In this gallery, I will try to illustrate what I did to a good piece of aluminum to enhance it's reliable performance.

I do not, and definitely would not, claim to be some kind of cylinder head guru.

[...because I don't have to be a cylinder head guru to accomplish what I want to on the Volvo SOHC head.]

The work I do on these SOHC heads is a basic smoothing and blending in the bowl and port transition areas to try to make all four cylinders flow the same.

It does not take a lot of metal removal to accomplish the uniformity I seek.

Without a flowbench to measure the results, getting in there with a die grinder and some carbide burrs and grinding away to make some bigger holes JUST to make them bigger is a really stupid thing to do.

I do not subscribe to the notion that 'bigger holes are better holes....just because the holes are bigger'.

I smooth and blend to achieve sameness of flow and velocity; and to enhance the swirl induction that the tangential intake ports offer.

I leave the efforts to go for big flow numbers to the people who have the Patience of Job, the technical and artistic talent of DaVinci, and the flowbenches to monitor their progress.

Compared to what a professional cylinder head porter has to deal with and do, especially on a NA head, I have it easy as pie:

Firstly, because my SOHC heads are laid out in four identical configurations...all four intake ports, combustion chambers, and exhaust ports are similarly positioned. There is no reversing of the layouts as I go down the row.
....this makes it easier to compare the runners and bowls and transitions as I do the work.

Secondly, because the intake ports are tangential to the crank centerline. Such a configuration is VERY assistive in generating swirl during the intake flow.
....with good swirl induction already there, I don't have to work to make it happen; I just have to work towards enhancing it.

Thirdly, if I can get the four sets of intake ports and exhaust ports to flow as close to the same as I can, then to get more volume of flow, I have a big assistant: the turbocharger.

The work I did to smooth and blend the ports and bowls on this head does not fit the commonly used [and much abused] term of: "porting and polishing".

What I did was to work towards removing or minimizing obstructions to good flow. It can be described as a "cleaning up" of the ports and bowls to enhance evenness of flow through the four cylinders.

My overall objective is to enhance the RELIABLE performance of my SOHC head.

Because: a boosted motor may or may not make a LOT of power...

...but one thing for absolute sure is that......it WILL make lots and LOTS of HEAT!!!

Therefore, my first priority is to not adversely affect the head's ability to handle and deal with the heat load that it must be able to withstand.

Then, I can work on increasing the power output.

The basic smoothing and blending work I illustrate in this gallery is not intended to be viewed as a collection of secret procedures to unlock big power gains from the Volvo SOHC heads, or any other such drivel.

It's purpose is to show what can be done to enhance what the head does, and do that without diminishing reliability.