Cylinder head upgrade for classic performance engines

Engine modernisation projects increasingly focus on improving airflow efficiency and mechanical performance in legacy performance engines. In this context, Swindon Powertrain reported the delivery of 100 M64 Cylinder Head Kits designed to upgrade Porsche 911 engines from the 964 and 993 generations.

Multi-valve conversion to improve airflow efficiency
Originally introduced in late 2023, the M64 Cylinder Head Kit is designed to retrofit the air-cooled flat-six engine architecture used in these vehicles. The conversion replaces the original two-valve-per-cylinder configuration with a 24-valve layout, improving volumetric efficiency and combustion airflow.

The four-valve-per-cylinder design increases peak airflow by approximately 40% compared with the standard Porsche 993 configuration. This architecture also enables higher engine speeds, supporting engine operation up to 12,000 rpm in certain configurations.

The design also reduces component mass by approximately 3.5 kg compared with the standard cylinder head configuration, supporting improved dynamic engine response.




Materials and manufacturing approach
The cylinder heads are produced in the United Kingdom using aerospace-grade A356 aluminium casting processes and are CNC-machined at Swindon Powertrain’s Wiltshire production facility. This manufacturing approach supports the dimensional tolerances required for high-performance engine applications.

The kit also includes titanium intake and exhaust valves as well as associated valvetrain components such as springs, retainers, collets, shims, finger followers, camshafts, cam covers and timing drive components.

Completed kits have been supplied to engine builders in Europe as well as markets including the United States, Japan and Australia for use in both road and track applications.




Applications in restoration and performance upgrades
The cylinder head technology is being used in restoration and modification projects involving classic Porsche 911 models. One example is its use by restoration specialist Thornley Kelham in the European RS programme, a limited production vehicle project based on modified Porsche 911 platforms.

Two engine configurations are offered within that programme: a 3.6-litre engine producing more than 380 bhp and 290 lb-ft of torque with a 10,000 rpm rev limit, and a 4.0-litre version delivering over 425 bhp and 325 lb-ft of torque with a 9,000 rpm rev limit.

The multi-valve design addresses airflow limitations associated with earlier two-valve cylinder head designs, which can restrict intake flow and require heavier valve springs that may limit achievable engine speeds.

Development work on future engine architectures
Beyond the M64 upgrade programme, Swindon Powertrain is also involved in the development of a flat-eight engine architecture. Runge Sportscars announced collaboration with the company on a 5.3-litre, 32-valve, four-cam air-cooled engine project.

This work reflects ongoing engineering activity in the performance vehicle sector focused on extending the technical capabilities of air-cooled engine platforms through modern materials, manufacturing processes and valvetrain design.

Edited by industrial journalist Aishwarya Mambet, with AI-assistance.

www.swindonpowertrain.com