Do I really need a port divider? Will I get better performance with a port divider? Will a port divider increase my mileage? Will my exhaust sound better with a port divider? Will a port divider prevent a blown header gasket? These are questions that have been asked and discussed many times over on the fordsix forum, and questions I get via e-mail almost on a weekly basis. As such, I decided to share my thoughts and let you make up your own mind.

According to the manufacturer's website, the port divider was designed to separate the siamese ports (3 & 4) to create equal exhaust flow, which creates equal amounts of power from each cylinder at all RPM's, thus resulting in an increase in horsepower, up to 10%.

We have never seen documented proof, hard data, or dyno results which supports the manufacturer's claims. Nor has there been any independent testing, that we are aware of. Therefore we will not dispute their claims, we will simply state what we know to be fact.

First, in order for each cylinder to create an equal amount of power, each cylinder must receive an equal amount of air/fuel mixture. Given the design of the log intake manifold, with unequal runner lengths, the center two cylinders receive a greater charge than do the outer two cylinders. As such, the center two cylinders have a tenancy to run rich, while the outer two cylinders run leaner.

Ford intentionally designed the cylinder head with Siamese ports, therefore one must assume that they had a reason for doing so. It has been theorized that Siamese ports may provide greater savaging of the exhaust gases, as well as a portion of the intake charge. Could this have been done to offset the poor air/fuel distribution of the log manifold, in an attempt to balance the intake charge? The additional savaging might help to lower cylinder head temperatures as well? If so, installing the port divider may actually have a negative result.

While the manufacturer now recommends tack welding the port divider in place, many forum members used JB Weld, as this method did not require removal of the cylinder head. As such many of the port dividers broke loose, which resulted in a loud and annoying rattle. Not wanting to pull the cylinder head off a freshly rebuilt motor, most members simply removed the port divider to put an end to the rattling. While they had no idea if the port divider added power, simply because they did more than just add the divider when building their motors, they now had the opportunity to see if it made a difference once removed. Not one single member observed any difference whatsoever in the performance or mileage. As for the exhaust note, there were no comments one way or the other. Therefore we assume it made no difference, or the change was so minuet, it simply wasn't detectable.

The final question, does it help to prevent blown header gaskets? This is a tough one to answer, as we have heard of blown header gaskets with the port divider, and without. However, while blown gaskets seem to be more common without the divider, this is not to say that it makes any difference, as there are literally hundreds of engines without the divider that have never blown a gasket. My own personal opinion is that it may make a slight difference when the header is installed improperly, but if the installer follows proper procedures, they won't have an issue either way, with or without.

Considering the above information is based on hearsay, and not from our own personal experience, we plan to dyno test a port divider sometime this spring, while we are testing a few modified cylinder heads. Our goal is to provide our customers with the best possible advise for building a performance six, even when the product is one we don't make, or sell.

Manufacturers recommendation for installation: The port divider is to be hand filed and placed in the siamese exhaust port (cylinders 3 & 4) and tack welded in 3 spots with N-99 welding rod, to keep it securely in place. DO NOT pin, braze, JB Weld, etc.

Without Port Divider	With Port Divider