Project X-Rated

In the past installments of Project X-Rated, we worked on our chassis and did an overview of the transmission buildup. Although our racecar is rolling around the shop, it still needs some more work to get it ready for dragstrip action. We are moving along with our project, and in the next few issues, you will be reading about the engine buildup. This car is slated for action in the PRO-Edelbrock Street Legal Drag Racing Series, and the class we have chosen is called Xtreme Street. We went to a few races to scout out our competition, and let us tell you, these guys are serious! It prompted us to build a stout engine in order to run in the mid-8s.

The first order of business in our engine buildup is the cylinder heads. PRO tech officials provide a list of cylinder heads for all engine combinations. This keeps the high-end exotic stuff out of competition. The small-block Ford engines can choose from virtually all in-line valve cylinder heads that are commercially available. Officials kept the exotic Yates, Brodix, and canted valve style heads out of the class. This does a few things. First it keeps our budget under control. We all know that the high-end racing heads require quite a bit of exotic (read: expensive) work. A serious set of Brodix or Yates heads can cost upwards of $10,000. That is definitely not in our budget. It also helps keep all the engine combinations running similarly since there is a wide variety of engine types. It is easy for the PRO officials to keep the small-block and big-block combinations at or near the same performance through the use of approved cylinder heads. It keeps the competition fair and, most importantly, equal. The class usually consists of cars running in the 8.40-8.50 range, right where we expect to be with X-Rated.

We chose Edelbrock Victor-Glidden (PN 7709) heads from the approved list. They feature a generous 15-degree valve angle and great flow numbers on the flow bench. The 7709 heads are essentially a modified version of the 7721 Victor heads. Racers stepped up to the 7721 Victor cylinder heads shortly after their release in 1999/2000. It did not take long for Billy Glidden to get his hands on a set and start playing with them. He convinced the Edelbrock folks to make some revisions and make this head even better for specific racing applications. That spawned the idea for the Victor-Glidden series of parts that now includes the 7709 cylinder heads and some intake manifolds. Edelbrock even has Glidden on the payroll as a consultant for its nitrous systems. The changes are not radical, but they do help performance, and most Hot Street and Street Bandit competitors in NMRA and Fun Ford Weekend utilize these heads.

We ordered these cylinder heads in the "as-cast" configuration since we'll be using our own cylinder head porter. Edelbrock does offer CNC versions from Chapman Racing, but we chose our own head guy to do the work. Dave Jack Cylinder Heads in Rahway, New Jersey, is home to a five-axis CNC machine, and owner Dave Jack is an accomplished cylinder head porter. His work can be seen on many heads up Mustangs racers, including Briante Racing, Jim Blair, Mike Modeste, Dwayne Gutridge, and Elias Delatorre.

After the heads were CNC-ported, they are brought to the hand-porting section of the shop. Here Jack worked on finishing off each port by hand, making sure everything is done correctly. A flow bench is used to maximize airflow and ensure each runner is equal. "The exhaust side of the head is important with a supercharged engine," said Jack. With that in mind he used a 2.150-inch valve for the intake and went with a large (by exhaust valve standards) 1.650-inch exhaust valve. What goes in, must come out. We plan on cramming over 20 psi of boost into this engine with a Vortech X-trim blower, and we need an efficient way of getting the spent gases out of the cylinders. Maximum flow on these heads is pegged at 381.60 cfm on the intake side and 280.85 cfm for the exhaust. Both numbers were generated at .800-inch lift. Jack used a 4.060 bore and 28-inches of water to conduct the tests on his flow bench.

"I like the Victor-Glidden heads because of the flatter valve angle, which helps the valve sit in the bore better--away from the cylinder wall," says Jack. He also pointed out the heads have a great spark plug location, and he likes the port location. Check back with us in the next installment when we bolt these heads on to our engine. We have an 8.2-deck, A4 block that has been filled with a Scat crank, Crower billet rods, and JE pistons. Once we have the engine assembled, we will be bolting on the supercharger. Horsepower numbers are expected to be over 1,200, and we hope that will push us to mid-8-second times at around 165 mph in quarter-mile competition.

Stay tuned.