The car has a lot of interesting details that only auto mechanics or people who are very passionate about technology know about. One of these parts is a split gear. Tuning enthusiasts also know about this element. Let's find out what this part is and why it is needed.
Phase shifters and their function
Most new engines are equipped with phase shifters, which make it possible to adjust the operation of the power unit based on the speed of the crankshaft. This is necessary in order to obtain maximum torque in a wider range of revolutions.
If you take any manual for the operation of a car, then it will indicate such characteristics as engine power in horsepower and the maximum torque that the motor is capable of delivering at certain crankshaft revolutions per minute.
Here take, for example, the common Renault Logan model. The engine is capable of producing 170 horsepower at 6 thousand revolutions of the crankshaft. The maximum torque is 270 Nm at 3250 rpm. From these figures it can be seen that the maximum torque can be achieved even at medium speeds. And the maximum power becomes available only after 6000 rpm. If such a motor is equipped with a phase shifter system, it will have a wider range at which the engine will give the highest torque, and not the one laid down in the design by the manufacturer.
The camshaft split gear performs approximately the same functions as the phase shifter. This part has a similar construction as the camshaft. It can be rotated at certain angles forward or backward.
Split gear function
The usual gear mounted on the camshaft is designed to transmit torque from the crankshaft to the camshaft of the gas distribution mechanism. The part is a one-piece element without any moving parts. The split gear consists of two components - they can move relative to each other. This design allows you to change the angles of the camshaft, without affecting the tension of the timing belt or drive chain.
For example, this part on VAZ engines can rotate the shaft by 5 ° in one or the other direction. Here it is necessary to understand that in this way it is possible to change the characteristics of the engine only in specific modes - in the upper or lower ranges.
Very often, to increase the power and other characteristics of the engine, the camshaft and its gear are changed. If you replace them, you can differently configure the valve timing. It will also be possible to change the delay angles of the valves. If a split gear is installed on the engine instead of the factory one without changing the camshaft, then only the overlap angles can be changed.
How it works?
For example, the torque will change from 4000 revolutions in a smaller direction, for example, to 3000. This effect is achieved by turning the camshaft in the direction of the crankshaft. At the same time, the valve timing is set so that there is a slight lead. This affects a decrease in the closing angle of the intake valves.
But you need to remember that if the engine spins up to the maximum possible speed, there will no longer be such a dense filling in its cylinders. This will not affect speed and power output in the best way.
Design
The split gear consists of two elements - a ring gear and a hub. They are interconnected by bolts. The holes for this are made so that the hub can be turned in relation to the crown. The hub is attached to the camshaft by means of a key. This fixation ensures the rotation of the hub together with the camshaft.
The main reasons for installing the split gear
Engine tuning experts point out two reasons why many install this part. It should be borne in mind that the sports camshaft will not give anything if the split camshaft gear is not installed (the VAZ will not go faster). When assembling at the factory, the manufacturer often deviates from the data indicated in the drawings. Therefore, the parameters of motors designed for one model of cars differ from the original ones. These errors are not more than ten degrees on each side. Naturally, this affects the power characteristics of the motors. By installing a split gear, the car owner gets the opportunity to adjust and optimize the torque, if necessary.
Installation of tuned camshafts can significantly increase the torque of the power unit. VAZ split gear - another + 5% to power characteristics. This is pretty good.
Adjustment technique
Today in the automotive market there are gears designed for almost any car from AvtoVAZ. Each model has its own tuning methodology. Consider the principle of adjustment on the example of the VAZ-2108-2112.
VAZ-2108-21099
So, the first thing on the gear mark the points on the moving and fixed parts. They are needed to carry out the correct installation - all operations are the same as in the case with the standard part. Further, after the points are plotted, the split gear is put in place. Installing it is no different from the standard. Then you can put on the belt just installed part.
It’s important to check several times that the labels match exactly. To obtain optimal performance, it is necessary to control the degree of opening of the valves. This indicator is strictly defined and set at the design stage of a particular camshaft. If the valves are open a large amount from the passport data, then loosen the bolts on the gear, which are located outside. Then the distribution element is rotated to the outer half of the split so that the parameter can be easily adjusted.
When it is possible to correctly set the zero position of the camshaft, it is necessary to carry out a more precise adjustment of the phases. If the upper shaft is rotated in the direction of rotation of the lower (crankshaft), thus increasing traction. Torque will be available in the middle and low ranges. If the camshaft split gear (VAZ-2108 or another car model is not so important) and the shaft itself will be turned in the direction opposite to the crankshaft rotation, then the power will increase.
Performing this correction procedure, it is important not to leave the starting point more than half the tooth on the pulley. If the gear is adjusted for carburetors, then after each manipulation with the shaft, a correction of the ignition angle is required. Otherwise, there will be interruptions in the system.
16-valve engines VAZ-2110-2112
If the adjustment of the split gear is carried out for these motors, then it is also recommended to install tuned camshafts with it. You should focus on the marks made at the factory. They approximately adjust the closing / opening of the valves. Then, the piston on the first and second cylinders is brought to the top dead center position. Also, the belt is carefully put on the gear.
After that, you need to install the indicators. They will help determine how the valves will move. It is necessary to find a position in which the mechanisms of the fourth cylinder are completely closed. Next, with the help of a gear and indicator, adjust the closure. Then you can tighten the fixing bolts, assemble the power unit and perform a test run.
Classic VAZ
On classic eight-valve engines, the gear is set to standard factory marks. Next, the closing of the valves is configured. The first and fourth pistons are set at TDC. The indicator legs should rest against the rocker.
The point is set in turn when the valves are closed on the first cylinder. After that, the exact position of the TDC on the tuned gear is set. Do not forget about gear ratios on rockers and the point where the indicator is installed. Next, the gear is fixed, assembled and the engine is started.
Conclusion
Thus, with the help of one gear, the initial parameters of VAZ engines can be significantly improved. This is a fairly popular tuning of domestic engines.