The global automotive cylinder head market reached a value of $92.1 million in 2020.

Cylinder head efficiency is integral to getting the most out of a combustion engine. Stock parts do the job, but there are several ways you can make improvements.

For a guide on how you can improve cylinder head performance keep reading.

Head Reconditioning

Head Reconditioning

This is the first step for any cylinder head build-up. This involves a number of steps that consist of things like cleaning, installing new parts, and testing components.

Guides And Seals

You should check the valve guides to see if they are worn down. if they are oil can leak into the combustion chamber. An easy way to check this is to watch on a cold start-up. If there is a puff of blue smoke you know they are worn.

In very bad cases they may produce a smoke screen when you drive off after your car has been idling for a while. If your guides are worn it will affect the movement of the cylinders, and the valve won’t seat fully during each cycle. This means the combustion chamber won’t seal, leading to a drop in horsepower.

If you replace your guides, you should always also replace your valve seals.

Valve Jobs And Airflow

You can improve the airflow levels by back-cutting the valves to a narrower face angle. This will result in the air having less material to flow around providing a smoother transition.

You can also implement a three-angle valve job. This involves three cuts (30, 45, and 60 degrees) in the cylinder head, with the valve in the 45-degree cut, the 30-degree cut between the valve and the combustion chamber, and the 60-degree cut between the valve and the bowl.

These angles are just examples and can vary based on the applications.


Heads with large combustion chambers can be milled to increase the compression ratio. Just a small amount of milling can result In a significant performance gain.

Be cautious with this – if you take off too much material things won’t fit together properly, and you’ll have to buy non-standard push rods or alter the intake manifold mounting flange.

Studs And Rocker Arms

Studs and Rocker Arms

Stock rocker arms sometimes flex and don’t quite deliver the ratio they advertise. If you choose to replace the studs, you may need to replace the rocker arms to fit them, so you can use higher quality arms that give a better ratio.

Upgraded arms can also be a lot stronger, increasing the lifetime and reliability of them.


Springs are affected by various factors such as valve/retainer/keeper weight, the shape of the cam love, and opening/closing speed. Finding the most effective springs involves some trial and error, but a slightly high spring pressure is better than a slightly low one.

Experienced engine builders may be able to recommend suitable springs for your configurations.


Adjusting the port parameters involves changing the size and shape of runners, as well as the finish. If done right this can provide increased airflow, but if done wrong it can ruin your cylinder heads. You can do this by hand or using a CNC machine, but it is best to have this done by a professional engine builder.

It will allow stock cylinder heads to breathe more efficiently by increasing the velocity of airflow into or out of the combustion chamber.

Improving Cylinder Head Performance

Improving Cylinder Head Performance

Upgrading components is one of the most effective ways to improve your performance cylinder heads. Jegs stock a range of parts that you can do this with, as well as many other automotive parts.

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