Swindon Powertrain, a leading designer and manufacturer of high-performance road and race engines and components, has reached a significant milestone with the sale of 100 units of its M64 cylinder head kits. Supplied to specialists and builders, such as Thornley Kelham, the 24-valve engine upgrade enables 964 and 993-generation Porsche 911 engines to rev up to 12,000rev/min.
Launched at the end of 2023, the retrofit kit transforms the M64 air-cooled flat-six engine by increasing power and torque while reducing weight by 3.5kg compared to standard. Designed for fast road, track and race applications, the upgrade replaces the original two-valve per cylinder layout with a 24-valve architecture to significantly enhance breathing efficiency. With four valves per cylinder, the kit increases peak flow by 40% when compared to the standard 993.
Cast in the UK utilising aerospace-grade A356 aluminium, the cylinder heads are then CNC-machined in-house at Swindon Powertrain’s facilities in Wiltshire. Once assembled, the kits have been shipped to engine builders across Europe and around the world including the USA, Japan and Australia for use in both road and track 911s. Cotswolds-based restoration and modification specialist Thornley Kelham selected the heads for its limited-edition Porsche 911 European RS model.
Only 15 cars will be produced with customers offered two 24V options: a 3.6-litre, 380bhp+ unit generating 290lb-ft torque with a 10,000rev/min rev limit, or a 4.0-litre engine producing 425bhp+, 325lb-ft torque with a 9,000rev/min limit.
More power and performanceSylvain Rubio, technical director at Swindon Powertrain, explained: “Relying on low-flow, two-valve per cylinder architectures, the M64 air-cooled engines typically have restricted air flow into the combustion chamber, while the need for heavier springs stresses the rockers and limits rev/min. Our M64 cylinder head kit is helping deliver more power and performance to a new generation of upgraded Porsche 964 and 993 models, benefitting from the latest materials and the finest of CNC machining tolerances.”
Raphaël Caillé, managing director at Swindon Powertrain, said: “The comprehensive M64 kit also includes titanium inlet and exhaust valves with springs, caps, collets, shims, finger followers and shafts, alongside camshafts, cam covers and timing drive input. We are proud to be helping so many engine builders and 911 enthusiasts around the world unlock substantial extra power and torque to create truly standout builds with this high-revving upgrade.
Pushing the boundaries of engineering – often beyond what seems conceivable – is a challenge we thrive on. We are never content to stand still, so expect further high-performance developments set to be announced soon.”
Those developments include the creation of a flat-eight engine. In late 2025, Runge Sportscars announced it was working with Swindon Powertrain to create a 5.3-litre, 32-valve, four-cam, air-cooled engine.