The Nissan and Mercedes teams have expressed frustration with V8 Supercars’ decision not to allow the 70 percent ethanol fuel blend in this year’s Pirtek Enduro Cup.

V8 Supercars confirmed on Monday that it will instead mandate a set number of compulsory pitstops in each of the three endurance races in an effort to help the thirstier four-valve engined cars.

The decision against using the E70 comes despite V8 Supercars stressing that analysis of its track and dyno testing of the alternate fuel has proven that it provides no performance advantage over the regular E85

Although mandating four stops for the Sandown 500 will ensure that the Ford and Holden entries will not be able to squeak through with one less stop than their rivals, pre-event estimates suggest that the four-valve cars will lose up to 12 seconds across the course of the race while taking on the additional fuel that their higher consumption will demand.

“No matter what anyone tries to portray, we’re still at a disadvantage in that we still carry the extra fuel load and consume more fuel,” Erebus Motorsport team manager David Stuart told Speedcafe.com.

“It (the pitstop rule) is an attempt to try and achieve parity but at the end of the day it’s not achieving what E70 would achieve.

“We complied with every wish and direction from V8 Supercars in testing the E70 and they had all the information there (proving the legitimacy of the E70).

“I can’t really say any more than that. The information (that V8 Supercars has) should speak for itself.”

The fuel parity issue had been debated by the V8 Supercars Commission at length for some months, with solutions recommended by V8 Supercars’ technical department needing sign-off from both the Commission and the Board in order to proceed.

Nissan Motorsport co-owner Todd Kelly, who is the only team representative on either panel whose squad runs a four-valve engine, told the Australian Associated Press that his team could be forced out of the category if the current situation continues.

“Whether we exit the sport because we can’t afford the R&D … there’ll come a time we have to make that decision,” he said.

“If it was put upon the new manufacturers to reach the current fuel economy and engine parity windows with their own means, it may be physically impossible to achieve that with a road car-based engine.

“We certainly don’t have the funds to go through that process and keep putting race cars on the track into the future … there’s no way our sponsors and business partners will be that patient while we run mid to late-field to go through that process either.

“It’s a pretty sticky situation where we sit right now. Our future is almost in the hands of the sport as to how we can make sure we can all play on an equal playing field.”

V8 Supercars has to date proven unwilling to relax any key elements of the pre-existing engine parameters that the new players have had to comply with this year, including the total capacity, compression ratio and rev limit.

AMG has held off on the development of its previously scheduled major pre-Sandown upgrade package for Erebus due to the uncertainty over what V8 Supercars would do about fuel parity for the Enduro Cup.

Amid the storm over the E70 at Winton, V8 Supercars’ general manager of motorsport Damien White told Speedcafe.com that any permanent engine rule changes to equalise the two and four-valve engines were “not on the radar”, but will likely be assessed in November.

“When you think about how simple it is to vary an ethanol blend in a fuel and how simple it is to monitor and you look at the controversy and energy around it, if you then went down the path of some sort of technical or structural change to an engine… think about how difficult that would be to manage,” he said.

“Let’s get through the Enduro Cup and then we’ve got Phillip Island and Sydney. It’s a short off-season, but in that period between Phillip Island and Sydney we’ll look at it.”

V8 Supercars’ announcement on Monday sparked further debate over the fuel parity on social media, where leading Holden driver Jason Bright made perhaps the boldest claim.

“Time for control engines,” he wrote on Twitter. “If I had my way COTF would’ve had a control engine but I was told it was under control and parity would be easy.”

Nissan, Mercedes-AMG and new-for-2014 marque Volvo have all stated that they would not be involved in the championship is they were not allowed to run their own engines.

Have your say on the fuel solution debate by clicking through to Speedcafe.com’s Pirtek Poll