Looking to free up a few extra horsepower from your stock engine? Aren’t we all. Tons of DIY or miracle cure products are on the market, claiming to pull a few extra ponies in just a couple minutes. It’s not worth it. You won’t feel the gains in the seat of your pants with a free-flowing air filter, a “tornado” air intake or a fuel system additive. At best, you’re improving your fuel efficiency. At worst, you’re wasting your hard-earned cash.
If you really want to see gains, be prepared to put in some hours with your car. Porting your cylinder head is a car modification you can make to improve performance. It’s hands-down the best upgrade you can perform for the least amount of money.
Why Port Your Cylinder Head?
An engine is, in the most basic explanation, a large air pump. The more airflow into and out of the engine, the more power you can produce (within reason, of course). You can open up the size of your intake ports in your cylinder head, but that’s not the main purpose of porting. You want to smooth out the air’s flow pattern, minimizing the turbulence on its way into and out of the combustion chamber.
The amount of horsepower you’ll gain isn’t an exact science because the casting inside each cylinder head is slightly different. On some V8 engines such as a Chevy LS1 engine, gains of 100 to 150 horsepower have been made – some even claim up to 200 extra horsepower!
How to Port Cylinder Heads
These are the basic steps to porting your cylinder head. Most 4-cylinder, 6-cylinder, and 8-cylinder engines follow roughly the same process. Take each step slowly. Any damage you do can’t be easily undone unless you have wads of cash.
Make sure you’ve got all the car tools you’ll need for the project before you begin.
Let’s assume you already have the cylinder head off. If you need a step-by-step to remove the head, you probably shouldn’t be tackling a porting job.
Scribe your porting limits.
You want to match the shape and size of the cylinder head and the intake manifold’s ports. Paint the area around the intake ports with Dykem. Line up your intake manifold gasket on the port, then scribe an outline of the inner portion of the gasket into the dried Dykem. You’re only going to grind up to the scribed line.
Grind the inside of the port runners.
Take your die grinder and get to work. Use either a sanding drum or a carbide tip to remove the material up to your scribed line. If you’re a beginner, go with the sanding drum. You’re less likely to grind into your water jacket with the sanding drum than the carbide tip.
Then, get deeper.
Your goal is to remove any rough casting material, sharp edges, and bits of casting slag that stick on the inside. It doesn’t have to be pretty, but you want it as smooth as possible. Air doesn’t like making sharp turns. Rough surfaces and sharp angles create turbulence, which robs you of precious horsepower.
Rinse and repeat.
Complete this process on all your cylinder head intake ports. Smooth out the full surface, all the way to the intake valves without affecting the valve seat at all – that’s very important. Blow the metal filings out with compressed air when you’ve done all the port runners.
Go for the gusto.
You’ve gone this far, so what are a few more measly hours…or days? Do the exact same procedure on the intake manifold, matching the intake ports to the cylinder head in size and shape.
Free-flowing intake runners let you pump more air into the engine, achieving maximum potential for very little coin.
If you’re planning on changing up your exhaust for a more free-flowing system, you might as well clean up the exhaust ports at the same time.
If you’re serious about making power from your engine, establish a baseline. Get a dyno test before you get all up in that business, and then re-test on a dyno once you’ve finished your engine work. A couple hundred bucks will get you bragging rights on paper!
About the Author
We here at WheelScene are a group of like-minded automotive enthusiasts. We love all aspects of self-powered, wheeled machines that transport us to places both real and imaginary. From taking them apart to putting them back together, from old to new, from everyday family haulers to high-performance models and racing cars, WheelScene loves it all! Jason Unrau is an automotive writer with 15 years experience in the automotive industry. Based out of Winnipeg, Canada, he has always been around cars and car repairs from an early age. He is a Certified Technology Expert and wants to share about his hands-on and service advisory experience. Learn more about WheelScene.