INDYCAR made it official - Lotus has been allowed to modify certain homologated parts to improve the performance of the 2.2-liter V-6 twin-turbocharged engine it uses in the IZOD IndyCar Series.

When the rules were first vested for the Indy cars' new 2012 engines, any manufacturer that felt their engines were more then 2.5-percent deficient in power to the balance of the field could request a mid-season upgrade (during the Iowa meeting last week). Manufacturers may also request an upgrade to parts at the close of the season, which would be after the 500-mile race at Auto Club Speedway on September 15.

Alterations to the Lotus engine are intended to place it within the magic 2.5-percent window - updated parts are only allowed to be introduced on new engines sent to the track; otherwise the standard 10-position penalty goes into effect.

Lotus had to present data to support their case, which was reviewed by the engine development department, together with relevant data that was collected by INDYCAR's engine support engineers. Lotus had to dictate which components they were looking to modify, together with the projected gains and their scheduled introductions.

The first modification is scheduled to be introduced on July 2 when the No. 78 Lotus-HVM Racing Indy car tests at Mid-Ohio Sports Car Course with driver Simona de Silvestro. Subsequent modifications are scheduled to be incorporated, INDYCAR said, for the Honda Indy Toronto on July 6-8, the Indy Grand Prix of Sonoma (August 26-28) and the Grand Prix of Baltimore the following week, September 2-4.

According to INDYCAR director of engine development, both Chevrolet and Honda have been apprised of Lotus' modification schedule. The older parts remain homologated until 2013, he said.

INDYCAR'S engine rules are intended to remain stable through the 2016 season, with any corrections or modifications decided by the sanctioning body after consultation with the INDYCAR engine committee.