Wednesday, December 12Serving the aftermarket

What goes into a Le Mans engine?

The Le Mans 24-hour race is a high endurance, day-long race that puts the world’s best race cars to the test. In 2017, jaws dropped when an LMP2 car was placed second and third overall. But, why was this a poignant moment for this engine type and why is this significant to the design and development of these race car engines? And how does miniature bearing specialist, SMB Bearings fit in to this?

A Le Mans Prototype (LMP) is the type of sports prototype race car used in the 24 Hours of Le Mans, FIA World Endurance Championship (WEC), IMSA WeatherTech SportsCar Championship, European Le Mans Series(ELMS) and Asian Le Mans Series. For a car to be compliant for entry in either the LMP1 or LMP2 category, certain design criteria must be fulfilled.

In a previously LMP1 dominated race, the 2017 Le Mans 24-hour race saw two LMP2s on the overall podium. For a race that had never previously seen an LMP2 car lead, let alone take an overall podium place, it does pose the question, what has changed?

High performance powertrain manufacturer, Gibson Technology has been chosen by the FIA/ACO as the sole engine supplier for LMP2 class sports cars from 2017 to 2020. Therefore, all race cars in the LMP2 category during this time are equipped with the latest development from Gibson, the GK428 engine.

The GK428 is the current spec engine supplied to all the LMP2 teams competing in the WEC, the Le Mans 24 Hours, ELMS, IMSA Weathertech Championship and the Asian Le Mans Series (from 2019 onwards). It has been specifically developed for endurance racing and is one of the most technically advanced engines that Gibson has ever produced, incorporating the latest design, manufacturing and development techniques available.

Hard work

Producing a race engine that maintains efficiency consistently over 24 hours is no easy task, especially as it is at full throttle for 70% of the lap at Le Mans. Therefore, a great amount of work goes into the design, simulation and material technology to ensure the engine is able to perform at the highest level

Getting to this milestone had been quite the journey since Gibson Technology was established in 1987 (formerly known as Zytek Engineering). The company has endured business acquisition, rebranding and ongoing engineering refinements across all engine types, including those for LMP1 and LMP2 race cars, over the last 31years. However, one thing that has been constant in the last decade is the bearings used across all Gibson Technology racing engines, courtesy of miniature bearing specialist, SMB Bearings.

The engineering department at Gibson had a challenge on their hands ten years ago — to source thin section bearings for the throttle barrels that would be able to function in the hostile environment of a race engine. The throttle system is an extremely important part of the engine, designed to control the flow of air or fuel mixture into each cylinder of the engine.

The design of the throttle system has been highly developed, to ensure that good driveability and optimum performance are achieved, along with a reduction in the level of friction which is generated during the rapid throttle movements.  This called for thin section bearings that could perform in a race engine environment. The area of the engine where these bearings are located is subjected to extremely high temperatures, and very high levels of vibration creating considerable stress and load on bearings. In such extreme conditions it is no surprise that so many other bearings failed to meet the brief.

Finding bearings

After going through several bearing suppliers, all of which were unable to provide a bearing that would function correctly under these conditions, Gibson turned to SMB Bearings in the hope of finding high performance bearings that could last the test of Le Mans. The bearing specialist supplied EZO thin section ball bearings, suited to applications when weight reduction is required and where space is at a premium, as with the case of the throttle barrel.

“The success of these bearings in Gibson’s engines has been a huge testament to the skilled manufacturing that goes into EZO’s bearings,” said Chris Johnson, managing director of SMB Bearings. “The endurance, as demonstrated out on the Le Mans track, has been amazing to watch. It is fantastic to have such a loyal customer in Gibson Technology, and we’ll always be on hand to assist with any problems they might have.”

“This unique bearing design isn’t readily available, so we are pleased to have SMB on hand to ensure there is always a good supply available,” said John Manchester, operations director at Gibson Technology. “When we’re happy with a supplier, we don’t have the need to look elsewhere. This is the case with SMB — the performance of the EZO bearings has been excellent, and we would not consider sourcing bearings, for this application, from any alternative supplier.”

When it came to testing and validating the race car engines, with SMB’s bearings installed, the entire engine was evaluated on a test bed, enduring the equivalent cycles of two races of Le Mans (48 hours). After this test, all parts were stripped and analysed. Satisfied with the performance of these bearings, SMB’s bearings have now been used in the assembly of every single Gibson Technology engine for the last ten years.

In LMP2 there will be a total of 17 cars in ELMS, 7 in WEC and 20 in the Le Mans 24 hours and 6 in the IMSA Weathertech Sportscar Championship, all powered by Gibson GK428 engines. In LMP1, three cars will take to the grid at Le Mans and WEC powered by the new Gibson GL458 engine.