Swindon Powertrain has launched a new 24-valve cylinder head upgrade for the Porsche 964 and 993. Priced at £29,950 (US$36,400), the M64 cylinder head kit has been engineered to rev to 12,000rpm. The company says it improves power and breathing efficiency while reducing weight by 3.5kg compared with a regular cylinder head.
The standard production air-cooled engines of these Porsche models used a traditional, low-flow, two-valve-per-cylinder architecture. This, says the UK-based company, limits the total valve area, restricting the mass of air entering the combustion chamber during each cycle. Additionally, these larger valves required heavier springs that tended to stress the rockers and limit rpm.
Thanks to its 24-valve configuration, Swindon says the new kit solves these issues. The redesigned four-valve-per-cylinder castings increase both power and torque, making the kit suitable for performance, track and race applications. Internal testing by the company revealed 40% peak flow improvements over a standard 993 at the inlet and 66% on the exhaust. Further to the increased efficiency, the ability to rev to 12,000rpm allows engine builders to exploit additional performance available at increased engine speeds.
“Factory cylinder heads traditionally held back worthwhile gains for the traditional over-square Porsche air-cooled flat-six engines. Our extensive research and development program enabled us to eliminate the compromise to create, arguably, the ultimate cylinder head for an air-cooled 911,” said Raphaël Caillé, managing director at Swindon Powertrain.
Cast in the UK from A356 grade aluminum, usually found in aerospace applications, the cylinder heads and cam chests are CNC-machined in the Swindon Powertrain facility that also builds competition engines, including power units for the British Touring Car Championship. The comprehensive kit also features titanium inlet and exhaust valves with springs, caps, collets, shims, finger followers and shafts, alongside camshafts, cam covers and timing drive input. The company says it can also supply a power steering drive to enable the use of the 993’s production system, custom pistons designed to take full advantage of the increased breathing efficiency, inlet porting and bespoke cam profiles.
To simplify the upgrade process and enable further staged upgrades, the kit is fully compatible with the standard production Porsche 993’s lubrication system, cam chain drive, barrels ranging from 95mm to 102.7mm bore diameter, crankcase and exhaust.
“Using the latest innovations in materials alongside CNC machining to F1 tolerance standards, our cylinder heads transform an air-cooled engine,” said Caillé. “The improved breathing and ability to rev unleash the potential to experience your 911 like never before.”
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