CNC engineered gas flowed cylinder heads

Mitsubishi Evolution 4-8-IX (Big Valve)




Before we started work on this head we knew we would have to produce something pretty special to be competitive in a huge market for Evo tuned heads. We would have to extend our extensive development phase and push development to the absolute limit that this head can offer.

We started with a stack of used heads to work on. We also bought in a few of the best known heads from the USA in order to establish what the competition was doing. We also cut some scrap heads open with a band-saw to reveal the profile of the port chambers and the material available to machine.

We set to work on an extended development programme with the aim of producing the highest performing gas flowed cylinder head on the market for the Mitsubishi Evo. Ultimate performance was our aim.

The standard head starts off at 135.8CFM inlet and (unusually) an almost identical exhaust flow of 134.8 CFM. The near 100% inlet/exhaust ratio is very unusual and shows a great deal of effort was made by Mitsubishi to get the most from the standard head. The exhaust flow is very significant on a turbo engine to maintain turbo response and reduce turbo lag and Mitsubishi have done a good job in this respect. We had our work cut out for sure !!

After several weeks of development we were more than pleased with the results. 174.2 CFM inlet and 175.6 CFM exhaust. An improvement of 28% for inlet and 30% for exhaust.

This head would produce over 300bhp WITHOUT a turbo. With a modest turbo, setup it is easliy capable of 500+BHP. We have customers who have used this head for 900 – 1200 bhp!

As you see with all our heads we publish all the flow figures from the Port Flow Analyzer software straight off the flow bench. The flow curves are scanned images straight off the printer so you know the figures are real. How many other head shops do that ? The fact is very few head shops publish figures because a) They are not that impressive and b) there is no guarantee the head you buy will perform as they say it will. NOT SO WITH A CNCHEADS HEAD. You get exactly what we promise.

We believe you won’t find a higher performing head for a Mitsubishi Evo anywhere in the world. You may also pay a lot more for less performance elsewhere.


Note : flow diagrams show flow against specific valve openings at 0.050 inch valve openings at 10″ pressure. Therefore actual flow volume increase is measured as the area under the graph (indicated in yellow for inlet and blue for exhaust). Standard valve sizes are used on our heads unless specified as a big valve version. Tests shown here are carried out on a flow bench on a bare head without filters. Therefore the difference between a standard engine with standard inlet ducting and filters will be larger than shown here.

Click any image below to see the full reports as generated by our gas flow bench and Port Flow Analyzer software. Click on the images for full size image:



Cost for this head is £1560.00 + vat on an exchange basis. (£600 exchange). 

A ‘taping’ service is also available for this head at an additional cost of £100 which will give the final hand finish to the ports and provide a further 1% flow. This price includes valves.

Call us on +44 (0)161 483 4810 or email on SALES @ CNCHEADS.CO.UK . Check out our FREQUENTLY ASKED QUESTIONS PAGE for more information.

Custom made CamshaftsWith all of our gas flowed heads we also provide a custom made camshaft service. These camshafts are designed to optimise the flow characteristics of our heads. They can also be specifically designed to deliver the power characteristcs you require for your specific application.Your existing camshaft will work with our heads, however, if you want to get the most from one of these heads or you have a particular power characteristc you are looking for, we recommend that you consider our custom camshafts.Price £500 + vat

We are happy to discuss and advise on any aspect of modifying your engine with one of our heads to achieve the results we predict above. We can also supply the best quality gaskets, camshaft, valves, valve springs and head bolts to go with your new cylinder head. We also specialise in electronic engine management, carb and fuel injection , turbo and supercharger systems. We build race engines too. Built and tested on our own 1000bhp Engine Dyno. We can also fit your head to your engine if required and test your vehicle on our rolling road.

What ever your requirements, race, track day or fast road, we have a full range of the latest and best performance products and techniques. Our competition results year on year prove we have the expertise to make your car competitive at what ever class you chose to compete.