Erebus Motorsport will run an updated engine package in both of its Mercedes-AMGs at the Coates Hire Ipswich 400 after completing a pre-event test at the circuit on Wednesday.

A variety of new engine components were run across the #4 Lee Holdsworth and #9 Will Davison driven entries during the test, which also saw co-drivers Craig Baird and Alex Davison cut laps.

The squad took its engine work in-house at the beginning of this year after running its initial design and development through AMG Customer Sports in Germany during the program’s maiden season.

Although the next upgrade package had been expected to mark a significant step forward, Erebus general manager Ross Stone is downplaying the importance of the changes.

Stone, who has spearheaded the team’s restructured engine program, says the pre-Ipswich upgrades are just the third part of a five-stage process.

The team rolled out initial improvements for the start of the season before debuting lightened flywheels last time out at the Castrol Townsville 500.

“It’s the next area that we’ve worked on and it will move to both cars for the race meeting,” Stone told Speedcafe.com of the upgrades.

“The engine is not quite good enough yet but it’s not that far away either.

“It’s such long lead times developing these things so it won’t be massive, but it’s the first part of a few things we need to do before we have the complete package.”

Erebus has faced a major challenge to get its engines up to pace this season after the category set a higher than expected cumulative horsepower parity target in March.

Understood to have been triggered by significant off-season gains from Red Bull supplier KRE and the performance of the new-for-2014 Volvo, Erebus has been one of many teams having to pour significant resource into engine development.

Stone says that the next phase of upgrades will most likely come online for the Sandown 500 in mid-September.

“Because of what we’re doing it needs to be done (evaluated) on test days,” he said of when the next package will be ready.

“We’ve only got one test left (scheduled for September 2) so it really has to be done and dusted before that, leading into Sandown.”

Davison and Holdsworth sit 13th and 14th in the championship respectively after 23 races.

Holdsworth underlined the strength of the team’s chassis program with a maiden win for the team at Winton in April, while Davison scored his first podium with the squad last time out in Townsville.

Queensland Raceway meanwhile was the scene of arguably Erebus’ most competitive outing during a difficult 2013 season.

The weekend saw Tim Slade qualify fourth and fight for victory in Sunday’s final race before sliding off-track in greasy conditions.

Stone is confident that the team’s package has improved considerably in the last 12 months, but isn’t making any bold predictions for the upcoming three races.

“It’s the old story in V8 Supercars that if you’re doing this year what you were doing last year you’re going to get left behind,” said Stone of the team’s Ipswich chances.

“You really don’t know until you get there on the day and everybody is on the same tyres under the same track conditions.

“We’re not doing handstands thinking we’re going to be on pole or anything like that but it’s definitely an improvement.”

Erebus shared Queensland Raceway with Dick Johnson Racing on Wednesday in a test that saw Ford Performance Racing’s Chaz Mostert make an appearance with the customer Falcon operation.

Both Mercedes-AMGs were meanwhile displaying new backing following the signing of two-event bonnet sponsorship deals with Tasmanian-based car dealer Buckby Motors and MEX Maintenance Software.