Porsche LMDh hybrid racer draws power from decade-old 4.6-litre V8 from 918 Spyder

The 90-deg V8 endurance racing engine has a minimum weight of just 180kg, including peripherals.

Published On Aug 16, 2023 08:00:00 AM

Despite the race to electrify, there’s still plenty of room for interesting combustion engine stuff, especially in motorsport. Even if motor racing isn’t your bag, the statistics for Porsche’s latest thriller, the 680hp V8 hybrid 963, are enough to warm the cockles of any self-respecting petrolhead.

For those who don’t follow endurance racing, the 963 is an LMDh (Le Mans Daytona Hybrid) machine, giving Porsche the opportunity to compete in both the FIA World Endurance Championship and North America’s IMSA Sportscar Championship, which, respectively, include the two ‘big ones’ – the Le Mans 24 Hours and the Daytona 24 Hours.

LMDh sits alongside Le Mans Hypercar (LMH) and, in essence, is a full-on, purpose-built racing sports car formula for the highest level of racing and nothing else. Using the LMP2 chassis (LMP2 being endurance racing’s second-rung class), LMDh fits into the GTP class of the IMSA series and the Hypercar class of the WEC.

Most of the 963’s power comes from a turbocharged derivative of the 4,593cc V8 engine from the 918 Spyder, a road-going supercar. This may have been revealed a decade ago, but it’s still a mighty thing with all the right credentials on which to build an endurance racing engine capable of taking on the best of the best.

It has proved durable in testing, which is a good start, has a flat-plane crank (making it a howler rather than a waffler) and has a short stroke to enable high revs. This also helps to reduce the engine’s height, and, combined with a dry sump (which allows a low mounting position in the chassis), helps achieve a low centre of gravity, thereby providing ideal positioning for the suspension pick-up points.

One of the main additions to the engine is a brace of turbochargers from Dutch turbocharger specialist Van der Lee, working at a low pressure of 0.3 bar. The ‘hot’ side of each cylinder bank is on the inside of the vee, which is where the turbos are located. Because the maximum boost pressure is low, pressure build-up is swift, with no lag, and the intrinsic characteristics of the naturally aspirated original creation remain.

Around 80 percent of the V8 is derived from the original 918 Spyder engine, and there has been some additional strengthening to make the engine capable of being a structural part of the chassis.

The LMDh regulations were at first going to allow teams to develop their own hybrid powertrains, but in the end the decision was to use suppliers to reduce costs and keep that part of the playing field level.

Oxford-based WAE Technologies supplies the small, 800V, 1.35kWh battery and Bosch supplies the motor-generator unit (MGU) that sits between the engine and the Xtracmade seven-speed sequential gearbox, along with the electronics to go with it.

The MGU drives the rear wheels only, develops between 40hp and 68hp, is designed only to work in short bursts and contributes to the maximum power in race mode of 680hp.

Electric endurance hope 

Electric powertrain specialist Hofer has announced a battery for endurance racing. Called Bluefire, it can be charged at rates of up to 3,750kW, taking it from 5-85 percent in less than 90 seconds. The battery chemistry is lithium titanate oxide, and it can be scaled to fit different applications. It is currently in the pilot project stage.

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