OEM VW Parts - Discount Volkswagen Parts

Performance - VR6 Big Valve Heads

VR6 Big Valve Head - Why? What does it do?

One of the few weaknesses of the Volkswagen 12v VR6 found in the VW Corrado, VW Jetta, VW Golf / GTI, and VW Passat from 1992 to 1999 is the head design. It does what it needs to just fine, but there is much room for improvement in air flow. There are a few things involved that make this somewhat difficult to really improve the Volkswagen VR6 head design. The VW VR6 head is not that great at moving air.

One of those things is the fact that the air intake runner length from manifold to valve is longer for the rear 3 cylinders than it is for the front 3. This is because the runners feeding rear bank need to be routed past the first bank of cylinders to get to the rear bank of cylinders. Ideally this runner length would be equal for all 6 cylinders. Again . . . the VW VR6 head is not that great at moving air.

Another catch is that the port openings for the rear bank is a different shape and size than the port opening for the front bank of cylinders on the VR6 head. This makes good results by porting the head difficult. The VW intake manifold has some role in equalizing the amount of air reaching the cylinders too. Once more. . . the VW VR6 head is not that great at moving air.

And finally, the Volkswagen 12v VR6 only has 2 valves per cylinder. The 24v VR6 sees a large power increase mainly due to the better flowing head with the 4 valves per cylinder design. Both are 2.8 liter 15degree V6 engines. . . You know....

One solution for opening up the VR6 head and allowing it to 'breathe' more efficiently is by installing bigger intake and exhaust valves along with the port and polish. Bigger valves can ultimately flow more air. The biggest gains in power are while using a big valve VR6 head with forced induction, but the big valve heads are also used in naturally aspirated form.

Now add to the big valves, a 'bigger' cam, higher lift that is. This will cause the valves (which are already large in a big valve head) to lift open further, allowing even more air into the cylinder. When you start messing this seriously with a VW VR6 head, you need to consider engine management too. Your stock ECU (Electronic Control Unit) might not have the ability to control the fuel to air ratio good enough in these conditions. By having a reprogrammed ECU, the engine will get the right fuel injected to match the new amount of airflow.

The more air and fuel the engine can burn effectively, the more power the car will make.