronte LC20
Specifications Dimensions Carburettor Power atrpm Torque atrpm dates fitment PS kW kgm Nm lbft356 cc I3bore: stroke: 1 x Solex 6,000 4,500 07.1971-05.1974 Fronte LC10W, Coupé 5,500 4,500 05.1974-06.1976 Fronte LC20 07.1973-06.1974 Fronte LC20 3 x Mikuni VM18 6,000 4,500 05.1971-05.1974 Fronte LC10W, Coupé 3 x Mikuni VM22 6,000 4,500 05.1974-06.1976 Fronte LC20, Coupé 6,500 4,500 05.1971-06.1974 Fronte LC10W, LC20, Coupé
LC50 A bored-out version of the air-cooled LC10, called the LC50 in reference to its near half-litre displacement (actually ) appeared in January 1969.Ozeki, Suzuki Story, p. 57 In street applications, this engine was only for export, and was only ever made with air cooling. Like its smaller brethren, the LC50 breathed through triple carburettors.
Water-cooled triples were built for racing purposes, producing at 9,000 rpm. These took part in the JAF Grand Prix Formula Junior class as well as "MR" (Minicar Racing) meets. Thus equipped, the Can-Am style Fronte RF with Mitsuo Itoh at the helm took the victory at the 1970 "Junior Seven Challenge Cup" race, held at Fuji International Speedway, with an average speed of .
1969.01–1970 Suzuki Fronte 500 1970–1973.07 Suzuki Fronte 500/LC50 ("Sting Ray")
T4A In response to the changed Kei car regulations taking effect on January 1, 1976, Suzuki developed a bored out and cleaner version of the LC10W, featuring Suzuki TC (Twin Catalyst, a double muffler in which uncombusted fuel was burned) emissions equipment. The watercooled engine was bored out to . Like the other engines in this family, is used an iron block and an aluminium head. Sometime between 1973 and 1976 Suzuki had changed their system of naming engines, so this engine became the T4A. This meant that it was the first ("A") engine with a 0.4-litre displacement. To help reduce emissions the T4A employed a semi-automatic choke; if left on when driving, it would disengage automatically once the engine coolant reached .
The T4A was fairly short-lived (only used in the Fronte 7-S for just shy of a year and a half), and was soon replaced by an unrelated "full size" (550 cc) engine called the T5A/T5B. The emissions strangled T4A put out at 4,500 rpm in its final "TC53" form: specific power was 54% of what a 1972 Fronte GT had managed. This updated version had one small catalyst in a shortened exhaust manifold with a new liner and a much larger catalytic converter in the muffler (twice the size of the one used on the initial model), along with changes to the carburetor, secondary air supply, and ignition coil. The new catalytic converters used palladium and were developed in close cooperation with Mitsui Mining & Smelting.
1976.05–1977.10 Suzuki Fronte 7-S SS10/SS12
Specifications Dimensions Carburettor Power atrpm Torque atrpm dates fitment PS kW kgm Nm lbft443 cc I3bore: stroke: Single, downdraught Solex 4,500 3,500 05.1976-05.1977 Fronte SS10, SS10-2 05.1977-10.1977 Fronte SS12
See also List of Suzuki engines
References