Cylinder Head Gas Flow, Porting & Polishing

SAC Engineering successfully gas flowed more than 20 000 cylinder heads over the past 33 years and have built at least 2000 very special race-ready cylinder heads. We are undoubtedly South Africa’s leading cylinder head specialist one stop shop and are capable of preparing very high-tech quality heads.

How do we do it? Gas Flowed Cylinder Heads is a very technical and scientific topic! So let make it simple and easier to understand, try and imagine an aeroplane flying, aeroplanes are very aerodynamically designed so that they can move easily through the air with as little restriction as possible. The less restriction or wind resistance they have the easier they fly and stay in the air. Also, they can achieve much higher speeds with far less engine power.

A cylinder head port is much the same as an aeroplane, the only difference is that it is a stationary piece of material on the engine that has an opening which allows air to enter the engine “a port”. Since an engine is really only an air pump that essentially sucks in huge amounts of air, mixes it with fuel and a spark to create combustion which intern becomes power it stands to reason that the more air we can get into the engine the more power we will make. Obviously, the air needs to be combined with the correct amount of fuel and ignited at the right time for this to be the case.

The port and everything related needs to be as aerodynamic as possible to encourage enhanced cylinder filling. This is where gas flowing or porting takes place. All the sharp edges and obstructions in a port are tidied up and or removed in order for the air to flow over them easier and with less restriction. This would include the valve guide, the valve stem as well as the valve seat and its receiving insert in the combustion chamber. As mentioned above, this is a highly technical and scientific process. On race heads there is much more to it, air speed and volume of air also need to be taken into consideration. For road performance or road race engines, the work is generally the same as on a racing head with a few more boundaries. We are able to flow heads and issue a flow bench certificate as we are one of the few if not the only cylinder head engineering shop to use a flow bench in the country.

The valve seats play a very important role in the porting process and although on most road race jobs we go for three angle seats to ease the air through with much less restriction we can also do multiple angle seats, as much as six angles or even rounded off seats much like the front of an airplane wing.

What are the benefits of porting and polishing a head?

A properly flowed or ported cylinder head can significantly increase a cylinder filling of an engine which in turn will increase the power output after the tuning has been optimised to match the increased air.

It would be a no-brainer to add a gas flow or porting job to a cylinder head that gets removed from an engine because it broke or blew a head gasket. It makes logical and financial sense because this would only add a few rand to the repair or recondition job but the benefit will be huge in terms of power delivery. Most cylinder heads today on vehicles are production orientated and are moderately produced to speed up the production time. A hand finished cylinder head makes absolute sense if you consider that some of the exotic high-end performance cars like Ferrari, Porsche and Lamborghini to mention only a few have hand finished cylinder heads from the factory.

When you speak to one of SAC Engineering sales consultants regarding a gas flow cylinder head you should also ask about gas flowing the throttle body and/or intake manifold. When this is done together the benefits are greater. You might also want to ask about a special gas flow which would be more race orientated without compromising reliability while significantly increasing the performance of your vehicle. In our SAC Engineering shop, we also gas flow heads in different stages for obvious reasons. It is all about time spent on the job, the more time and TLC, the better the head.

Gasflowing Cylinder Heads on different vehicles

Over the past 33 years that have gone by, we have gas flowed cylinder heads of all sorts, whatever the fashion was at the time – we made the cylinder heads more volumetric efficient. Gas flowing cylinder heads is a scientific phenomenon that can literally be applied to any internal combustion engines cylinder head and or inlet system.

Even high-end performance engines found in sports cars, race cars, competition orientated motorcycles, quads bikes etc will benefit from a gas flowed cylinder head – Head tidy up,  blueprint – gas flow – gas flowing – gas flow, what ever you want to call it!

So whatever you drive, you can definitely consider a gas flowed cylinder head – it’s all about volumetric and flow efficiency.
Toyota Gas Flow, BMW Gas Flow, Volkswagen (VW) Gas Flow, Audi Gas Flow, Ford Gas Flow, Noble Gas Flow, Nissan Gas Flow – to name only a few.

* All manufacturer’s names, numbers, symbols & descriptions are for reference purposes only. It is not implied that any part, conversion or modification is the product of these manufacturers.