More power! Horsepower! The goal of porting is to establish better airflow through the cylinder head. Some people mistakenly believe that cylinder head porting is about the port size – but it’s actually about air flow and how well the air travels through the ports. Many companies provide a cylinder head porting service to improve performance – but some die hard horsepower enthusiasts would prefer to do their own cylinder head porting.
For a novice, you won’t want to start with high performance racing heads, since they’re already top of the line and would offer little room to improve those through porting. It’s also important to understand that porting by inexperienced people offers unreliable results and a lot of trial and error as you learn the process. Most people who have tried cylinder head porting on their own fail to improve successful porting because they don’t have thorough knowledge of the fluid dynamics involved, or possess the tools and knowledge necessary to optimize a port.
At the very least, porting cylinder heads requires an air flow bench, and ideally the use of engine simulation software. An egg shaped carbide cutter will help you speed up the process of cutting. Using a Craftsman Professional 1/4hp rotary grinder and polishing kits from Standard Abrasives will help in the process of deburring a block, and polishing exhaust ports and chambers.
Don’t attempt this process for the first time on a good cylinder head. You should always practice on one that you don’t care about or need first.
Test the production of the cylinder head on an air flow bench before beginning cylinder head porting so that you can measure the results again when you’re done – to see whether you successfully made improvements – or reduced the air flow.
Remove Ridge from Intake and Exhaust Bowls
Before you start hacking away at the cylinder head, keep in mind that you want to remove as little material as possible. If you remove too much and create concaved or holes, the air flow is going to be adversely affected regardless of the size of cylinder head you are porting.
Start by placing the cylinder head on it’s exhaust ports and remove the ridge that forms within both the intake and exhaust, being careful to only remove material to half an inch of the bottom of the valve.
Feel around inside with your fingers for any high spots and use a marker to mark any area that still needs material removed.
Flip the cylinder head over so it is sitting on the intake ports, and remove the ridge from this angle. You should be left with all of the cylinder bowls having a nice, smooth circular contour.
Unshroud the Valves
Remove the good intake and exhaust valve and set aside. Place the old valves in the cylinder in place of the good ones, in case you accidentally nick them when doing the next step.
Get the head gasket to line up with the dowel pins and the bolt holes. Stay within the bore line of the cylinder, and use the carbide cutter to scribe the line. Be careful though, if you get carried away and take off too much it will create a problem with sealing.
Replace the bad valves with the good ones again.
Polish
Using a Standard Abrasives (or other type of your choice) porting kit, polish all except for the intake bowls. Don’t polish the intake.
Test on Air Flow Bench
Once you’ve completed your cylinder head porting service yourself, test the flow of the heads on the air flow bench to see what kind of improvement you’ve made in air flow. After you test the air flow, test out the horsepower to see how much it increased.
Tags: Cylinder Head Porting