Advanced Technology Gives Cylinder Porting a Boost

      Cylinder porting is one of the most difficult types of machining jobs. That job is especially critical for the engine shops that build the 700-plus horsepower engines for NASCAR racing. Horsepower, torque, and acceleration are the keys to winning a race and refining the art of porting can give a team the edge they need to win.

      For the lowdown on NASCAR racing you have to visit Mooresville, North Carolina, also known as Race City U.S.A. When it comes to superior cylinder porting the majority of engine shops in the area have one thing in common: Surfcam CAD/CAM software by Surfware, Inc. Why? Because Creative Dezign Concepts (Mooresville, North Carolina) located at the heart of NASCAR action, has been involved in the development of a software utility specifically designed for the challenges of porting that works inside Surfcam. Called AME (Advance Motion Engineering) Utility, it increases the productivity of porting cylinder heads and intake manifolds.

      The process of porting is more of an art than a science. An initial prototype is created by hand, tested for optimum airflow and power, then refined by hand until the desired performance is achieved. For a prototype cylinder head one exhaust port, one intake port, and one chamber are developed. Once the design is complete, the part is digitized and computerized surfaces are generated. To create all of the ports required for a cylinder head, the port surfaces are duplicated and positioned in the correct locations. Then the CNC tool path is generated to cut the part. Creating the ports in this manner is faster and produces a better quality product. Ports can be cut in less than one tenth the time it takes to cut them by hand and the ports are consistently the same. Once a design is complete any number of heads or manifolds can be produced that are exactly alike.

      One feature of the AME Utility is a filter that corrects imperfections in the digitized point data. Digitized data passes through the AME filter where points are smoothed and aligned then brought directly into Surfcam. From there, surfaces can be created using a variety of methods. The strength of the AME Utility becomes obvious when tool paths are generated. Because of the complex shapes involved, there is a strong likelihood of the tool crashing into the part. With AME, the tool is constrained to cut through a pivot point and new pivot points are calculated based on what has already been cut and what remains to be cut.

      Steve Long, CNC shop manager for Dale Earnhardt Inc., uses the AME Utility extensively "The ports on a cylinder head are just like a worm hole. They go in and start twisting around. You've got to be able to keep the shank of the tool from running into the side of the part, so the only way you can go very far in there is if you move the vector point. With AME, it moves the pivot point around so you can keep the tool from crashing into the opening of the part. No matter where you go on the inside of the part you've got to go through the hole you've just cut so you're very restricted in machine movement."

      Wilson Manifolds (Ft. Lauderdale, Florida) is on the cutting edge of induction technology for intake manifolds used on NASCAR racecars and trucks. The manifold is the main distributor of air and fuel to the cylinder heads and by making adjustments to the manifold a race team can generate more torque for short tracks or higher horsepower for high-speed tracks. Wilson Manifolds has helped the top NASCAR teams achieve poles and wins at every NASCAR track. Mike Littlejohn, CNC manager, is responsible for all of the digitizing, surfacing and CNC programming at Wilson Manifolds. Littlejohn states "I use a CMM to digitize the prototype, then take the IGES point data through the AME filter, import it into Surfcam and build surfaces through the points. Then I generate tool path using a variety of methods. Surfcam is very strong in four and five axis machining. I use the AME Utility for all of my five axis machining. What I do is impossible without the AME Utility. It also eliminates the problems of digitized surfaces with imperfections or ripples."

      When asked about automating the process of engine design, Steve Long of Dale Earnhardt Inc., remarked "It hasn't been that many years ago you had to be in the aircraft industry to even have access to the money it took to buy the machines and the software to do this. Surfcam is probably one of the better and more affordable modeling packages. For my ports and reverse engineering it's pretty easy. It's fast and PC-based. There are other CAM packages out there that have very powerful features, but they are labor-intensive and the training periods are naturally going to be a lot longer. With Surfcam you can take someone with a solid machining background who's patient and willing to tackle the job and get it handled in a relatively short period of time."

      Jim Mann, CNC shop manager at Petty Enterprises, says, "I machine just about everything. Cylinder heads, all the fixturing, all the bracketry and anything else. I use the AME Utility for porting the cylinder heads. That's the only way to go as far as I'm concerned." Mann does all of the CNC programming, all the digitizing, all the surfacing, and all the machining in the engine shop.      

      "It's about a six-day job to get a set of heads ready to cut. Then I can make as many as I want. I've made 56 sets in the last four months." It's a true understatement when Mann says "It keeps me busy."

      For more information contact:
      Surfware, Inc.
      5703 Corsa Avenue
      Westlake Village, CA 91362
      818-991-1960
      Fax: 818-991-1980
      www.info@surfware.com
      E-mail: info@surfware.com