Welcome back to the second and final part of our series on upgrading Project Y2k, our in-house 2000 Corvette, with the help of Corvette Central Performance and their Stage 1-4 kits for the C5. In part one, we installed the Stage 1 and Stage 2 kits, which are comprised of bolt-on intake and exhaust upgrades, along with a flash tuner to maximize the power gains from the hardware improvements.
We want to eliminate the guesswork for late model Corvette owners who are searching for increased performance. – Matt Gessler
As with Stage 1 and 2, the Corvette Central Performance Stage 3 and Stage 4 kits are designed to give a turn-key upgrade path for 1997-2004 Corvettes, broken into logical chunks. Per Corvette Central’s Matt Gessler, “We want to eliminate the guesswork for late model Corvette owners who are searching for increased performance.” The C5 staged upgrade packages are just the beginning for Corvette Central Performance; “The initial focus was for the C5 Corvette,” Gessler explains. “It really hits the ‘sweet spot’ for affordability and performance at this moment. But we also realize that there are plenty of C4 Corvettes that see track duty, and there seems to be no performance limit for the C6. We continue to source the best performance products available for these cars.”
Talk is Cheap
As with our previous installment, we will be putting Y2k on the rollers after each stage, then taking the Corvette back to the dragstrip to measure our improvements in the real world. Our baseline going in to Stage 3 was 340.59 horsepower and 343 pound-feet of torque at the rear wheels – very healthy numbers for a decade-old LS1 with a few mods, but we were excited to see what the serious speed parts provided by Corvette Central Performance could add to the bottom line.
Stage 3: Goodbye Logs, Hello Long Tubes
The Corsa mufflers we installed in Stage 2 sound great, look awesome, and helped us pick up a few more ponies, but the rest of the stock exhaust plumbing was still in place. Corvette Central Performance’s Stage 3 kit remedies that situation with some of the best long-tube Corvette pipes on the market from Kooks Custom Headers with a matching X-pipe and mid-pipes, plus an SLP underdrive pulley and COMP billet tensioner.
Like the Stage 1 kit, there are two different part numbers available from Corvette Central Performance, depending on what year C5 you have. PN 305462 covers 1997-2000 cars, while 305488 takes care of the 2001-2004 Corvette. The main difference lies in the position of the passenger-side air injection port on the headers, which changed between the 2000-2001 model years.
Stage 3 Results
With our new exhaust and pulley installed, we were right back on the Dynojet to quantify our results. Three pulls later, with the same tune we had loaded for Stage 2, we had an average of 354.15 horsepower and 352.47 pound-feet of torque, a gain of 13.56 horsepower and 9.47 pound feet from our previous high-water mark.
[caption id="attachment_149771" align="aligncenter" width="640" caption="The heart of Stage 4 is COMP's XR275HR cam, and Corvette Central Performance also provides matching COMP valvesprings, pushrods, and titanium retainers."]
Stage 4 Contents:
- COMP XR275HR camshaft (PN 54-426-11)
- COMP 5/16-inch High Tech Pushrods (PN 7955-16)
- COMP High Performance Beehive Valve Springs (PN 26918-16)
- COMP 7-degree Titanium Retainers (PN 772-16)
- Stock GM LS2/LS7-style Timing Chain and Cam Gears
- SLP Heavy Duty Oil Pump (PN 55001)
- Cam Installation Kit
Finally, it was time to complete our Corvette Central Performance upgrades with the installation of Stage 4, consisting primarily of a new COMP camshaft, an SLP high-performance oil pump, and supporting hardware to increase reliability and the ability to turn revs. LS1/LS6 engines are well known for their responsiveness to cam swaps, so we were very curious to see what Corvette Central Performance’s choice of specs would do, both in terms of power to the wheels and day-to-day drivability.
The cam provided in the Stage 4 kit is a COMP XR275HR grind, part of the XFI RPM High Lift hydraulic roller family. COMP describes it as a “great street/strip camshaft for midrange and high RPM power” and notes that computer modifications are required. We like a nice, lopey cam, but looking at the lift and duration numbers, we wondered if we were getting ourselves into a Corvette that idled with a little more wiggle than we would like…
COMP XR275HR Vitals:
- Gross lift (intake/exhaust) – .566/.568
- Duration at .050 – 222/224
- Lobe Separation Angle: 112.0 degrees