For our EVO4 engine, we want to use a DTA type engine controller and sensors supplied by Bosch. This is a completely individually written system, which is an essential condition for engine development and individual calibration. With the new sensors, we can achieve weight reduction on the engine, as well as get more accurate information about the operation of the engine. The engine controller is also capable of sending data on its own CAN network, using this and the telemetry system of the ART03 it will be possible to save various data about the engine during races. Later, we can use these collected data to further develop the engine.
With our previous generation engine, we used a mechanical water pump that was attached to the engine. However, we decided to use an electric water pump for our EVO4 engine. This pump can be placed almost anywhere on the car, thus we can use much shorter pipes full of coolant, which saved us a lot of unnecessary weight. The delivery of the water pump varies depending on the temperature of the coolant, so the cooling of the engine will always be optimal.
In the EVO4 engine, the biggest change can be observed in the lubrication system, compared to EVO3. We switched from dry-sump oiling to a semi-dry sump lubrication system, where the gearbox compartment and the clutch-side deck play the role of the oil tank. The oil pump was integrated into the crankcase and the number of exhaust sections was reduced. Omitting the external units (oil tank, oil pump), we do not need to use oil pipes, the weight of the oil system has been greatly reduced.
We are currently using a KTM 450 SX-F cylinder head, which can be assembled with the KTM 500 EXC cylinder of a larger category. With this combination, we put together a competition-optimized engine with sliding valve rocker control and a large cylinder capacity, which of course undergoes several changes before assembly.
The valve seats of the four-valve series cylinder head with SOHC control are machined first, thus improving the flow at small valve openings. Then, by transforming the geometry of the suction dust, increasing its diameter and refining its surface, we help as much of the mixture as possible enter the combustion chamber. The next modification affects the combustion chamber and the exhaust port, which means refining the surface to avoid deposits and knocking combustion in the combustion chamber.
Even though the valve control of our cylinder head is already competitive, in order to make full use of the post-machined intake port, i.e. to further increase performance, a unique camshaft is also being designed. Our own adjustable camshaft is a great help for this, with the help of which we can test the different cam profiles during brake bench tests under real conditions, which are the results of complex computer simulation work.
The crank mechanism has changed compared to the previous one in that the encoder disc has been removed from the end of the crankshaft and integrated into the hams of the crankshaft. We have integrated two types of transmitter discs, so in the future we can use two types of motor controllers when running the motor. As a result of the changes, the number of parts to be manufactured was reduced, the crankshaft was shortened, and we also achieved weight reduction.
When designing the fourth-generation engine, the main goal was weight optimization and the best possible vehicle-engine concept, which is why we considered the Evo3 engine as a base. The main change is that instead of the dry sump system, we switched to a semi-dry sump system, so the oil pump, oil tank and oil lines were also installed in the crankcase. As a result of the integrated components, the total weight of the Evo4 engine has been greatly reduced. The weight of the crankcase was reduced by 800 grams, while the angle of inclination of the cylinder was increased to 24.6 degrees in order to achieve the lowest possible center of gravity. As a result of the greater cylinder tilt, the combined weight of the engine and the rider can be closer to the driven axle. Single-cylinder Formula Student cars are in most cases nose-heavy, so it is important to have as much weight as possible close to the driven rear axle. Compared to the Evo3 engine, the three connection points were reduced to two by using the appropriate position of the shift shafts. During the finite element test, the strength values showed almost similar values compared to the previous generation engine, despite the weight reduction.
Like the previous generation, our EVO4 engine has an integrated gearbox, thanks to which we gain volume and weight, and the layout is also better. Since these parameters are crucial in motorsport, we place sufficient emphasis on them. In terms of further weight reduction, we have redesigned our shifter shaft, which thus weighs a third of the previous generation component. The part has a particularly extreme geometry, with cutting made of steel.