OEM VW Parts - Discount Volkswagen Parts

Performance - Gasket Matching Manifolds

Port matching VW intake and exhaust manifolds.

This is not meant to be a step by step guide or instruction on how to port match your manifolds. It is simply an overview of what it is and how it is done.

The idea here goes along with the thought that a Volkswagen internal combustion engine is a giant pump. Air goes in and gets pumped out as exhaust. The faster you can get more air in and exhaust out, the more power you will make.

We're not going to increase the volume of the VW manifolds to allow more air in, however, we are going to make them work more efficiently. Every time a VW manifold bolts up to a manifold part or the head, there is a step up or down, or a simple misalignment. Either way, its is not a smooth transition on most cast VW parts. It can be a step of over a 16 th of an inch on some cars. This step causes a ton of turbulence, slowing the air flow. This happens on the intake manifolds when it reaches the head, and on the exhaust manifolds. On a VR6, there are two part intake manifolds and exhaust manifolds, so there is even more room for a bad transition. Now through in another possible interference from the gaskets not lining up nicely and you've got yourself the makings for poor air flow.

The fix? Well, the cheapest (nearly free) way to fix this is to use a dremel tool or air powered die grinder (only if you know how to use one!). The dremel is the safest way, since it cuts so much slower. Using the larger sized coarse sanding drum the idea is to grind away the material where the gaskets, manifolds and head do not line up straight with each other. An easy way to check this is to put the gasket on one side of the manifold, and mark the inside where the manifold material is a smaller diameter than the gasket opening. Mark it with a sharpie, then place the gasket on the other part that the manifold mates to, the head or another manifold section. Mark the material that shows through the opening in the gasket.

With your dremel and sanding drum, start grinding out the area you've marked into a smooth transition, probably about 2 or 3 inches into the manifold. On the head go no more than a 1/2 inch in or so, or you could start to change the shape of the ports inside. 1/2 inch should be plenty safe for VW heads. Go back over the grinds with the find sanding drum.

The idea is that the airflow never runs into a vertical edge of material. It is ok if the airflow drops into a larger area, but not if it suddenly runs into a vertical area from the manifolds not lining up or a gasket protruding into the manifold. Most gaskets on intake and exhaust manifolds have larger openings to be sure that the gasket material won't get in the way of the flow, so this allows you to have room to grind some of the manifold material away.

On the intake side of the head, you want the opening on the head to be larger than the manifold, so always do the downstream parts first, so that you don't make transitions that work against what we are trying to fix. on the VW exhaust side of the head, the manifold should be the larger opening, so that the exhaust does not run into a road block on it's way out.

Again, only remove the minimal amount of material to accomplis a smooth transition. This is not a port and polish, it is a simple gasket / manifold port matching job. Some people have reported several HP gains from smoothing out the transitions on a VR6.
For the price, it's worth it.