Mibosport Cup - Hrotvice

Technical report from MIBO International 2025 race:

The MIBO International 2025 was my 3rd international race in a row in the stock spec class. After the back to back GP3F and Snowbirds events, I had a chance to come back to work for 2 days before heading over to MIBO. As I had to catch up on my urgent office work, I had no time to prepare at all, so I just grabbed my GP3F car as it came off the track, changed the motor from 13.5T which we used at GP3F in the stock spec class to a 17.5T, which was the stock spec motor used for the MIBO race. We used RUSH 28 on GP3F, whereas on MIBO the handout tire was the slightly harder RUSH 30.

As mentioned, I started with my GP3F set-up, since I was expecting similar traction conditions, with slightly less steering and traction due to the harder rubber used. The first round of practice rounds were quite loose in terms of the track grip, and therefore I wanted to make the car more stable, to avoid unexpected spins in the middle of the corner. To achieve this, I added a T-brace chassis stiffener in the rear, with using the most forward and backward screws mounted. This helped a lot to reduce or eliminate those spin tendencies.

The track layout of the GP3F was rather tight, where a lot of low speed steering was needed, while at MIBO, the layout was more open, with many high speed long sweepers. As I had too much steering, and a lot of roll in the car in those sweepers, I changed the front anti-roll bar from 1.2 to 1.3mm to make the car more stable, and easier to drive in these corners.

As the traction was low in the practice, I changed from 2 to 3 degrees of toe-in to improve the overall stability as well.

Since we were using harder tires, I wanted to make the car more aggressive, and to make it have more chassis roll. To achieve this, I raised the shocks from 3 to 4mm, and went slightly lighter with the shock oil, from 425 to 400.

At this point, the car was working really well, and I was very happy with car’s performance, as well as with my pace.

As the race was proceeding and traction increasing, as well as the carpet becoming more oily from various additives used, the car started to become too stable, compared to beginning of the event where it was too loose. So, when the car started to be too stable, I had to slightly adapt my set-up to retain the off-power steering as well as rotation. To achieve this, I removed the T-brace, and decreased the toe-in back to 2 degrees only.

Finally, to make the car more stable in higher speed corners, and to improve cornering speed, I also changed the rear springs from 2.6 to the stiffer 2.7.

By making these changes, I made the car perfect for these pushy track conditions, and I was able to finish 2nd overall behind my team mate Adam Izsay. Overall, it was very successful race for us, as we had full podium lockout in the stock class (the biggest class of the event), and also 5 cars in the top 10.