Published on May 31st, 2013 | by F_Zanier0
F.Renault 3.5: How the Engine Issue Was Solved
While the engine issues that in Alcaniz forced Renault to reduce the Race 2 mileage got broad coverage in the motorsport press, little or nothing was written to report if the problem was identified. The Monaco race weekend went by with no technical drama at all, so it was safe to assume that the issue was promptly found and addressed, but how?
First of all, let’s explain what the problem was: increased oil consumption was reported as one of the symptoms, but that clearly wasn’t the primary worry, as both Renault and Zytek knew already in Alcaniz. Engines were flown to the Zytek HQ in Repton to be examined, and there the real problem was identified: fatigue signs had appeared on some engines, in worst cases bad enough to cause an engine fail if ignored.
The surprise didn’t consist in the nature on those fatigue signs, that normally happen on engines with a high mileage, but in the fact that in this case they appeared earlier than expected.
The reason for that was identified in the extreme performances of the current F.Renault 3.5 car generating an high and unforeseen amount of stress on the V8 unit. To better understand this, it’s important to remember that the Zytek-Renault engine wasn’t really designed from a clean sheet for this car: instead, it’s a well-known quantity in the single-seater arena: whilst some parts were created from scratch and others were amended to achieve a perfect match with the Dallara chassis and the Ricardo gearbox, the core of the unit is the universally praised Zytek ZA348 engine, the powerplant originally created for A1 GP, that used it until 2008. After A1 GP switched to Ferrari, the Zytek V8 powered the Coloni-run Auto GP championship, based on an improved version of the same Lola B05/52 chassis (and still does).
Thanks to those two installations, Zytek gathered a huge amount of experience on this unit, data that were used as guidelines to create the revision and rebuild programme for the Renault engine.
It sure made sense, but the higher performance range of the new F.Renault 3.5 proved to be a wear factor that wasn’t taken into account. Currently the quickest feeder formula around on a par with GP2, the F.Renault 3.5 boasts a mesmerizing cornering speed as its strongpoint: while that feature is broadly praised by drivers, it comes at a cost, namely a huge strain on mechanical bits, especially in terms of torsion forces. Last year the gearbox was the first part to suffer from that excessive stress, and changes were carried out to make it stronger. Anyway, it’s possible that with the gearbox casing now stiffer, the torsion issues passed on to the engine, causing the problems that emerged in Alcaniz.
So how the issue was solved? After some thinking, the installation of a stiffening plate under the car was deemed the best solution. Creating a further strong link between the engine and the chassis, this plate will help shifting some of that torsion load from the V8 to the monocoque, so bringing the wear levels back to the expected progession.
Then, knowing what the issue was, Renault and Zytek will sure keep an eye on the engine rebuild and change schedule, making amendments if needed.
It’s worth to highlight that with just three weeks available between the Motorland Aragon round and the Monaco weekend, all the cars were equipped with the stiffening plate and all the engines that caused concern were replaced, a very quick reaction from both Renault and Zytek.