It has long been known that the Chrysler LA series small-block engine can be a real powerhouse if the proper combination of parts is used during the build, and that cylinder head choice is an important factor when it comes to engine power. Even more important than cylinder head selection, however, is the work that goes into those cylinder heads. While many factory and aftermarket cylinder heads can make decent power right out of the box, power potential can be greatly improved by properly performed port and combustion chamber work as well as a good multi-angle valvejob. Unfortunately, if port work is done improperly, there can be great expense with limited benefit in terms of real engine power. Luckily, there are companies like Hughes Engines that have done their research, providing cylinder head modifications that are not only cost effective, but have proven results in terms of cylinder head flow, torque, and horsepower. This month we'll follow along as the Hughes team discusses cylinder head theory, and applies what they've learned to Edelbrock's popular Performer RPM line of small-block Mopar cylinder heads.

Any engine can benefit from cylinder head air flow increase, whether it comes from a custom valve and seat job, bowl porting, or all-out port and combustion chamber work. But when considering how far to go with the heads, an engine builder has to decide what gives the most bang for the buck. The cost of ported heads directly relates to how much work is put into the cylinder heads, and at some point cost can go way up with limited benefit which is called the point of diminishing returns. What Hughes has figured out is that the most beneficial cylinder head work actually involves increasing flow at the low and mid valve lifts, because it benefits the total air flow twice, once during valve opening and again as the valve is closing. Porting for flow at maximum lift can have benefits, but since the valve is only at max lift for a short period of time, contribution to total air flow isn't nearly as beneficial as porting for maximum flow at low and mid-valve lift.

This is not to say that you shouldn't port for the best flow at max lift, but if you're on a budget, you'll see higher power and torque improvements by working the cylinder head for the low- and mid-lift portions of valve travel. Also, if this work is done properly, the head can be fully CNC or hand ported at a later time, to improve flow at maximum valve lift if desired. To demonstrate this theory, Hughes applied their CNC Super Prepped Heads program to a set of the popular Edelbrock Performer cylinder heads for the Chrysler small-block engine.

Hughes Engines has found that the most important area of the port is the valve seat and the one half inch area before and after the seat. The actual valve seat and the angles and widths are the most critical area and receive as much attention during research and development as the rest of the entire port, so they begin any port job with the seat. The intake seat is generally comprised of a number of special angles and widths, and will vary depending on the configuration of the port and valve. Hughes specifically designs the angles and widths of the intake valve seat to improve the low- and mid-lift air flow and wet flow of the head. Don't be confused, however, that the low- and mid-lift improvements only improve low- and mid-range power. Improving flow at these lifts will improve power at all RPM levels.