What happens when you run out of injector, and can't see spending big money on an aftermarket computer system for low-impedance injectors? You build your own piggybacked system to convert the saturated factory signal to peak and hold, so you can run the big squirters. Things are only this simple if you have a degree in Electrical Engineering like Jeff Stevens, the owner of Acceleronics and creator of the VersaFueler. Just as remarkable as this budget-m
inded system is the car it was tested and developed on, Jeff's blown 1996 Z28.The LT1 Camaro was the perfect specimen for a budget build as it was "the best performance bang for the buck back then," said Jeff. While this Pleasanton, California, resident never intended to start modifying the Z, things went from bad to worse when he hooked into an F-body email group, before the days of message boards. It had been many years since he had a modified musclecar, but with a few bolt-ons all that changed. Suddenly he was back at the track and running low 13s, until he was offered a deal on a Vortech S-trim kit that was too good to pass up. Not long after Jeff took his LT1 over to Mike Blackstone at Watson Racing and Engineering in Concord, California, for the first of many rebuilds. Thinking the eutectic pistons were the biggest weak point with the stock bottom end, the rods and crank were reused. With the motor already apart it was decidedly a good time to add a lumpier cam and port the heads. The e.t. dropped down to 11.18 at 128 mph before spitting out several rods at the track. A new block was required for the next rebuild and Jeff was not playing around this time. A forged stroker bottom end and a larger duration hydraulic cam went into the six-speed Camaro, inspiring a 10.74 at 135 mph timeslip.
At the time Jeff had been spending as much time at the Thunder Hill road course as at the dragstrip, so a few upgrades to his stock suspension was in order. QA1 shocks, 1LE springs and swaybar, and a BMR K-member keep the front end tight while still enabling weight transfer at the tree. Rear traction is enabled by a BMR torque arm, lower control arms and panhard bar with an Addco 1-inch solid swaybar, AirLift air bag (in the right rear spring), and Blaine Fabrication custom subframe connectors. Corvette C4 13-inch front brakes and polished ZR1 wheels with Nitto NT 555 R and 555 RII road race tires also help Jeff negotiate the twisty canyon roads of Northern California.
Though the T56 excelled at its stints on the road coarse and the highway, it simply couldn't hold up at the dragstrip. After the initial breakage it was rebuilt only to break again on its first pass. With no other choice, a trusty TH400 built by Carl Rossler took its place, but Jeff still entertains the idea of going back to a manual with some of the trannies that aftermarket companies are building. A Mark Williams chrome moly 3-inch driveshaft was used to connect the new tranny and a JW Performance 3800-stall converter to a KTRE 12-bolt rear. The 12-bolt was later re-fortified by Tom's Differential with its own beefy "Best of Everything" posi, Moser 31-spline axles and 3.42 gears replacing the old 3.73s.
Eventually with the new tranny and an upgraded fuel system Jeff broke into the nines with the S-trim blower. Now at the limit of the entry-level blower's capacities, it was traded for a YS-trim and again the bottom end was strengthened with even beefier forged components while sticking with the ported LT1 heads. The potential of this combo was shown with a 9.82 at 145-mph pass while limited to a soft launch due to the lack of an NHRA approved roll cage. Unfortunately in the process of this run, the motor detonated. Despite Jeff's best effort in updating the fuel system and tuning, smoke and a thirsty cooling system indicated the LT1's demise. "I was in denial until I poured pieces of piston ring out of the Y-pipe one day. They had been trapped by the cat honeycomb."
At that point it was decided that AFR's LT4 castings would be a wise move, as the 76cc combustion chambers would enable a smaller piston dish, and a stronger piston. Under the advice of Mike Blackstone the switch was made to ported and polished AFR heads with Ferrea 2.08-inch intake and 1.60-inch exhaust valves. Manley valve springs, T&D shaft rockers with 1.75 intake and 1.70 exhaust ratios, Smith Brothers tapered pushrods, and a Bullet solid roller cam help the engine rev to 7000 rpm without valve float. Blackstone, true to his NHRA Pro Stock roots, was tight-lipped on the custom ground cam's LSA, but he did say that the lift is 0.650/0.650-inch and the duration at 0.050-inch equals 224/232 degrees. A home-ported LT4 manifold, AS&M 58mm throttle body, enlarged blower and intercooler plumbing, and a custom Spearco three core air to air intercooler were all added to enhance the new blower's 18psi of charged air. Exhaust gases depart through a set of Hooker 1.75-inch long-tubes, Blaire Fabrication 3-inch Y-pipe and a Mufflex 4-inch catback with a Borla XR1 muffler.
Moving so much air from a stroked and blown motor with this type of exhaust make earplugs a necessary requirement for long trips, says Jeff, but other than that, it is still completely streetable. Very good reasons for its streetability are the quality of the tune that he supplied and the VersaFueler. Even with an Aeromotive Eliminator fuel pump cranking 80 psi through the largest high impedance injectors available at the time (50 lbs./hr.), the mixture was still leaning out. The injectors were at 118-percent duty cycle, he said, and just could not keep up. This lead to detonation and the destruction of a few motors until the first VersaFueler was created and 75-pound injectors were implemented. Since then the original "Frankenstein circuit board," as he called it, has been refined considerably into the neat little package it is today. Jeff also currently uses Delphi 95 lb/hr flow matched injectors and a Paxton regulator to maintain 40-psi of static fuel pressure (1:1 rise with boost). The latest tune on the new engine, he thinks, will give the Z enough juice to run low 9s, and if that doesn't do it a shot of nitrous will.
Despite the incredible performance enhancements on Jeff Stevens' Camaro, there is little to separate it visually from other Z28s. "Except for the roll cage it looks bone stock inside, too. I wanted something that if you saw it in a parking lot you would think it was ordinary, even though it could suck your headlights out." Factory styling, factory computer, but far from factory performance. Even the General himself would admire this handiwork.
Jeff's Z looks innocent--apparently...
Jeff's Z looks innocent--apparently even when he's annihilating the Nittos in front of a California Highway Patrol officer during our photo shoot. "This car is obviously set up for racing and you obviously know how to drive it," was the compliment from the cop, who only gave Jeff a verbal warning!
Keepin' it simple and stealth....
Keepin' it simple and stealth. An NHRA legal roll cage (to 8.50), six-point harness, and window net were all necessary additions.
The 385 LT1's splayed 4-bolt...
The 385 LT1's splayed 4-bolt main caps and a forged bottom end do everything they can to stand tall against the YS-trim's punishment. The large hose coming from the valve cover leads to a Peterson Fluid Systems vented catch to help cool the overworked oil supply without spilling oil all over the engine.
The YS-trim Vortech pushes...
The YS-trim Vortech pushes 18 pounds of boost through the 8.5 to 1 LT1.
In many cases high-powered...
In many cases high-powered vehicles need more fuel than a high-impedance injector--and a stock ECU--can provide. The VersaFueler decreases the amplitude after the injectors initially open, allowing low-impedance squirters without frying the stock PCM. Jeff typically uses the analogy of a light switch dimmer.
|DATA FILE |
|1996 Camaro |
|Owner: ||Jeff Stevens |
|Block: ||LT1, 385 cubic inches |
|Compression ratio: ||8.5 to 1 |
|Heads: ||AFR 220cc LT4, ported and polished by Watson Racing and Engineering, 2.08 intake, 1.60 exhaust |
|Cam: ||Bullet custom solid roller 224/232 duration at 0.050, 0.650/0.650-inch lift |
|Pushrods: ||Smith Brothers tapered 7.825 inches |
|Rocker arms: ||T&D 1.75/1.70:1 |
|Pistons: ||CP forged aluminum |
|Rings: ||Childs and Albert |
|Crankshaft: ||Lunati forged |
|Rods: ||Lunati Pro Mod forged |
|Throttle body: ||AS&M 58mm |
|Fuel injectors: ||Delphi 95 lb/hr |
|Fuel pump: ||Aeromotive Eliminator |
|Ignition: ||MSD Digital 7 |
|Engine management: ||Stock ECU with Acceleronics VersaFueler, tuned by owner |
|Power adder: ||Vortech YS-trim |
|Boost: ||18 psi |
|Intercooler: ||Spearco custom air to air |
|Exhaust system: ||Hooker 1.75-inch long-tube headers, Blaine Fabrication Y-pipe with Carsound cats, Borla XR1 muffler |
|Transmission: ||TH400 built by Carl Rossler |
|Torque converter: ||JW Performance Transmission 3800-stall |
|Driveshaft: ||Mark Williams 3-inch Chrome Moly |
|Front suspension: ||QA1 shocks, GM 1LE sway bar and springs, BMR K-member |
|Rear suspension: ||Bilstein shocks, stock springs, BMR torque arm, lower control arms and panhard bar, Addco 1-inch solid sway bar, AirLift air bag |
|Rear end: ||KTRE 12-bolt, 3.42 gears, Moser 31 spline axles, Tom's Differentials posi |
|Brakes: ||C4 Corvette 13-inch front brakes, stock rear |
|Wheels: ||Street: ZR1 17x9.5 front, GS 17x11 rear; Track: Weld Draglite 15x3.5 front, 15x10 rear |
|Front tires: ||Nitto NT 555 RII 275/40/17, M/T ET Fronts 26x4.5 |
|Rear tires: ||Nitto NT 555 R 315/35/17, M/T ET Drag 28x10.5 |
|Fuel octane: ||110 |
|Race weight: ||3,600 pounds |
|Best ET/mph: ||9.76 at 145 |
|Best 60-ft. time: ||1.40 |
|Current mileage: ||48,000 |
|Miles driven weekly: ||78 |