Despite what the name might suggest, Sound Performance isn't a tinting/alarm/audio install shop. No rack of chrome-dipped rental rims basking in the window; no airbrushed, airbagged, circa-'90 IASCA sound comp winners parked out front. What you will find on the Bensenville, IL, performance specialists' grounds, however, is any number of the modern day's most potent performance platforms, modified to the hilt, each flexing more power than the other shops' best efforts, combined. Supras have conventionally forged SP's power-plentiful reputation (what with their 1,500whp shop drag car), and after 21 years in business, they continue to find new and innovative ways of turning tuning convention on its cranium. Just ask Lee Cabelof, of Troy, MI. His JZA80 is doing so for the third time.
There was virtually never a time when Lee's Supra was a stranger to the Sound Performance crew. Its previous owner was a man named Dan Soleto, who purchased the car from its original owner in 2001 and immediately brought it to SP for upgrades. Bolt-ons like twin K&N intake filters, a turbo-back four-inch titanium HKS exhaust, Tein Flex suspension, molded TRD widebody kit, and custom-upholstered interior made it one of the Chicagoland area's most well-respected Supras-a reputation it re-captured a couple years later with its prototype 700whp single turbo conversion, full Coarse Gray Metallic colorchange with black interior (it was previously Renaissance Red with tan leather), tucked engine bay, and ultra-clean audio install, all courtesy of SP. The car had become such a permanent fixture to the Sound Performance install bays and dyno that many regarded it as a shop car-maybe even SP owner Larry Prebis. "Dan was cool enough to let us try all our crazy ideas on his car," Larry explains, "and that meant we were messing around with it nearly every day."
One of Larry's "crazy ideas" that was moved to the backburner over the years was brought to a boil once Lee caught word of it. "Dan and I were thinking of ways to improve the car's mid-range power," explains Larry, "and the idea of developing an improved sequential twin turbo system came up, but we never really moved on it." After owning the car for nearly a decade, Dan was looking for a change. Fortunately for us, so was Lee. And as another faithful SP customer, Lee reinstated Larry and his crazy ideas as soon as the title changed hands. "Almost the very day Lee bought the Supra," says Larry, "he and I were tearing apart its engine bay and drawing up plans for the sequential system."
SP's first order of business was to build the dated stock-block engine-not that 2JZs can't handle ridiculous power levels in stock form, but bumping their 3.0-liter displacement to 3.25 by way of an offset-ground crankshaft, Wiseco pistons and Pauter rods builds mid-range power, spools turbos faster, and holds even more power. The 2JZ's head was also worked over: machined to accept +1mm-oversized Ferrea valves, springs, retainers, keepers and rockers, and custom Crane cams, tuned by Unorthodox Racing adjustable cam gears. Then it was time for the fun to begin.
Looking down at the incomparably clean inline-six, two 6262 Precision turbos and their charge pipes in the Supra's bay, it's near impossible to believe such a massive network of manifold, bypass valves, and exhaust plumbing lurks beneath. Even more difficult to osmote is how it all works. "It's actually pretty simple," explains Larry, "think of how the stock sequential system works, and then just imagine it on a larger scale, with schedule 10 tubing." In contrast to a parallel twin-turbo setup which feeds each turbo solely with the exhaust gasses from three dedicated cylinders, SP's sequential system implements a common manifold that allows all cylinders' exhaust gasses to feed one or both turbos, depending on the phase of wastegates downstream. Notice how the front turbo's downpipe Ys off into two Turbonetics swing-valve wastegates, with a 38mm Tial wastegate jetting off one of them. At low rpm, all wastegates are closed, keeping exhaust gasses from passing through the front turbine, thereby directing all the pressure toward spooling the rear. As the rear turbo rapidly builds boost, the 38mm Tial cracks open, allowing some exhaust to pass through the front turbo and begin spooling it without severely cutting into the rear's supply. As engine speed and boost increase, generating more exhaust gas, each of the Turbonetics swing-valves gradually opens to let increasingly more exhaust pass through the front turbine, spooling it to life to generate more and more boost, until both turbos produce the same pressure. And if that's not complicated enough, both turbos share yet another 60mm Tial (not visible) to bleed off excess exhaust once peak boost is met.
The compression side of the equation, along with driveline mods, is much simpler. Most of what was added by Dan-like the Greddy 600mm x 300mm four-row intercooler; custom SP intercooler piping, throttle body and intake manifold; and RPS carbon clutch and lightweight flywheel-was retained. Fuel management was bumped up to six 1,200cc Precision injectors and a ProEFI engine management system, and the end result is a fat 1,022 whp and 806 lb-ft of torque with low- and mid-range power production typical of a system rated at around half the peak numbers. "The sequential system hits 16 psi of boost at 3,600 rpm on one turbo," explains Larry. "Once the second one comes online, the system is making 635 whp on pump gas, with tons more available with C116."
"We hit a few snags along the way, but now that the system is up and running reliably, the kit is becoming quite popular," Larry says. "I don't want to think about all the overtime I'll be paying my fabricator, Vince Fiore!" As for the fate of this particular car, "I'd like to work some Spool Valves into it," he explains, regarding another one of his crazy ideas which makes creative use of twin-scroll turbo/manifold design to decrease spool time. Will we see Lee's Supra re-write convention yet again? "He wants to start taking it to the track," says Larry. "So it's definitely got a few more interesting years ahead of it!"
Behind The Build
Bensenville (Chicago), IL
Making monster power; inventing parts
10 years and counting
Taking it to the track, live music,
"it just might work!"
'97 Toyota Supra
Output: 1,022 whp; 806 lb-ft of torque
Engine Sound Performance intake manifold, throttle body, intercooler piping, up pipe, downpipe, diversion panels, dual-pass radiator, radiator plumbing, stroker kit (re-machined crankshaft; Pauter rods; Wiseco 9.0:1 pistons), sequential turbo system (two Precision Turbo billet 6262 turbochargers, two 60mm Turbonetics swing-valve wastegates, 60mm Tial wastegate, 38mm Tial "pre-spool" wastegate, turbo manifold, downpipes, dump tubes), tuning; Greddy four-row front-mount intercooler; Ferrea valves, retainers, rockers, keepers, valve springs; Crane cams; Unorthodox Racing adjustable cam gears, pulley set; HKS four-inch titanium racing exhaust; Precision 1,200cc injectors; TRD oil cap; custom carbon engine dress-up pieces; ProEFI engine management system
Drivetrain RPS carbon clutch, lightened flywheel; Sound Performance one-piece aluminum driveshaft
Suspension Tein Flex coilovers; TRD sway bars
Wheels/Tires CCW 5W wheels (19x9 front, 19x10.5 rear)
Brakes AP Racing big brake kit, stainless steel lines
Exterior TRD widebody kit (front bumper, rear bumper, side skirts, front fenders, rear fenders); Top Secret hood; Rod Millen carbon fiber spoiler; shaved antenna; molded side skirts and rear bumper; Sparco billet aluminum fuel door
Interior OEM black Toyota Supra interior conversion; Cobra Misano seats; TRD steering wheel
Electronics Alpine IVA-0310 head unit; JL Audio speakers (x6), amplifiers (x2); Blitz SBC-iD (x2)
"Another one of Larry's Crazy Ideas"
In much the same way as Sound Performance's sequential twin turbo system dramatically increases boost production at low engine speeds, the company's "Spool Valve" maximizes boost production on an individual level, in twin-scroll applications. The Spool Valve fits between a twin-scroll turbo and manifold, and blocks off one of the twin-scroll system's two exhaust passages at low engine speeds, maximizing exhaust velocity in the other side for faster spool. As boost increases, a vacuum-actuated diaphragm (think wastegate) opens the blocked passage accordingly, allowing for uninhibited exhaust flow into the turbo. The low-buck mod has been proven to increase mid-range torque by as much as 140 lb-ft in some applications.