Teams fitted with KRE-built engines are running an upgraded package at this weekend’s Merlin Darwin Triple Crown.
Five teams are affected by the change, including Brad Jones Racing, Matt Stone Racing, Team 18, Team Sydney and Triple Eight Race Engineering.
Their entries represent half of the Repco Supercars Championship grid.
The change has come in a bid to balance the field on horsepower.
Following the close of the 2020 season, it was revealed the KRE Engines were suffering a four to five horsepower deficit relative to the other Holden and Ford teams.
That was discovered after the engines of Shane van Gisbergen (KRE), Chaz Mostert (Walkinshaw) and Cameron Waters (Tickford) were dynoed.
In 2019, KRE-powered cars ran a 1.75 rocker ratio, which was then changed to 1.60 for the 2020 season.
A change to the engine rings in 2020 proved to be costly for teams as they were affected by reliability issues.
That change has since been reversed in conjunction with the rocker ratio amendment to 1.65 for the KRE-built engines. Ironically, the ring change was initially made in an effort to lower costs.
Prior to last year’s Bathurst 1000, it is believed Tickford Racing and Kelly Grove Racing (then Kelly Racing) cars were allowed to run a 1.65 rocker ratio.
Dick Johnson Racing’ Mostech-built engines are believed to run a 1.60 ratio.
Speedcafe.com understands rocker ratios aren’t identical across all engine builders.
Walkinshaw-built engines (run by Walkinshaw Andretti United and Erebus Motorsport) all run a 1.60 ratio.
