Engineering Talk #6 Turbocharge the joy of driving

The Civic Type R recently broke with tradition by using a turbocharged engine but Honda’s engineers made sure it was every bit as responsive as its predecessors.

A HIGH PERFORMANCE CHALLENGE

Turbocharging is one of the most efficient ways of increasing both the power and torque produced by an engine while at the same time reducing fuel consumption and emissions. In the past however, turbocharging was felt by enthusiasts to make an engine less responsive to the accelerator.

The reason for this is that turbochargers, which compress the air going into the cylinders for better combustion, are driven by exhaust gases and take time to come up to speed; known as  ‘turbo lag’. When the decision was taken that the new Civic Type R would use the turbocharged version of Honda’s 2.0-litre VTEC engine, it was vital to the engineers on the vehicle performance team that it would be as instantly responsive as a naturally aspirated (non-turbocharged) engine because that is such an integral part of every Type R’s character.

IMMEDIATE ENGINE RESPONSE

Hayao Matsutani, performance engineer explains, “Every Type R was not just fast, but taught the driver the joy of conversing with the car. Every aspect of the new Civic Type R’s engine performance has been reviewed, to enhance this joy even further. Every Type R has had immediate response with its drive force to the accelerator, whether it be pressing down, or letting up. This is what makes driving fun, and is the performance we engineers strive to achieve.”

To combat the feeling of turbo lag, the Civic Type R’s engineers reduced the mass of the flywheel by 25 per cent, meaning that the engine revs will rise and fall more quickly in response to the driver putting their foot down or letting off the accelerator. Turbochargers are particularly good at increasing the torque of an engine and changes to the exhaust flow and ignition timing on the new model means that the difference felt by the driver is much more than the 7kW power increase. Torque, more than power is what produces the feeling of acceleration and the new car has more torque in the mid to high rev range meaning it gets to high speeds more quickly, helped by a lower ratio gearbox.

ACCELERATION THROUGHOUT THE REV RANGE

That feeling is very important to in all driving conditions according to Matsutani, “We placed most emphasis on what is hard to numerate, the improvement of acceleration in the rev range for normal driving. For example, the driver will probably be surprised by the sharp acceleration when merging into traffic. This is due to the lower ratio transmission which improves mid-rev range acceleration. The new Civic Type R’s evolution will undoubtedly be felt by every customer, in every aspect of their driving life.”

FASTER LAP TIMES

The final proof came in testing the car at the famous Nurburgring in Germany where the Civic Type R holds the lap record for front-wheel drive cars. Matsutani explains what happened, “To finalize the new Civic Type R’s performance, we conducted tests at the Nurburgring’s Nordschleife. About half of one lap consists of acceleration zones, and the latter half has an ultra-high speed straight. The new Civic Type R was around 1 second faster than its predecessor on this straight, and was faster on even the short acceleration zones. This indicates that the new Type R’s acceleration is superior over a wide rev range.”