Good-Win Racing Mazda Performance Parts

Cosworth Mazda MX5 Miata Big Valve Cylinder Head


MX5 2006-2015 · Engine

Part Number: 61-0304

Application: 2006-2015

Price: $3,229.00


Cosworth Mazda MX5 Miata Big Valve Cylinder Head
The Cosworth MX5 Miata CNC ported Big Valve cylinder head is the result of countless hours of development and testing. Starting with fresh large port castings, Cosworth precision machines both intake and exhaust ports to maximize flow. Cosworth then reshapes the MX5 combustion chamber to un-shroud the larger stainless steel valves. This MX5 head is then assembled using Cosworth hi-rev tapered springs along with new valve stem seals and retainers.

This Cosworth MX5 cylinder head is the key to making big power and will flow enough to support 300bhp. Picture supplied by Cosworth is not the exact part. Cosworth CNC ported MX5 cylinder heads feature dyno tested and flow bench proven ports, engineered for maximum usable power. Each new MX5 Miata cylinder head is ported on a 5 axis machine to ensure consistency and perfect port shape every time.

Additionally, larger intake (+1mm) and exhaust valves (+1mm) are utilized to help increase flow. Cosworth CNC MX5 ported Big Valve cylinder heads come complete with a performance valve job, hi rev (max 10,500rpm) valve springs with titanium retainers and are ready to install. Perfect for high performance MX5 Miata applications.

NOTE: These require an 8 week build time from date of order.

About Manufacturer: Cosworth Over the years we have developed in-depth knowledge of engines, engine components and engine management systems. This has been successfully used to supply engines to some of the most successful Formula One teams and vehicle manufacturers. Our unprecedented success in the performance market has fueled customer demand from diverse market sectors. In addition to the traditional markets, Cosworth is engaged in designing and developing, engines and components for marine, locomotive and aerospace applications.


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-- Matt C.

First I want to again thank you for working with me on this muffler. I have almost 100 miles on it now, and it has a nice mellow sound. a little Bass, but not too much. A little louder than stock, but not too loud. Plus it is nice inside the car with the top up. I am happy so far I bought this one.

I belong to a local Miata club, and am very active with it. When Spring comes I will tell everyone how much I like the muffler, and how great you are to work with. Maybe I can get some extra business for you.

-- Bill