5.0 Mustang & Super FordsHow To Engine
Pure Street Mustang Engine - Pure Power
Flowtech Induction And Paul's Automotive Engineering Team Up For A Wild Trip Through A Pure Street Engine Combo
Horse Sense: At the time of this writing, the NMRA Pure Street class is booming. Expect to be heavily contesting for the 16 available qualifying positions if you decide this is your next racing endeavor.
Brought into existence during the birth of the National Mustang Racers Association in 1999, Pure Street has attracted an impressive number of 5.0 Mustang racers and fans. One of the most limited, and therefore most strictly enforced, classes in our sport, Pure Street requires racers to confine their engine combinations to less than 311 ci with mostly stock internals. A hydraulic roller camshaft of no bigger than 0.500-inch lift and stock hydraulic lifters are also mandatory. P/S engine builders must select their heads and intake from a list of street-oriented pieces that the NMRA has deemed legal. Other rules mandated by the NMRA include a minimum combustion-chamber size (58 cc for aluminum heads) to limit the degree of head milling done to raise compression ratio in an attempt to find power.
Racers must also decide if they want to run cast-iron GT-40P or stock-style heads, which allow for a smaller combustion chamber (40 cc), and therefore more compression at the expense of a less efficient head design as compared to some of the more exotic aluminum street castings available. Delving deeper into the NMRA rule book, you will find other small intricacies that are designed to keep P/S an economical and level playing field for all interested parties.
The bottom line is that P/S is a wildly popular class that requires strict attention to the guidelines laid out by the sanctioning body. Not surprisingly, there are more than a few experts who have stepped forward to address the growing needs of P/S racers across the country. One of the foremost experts on Pure Street racing in general and builder of killer class combinations is Ed Curtis from Coventry, Rhode Island. Ed's FlowTech Induction speed shop has been kicking out some awesome setups for this class since its inception. His dragstrip education began as a hands-on partner for a successful NHRA Stock Eliminator team. From there, his home-brewed horsepower turned into a lucrative sideline that still feeds many a 5.0 enthusiast full of motivation (see Street Car Desire sidebar). We had long wanted to work with Ed on a Pure Street combination story, but location and timing never seemed to work in our favor-until recently.
Enter Mike Wilson, head technician at Paul's Automotive Engineering in Cincinnati, Ohio (your author's hometown). When Mike's not tuning on 10-second supercharged modular cars or putting together 180-mph road racers, he works on his '82 GT project car that is destined to run in NMRA's Pure Street class. While Paul Faessler's shop is more than capable of putting together a competitive P/S combination, we persuaded Mike to try out some of the goodies offered by Ed Curtis so we could see things up close ourselves. In addition, Paul was quite interested in testing some of the newest Airflow Research cylinder-head castings (Ed has a long-standing relationship with that firm, which offers him sometimes proprietary access to its products). And Ed was looking for feedback from others in this field as a way to showcase his talents. Two speed shop owners who are willing to share ideas with each other? How refreshing!
What follows is a detailed parts examination of what it takes to make a killer Pure Street engine-almost 380 rwhp worth. If you follow what has been laid out in this story, there's no reason you can't be at the least competitive in NMRA Pure Street. As we watched the assembly of this 310, we couldn't help but be impressed with the thought that has gone into these class-legal motors. From the Faessler-built bottom-end components to the Curtis top end to Mike's "whole-car" attitude, we think you will be delighted with the results.
Street Car Desire
If you've read this story and thought to yourself, Gee, I bet this combination would make a nice street car regardless of the Pure Street rules, you're not alone. Much of Ed Curtis' experience with these parts has come through extensive testing on street-driven (and, um, street-raced) 'Stangs in his home area. A typical combination would consist of the AFR 165 head custom ported and prepared by Ed, a simple Cobra intake with some minor clean-up work, and a custom cam as prescribed by Curtis. Ed reports that there are dozens of cars across the country set up with this simple recipe for speed that he has worked with during the last few years. The results of this combination with the typical bolt-on supporting equipment that you probably already have is a car that makes from 315 to 335 rwhp and can rip off 11.80-12.20s depending on vehicle weight and other variables. The best part, Ed tells us, is that these cars suffer absolutely no loss in driveability and street-worthiness. Besides awesome power and good street manners, Ed says owners often report more than 25 mpg in fuel consumption. Sounds like a nice little package to us.