Project Y2k: Stage 3 & 4 Upgrades from Corvette Central Performance
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.
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
Stage 4 Results
ProTip: If you are considering doing both the Stage 3 and Stage 4 upgrades, it’s best to do them both at the same time so you only have to remove the steering rack to R&R the harmonic balancer once.
After checking for leaks and admiring the car’s new rumble (and giving the computer a few minutes at idle to settle in and get up to temperature) we headed one slot over in the shop to the Dynojet to see what we had wrought. Three dyno pulls gave us an average of 385.37 horsepower and 372.54 pound feet to the rear wheels, a net gain of 31.22 ponies and 20.07 pounds compared to Stage 3, and a whopping 67.58/38.54 over our stock dyno pulls.
Figuring 12-15% loss through the manual transmission and driveline, that means we are making something like 430-440 horsepower at the crank – more than a stock LS3 C6, with fewer cubes (and for less money total, even considering the purchase price of the car and the cost of the Stage 1-4 upgrades.) Of course, to prove the point we needed to make another dragstrip visit, and despite a flagging stock clutch that kept us from launching the car as hard as we might have (this car is no trailer queen, so we made sure we didn’t break it too bad to drive home) we still managed to cut a 12.787 at 11.111 MPH in the quarter mile
Drag Results (Stock / Stage 4 / Net Gain)
- 60-Foot – 2.027 / 1.922 / .105
- 330 – 5.736 / 5.457 / .279
- 1/8 Mile – 8.751 / 8.312 / .439
- MPH – 80.67 / 86.53 / 5.86
- 1000 – 11.335 / 10.764 / .571
- 1/4 Mile – 13.480 / 12.787 / .693
- MPH – 105.43 / 111.11 / 5.68
On the road, our once-ordinary C5 is now something else entirely – if you want to turn heads at every stoplight, that unmistakeable cammed-up lope will certainly do it. The changes don’t appreciably harm the car’s drivability; it starts and putters around town just as well as it did when we bought it, but the new power is just a stab of the throttle away. Ongoing analysis of fuel economy shows we haven’t taken a big hit there either, mostly thanks to the deep double-overdrive transmission that keeps revs and interior noise way down on the highway. Step on the go pedal, though, and the beefed-up LS1 roars to life.
Overall, we’ve achieved exactly what we hoped for with Corvette Central Performance’s Stage 1-4 upgrades, taking what was good about the stock car and making it better. Corvette Central Performance’s upgrade stages for the C5 provide a no-guesswork way to put some extra oomph in your Corvette, and should you decide to go the DIY route, their technical support is there to help guide you every step of the way.
In the coming months, we’ll be continuing on with our improvements to Project Y2k, increasing handling and brake performance to compliment our new-found horsepower, so keep an eye out for future updates…