Studying car forums, you can often meet the same question. It concerns the engines and their devices. A lot of people argue over which engine is better - 16-valve or 8.
One half of the car owners is sure that the 8V models are already hopelessly outdated. And to buy a car with such a motor today - in vain to spend money. But the 16-valve power plant is quite another matter.
The second half argues that, with all their merits, such units require more attention, are more expensive to maintain, they want a better quality oil. And if such a motor decides to break down, then it's easier to surrender it to scrap metal. Especially when you consider how much the engine costs, the 8-valve motor in this respect is much better.
Let's try to find out what's best, consider all the pros and cons of each motor. Although it is specific to say that one of these two units has superiority, it is impossible. Some want the power plant to be reliable and unpretentious, others need power, high technical characteristics, smooth operation. As you can see, different categories of motorists put different tasks. And the motors are different.
A bit about the technical component
In technical terms, 8- and 16-valve internal combustion engines differ among themselves quite seriously. But all the differences between them are in the upper part - in the head of the motor. Here there are camshafts. This is the main constructive feature hidden.
And for those who want to know which engine is better - 16-valve or 8, it should be said that from any unit you can make the version 8V or 16V. For example, on most cars from AvtoVAZ engines are very similar to each other in a constructive way on the details and mechanisms. The same engine block can be equipped with different cylinder head with one or two camshafts.
Only one camshaft is installed in this power unit. It controls the operation of the injection and exhaust systems. In theory, it looks like this. In the design of each cylinder there are two valves. One of them is designed to feed the fuel mixture into the combustion chamber. It opens when the fuel is injected into the cylinder. The second serves for the discharge of exhaust gases. This element is opened at a time when the combustible mixture has already burned and it is only necessary to release the gases into the exhaust system. The opening / closing of the valves is controlled by the camshaft. It has conical metal areas. When the shaft rotates, it presses these sections on the valves. It opens or closes.
So, each cylinder is equipped with two valves. And since the cylinders are in the standard type 4 engine, we get 8 elements. Of course, the 4-cylinder engine is not the only unit, only more common. There are 6-, and 8-, and 12-cylinder engines. But these engines are a rarity for cars. In trucks, 8-cylinder engines are more relevant. For example, the engine YMZ 238. It has 16 valves. But in fact, for each cylinder, there is only one entry and exit. The power of this unit is from 180 to 240 hp with a working volume of 14.8 liters.
Advantages of 8V engines
To correctly answer the question of which engine is better - 16-valve or 8, you need to consider the advantages and disadvantages. Let's start with the advantages that the second type of ICE possesses. The first advantage is simplicity. The simpler the unit is, the better for the owner. The design of traditional engines has already been tested by time. There is only one camshaft in the system. There are two valves per cylinder.
Mechanical nodes are few, spare parts for the engine are easily accessible and inexpensive. Therefore, repairs will be easier and cheaper. The lack of hydraulic compensators - this can also be attributed to the merits. This fact makes the design of the 8-valve unit even simpler. But the design provides for the presence of mechanical pushers, and this is both a plus and a minus. It is very good that this mechanism is simpler than hydraulic compensators. Therefore, if necessary, the unit can be easily replaced or repaired.
And yet - the data of ICE set the pistons, which, if the timing belt breaks, they will not meet with the valves. This is a big plus, especially when you consider that after such a major overhaul of the engine is needed . The price of such "pleasure" is 35-40 thousand rubles. Also, the benefits can be attributed to the "omnivorousness" of the unit. It has practically no requirements for oils and perfectly digest semisynthetic. The engine is also undemanding for fuel (naturally within reasonable limits). It will work fine even on gasoline grade A92.
Here you can also note the cost of ownership. Repair will not be relatively expensive, and spare parts for the engine will not be difficult, if it concerns the engines of AvtoVAZ. Another plus is compact size. The camshaft is one, respectively, the upper part is smaller than in the 16-valve version. In the case of repair it is much easier to get to the generator, starter and other equipment. This will be agreed by those who put the 16-valve engine on the classics.
Disadvantages of 8V ICE
The first negative - a relatively small capacity. Sometimes you can get only 15-20%. If the power of the unit is 100 horsepower, it is only 15-20 hp. Two valves per cylinder are designed for intake and exhaust. This means that the intake and exhaust processes are slower. Therefore, it will not be possible to obtain high revolutions at such an aggregate. Go ahead. DVS 8V differ by higher fuel consumption. The expense is more due to slower "injection-retraction" cycles. The engine has to push the exhaust gases more strongly through a single outlet element.
And, finally, high noise, especially when driving at high speeds. Since the pusher is mechanical, it constantly requires adjustment. In the process of exploitation, the production is formed on them, as a result of which gaps appear. Because of them the efficiency of the power plant falls, and the motor starts to make noise. Hence the negative effect of the use of mechanical pushers. Many more do not like to adjust the valve clearances frequently . It is necessary that the engine works better, and there is no over-expenditure of fuel. As a result, the 8-valve engine is a reliable, unpretentious, simple, operating on any oil and fuel system. But in return we get the impossibility of stable operation at high rpm, low power and noise. If you consider how much the engine is, then you can close your eyes to these disadvantages. On the engines with the layout of the 8V they successfully drive today. But serially they are no longer produced.
On the technical side, this engine is more complicated. The cylinder head is one, but it has two camshafts. They are divorced in different directions, so the number of valves has increased. There are not two, but four valves per cylinder. Two of them are designed for fuel admission. The rest - for release.
What can this give the car owner?
The first thing any VAZ 16-valve - this is quite good power. The engine is powered by a large amount of fuel mixture, and also exhaust gases are emitted from the cylinders much more quickly. Naturally, the efficiency of the motor increases. To the power can be added from 15 to 20 hp. It is possible and more, but this depends on the volume of the concrete unit. The second feature - hydraulic compensators. New engines VAZ and old 16V are equipped with these mechanisms. Due to them, the valve is better pressed against the camshaft. The operation of the motor is accompanied by a lower noise level.
It is worth noting the smoothness of the work. Also this motor is economical. Such units are more environmentally friendly. This was achieved by a more accurate timing adjustment. Naturally, environmental friendliness does not apply to diesel engines, although the YaMZ 238 engine is also 16V. But as for YaMZ, there are not four but eight cylinders in it. Accordingly, each cylinder has two valves.
DVS is much more powerful than its 8V colleague. Naturally, the situation is better with the dynamics of acceleration, and with maximum speed.
The fuel consumption is reduced, first of all due to the design features of the engine, and also because the machine can accelerate faster and do not need to rotate the motor for a long time at high revs. Work is accompanied by less noise due to design features, as well as due to the presence of hydraulic compensators. There is no need to adjust the valves. And this is a huge time saving.
Virtually all 16-valve, regardless of the manufacturer, equipped with hydraulic compensators. For their normal operation, you need a quality oil (best synthetic). Today such products are not cheap.
Also, the motor is demanding for the quality of fuel. It is best to refuel the engine with high-octane gasolines. Finally, the unit has a more complex structure. If the pistons meet the valves, a major overhaul of the engine is necessary. The price of the procedure is from 35 000 rubles. Also, ICE data is large, which makes maintenance and repair difficult. In addition, the manufacturer often puts a plastic cover on the head. That's all about the advantages and disadvantages of these two engines. But I must say that on the secondary market, among domestic and foreign manufacturers, you can meet a large number of 8V engines. But their popularity is constantly falling. Now even install a 16-valve engine on the classics.
Power, speed, repairs on SRT
For those who like to push the accelerator hard, get good dynamic characteristics from the car, high speed, the best choice is a 16-valve ICE. About 8-valve models must be forgotten forever. But it is necessary to visit often SRT.
Simplicity, reliability, self-service
For those who live outside the city and think about which engine is better - a 16-valve or 8, while planning to ride on bad roads or carry a trailer, definitely a choice for the latter. But you have to get used to the noise and increased fuel consumption.
Fears about timing
Many motorists are seriously concerned about the bent valves in the engines of the 16V. These fears are justified.
But it should be said that not every engine is affected by this. If the unit is serviced on time, there will be no question of the fact that the valves and pistons will ever meet. Moreover, now there are 16V units, where a chain is used instead of the timing belt. It does not tear and lasts much longer than the strap. Therefore, do not give up the advantages of ICE 16V.