Tom Wilson
January 1, 2003

Horse Sense:
While turbos muffle the exhaust, they make noise of their own. With whistling from the intake, whooshing from all the pipes, and a big ssssssh from the pop-off valve, this twin-turbo setup has a definite presence.

Chris Barnes was clearly thrilled about the power his 1,253hp twin-turbo small-block put out, yet in a bit of shock about it as well. After years of scrounging together parts, laying out acres of green cash, and jumping through the flaming hoop of technology several times, suddenly The Engine was a real and formidable entity. Chris now thoroughly understood he was going to have to strap it to his back and step on the loud pedal. Hmmm.

That, and how in the world did all this come about?

Well, it transpired in the usual way, through a bit of craziness and a lot of hard work. Because you are reading this magazine, we don't have to explain the crazy part. The hard work, well, that's as simple as putting a working man's fun budget into the "Speed costs money-how fast do you want to go?" formula and making the necessary calculations for "really fast."

When Chris bought his Cartech Twin Outlaw turbo kit, it included 131/44-inch primary headers collecting into four-bolt TO-4 flanges and wastegate mounting assemblies. After the turbos, the so-called "down pipes" are 3-inch units, flaring to 311/42 inches right before the muffler.

A mining-equipment manufacturer's representative, Chris figured he'd do something a bit out there this time around with his clean, blue '89 Mustang LX. A Powerdyne had already been through the engine compartment, followed by a ProCharger. Why not install a twin-turbo setup and have a go at Wild Street? Well, if you live in Phoenix, Arizona, we can think of a couple thousand miles of reasons why, but what the heck, John Urist goes almost that far for Outlaw.

Not having a huge budget, Chris carefully shopped for good used parts, ending up with a second-hand but unused Cartech twin-turbo kit and all the parts for the basic engine. All told, Chris believes he has $12,000-$13,000 in the engine, which is real money, but in dollar-to-horsepower terms is actually quite reasonable. Scratch-built, dedicated race engines in this league can run twice that amount.

The "good-used" approach on a turbo engine is not so bad, because dedicated turbo engines are not exotic, just built from really strong parts. An A4 block bored to 4.060 inches, a billet Scat crankshaft whittled in the good, old USA to a 3.250-inch stroke, forged Ultralite Oliver rods, and forged JE reverse-dome pistons provide the stout foundation with a turbo-friendly 8.0:1 com- pression ratio. Breathing is via 2.05x 1.600-inch stainless steel-valved Edelbrock Victor Jr. cylinder heads and intake manifold, all given the usual light porting by Duffee Motorsports in Phoenix, Arizona. Displacement is 336 inches.

ProCharger was the source for the rather heavy-duty-looking pop-off valves. One of these is mounted near each turbo to vent excess boost pressure. A screw adjuster allows fine-tuning of the boost-release pressure, while springs inside the unit give a coarser adjustment. As delivered, the springs would not allow less than 14 pounds of boost, for example. Later, Chris changed these to allow 12 pounds at the low end while still giving him well over 20 pounds of boost on top. During the dyno test, the system was adjusted to a hair under 18 pounds.

Naturally, Chris needed those items normally thought of as extras on naturally aspirated engines but required in a high-boost turbo powerplant. The block is O-ringed with stainless steel wire, soft copper SCE head gaskets are used (along with Total Seal piston rings), and the designed rev limit is a relatively low 7,200 rpm.

Camming is where you realize you aren't in Kansas anymore. Chris sent the specs off to Cam Motion, which in turn sent back a 0.684/0.686-inch lift, 242/236-degree at 0.050-inch-valve-lift mechanical roller. The big lobes raised Chris' eyebrow, for sure, but he was on an Africa-sized horsepower safari, after all. The remainder of the valvetrain is a mix of Crower solid-roller lifters, Comp Cams pushrods, and Pro Magnum 1.6 stud-type bolt-down rockers, buttressed by a Probe stud girdle.

Providing the boost and visual excitement is the Cartech Twin Outlaw turbo kit. The turbos are TO-4 60-1 hybrids from Arizona Turbo, and the air-to-air intercooler is a six-core unit also from Cartech, as are the headers and air tubing. Going into the dyno test, where we caught up to the project, Chris said he was hoping the wastegates were set to "around 20 pounds," and noted the system was incapable of providing less than 14 pounds of boost due to turbo sizing and spring pressures in the wastegates. Happily, it turned out the system provided a safe but respectable 17-plus pounds of boost on the Stuska water brake. All boost was funneled through a garden-variety 75mm BBK throttle body.

Bart Spivey and Brian Duffee mounted the EPEC control box to the rear of the dyno. Because the EPEC box and harness are plug-ins with Ford harnesses, typically there is a minimum of wiring to perform. However, EPEC's multiple digital and analog data and control functions can call for a soldering gun when dealing with complex turbo engines such as Chris'. For the dyno test, there was no need to max out all these circuits, and Bart had the EPEC up and running in short order.

More exotic is the air metering and engine management. Concerned about supplying enough air on the critical, naturally aspirated side of the turbos, Chris selected a huge Pro-M Univer 3-inch-diameter mass air meter. This is the same meter used by Jimmy LaRocca, and it was trimmed to Jimmy's specs as a starting point for Chris' engine.

Also like Jimmy, Chris opted for EPEC engine management. Not incidentally, Bart Spivey of Barts Works in nearby Tucson is an EPEC distributor and all-around booster. Chris bought his EPEC system through Bart, who was on hand during the dyno day to debug and tune the electronically intensive turbo engine. EPEC software also from Jimmy was loaded into the computer to provide baseline management settings. Bart had the EPEC configured as he always does, in stand-alone trim (no EEC IV box). The EPEC's easy laptop tuning and data-logger functions were to prove their worth on the dyno, as was a little watchdog in a black box from FJO Enterprises. A wide-band, high-speed air/fuel monitor, the FJO black box monitored the A/F ratio in real time as the vital check of what EPEC and friends were actually doling out.

Another member of the Phoenix/Tucson performance mafia-Brian Duffee-was also on hand. The pro-prietor at Duffee Motorsports in Phoenix, Brian specialized in keeping the mech-anical package together for Chris. On dyno day, that really meant fitting the engine to the brake and running the valves once, as the package proved mechanically sound and leak-free.

Chris selected Performance Engine and Machine in Tucson to dyno the engine. Main man Steve Scheick performed the decidedly tricky task of driving the beast on his Stuska brake, where the throttle and dyno water are constantly adjusted manually. The one-day testing went along with the totally normal fits and starts, guesses, and "let's see" adjustments expected with such a complex engine-management environment, but without major problems. After a few pulls to dial in a toe-curling lean A/F ratio and allow Steve to learn the twin-turbo's ways, the verdict was 1,253.9 hp at 6,600 rpm and 997.9 lb-ft of torque at 6,600 rpm.

Chris opted to go large and to go with a relatively proven part for his mass air metering-still something of a black art on big-power engines. This handbuilt Pro-M Univer piece is the result. Jimmy LaRocca has used these meters probably more than anyone, and he's also an EPEC dealer, so he was able to help Chris and Bart get started using his airflow data numbers. Bart believes that at this power level it's necessary to dyno test each mass air meter using a huge air pump, and to custom calibrate each meter rather than trim all to a blueprint standard.

Chris had been hoping to see 1,000 hp, so he got that and then some. The turbo types had said his turbines were easily capable of 1,200 hp and could go an extra couple hundred horsepower yet, but we think Chris hadn't really dared hope that high. But now he has to, and that's before cranking down on the wastegates any. See you in St. Louis, Chris.

Electro-Mechanical Fusion
Our first dyno experience was with a water-brake Stuska. Its full instrumentation was a bubble manometer for fuel flow, an analog pressure readout from the brake, and a cable-driven tachometer. It was definitely the mechanical age.

Interestingly, even today, testing high-power engines-the 1,000hp-and-up variety-is often done on similarly mechanical dynos. This is partially because the big-power dynos tend to be older units originally developed for high-torque, lower-rpm big-blocks, and partially because the trick, electronically controlled dynos don't have the response speed to hang on to the rapidly building power of a turbo small-block.

That's how Chris came to test his engine-an all-digital wonder with computer-controlled fuel injection and coil-pack ignition-on a dyno where it takes real skill to feed in the throttle; manually turn the brake's water valve; and eyeball the air/fuel ratio, tach, oil pressure and about 10 other things. So, while the power data was acquired via Depak computer software, the engine was still "driven" on the dyno in a huge juggling match between dyno load and ramping turbo power. It was a good show!

Chris wanted to go with a modern distributorless ignition system, which meant assembling a custom system from a combination of stock and aftermarket parts. An MSD DIS 4 box does the brainiac and spark-generation part in conjunction with the EPEC, while stock Ford Explorer/ Cobra coil packs (both vehicles use the same units) jump up the voltage. The ignition wires are off an Explorer; the sparkplugs are NGK. Chris had heard about the big power from Denso Iridium plugs and had a set on hand, but he didn't get a chance to try them before the dyno session was over.

EPEC News
We've long been fans of the powerful and easily tuned EPEC engine management. Developed by Sam Guido exclusively for Ford Racing Performance Parts, this comprehensive management system and data logger is now available through independent EPEC dealers, namely Bart Spivey in Tucson/Phoenix and Jimmy LaRocca in New Jersey.

Rigging any stand-alone engine-management system requires some fabrication work, and on Chris' engine the crank trigger makes a good example. The trigger wheel needed to be built, so Bart drew it on a CAD program, then e-mailed it to a fellow who laser-cut the unit out of metal. The electronic pickup working off that wheel is from a Mustang GT, while the bracket holding the pickup is custom.

Because EPEC is batch-fire (it fires all eight injectors at the same time), there was no need for a distributor. An Explorer stub shaft replaced it with the camshaft sensor removed as shown in the photo.

Not wanting to take any chances with too low an octane, Chris fuels his engine with 116-octane C16 gasoline. At $8 per gallon, he's considering leaded avgas at one-third the price. As seen here, the entire fuel system from the car was rigged on the dyno, including the small cell, the twin Aeromotive pumps, and the stainless steel braided plumbing.

Much EPEC hardware is available off-the-shelf for small-block Fords, however. From Barts Works, the basic EPEC box, wiring, and support literature is $1,195. An adapter harness is also required. The price is $250 for a Ford harness, and it is currently available in the following styles:
1) Stand-alone for '88-'93 cars
2) '94-'95 Mustang piggyback harness
3) '94-'95 stand-alone harness, with a distributor
4) '96-'98 stand-alone harness for Two- or Four-Valve engines; has EDIS connector and is good for coil-pack ignition applications

Bart says more stand-alone harnesses are coming, including some that will place the EDIS connector under the dashboard. On Chris' engine, the EDIS connector was under the hood.

Bart also brought us up to date on EPEC injector requirements. It's no longer necessary to use low-impedance (2-4 ohm) injectors; 12-16 ohm high-impedance units are fine with the latest EPECs. That's one less expense-new injectors-to worry about.

Familiar parts are used throughout the basic engine. The oil pan is a Canton drag-racing unit, the pump is a Ford high-volume number, and the oil is good, old 20W-50 dinosaur squeezings.

So, EPEC not only lives, but has also continued to develop as an even stronger management option on highly tuned engines. This is especially true when mass air metering is used.

On the Dyno
RPM TORQUE POWER
6,208 894.6 1,057.4
6,{{{300}}} 915.2 1,097.8
6,400 919.5 1,120.4
6,500 963.4 1,192.3
6,{{{600}}} 997.9 1,253.9
6,700 875.3 1,116.1
6,800 {{{924}}}.7 1,197.2
6,{{{900}}} 913.1 1,199.7
7,000 880.9 1,173.9
7,{{{100}}} 880.2 1,189.9
7,156 874.6 1,191.6

Notes: Power drop at 6,700 is due to 10 percent increase in fuel delivery starting at that rpm as detonation insurance. With mixture leaned, the power peak would be at 6,900 rpm. Depak data acquisition on Stuska manual water brake dyno.