We would like to use in our EVO4 engine a DTA engine control unit (ECU) and Bosch sensors. This is a fully custom writable system for engine development and necessary for engine calibration. With the new sensors we can save weight and the parameters of the engine will be more detailed. The engine control unit can send controller area network (CAN) messages. Used by this network protocol we can store a lot of engine parameters at the races with the ART telemetry. Later the team can use this high resolution data in the engine development.
In EVO4 instead of mechanic we use electric water pump, so the water pipe’s length became shorter and we could reduce some weight. The water’s flow depends on its temperature, this way the cooling of the engine will be optimal in any case.
The main change between EVO3 and EVO4 was connected to the lubrication system, instead of dry sump lubrication we use semi dry sump lubrication. Now we do not use external oil tank, so we integrated to the transmission space this function. The oil pump and the oil pipes were integrated to the crankcase, so the weight and external units resources were reduced as well.
We are using a KTM 450 SX-F cylinder head, which can be built onto a KTM 500 EXC cylinder. In this combination, we can assemble a sliding rocker armed and big cylinder capacity which is optimized for races. There are some more modifications before it is fully assembled.
First we post-manufacturing the valve seats of the SOHC controlled, stock cylinder head which has four valve. In this way we can increase the flow at low valve lift. After this we modify the geometry of the intake port with increasing its diameter and refining the surface. It will increase the amount of the charge which will get in the combustion chamber. The next change affects the exhaust port and the combustion chamber, where we refine the surface against the deposits and to avoid knocking in the combustion chamber.
There are plans for testing our custom adjustable camshaft to test the different cam profiles come from computer simulations.
The crank mechanism has changed from the last years one. We left the crank trigger from the end of the crankshaft and integrated it into the balancing weight of the crankshaft. We integrated 2 types of crank trigger, so we can use 2 different ECU’s while dyno tests. Because of the changes, the number of the manufactured parts would be reduced, the crankshaft would be shorter and we also lose weight.
The main goal of EVO 4 was to reach mass optimization and the best engine – vehicle cooperation, so the basis was the EVO 3 engine. The main difference between EVO 3 and EVO 4 is the lubrication system. Instead of dry – sump lubrication, we designed a semi – dry sump lubrication system, so most of the parts are integrated into the crankcase.
However a lot of previously mentioned functions were integrated into the crankcase, the mass of the part is 800g lower than the previous generation’s crankcase. We increased the cylinder’s tilt from 20 degrees to 24,6 degrees, so we reached the optimal position of the center of gravity’s height. The distance between the engine and the driver became shorter and in this case their overall weight placed closer to the driven shaft. It is very important in case of a Formula Student car to get as much mass in the near of the rear axle as possible. In order to keep the gear shafts in accurate position, the engine mounting points were reducated to 2 instead of 3.
In finite element methods the results showed that the crankcase quality is similar to the previous one’s, but its weight is less.
In our EVO4 engine there is integrated transmission, thanks for this we win weight, volume and the arranging will be better. We pay attention for these parameters, because in the motorsport they are very important.
For further weight loss, we redesigned the shift drum which became 66% lighter. It has an extreme geometry and made from steel with chipping.
The transmission’s function is to change the drive coming from the engine and give it toward the wheels. The time of shift is very important. Our goal is to minimize this time and grant more drive to the wheels at the same time. The plan for this solution is that a DC motor will rotate the shift drum to the correct speed, by this the shift will be much faster. The motor will be controlled by buttons from the steering wheel. We might reach advantage in the races by winning seconds with this solution.