World Touring Car Championship Honda Civics set for power boost

For much of the season the Civics were well beaten by Citroen's fleet of works C-Elysees, though in-season development reduced the gap and helped Mehdi Bennani win in China and Gabriele Tarquini in Japan.

"Last year we were able to fit a bigger air restrictor [enlarged from 33mm to 36mm] but this did not raise our power so much," said Daisuke Horiuchi, Honda's large project leader for Civic WTCC development.

"For this year we have changed our engine's compression ratio, making it higher, and we have altered the exhaust system to make for a smoother exit of the exhaust gases.

"With a higher compression ratio comes the risk of knocking [pre-ignition] so good engine mapping is important - we are continuing to develop this every time we test."

Under the WTCC's technical regulations, manufacturers are permitted just five 'joker' changes to homologated parts during the season.

Many components that could be modified or replaced to increase the compression ratio, such as the cylinder head and pistons, are on the list of homologated parts, although the piston rings are 'free'.

"We have been planning these developments since the second half of last season, when we identified the problems and the critical areas," said Alessandro Mariani, team principal of Honda's WTCC partner JAS Motorsport.

"But of course, due to the regulations and the way the calendar was, it was not easy to improve the car while the season was running.

"We did some things and after that the pace was not so bad in comparison with the Citroens.

"Then, after we got back from Macau - where we had missed a good opportunity to win - we began a programme we had agreed with Honda R&D."

Tarquini emphasised that engine development was not the sole focus.

"We are working on both sides - engine and chassis," he told AUTOSPORT. "All of the winter we've tested a new solution.

"Part of the solution was already homologated and we can use it at the first race. From the other elements, we must choose which to homologate.

"We have two problems: one is to try to improve the performance of the car, the other is to identify which are the right solutions to homologate - because we only have five 'jokers'."