Cylinder Head Air Flow

The high performance aftermarket world I must say has come a long way in producing some excellent parts that the average hot rodder has easy access to. A simple point and click from your home computer and you can have the latest in high performance parts delivered to your door in a matter of days. Most of these fine parts you are able to bolt on with little or no modifications.

But as I sit in my garage and look at the beautiful 523 cubic inch engine I recently built for my drag boat I think to myself what really has changed? It’s pretty much the same as every other engine I’ve built in my life, block, crank, rods, pistons, heads, valvetrain, intake system, etc. The basic concept of the internal combustion engine remains the same. So my question to myself is what has changed?  Today’s high performance and racing engines produce much more power than they did even ten years ago, so again, what has changed?  The answer I came up with is simple- air flow. Although the concept has never changed, the more air you can get into the cylinders the more power you will produce. What is the path the air needs to take to make it to the cylinders to be combusted? It travels and is distributed through the cylinder heads. Cylinder head air flow is, and in my opinion, will always be the major factor in producing more power in the internal combustion engine whether it be through larger camshafts, bigger valves, larger cubic inches, ( which seems to be the case nowadays) or bigger superchargers, it still comes down to airflow.

Like I stated in the beginning of this article the aftermarket manufacturers are producing parts that are stronger and more reliable but the cylinder heads they are producing is what makes the power. That’s not to say you can’t take a stock set of heads and make them better because that is a low cost option that will likely give you the greatest gains per dollar spent and can also be fun and rewarding when done yourself. Even some “as cast” aftermarket heads have room for improvement with some port matching, smoothing of the ports, proper shaping of the guide boss and blending of the bowel area you will see some power gains.

If you have never done any porting work before I suggest you find yourself a junk head to practice on first and get the feel of things and then move on to the heads you intend on using.

Remember bigger is not always better when it comes to cylinder heads.  It’s all about proper shape and velocity.

It’s also important to know your intended use, street, street rod, drag race, rpm range, etc. so you can choose the right cylinder heads or modifications needed for your application. Just having your heads ported or choosing the heads with the biggest ports doesn’t mean you’ll make more or the most power from your engine.  Answering these questions first will help you determine optimum port size and air flow requirements.  It’s also a good idea to call the manufacturer and get their recommendations.

There’s plenty to choose from out there, choosing the right parts is what’s important. Good luck and have fun.