Bryce Mulvey: "A CNC machine only cuts the ports. It takes someone that knows what they're doing to create that port in the first place. Just because a head is CNC machined doesn't mean it performs as well as any other CNC head. It takes us three to four months just to design a port, and we might ruin five to six heads in the process. We then digitize the ports, cut the heads, and figure out which parts of the head are off the mark and correct the program accordingly. The tooling used to cut the head also impacts consistency. It takes a tremendous effort, but once the process is complete, you can replicate the port you spent hundreds of hours creating very precisely. Our goal is to get our CNC heads flowing within five cfm of our prototype ports, which is very hard to do. No one's going to be able to pay $6,000 for a set of heads, and the CNC machine allows you to pack $6,000 worth of performance for a fraction of the cost."

Airflow Needs
Darin Morgan: "To properly select the correct heads for any given application, you need to determine your engine's intended use (drag, endurance, etc), volumetric efficiency, rpm range needed for your target hp, valve area needed to achieve sufficient airflow for your target hp, piston and cylinder head peak cfm demands, target air speeds throughout the induction system, volume of the overall induction system, resonant tuning characteristics, and carburetor airflow requirements. Once you answer all these questions, then you can pick out the perfect cylinder head and induction system. It's complex and no simple three or four variable equation is going to give you a sufficient answer. It takes experience and a lot of mathematical evaluation of the entire system to come up with the answer. Port design is not as simple as most people would like to think. This is why you see that most of the top port designers have 25-plus years of experience under their belts. So how is a new up-and-coming engine builder or hot rod enthusiast supposed to make a well-informed decision? With education, a person can now learn the underlying variables and characteristics that govern the induction system. With today's porting schools and long-term tech schools, a novice can learn to design basic ports in one tenth the time it took my generation. One short-term crash course is my two-day Advanced Induction System Design School. The school consists of a decade of information crammed into 20 hours. Anyone who has been through it can tell you that it will leave your head spinning with enough information to keep you thinking for the next year. There are also software programs such as Engine Analyzer Pro and PipeMax that can show people their engine's all-important airflow demand versus their cylinder heads' expected airflow. With Engine Analyzer and PipeMax, I can run calculations to properly size certain areas in the port in as little as 30 minutes. Before this type of software came out, it would have taken a day to do all the calculations."

SOURCE
Air Flow Research
28611 W. Industry Drive
Valencia
CA  91355
661-257-8124
www.airflowresearch.com
Dart Machinery
353 Oliver Street
Troy
MI  48084
248-362-1188
http://www.dartheads.com
Trick Flow Specialties
1248 Southeast Avenue
Tallmadge
OH  44278
330-630-1555
www.trickflow.com
Racing Head Service
3416 Democrat Road
Memphis
TN  38118
877-776-4323
www.racingheadservice.com
Brodix
301 Maple P.O. Box 1347
Mena
AR  71953
479-394-1075
www.brodix.com
Darin Morgan Cylinder Heads
Dayton
OH
www.darinmorgan.com
Pro-Filer Performance Products
New Carlisle
OH  45344
937-846-1333
www.profilerperformance.com
Doctor J's Performance
531 SE Central Park Ave.
Anaheim
CA  92802
715-527-2769
j-performance.com