Mopar 906 Cylinder Head Improvements - Making The Most Of 906 Heads

If you're like us, you remember the days when there were literally no aftermarket aluminum cylinder heads available for the big-block Mopar. Back then, enthusiasts who wanted more power either hand-ported their own heads using the Mopar Performance templates, or paid a professional to perform the time-consuming work. While the end result of hand-porting depends on the skill of the person doing the work, ported 906 heads can perform very well, and are generally able to provide enough flow for 600 or more horsepower in extreme cases. So why don't more racers and engine builders use the 906 heads? The answer is purely economical.

While 906 heads do perform well when ported, the labor involved with hand-porting these heads, combined with the cost of new valves, springs, etc, has made it more economical in most cases to simply buy a new set of aluminum aftermarket cylinder heads. So if you want the look of a factory head, or if the class you race requires a factory cylinder head, you could have a good chunk of change wrapped up in cast-iron cylinder heads. Realizing this, and knowing the potential of the 906 casting, engine builder Mike Ware of Muscle Motors decided to take action. Knowing that the hand labor of porting cylinder heads adds greatly to the cost, Mike decided to design a CNC program to port these heads, thereby reducing a good portion of the labor involved and making ported 906 heads more affordable than ever.

Starting with factory 906 castings, Muscle Motors completely cleans and inspects the heads before treating them to their proprietary CNC porting. This CNC machine work doesn't only address the intake and exhaust ports, but also reshapes the combustion chamber for more efficient flow. Once the machine work is finished, new guides are installed where needed, and the heads are assembled with Milodon 2.14-inch intake and 1.81-inch exhaust, one-piece stainless steel valves, Comp Cams retainers and 10-degree locks, and Comp springs to match the customer's camshaft. Though factory chamber volume is 79 cc's, the CNC ported 906 chamber volume is increased to 86 cc's. Hardened valve seats are available at the customer's request, and the heads can be further milled to reduce chamber volume if needed.

The net result is a set of factory appearing 906 heads, with well above factory performance, all at a reasonable price. After porting, the 906 heads flow an impressive 313.1 cfm on the intake side and 223.5 cfm on the exhaust side at .600-inch lift. Using the rule of thumb that cylinder heads have the potential to support horsepower double their intake flow, these heads are capable of 600 hp or more when used on a well-built engine. That kind of potential certainly makes the Muscle Motors CNC ported 906 a viable competitor when compared to other heads in the same price range, and gives enthusiasts a good product while retaining a stock appearance.