5.0 Mustang & Super Fords
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.
With the power and durability goals met, production began in November 2006. Only 500 PJ Saleens are to be built, and with production running anywhere from four to six cars-and thus engines-per day, the PJ program will last until mid-summer 2007.
Of course, veteran Saleen watchers that we are, we can't expect the PJ to be the only platform for which the naturally aspirated 5.0 Saleen engine is destined. Saleen has too much money invested in developing and certifying the engine to make a go of it with only 500 examples, so we're expecting another exciting development from this engine before it's done.
Being forgetful, we waltzed right out of Saleen's Irvine, California, headquarters without inquiring if the 5.0 engine parts would be available separately, but we suspect they will. Saleen has a goal of making every Saleen part available to the aftermarket-it's profitable and helps build the brand-so we suspect the crankshaft, connecting rods, pistons, and camshafts that are core to the Saleen engine will be available separately or in short- and long-block form.
Whether you buy a Saleen/Parnelli Jones Mustang, buy the parts to install in your own car, or are just looking for ideas, watch the PJ engine come together to see how and what is possible with the current Three-Valve Mustang GT engine. Enjoy the peek behind the curtain.
Everything not being reused goes into a scrap-metal bin. It's tough to watch perfectly good, new engine parts getting tossed into a scrap heap, but that's exactly what happens to the crankshaft, connecting rod/piston assemblies, bearing inserts, head bolts, dampers, camshafts, and a few other small parts. There's no ready market for the stock stuff, so it's off to the smelter with it. It still hurts to watch.
Here's a day's work, along with a few odds and ends from other projects taking place elsewhere in the building.
All parts are cleaned as necessary, which in many cases is not much. The engines have minimal run time, just the hot test at the Ford assembly plant, followed by whatever running they do driving the car off the line, onto the transporter, and onto the Saleen parking lot. That's just enough to put some color on the pistons and in the ports.
Saleen says Ford's machine work is surprisingly good, with extremely high accuracy in the align-hone and other critical areas. Apparently, cylinder bore accuracy isn't a high priority, so Saleen hones all PJ bores to 3.554 inches with torque plates. This 0.002-inch honing is to rid the cylinders of taper and make the power output more consistent engine-to-engine. It has nothing to do with increasing the engine's displacement; that's done by increasing the stroke.
Saleen found that Ford's 4.6 Mustang blocks taper 0.001 to 0.0015 inch in almost every cylinder. That may be good enough with a hypereutectic piston and so-so production tolerances, but not with the more precise fit Saleen needs with its forged pistons. To make untapered cylinders, Saleen bought a Sunnen CV-10 hone. It's a sophisticated honing machine, automatically measuring each bore's taper, then correcting it by dwelling or stroking as necessary. This graphical interface gives the operator a rough idea of the cylinder's shape.
Another area on the production Three-Valve engine that varies is the valve-bowl-to-valve-seat transition. Core shift can leave divots and ledges just above the valve seats, which Saleen cleans with hand porting. Only the bowl transitions are worked; the port match, shape, and other areas are left as-cast.
To get 302 ci of displacement, Saleen uses its own forged-steel crankshaft with the stroke lengthened to 3.800 inches. Bill Talley specifies an American forging for quality-control reasons; he knows where the steel came from and can better control the grinding finish. The resulting crank is of consistent high quality, sports the longer stroke, but doesn't include racy features such as weight reduction or knife-edging. They're not needed on a street engine.
Because high-rpm durability is important in the PJ engine, the Saleen crankshaft is internally balanced with slugs of heavy metal. "You aren't going to hurt this thing," Bill says of his 302 crank.
Saleen also fits its own billet-steel, SFI-approved harmonic damper to the PJ engine. It's balanced differently from the stocker due to the longer stroke and the different bob weights of the forged pistons and rods. It's designed with the PJ engine's internal balance in mind. The assembly also includes an underdrive belt pulley to avoid overspeeding the accessories at high rpm.
Bill selected strong-but-light American 4340 H-beam forgings for the PJ's connecting rods. They're slightly shorter than stock-5.850 inches-to package the stroke in the stock height block without pushing the ring pack into the piston pin. Otherwise, Bill is a long-rod sort of engine guy.
Bill wanted a strong forged piston but knew he had to fit it tightly to the cylinder for noise- and oil-control issues. Profiling the piston was the toughest job, done with much trial and error until the piston's barrel profile worked with a slender 0.002-inch piston-to-wall clearance. The tight fit is the main reason Saleen had to hone the cylinders to tolerances much tighter than Ford's. The lightweight versions are low silicon for low expansion, yet much stronger than stock. "Strength was the easy part," Bill says. The first attempts were durable, but horribly noisy. Fitting different profile pistons to test engines, running them to establish a wear pattern, then tearing down the engines to read the wear marks was the primary method of finding a profile that worked.
A good tool-steel, fully floating piston pin was one of the easier points to design in the PJ engine. Getting the pin below the oil ring was a bit more challenging but hardly impossible given the standard 1.5mm x 1.5mm x 3mm ring dimensions. The Saleen piston also features a V-shaped groove between the top and second compression rings. Bill says this groove fills with compression gas and prevents the piston from rocking so hard.
Sighting through the piston pin bore shows the snap-ring groove, an oiling groove, and a pair of oil passages used to lube the full-floating piston pin. The holes in the piston pin bore are visible directly; the matching holes in the oil ring groove are mainly seen here as reflections in the upper portion of the oil ring groove.
Camming up was a given for the rev-happy, naturally aspirated PJ engine. The difficult part was making power without stepping out of the 50-state emission limits Saleen faces in EPA certification as a manufacturer. The easier part is Ford has such tight noise, vibration, and harshness constraints-Bill describes them as crippling-that Saleen could find meaningful power in exchange for minor increases in NVH. The left and right cams are made to Saleen's specification by Comp Cams and are supplied with matching valvesprings and tough steel retainers. Lift and duration are nothing radical, staying within the 230 degrees of duration and 0.440-inch valve lift range. Having two intake valves keeps camming requirements sensible.
Variable cam timing is a relatively new tool for Saleen to explore in Ford V-8s. The Three-Valve's variable cam timing is driven by oil pressure and controlled by the engine management computer. Bill says Saleen's calibration differs from Ford's, but won't say exactly how. He does say that the system's default is fully advanced, with movement to retard powered by oil pressure. It's also finely adjustable. The high oil pressure over-powering the spring-loaded mechanism on the cam sprocket comes from the small electric motor mounted vertically at the front corner of the cylinder head. The cam timing is mainly joined with the electronic throttle to meet emissions, not produce more power. Bill characterizes the variable system as "a good little part. It has allowed us to do a lot more stuff."
Along with the smaller crankshaft pulley, the PJ uses Saleen's standard underdrive water pump and alternator pulleys.
Befitting their semicustom nature, the PJ engines are hand-assembled with the sort of care you'd expect from a hot rod motor builder. Rings are file-fit using this handy gap grinder, valvesprings are individually set up, and so on.
PJ engine assembly follows standard procedures and is done on typical engine stands moved through several locations inside the Saleen engine assembly department. The crankshaft and reciprocating parts are installed at one end of a climate-controlled room, which also sees supercharger system assembly. Here, a pair of PJ engines begins reassembly, a typical scene as the techs drop in one of the 2,000 piston and rod assemblies in the PJ program.
New Fel-Pro head gaskets are used, as are new cylinder head bolts.
After porting, PJ cylinder heads are assembled using their stock valves (lapped to check the valve job) and the upgraded valvesprings and retainers in a room near the porting closet. No other milling or cleanup operations are necessary. Once assembled, the heads are carted to engine assembly, where they reunite with a short-block.
To avoid any unpleasantness associated with loose hardware dropping down an intake port during assembly, Saleen temporarily fits blanking plates over those ports. Pointing straight up as they do, they make handy funnels.
Likewise, with the engine timed, stock valve covers are bolted in place. At this point, the engine is beginning to take shape in a surprisingly short time. Of course, most of the tedium in building modular V-8s is in setting up the cylinder heads-even the timing chain assembly goes fast when you do five engines a day. The techs admit to having an engine nearly all together, then spying the crankshaft timing wheel on the bench. It's a mistake they only make once.
As the new head bolts are being torqued, the stock oil pump, timing sprockets, guides, chain, tensioners, hardware, and so on are reinstalled, as they all work fine in the PJ engine. Two-man teams such as these are common during assembly, but aren't necessarily the norm. In the background, rows of black superchargers await assembly once the PJ production run is finished.
Bill says most aftermarket forged-piston short-blocks are so noisy from piston slap that the detonation sensors must be switched off. The PJ engine's tight-fitting pistons are quiet enough to work with the stock knock sensors, so they're reinstalled and used to provide Ford's excellent antidetonation protection from low-octane fuel, hot weather, and so on. Next to the knock sensors in the valley is the coolant temperature sending unit. The techs say it must be lightly torqued, as shown here, or it breaks off in the head.
Testing showed the stock cast-iron exhaust manifolds were not a hindrance to making 400 hp, so they are reused. This has many benefits, including a quiet, durable, leakproof seal at the cylinder head, and along with easier emission compliance. As the manifolds are well hidden by the wide engine, no attempt at cleaning or painting them is made.
When the long block is complete, it's wheeled to the next bay in engine assembly. There, the intake manifold and front engine dress is installed.
Saleen uses the stock plastic intake manifold, but without the Charge Motion Rumor Controls Ford uses to control in-cylinder airflow. Saleen finds them restrictive, and the company is able to get the desired torque and the low emissions needed without them. In the car, the PJ engine uses the stock 2x54mm throttle body, a Saleen 98mm mass air molded into the air filter box cover, 98mm intake tubing, and its own Shaker hoodscoop.
Once dressed, the finished PJ engine is ready to rejoin a PJ chassis. No attempt is made to fit the same heads and blocks together, nor are blocks rejoined to their original chassis. The installation itself goes quickly, as the techs know the right angles and tricks to dropping these engines in place. As noted earlier, the PJ engine is installed immediately after the stock engine is removed on the assembly line. This is done at one end of the three-row line so access with the engine hoist is good. A vacuum-powered coolant fill and a bulk oil fill finish off the job.