COMPETITION SEASON
For the 2019 racing season, we provided resources for not one, but two teams, so instead of completely new developments, we focused on the further development of the EVO6 construction in order to create a reliable and efficient engine construction, which was codenamed EVO6+. With regard to the two teams, it was necessary to create a composition that would hold its own in both cars. This concept was composed of the most reliable systems in the past years.
INTAKE SYSTEM
We kept the geometry and volume of the airbox from the previous year’s construction, while optimizing it for the engine’s 5-7 thousand rpm range, where the engine is used the most. We changed the length of the intake pipe, which reduced it from the 230 mm used last year to 200 mm. Due to the location of the engine in the car, the curvature of the intake pipes had to be modified so that it could fit properly in both cars, despite the different locations. Again this year, we made the airboxes out of carbon fiber plastic, thus achieving high strength with a low weight.
CRANK MECHANISM
Instead of a Wiseco piston, which exposed the cylinder walls to a lot of stress, we used a CP piston in this generation. With this, we were able to improve the service life of the cylinders and increase the reliability of the engine. However, this meant that the compression ratio became 14.3:1, for which gasoline (RON98) proved to be a better fuel than the ethanol used the previous year. This compression ratio is already at the limit of how long it is worth going. Together with the fine-tuning of the brake pad, a very efficient engine was put together for the races.
GEAR MECHANISM
Prior to the 2018 racing season, there was an issue where downshifts were often double-shifted. In order to eliminate this, we realized that the mechanism first hits the striking part of the doorknob by welding it, so that the worm shaft receives less momentum and only one shift takes place. In addition, the shift gear allocation was changed, as in some situations the pilots could not find the right gear, so we switched from 3 gears to 4 gears.
CRANKSHAFT
In the EVO6 engine, the team used an increased stroke crankshaft, which resulted in a high compression ratio, but this was only optimal for using ethanol. We used a lower compression ratio for the gasoline engine, which was used in the EVO5 engine.
EXHAUST SYSTEM
A new exhaust system had to be designed for the BME motorsport team, as the car would have been equipped with a completely different system. The system was implemented in a double-drum, bifurcated arrangement operating on the adsorption principle. Due to the limited space, the sound attenuation of the system became very critical. Several fillings, different perforations and filling thicknesses were tested against noise, so with the finalized system we successfully fulfilled the noise criteria prescribed by the competition regulations.