Engine

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  • 4 cylinders, 2445 cc / 149 ci
  • 92×92 mm bore and stroke, giving 1:1 bore/stroke ratio (“square” engine)
  • aluminum alloy open-deck block with replaceable cast iron wet-liners
  • aluminum alloy pistons with floating pins and two chrome plated compression rings
  • aluminum alloy reverse-flow cylinder head with cermet valve guides & high-strength cast iron valve seats
  • aluminum alloy intake manifold, 2-bbl carburettor
  • overhead valves, cam-in-block pushrod valvetrain, solid lifters
  • two compression ratios available – 8.2:1 (model 24D) or 6.7:1 (model 2401)
  • max power output: 95 net hp / 110 SAE gross hp @ 4400 RPM (high compression)
  • max torque output: 186 N·m / 137.4 ft·lb @ 2200…2400 RPM (high compression)
  • very flat torque curve between 1500 and 3500 RPM

The absolute majority of GAZ-24 Volga cars were equipped with the four-cylinder gasoline engine, which was produced by Zavolzhsky motor plant (ZMZ) and available in two versions – the 24D and the 2401 – that differed only in compression ratio (the 24D should not to be confused with diesel engines available on the Volga on some foreign markets). The 2401 engine, despite lower perfomance figures, was by far the most popular of the two, as it could run on lower grade fuel which was both cheaper and more available in remote areas of the coutry; most of the taxicabs were equipped with this engine as well.

The GAZ-24 Volga’s engine was largely derived from the GAZ-21 Volga’s powerplant, produced from 1957–1970, which itself had been originally developed for the GAZ-56 1.5-ton truck. In turn, it became the basis for the later 4022.10 (1981; 3 valves per cylinder, lean burn, stratified charge) and 402.10 (1985; larger exhaust valves, new water pump, “breakerless” electronic ignition, added emissions control equipment) engines. Altogether they form the venerable family of GAZ / ZMZ OHV engines which soldiered on until mid-2000s (its 2.9-liter version with EFI is still produced by UMZ and used on GAZ commercial vehicles).

This low-revving four-cylinder power plant was designed for good low-end torque and long service life rather than high performance. Its power output in the stock configuration was severely limited by a low-CFM 2-bbl carburettor derived from the 1360-cc Moskvitch small car and a very restrictive exhaust system. Free from these restrictions, these engines could easily crank out up to 120-130 hp, and more intense performance modifications brought up to 175 hp – making the engine practical only for racing applications, though, with unstable idle speed somewhere near 2000 RPM.

ZMZ-24DLightweight aluminum alloy cylinder block (lighter than the much smaller Lada engine cast iron block) was injection-molded – a manufacturing process specifically designed for this engine at Zavolzhsky motor plant in the mid-1960s, heat treated and impregnated with special resin to fill the pores of the casting. Replaceable wet-type cylinder liners (also called sleeves) were spun-cast from special high-strength alloy cast iron and machined to fit the block. Short dry-liners cast from acid-resistant cast iron were pressed into the upper part of each wet-liner to further improve durability.

During the assembly of the engine the wet-liners were fitted into the block and sandwiched between copper seal ring at the bottom and the cylinder head gasket at the top. With proper assembly tolerances, this design was mostly trouble free for the whole life of the engine, unless it overheated badly, which could cause cooling agent leaks into the cylinders.

This design was neither cheap nor easy to produce, but had a substantial economical effect, as replaceable liners saved a tremendous amount of time, labor and costly machine works during engine rebuilt. For this reason, almost all Soviet-designed car engines had aluminum blocks since about mid-1950s, as well as many truck engines (UAZ & GAZ trucks). No critical corrosion problems, usually associated with aluminum engines with wet-liners, were experienced even when water was used as the cooling agent, which had been the case until 1975 when antifreeze was introduced (today it is strongly not recommended to use water as cooling agent, nonetheless).

Due to light weight, relatively large displacement for the inline-four layout and lack of balance shafts to smooth it’s shake, the Volga’s engine suffered from inherent more-than-usual amount of vibration, worsened by relatively crude balancing technology used back then. To counter it, the designers employed thick rubber engine mounts, extra-soft coil-spring rear transmission mount (after 1976) and elastic rubber joint in the transmission tail shaft housing (after 1976). In the 1980s, a crankshaft harmonic damper was added to further improve the effect. Yet, the engine still was not as smooth as an inline-six of the same displacement could have been. Severely out-of-tune, or assembled without proper attention to balancing, it could turn the otherwise comfortable Volga into a traveling fatigue machine. If properly tunded, however, it runs reasonably smooth and quiet.

ZMZ-24_power-torque_curves_ENGThis engine yielded a quick torque rise, with 175+ N·m (130 lbs. ft.) at as low as 1,600…1,700 rpm, and its torque curve was almost flat (±10 N·m) between about 1600 and 3500 RPM. It had great elasticity and provided decent acceleration in 0-70 km/h range. In city driving, little gear shift was involved as 3rd and 4th (direct drive) gears were sufficient for almost any task other than starting from stand-still. After about 3500 RPM, however, the volumetric efficiency of the intake system swiftly deteriorated, determining a rapid drop of the torque curve at this point and leading to anemic acceleration at speeds over 110 km/h (70 mph), at which point it started to feel as though the engine was working too hard.

24_speed_curves_ENGPowered by this engine, the Volga was by far not a performance car – about 20 second 0-100 km/h and a top speed of just under 150 km/h (100 mph), but at least on par with (or, should I say – as slow as ?), e.g., Chevy Nova (and other GM X-bodies) with the 4-banger, or late-1970s Chrysler M-Body Dodge Diplomat with the Slant-6, delivering slightly better fuel economy than the six. Amongh the Soviet cars of the epoch, it was just a little bit slower than the Lada or the newer Moskvitch-412 and 2140, but still faster than the veteran Moskvitch-408 or the kinky little Zaporozhets.

In the USSR, there were no speed limits for intercity roads until 1976, when it was set at 90 km/h / 55 mph. Later, a special 110 km/h / 70 mph speed limit was added for specifically designated highways.

volga_fuel_consumptionWhile the Volga was considered thirsty compared to other (smaller) Soviet cars, with engine displacement usually not exceeding 1500 cc, it was actually reasonably fuel effecient for the time and considering it’s size, weight and engine displacement. According to the manufacturer’s specifications, on the highway at steady 80 km/h (50 mph) it consumed creditable 10.5 liter of gas per 100 km (22.4 MPG). Under actual driving conditions, fuel consumption figures were higher, but still decent for a 1500 kg / 3000-pound car with a 2.5 liter engine, not going anywhere beyond 17-18 l/100 km / mid-teens MPG (see the graph). And, considering the fact that gas was ridiculously cheap in the Soviet Union, the Volga more than made up for the fuel it consumed  in power, driving comfort and  durability.

In the USSR the gas prices for individual motorists during most of the 1970s stayed at 1 rouble per 10 liters of 83 octane AI-93 and 75 kopeks per 10 liters of 76 octane A-76. This is roughly equal to 11 and 9.8 roubles per 1 liter in 2013 roubles, or ¢36.5 and ¢32.5 respectively in 2013 US cents. 1 gallon is equal to 3.78 liters, so that would be $1.38 and $1.23 per gallon in today dollars. Just to remind, in the USA gas was about $2 per gallon in today dollars just before 1973 price shock. Fuel crisis didn’t hit in the USSR until 1978, when the gas prices instantly doubled.

It was a robust engine, easily capable of 200,000 – 250,000 km (125 000 – 155,000 miles) before first overhaul, if maintained properly. Gentle driving could extend it’s life to 300,000 – 350,000 km (190,000 – 220,000 miles) or even further, and such mileages were quite common for privately owned cars. The highest recorded mileage before first overhaul was 700,000 km (440,000 miles) by a GAZ-24-04 (station wagon taxicab) with low-compression 2401 engine. After the first overhaul, the engine could run happily for another 150,000 – 200,000 km at the least, and many of them have had second or even third overhauls, sometimes boasting 1,000,000+ km of total mileage.

GAZ_24-34_Sedan_1985

From 1973, a V8-powered version was produced in limited numbers, too, mostly for the law enforcement agencies, including the (in)famous KGB.

The V8-powered Volga was designated GAZ-24-24 (24-34 in 1985-93) and nicknamed “the double” or “the catch-up”. Some of these cars indeed were used for pursuit applications, however the vast majority of them lived a more humble existance of an escort vehicle for VIP motorcades.

The V8 engine had a displacement of 5.53 L / 340 ci and produced 195 DIN hp with one 4-bbl carburettor (slightly more for later production cars with two 4-bbl carbs). It was a later design than the four-cylinder engine, and is often cited to be a better one. It was coupled to a 3-speed automatic transmission which dated back to 1950s vintage designs. All cars came with heavy-duty suspension, power brakes (four-wheel drums with non-organic linings, except for some late production car which had disks up front) and power steering.

GAZ-24-24 managed 0-100 km/h in 13-14 seconds and had a top speed of 170+ km/h (105 mph) – not a muscle car by any means, but absolutely adequate for the job it was doing.


 

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