More Power Awaits Us In KansasThis is the second installment of our build-up coverage and testing of a new, 383-inch/supercharged combo destined for our '96 Z28 convertible.
We sent the Camaro out from sunny Southern California to the fringes of industrial Flint, Michigan, to the high-end speed shop/tuning facility of Hardcore Racing. There, the tired 350 and its early-model ProCharger were dropped out of the car in preparation for a Scoggin-Dickey-supplied 383 and fresh supercharger.
Upon arrival at Hardcore Racing, some changes were made on the Scoggin-Dickey short-block to accommodate the supercharger. This included swapping out the 10.4:1 pistons for 9.1:1-compression slugs. Also, a more blower-appropriate camshaft was supplied by Crane Cams. Hardcore's Eric von Hentschel handled all of the engine work for this project.
Capping off the 383 is a complete LT4 head/intake kit from Pace Performance Warehouse and a trick TPIS billet throttle body. The kit is based on the LT4 engines found in a few limited edition '96 Corvette models. The upgrades include the famed, higher-lift "Hot" camshaft, 1.6-ratio roller rockers, high-flow aluminum cylinder heads, springs, and the signature red-painted intake manifold with raised intake runners.
 The starting point for our...  The starting point for our project was this Scoggin-Dickey-supplied 383 short-block. It's a custom-built engine that S-D offers, not simply a GM long-block assembly. It's got splayed four-bolt mains and a Lunati 4340 forged crank on the bottom end. To accommodate the supercharger, lower-compression 9.1:1 pistons and a blower-friendly cam were installed. |  The LT4 intake is instantly...  The LT4 intake is instantly identifiable because of red color. It also has raised intake runners, compared to the LT1 intake. Note here, too, the aluminum, roller-tip 1.6-ratio rocker arms that also are part of the LT4 setup. |  Breathing chores are handled...  Breathing chores are handled by a complete LT4 conversion kit from Pace Performance Warehouse, which included a pair of aluminum LT4 cylinder heads, which boast 195cc intake runners and 2.00/1.55 valves. |
Like the 383 short-block, a few changes were required to accommodate the LT4 to the new combination, including valvespring mods, handled by Crane Cams. (See the Feb. '05 issue for more details.)
When all fasteners were finally torqued to spec, the new 383 was pushed over to Hardcore's engine dyno for some break-in time.
Waiting On A D-1SC
The supercharger that already was on the engine, when the Camaro rolled into Hardcore Racing, was an older-model P-1 from ATI ProCharger. It performed well for the old combination and, initially, we were going to reuse it on the 383.
 Capping off the long-block...  Capping off the long-block assembly is a new, 58mm throttle body from TPIS. This replaces the 350 engine's stock throttle body. |  Before going nuts with the...  Before going nuts with the supercharger, we wanted to know what the engine did in normally aspirate mode. The results-340 hp at 5,300 rpm and 280 lb-ft at 3,900 rpm-didn't seem right for an LT4-fed 383, but the new cam and lower-compression pistons are designed for the supercharger, not NA power. Some tests were performed with the original blower, but the tuning wasn't right, so the testing was called off until we could secure a new D-1SC system. | |
Things changed, however, when the supercharger was bolted to the engine on Hardcore's engine dyno. With the higher-volume 383 and previous combination's tuning, the performance just wasn't what we expected-or wanted. The engine made 454 hp and 476 lb-ft, but maxed out with about 6 pounds of boost. Not bad, but certainly not great, either.
While the combination could have been made to work, the existing tune simply wasn't compatible with the increased airflow requirements of the 383-cid displacement and higher flowing LT4 heads. To put it simply, the old tune was good for the old 350 engine, but not for the new 383.
It seemed like a good opportunity to upgrade to ProCharger's D-1SC supercharger. Unfortunately, the castings for the D-1SC weren't ready to meet our deadlines for this issue. Rather than have the car hold down Hardcore's shop floor, Dan Jones, from ProCharger, offered to bring the car to the company's Kansas headquarters so that we could jump on it as soon as the blowers were ready. ProCharger's engineers would also be able to lend their tuning expertise to ensure that the system made optimal power.
The Hardcore crew bolted up the engine (with the old blower installed) and made the car ready for ProCharger's pick-up. And that's where we leave for this issue.
Look to a future issue as we extract all the power we can from our new, supercharged 383. If you ever thought LT1 performance was yesterday's news, you ain't seen nothing yet!