Hot VWs - November 2011 - Big Breathers!
CB Performance's Comp Eliminator street/strip performance heads have been around since 1993, and extensively updated in 2011.
BY BRUCE SIMURDA
Looking back, it's hard to imagine that CB Performance's Comp Eliminator cylinder heads were introduced over 18 years ago. Back then, the original design came about as a combination of two other popular heads of the time, CB's Street Eliminator and the Super Flo. The idea was to create a performance cylinder head with high-flowing Cosworth-style intake ports, but with VW-style valve covers so they would fit into a VW sedan. Not only were they great full-race heads, they could be used in radical street cars. In all, from design to testing and production they were a several year project, first going on sale in 1993. Since then, over 5,000 Comp Eliminator heads have been sold worldwide.
Of course, a lot has changed since 1993. Originally, these hand-ported heads had all the standard high performance components of the time - like stainless steel valves and stock Chevy springs - and they had extra long valve stems to accommodate mega-lift cams. Today, serious high performance engines utilize components far superior to those of yesteryear, like huge titanium valves, titanium retainers, super-heavy K-Motion racing valve springs and beryllium copper valve seats. Rocker arm designs and strength have improved greatly since 1993 as well, with ratios as high as 1.5:1 and valve lifts over .650-inch! All these improvements in the supporting components can produce more power than ever before when assembled properly, but they also increase the pressures and stresses on the basic cylinder head itself. That's why, in 2009, CB Performance decided to take a serious look at the Comp Eliminator head, and find ways to both strength it and improve its performance characteristics.
The newly redesigned Comp Eliminator head, which was released in March of 2011, has a variety of improvements that make it both more efficient and reliable. One area that has changed is the Cosworth-style ports themselves. Originally hand ported, and then CNC ported for the last several years, the new ports have been moved outward .040-inch to provide a straighter shot at the valve, which are (interestingly enough) cast smaller than the previous heads. The ports were kept smaller for several reasons, including to increase velocity, as well as to allow plenty of room for race engine builders to do their own thing (port to their own dimensions). The rocker box area also received several changes. Perhaps the most noteable is in the floor of the box, where additional material was added to strengthen the rocker stands. This change is very apparent when you look at the depth of the valve spring pockets, which themselves received a double-step to provide better clearance. To compensate for ultra-high rocker ratios, the pushrod tube holes have been moved down .100-inch to better match the location of the pushrods, and the bottom of the valve cover wall was moved down for clearance as well (stock valve covers still fit!). Even the rocker blocks were modified, with an increased radius for better strength. With all these improvements, there is one thing that has never changed - they're still made in the USA.
Today's CNC ported Comp Eliminator cylinder heads feature valve sizes up to 48mm intake and 40mm exhaust (with 94mm bore), and 54cc combustion chambers. On CB's own SuperFlow bench we watched as they flowed a maximum of 260cfm - out of the box with match-ported manifold - which is the kind of numbers you need to make big horsepower. And according to CB's Kevin Lewis, these heads are not just for drag cars, as many of them are running on the street today, including a So Cal group running 3-liter "street" engines. Definately, a lot has changed in 18 years!