What is better to choose between 8 and 16 valve engines?

• home
• Engine
• …

Somehow I began to wonder how many valves there are in an internal combustion engine. Indeed, now the market is dominated mainly by versions with 8 and 16 valves . BUT has no one ever done more or, on the contrary, less? What other options were there and why didn’t they go into mass production? Actually, this is what today’s talk will be about, as usual it will be interesting + a useful video. So read and watch...

In this material we will talk specifically about a four-stroke engine; about two-stroke engines this is a slightly different topic. It is worth noting that the entire timing system (gas distribution mechanism) is very important for the engine. Whoever “played” with it in order to increase its performance, but for some reason now the variant with 16 valves is considered the peak of the evolution of engine building. In this material I will tell you about the types of power units that had different numbers of valves, and why they were all discontinued and have not survived to this day. That is, let's say the material is educational, but it will answer the question - “so, how much” and “why”?

History of the creation of the VAZ 21124

AvtoVAZ engineers understood that by the time of mass production of domestic 10th generation cars, the power units of the eighth and ninth generation would be very outdated. The trends of the world automotive industry demanded an increase in the power and environmental friendliness of manufactured engines. After all, European manufacturers Volkswagen, Opel, Renault produced engines much more powerful than the domestic AVTOVAZ. But in addition to power, European engines were more economical and environmentally friendly. AvtoVAZ engineers were faced with the task of creating something similar.

There were several ways to get what you wanted. In order to achieve clean exhaust gases, an unconditional decision was made to switch to distributed injection. In addition to the cleanliness of the exhaust, this solution partially solved the issues of increasing power and efficiency.

To obtain the desired power, distributed injection alone was not enough, it was decided to increase the amount of horsepower by increasing the engine size. The volume of 1.6 liters was achieved by increasing the piston stroke to 76.5 mm, which became possible after reconstructing the engine height and using a crankshaft with a large crank. The cylinder diameter has become larger, now it is 82 mm. But this modernization was not enough.

16 valve version

Further improvement in engine performance was possible by installing turbocharging or switching to a BC head, where the number of valves was doubled.

1. The first option involved large capital investments and multiple technological innovations.
2. The second option was less expensive. Only the cylinder head was modernized; the remaining components and systems of the engine did not require major technical changes. Doubling the number of valves improved the filling of the cylinders with the combustible mixture. This increased torque and power by almost 15 percent. As a result of all the changes, the 1.6 liter engine, which has injection power and a 16-valve head, was able to develop power up to 90 hp.

Improvements from Porsche

It should be noted here that domestic designers had no experience in designing complex structures, which was the BC head. Therefore, AvtoVAZ engineers followed the well-worn path; they turned to well-known specialists from the German concern Porsche, who in the past designed the VAZ 2108 engine for AvtoVAZ.

However, Russian specialists did not sit idle and in parallel carried out work on creating the 16 V cylinder head. As a result, the design proposed by Porsche specialists required a gasket of a very complex shape. The Elring company from Germany offered to solve the issue of creating a gasket. The asking price was almost half a million German marks, which of course did not suit AvtoVAZ representatives. As a result, the issue with the invention of the gasket was solved by specialists from RTI STC for one and a half thousand Soviet rubles.

When completing the design of the 16 V cylinder head, Porsche specialists encountered certain difficulties. We had to involve highly specialized specialists from Italy and Australia. Ultimately, the 16 V cylinder head created for the 10th generation of Volzhsky Automobile Plant engines turned out to be original and multinational, with a unique design. At the same time, the first engines on which this cylinder head was installed had insert wells. And only on the VAZ 21124 engine, in 2004, the 16 V cylinder head, modernized by Russian engineers, received cast spark plug wells, as was originally intended at AvtoVAZ.

Cylinder block and CPG

The cast-iron cylinder block and cylinder-piston group of the 2.4-liter V6 do not cause any complaints. A major overhaul of this engine or replacement of the block is the result of poor quality maintenance or the use of counterfeit oils. If this engine begins to consume more than 0.5 liters of oil per 1000 km, then the piston rings will have to be changed.

Regarding the connecting rod bearings and repair dimensions, we can say that Audi does not provide repair dimensions for the bearings. But on sale there are repair main bearings of two sizes and connecting rod bearings of the same size. Those. In general, restoring the crankshaft to repair size is possible.

You can select and buy a cylinder block for an Audi engine in our catalog of contract spare parts.

You can select and buy an engine for the Audi A6 in our catalog of contract engines.

Here you can use the links to see the availability of specific Audi cars at the dismantling shop and order auto parts from them.

Technical data VAZ 21124

VAZ 21124 is a four-stroke gasoline engine with an injection power system. The four cylinders of the internal combustion engine are arranged in one row. The location in the engine compartment is transverse. The material used to make the BC is highly durable cast iron.

• The gas distribution system has two camshafts and 16 valves, 4 per cylinder.
• The exact engine capacity is 1599 cc. cm.
• The piston has a stroke length of 75.6 millimeters and its diameter is 82 mm.
• The torque of the internal combustion engine 21124 at 3700 rpm is 131 Nm. The power of this internal combustion engine is 89 hp. Compression ratio 21124 - 10.3:1.

Advantages

A huge number of them flow out here. The operating principle of a sixteen-valve engine tells us that the cylinders are filled to a much greater extent with a mixture of fuel, and this directly affects the power output of the unit. it is increasing. Moreover, the efficiency remains high. This is not the only advantage of this engine model. As noted earlier, the construction of a combustion chamber makes it possible to protect oneself from accidental detonation, even if poor quality fuel is poured into the tank. Modern reality is such that at many gas stations this is exactly what applies. The cooling system of such units is built in a unique way, which allows the 16-valve engine to be operated for many years without any problems. The arrangement of devices in the combustion chamber allows the intake and exhaust strokes to be spaced apart. This greatly affects the efficiency of the mechanism. Another distinctive feature of this model is improved traction at high speeds. The operating principle of the 8 valve unit does not allow this.

Main design features of the VAZ 21124 engine

The VAZ 21124 power unit is a union of two engines: the BC head is used from the VAZ 2112, and the ShPG, cylinder block, lubrication system and other internal components are copied from the VAZ 21114.

Cylinder head

The BC head on model 21124 was slightly modified. The spark plug wells on it are cast, instead of removable, which were originally used on the VAZ 2112. The design of other components is completely identical to the initial version, it also has two shafts for distributing flammable gases and 16 valves, 2 inlet and 2 outlet for each of the four cylinders Just like on the 12th head, there are hydraulic pushers here, eliminating the need for periodic adjustment of the thermal clearances of the valves. The dilution of the intake and exhaust gas flows is of great importance.

It is this technology that significantly increases the power of the power unit, its efficiency and reduces exhaust emissions. The timing belt drive has a safe and reliable mechanism. Thanks to the design of the pistons, which have holes on the bottom, drivers do not have to worry that when the timing belt breaks, the piston hits the valves. The use of a belt to drive the gas distribution mechanism contributed to the quiet operation of the internal combustion engine. To service the gas distribution drive mechanism, it is enough to tighten the belt using a roller after a mileage of 15 thousand km.

Cylinder block

We figured out the design of the cylinder head. Now let's look at the lower part of the engine, which is based on the 21114 power unit. The main idea of ​​the design is to increase the volume to 1.6 liters. To increase the volume of the power unit, AvtoVAZ engineers increased the diameter of the cylinders and their height. Accordingly, it was necessary to increase the piston stroke length. To do this, we had to increase the radius of the crankshaft crank. On the 124 engine there are ignition coils, separate for each cylinder. In addition, a number of modifications to the BC were introduced, which will be discussed in a separate chapter on the design of the cylinder block.

Design features of the cylinder block

The internal combustion engine cylinder block is made of especially durable cast iron. The cylinders are drilled directly into the cylinder block. Their diameter has been increased to 82 millimeters. The interaxial distance between the cylinders is 89 mm. The height of the BC from the crankshaft axis to the top point of the BC is 197.1 mm. The crankshaft support bore has a diameter of 54.52 millimeters. Cylinder block weight 31 kg.

The VAZ 21124 block has a distinctive feature. The designers of the 21124 motor provided for increased loads and possible overheating of the BC and ShPG. They decided to further cool the pistons while the power unit was running. For these purposes, special oil nozzles were pressed into the fifth, fourth, third, and second crankshaft supports. Their task is to cool the piston heads with jets of oil while the internal combustion engine is running. This technology was used for the first time in the domestic automotive industry.

Cylinder head design features

The powerful 124 engine has earned great popularity among numerous drivers, thanks to the two-shaft 16-valve BC head.

The VAZ 21083 cylinder head served as a blank for a sixteen-valve head for domestic cars. Despite the compactness of the 083 head, foreign inventors managed to place a second shaft and 8 more valves in it. In addition, there was room to place compact hydraulic pushers. The task is automatic adjustment of thermal clearances in valves. The separated design of the intake and exhaust gases was important.

German engineers changed the shape of the combustion chamber, which made it possible to use low-octane gasoline on the 124 engine. On AI 92, the VAZ 21124 engine runs smoothly without detonation.

Design features of the KSHG

The 124 model is equipped with a crankshaft marked 11183. Thanks to the increased crank radius of 37.8 mm, a larger piston stroke is obtained, up to 75.6 millimeters. A pulley with teeth is installed at the end of the crankshaft to drive the timing belt through a belt drive. The belt width is 25.4 mm, and its service life is 45 thousand kilometers.

Also, the pulley provides drive for additional units. The pulley design is made in the form of a damper that dampens vibration of internal combustion engine mechanisms and components. A gear wheel is built into the damper; it is needed to determine the position of the DPKV crankshaft.

The pistons for 124 engines have an improved design, thanks to which the valves do not bend. Piston rings made of cast iron or steel. The pistons are connected to the connecting rods using pins that have a floating connection and are secured with retaining rings. The connecting rods and fingers are taken from the VAZ 2110 model.

Features of the VAZ 21124 ignition system

The ignition control on the 124 engine is carried out by a Russian control unit of the January 7.2 or BoshM7.9.7 type. The ignition system provides individual ignition coils with additional fixation in the valve cover. With this design, high voltage wires were not needed. This system contributes to the smooth and reliable operation of the engine.

pros

• “The simpler, the better” is a popular proverb. This also applies to the 8-valve engine, a time-tested design that has only one camshaft, two valves per cylinder. There are few mechanical parts, and therefore repair and maintenance of this is much cheaper.
• Also, such a structure almost never has hydraulic compensators, which further simplifies its design. There are mechanical pushers here, which is both good and bad. Well - this mechanism is much simpler, so replacing or repairing it is also easy and cheap. By the way, these types are often equipped with stickless pistons.

• Not very picky about oil, you can fill it with semi-synthetic oils.
• It is undemanding to the quality of fuel (of course, within reason), you can safely pour 92 gasoline and not be afraid.
• Size. The upper part is much smaller, because there is only one shaft. Easier to reach attachments, generator, starter, etc.

Typical malfunctions of 124 motors

Engine tripping

The most common problem with this power unit is tripping. The engine is unstable, increased vibration and detonation appear. There can be many reasons for this. To find the real reason, you need to perform a number of actions in a certain sequence:

• the engine may stall due to mechanical reasons, namely due to burnout of one of the valves. To exclude this possibility, you need to measure the compression in all cylinders. If the compression in all cylinders is the same, then the reason should be sought elsewhere;
• The cause of the tripping may be the ignition system. To determine this suspicion, remove the caps from all candles one by one. If the shaking intensifies when you remove the cap, it means that the spark plug or the individual ignition coil is not working and needs to be replaced to solve the problem. If the tripping has not changed, you need to check the serviceability of the ignition module. To find out, you should replace the module with another, working electronic device. If this is not possible, then the ignition module should be ringed with the device;
• Engine trouble is often due to dirty injectors; to eliminate the problem, the injectors must be cleaned;
• It is possible that the engine will trip due to electronic glitches. You should try replacing the ECU with a known good one or diagnosing the electronic device;
• It happens that the motor stalls due to problems with some sensor. This could be a sensor indicating the position of the crankshaft, or a TPS.

On a 124 engine the idle speed often fluctuates

The reason is most often ECU glitches, or problems with the IAC or mass flow sensor. You can determine what exactly is faulty by replacing the spare part with a working one or by ringing the device.

Knocks

Engine knocking may be a sign of a stretched timing belt, or hydraulic tappets may be knocking if poor quality fuel is used.

Replacing hydraulic compensators

K4M service

Change of oil

The most important maintenance activities include replacing the oil filter and 5W40 or 5W30 engine lubricant. Manufacturers recommend performing this procedure after 15 thousand km. But owners of Renault cars whose engine has driven more than 500,000 km are advised to change the engine oil after 7.5 thousand km.

Phase regulator

The operating life of the phase regulator is designed for 100,000 kilometers; therefore, after the expiration of this period, it must be replaced.

Replacing the timing belt

The timing belt must be changed in a timely manner, no later than after 60,000 thousand kilometers.