5.0 Mustang & Super FordsHow To Engine
Parnelli Jones Mustang 5.0 Liter Engine Build - Jonesing For Displacement
Saleen Shows Us How The Cubic Inches Are Put Into The Parnelli 5.0 Three-Valve
Horse Sense: Following the PJ engine build reminded us just how large Saleen has become. Twenty years ago, when we first visited the old Saleen Autosport facility, the Mustangs were strictly bolt-on rides, assembled in a row of open-air, three-sided repair stalls at a Ford dealership. While it's been up, down, out, and back in again for Saleen since then, having to hike through the current Saleen facility to follow the PJ engine through removal, undress, machining, assembly, and reinstallation drove home the big changes the company has seen.
To scan our report on the Saleen/Parnelli Jones Mustang in the June issue is to know we find its engine a naturally effervescent wonder: 400 unblown, bubbling horsepower. It's a refreshing change from the "take two blowers and call me in the morning" speed prescription we've all gotten hooked on in the modular engine era, and it's certainly worth a deeper look.
Thinking an investigation into what makes the Saleen/PJ engine rip would make us better understand the car, as well as give all of us some Three-Valve ideas, we headed straight to Bill Talley's office at Saleen. For a get-it-done racer, Bill toils under the weight of the vice president of engineering title. That makes him responsible for everything from S7 Le Mans race engines to S281 hubcaps, but at his core, Bill is an engine man. With a long history in motorcycles, Sprint Cars, Winston Cup, Trophy Trucks, and now Saleens, he has been the big piston under the Saleen hood since the late '90s.
When Parnelli Jones and Steve Saleen got together on the PJ project, Bill knew he had to do something different, something evocative of the Boss 302 Parnelli made legendary. "Number one, we needed something to delineate ourselves from everyone else," he says. "We had already gone one way with the blower [on the S281 Super-charged and S281 Extreme Saleen Mustangs]. We're getting our niche in powertrain, more so than in the past, so we wanted to do a lot more to the engine. The 302 is a natural for the Mustang."
Putting all that together, Bill took the high (rpm) road, searching for horsepower the hard way in this age of stringent emission certifications and sophisticated driveability tastes. So, with a goal of 400 hp, the standard Mustang GT Three-Valve engine was poked, stroked, prodded, and combed through for workable, real-world power. Bill came up with the usual two needs-more air through the engine and an increase in its mechanical strength in the face of higher rpm.
We'll let the photos and captions give most of the details, but in general, Bill found his power in a combination of increased displacement via a longer stroke and better breathing through more aggressive camming and a higher power peak. As for working with the Three-Valve cylinder head in a street performance engine, Bill was favorably impressed. He cited that the Three-Valve has superior breathing without the expensive, large combustion chamber and the low-speed lazy intake dynamics of Ford's Four-Valve head.
It's important to note that Saleen is, as much as is necessary, blueprinting these PJ engines for power and longevity. The cylinder bores from Ford are too random for the tight clearances of the Saleen forged piston, so they're bored to tolerances of "a couple of tenths," which is tight.
The cylinder heads feature some core shift around the valve seats, so those are hand massaged to assure smooth airflow.
Other areas are left alone because Ford builds the engines right from the beginning. Ford's main bearing align-hone is spectacular, according to Bill. "Less than one percent [of PJ engines] need an align-hone, even for our tolerances." The blocks have proven well-machined in most other respects as well. As a rule, they require no decking or other straightening, meaning Saleen can disassemble the engines, hone the bores, put some TLC into the cylinder heads, then reassemble the engines using a few special Saleen parts.
Some Ford parts are pumped up. The main and rod bearings are antifriction coated, for example. They help with any dry starts, and the tight clearances run with today's thin oil. "We only run 0.001 inch on the mains and 0.0015 inch on the rods," Bill says. "If you don't keep the oil pressure up, the variable cam timing deal won't work, so you have to maintain tight clearances to keep the thing working right." It also means a tight, quiet, hard-running engine that should last.
Other parts were tried and found unnecessary. A high-pressure/high-volume oil pump didn't work with the variable cam mechanism and wasn't needed anyway, so the stock oil pump is reused, as are the stock pickup and oil pan. While the cylinder heads respond to cleanup around the valve seats, they need no milling and the valves are high quality.