The Point of No Return

Also from Issue 38

  • 1968 Sunray DX L88 racer
  • Market Report: C2
  • 1954 market analysis
  • History: Shinoda’s Monza show cars
  • Comparison Test: C4 ZR-1 vs. C6 Z06
  • 1996 Grand Sport coupe
  • History: Disc brakes
  • Racing: Pratt & Miller factory tour
  • How-To: Muncie gearbox rebuild, Part I
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When the pieces arrived, the staff reported back that the turbos looked to be on the smallish side—an observation that brought Schron in­to the garage on the double. After an inspection, “These are Turbonetics T3/T4 hybrids,” Schron told the ECS techs. “I’ve put a lot of these in. The performance has everything to do with the compressor wheel, and these are going to make a lot of power.”

Schron and ECS had no interest in a simple bolt-on installation; instead, the team was determined to fortify the entire LS6 package to accept massive infusions of boost—a goal that meant disassembling, strengthening, testing, balancing, and rebuil­ding the internals down the last nut and bolt. Nor could they re­sist making breathing tweaks while they were at it, leading to new Airflow Re­search heads.

Directly below these would be new pistons shaped to give 9.4:1 compression, a custom-ground Cam Motion shaft, Callies forged rods, and a Callies forged stroker crank, bumping total displacement to 382 cubic inches. According to Schron’s estimates all the new parts could withstand 25 pounds of boost—considerably more than his game plan called for. ECS upgraded the fuel system in kind, adding in-house-built rails, Motron 60-psi injectors, a Racetronics tank pump, and an auxiliary Bosch 420 ex­ternal fuel pump. The fuel lines were sent through the tranny tunnel initially, but when turbo heating led to fuel vaporization they got re-routed through the driver-side rocker. To keep intake temperatures down, ECS also built an alcohol-injection system feeding the air-intake bridge from a hand-fabricated tank in the trunk. “There’s a rheostat inside the car,” Jay explains, “that I use that to adjust how much methanol enters the intake. We did alcohol injection for two reasons: To reduce the internal temperatures in the combustion chambers, and also as supplemental fuel. The computer reads the temperature going in and adjusts the timing and fuel-delivery mapping to match. Turbochargers essentially pump hot gas right into the motor; an alcohol sprays cools everything back down.” In addition to the manual switch, the system is triggered automatically by a MAP sensor at three pounds of boost. Assuming he’s not too busy avoiding slower cars by that point, the driver can keep tabs on this underhood action via Auto Meter boost and fuel-pressure gauges, a wideband oxygen sensor, and an air/fuel-ratio monitor.

A handful of driveline upgrades were re­quired to turn all this potential performance into predictable forward motion. A Textralia OZ700 clutch now handles power flow to the transmission, which in turns has been fit with a DTE brace and Hurst shifter. Downstream, one finds the requisite hardened halfshafts.

All told, the conversion laid the car up at ECS for the better part of three months. Doug Ring, the ECS principle who did most of the physical installation, recalls some of the challenges he faced on this job. “The most tedious thing with a turbo system is properly heat-proofing all the wiring and lines; you’re talking about individually treating every wire. I’d work for a week on this project, and from the outside it didn’t look like I’d accomplished anything! Thankfully, Jay knows what it takes to do these projects right. He allowed us to do a proper job and build a proper product. It was a win-win for everyone.”