The second Civic Si racing car to be presented at the 2021 SEMA Show, next to the HPD Civic Si Race Car Prototype, comes from Team Honda Research West (THR-W).

The model was built to compete in the National Auto Sports Association’s (NASA) 25-hour of Thunderhill sports car race in Northern California Dec. 3-5, 2021.

What makes the Team Honda Research West Civic Si Race Car special?

Just like with the model design by TRD, the Civic Si from THR-W offers updates for both the exterior and the interior, but also for the powertrain and the chassis.

The most impressive list of updates was made under the hood. In standard form the Civic Si is powered by a 1.5-liter, four-cylinder turbocharged engine that makes 200 horsepower and 192 pound-feet of torque. However, a lot of work was required to obtain the extra 20 horsepower and 48 pound-feet of torque.

It started with some engine management tuning and by adding a new titanium exhaust system with racing down pipe and front pipe. A custom intake is also part of the deal and so is a 48 mm core aluminum racing radiator from Koyo. MAPerformance provided a new oi filter adapter, while M Factory came with a custom gear set.

The new wheels are combined with 4-piston racing calipers and 2-piece floating rotors, both from Paragon. Custom brake ducts and custom brake ducts from KW will make the car a lot safer. And, from RV6 the car gets a rear stabilizer bar and rear lower arms, toe links.

A more aggressive look was provided by added a new custom aero-vented carbon hood, a customer front splitter and air dam and a new carbon-fiber trunk lid. The racing look couldn't have been completed without the new GT250 rear wing.

A few changes were also made under the hood, where THR-W started by adding a new custom FIA safety cage, and new bucket seats with 6-point racing harness and window net. The standard steering wheel was replaced by a racing one from Sparco, while the acing pedal spacer and shifter bushing come from Acuity.

We will find out if all these updates made a difference in December, when the Civic Si will make its racing debut.