Previously, we bolted on American Racing Headers’ stainless long-tube headers and cross-pipe into a 2014 Corvette (“Better Breathing Stingray,” May ’14). We got substantial gains on the dyno and a significant reduction in elapsed time at the track. The exhaust changes laid the groundwork for future mods, so as soon as we learned Comp Cams introduced a new line of Gen V camshafts, we had to get one.
Comp’s new bumpsticks are designed to work with the direct injection, VVT (Variable Valve Timing), and AFM (Active Fuel Management) lifters featured in GM’s Gen V (LT1/L83/L86) engines. As this was being written, there were four grinds, two for the 2014 Corvette’s engine and two more suitable for the truck version.
Matt Hauffe and his experienced staff at Tune Time Performance (Lakewood, New Jersey) would handle their first LT1 cam swap on Matt’s new 2014 Corvette. This was to become a good learning experience for future swaps that TTP will perform on the redesigned C7 and LT1. While we love a good track test, this install happened in the dead of New Jersey’s winter, so this month you’ll have to be satisfied with just a dyno test. As soon as the ’strip opens, we’ll be shooting for 10s. For now, follow along for another new adventure with the C7 Corvette.
1. The Tune Time Performance (TTP) 2014 Corvette is a pretty sweet test mule. It will receive lots of upgrades and more testing over the course of its life. Here, Matt Hauffe eagerly begins to dive in to his personal C7 Corvette. When we put in our parts order, Comp informed us we were the first publication to request one of its new XFI AFM (Active Fuel Management) hydraulic roller camshafts designed for the new Gen V LT1.
2. Tune Time’s top tech, Justin Knapp, begins the teardown. At this point, the valve covers, coils, air intake, and electric and vacuum connections were removed. Check out the 2014 Corvette’s unique intake manifold, throttle body, cylinder head, and valvetrain layout.
3-4. With the belts and hoses disconnected, the water pump housing can easily be removed for access to the timing cover. The sway bar and the C7 Corvette’s new electric steering rack were removed for access to the harmonic balancer.
5. It was a welcome sight to see a keyway groove in the LT1’s balancer. No more drilling and pinning the crank and balancer when upgrading to a belt-driven supercharger.
6. Unfortunately the LT1 timing cover and oil pan do not utilize reusable gaskets like the LS engine family. Notice the gray-colored RTV silicone. The dry-sump pan needs to be dropped in order to move the oil pump forward for removal of the cam phaser gear and timing chain. Another reason the oil pump needs to be out of the way is to see and line up the dots on the timing gears and/or degree the cam.
7. Comp offers four different cam grinds of its new XFI series GM Gen V camshafts that work with the new LT1’s direct injection, AFM (Active Fuel Management) lifters, and VVT (Variable Valve Timing). We chose the most aggressive grind of the four. It specs out at 0.572/0.529-inch lift intake/exhaust, 224/236 intake/exhaust duration at 0.050 inch, with a 118 lobe separation (PN 624-536-13). Comp rates the power range from 2,000 to 7,100 rpm, with outstanding top-end power. We couldn’t wait to find out! Each of the four cam grinds will require custom tuning.
8. Notice the lower lobe has three noses. This triangular-shaped lobe is for the direct-injection (DI) fuel pump. This (DI) tri-lobe is unique to the new Gen V family.
9. A notable advancement in camshaft design for the Gen V is that the cam lobes feature a larger base circle and a wider ramp (nose) for the AFM deactivation cylinders. Another benefit of the larger lobe is faster valve action (opening and closing), along with less stress for better durability on the valvetrain parts.
10. This is after we removed the timing chain and phaser gear without removing the oil pump (for now). As mentioned earlier, we’ll need to remove the oil pump and dry-sump pan to install the cam and timing set.
11. The light is shining on the DI fuel pump. It presses down on the cam’s DI tri-lobe and needs to be removed to slip out of the old cam (and slip in the new one).
12. The DI fuel pump has a spring at its bottom to put pressure on its lifter. The pump’s spring has a function similar to a valvespring.
13. The camshaft was rotated to raise up the lifters. Then we placed the wooden dowels underneath to hold the lifters up in place. This dowel trick worked on the LS engine, and now the LT1 for camshaft swaps. Here are the specs of the stock stick: 0.551/.524-inch lift, 200/207 duration at 0.050-inch intake exhaust, with a 116.5 lobe separation. Comparing the specs, it looks like the additional duration (26 degrees intake, 29 degrees exhaust) from the new camshaft should broaden the powerband and raise peak power from 5,800-6,000 rpm (stock) to somewhere in the area of the mid-6,000.
14. This Comp Phaser Limiter Kit (PN 5456) is required with use of the new Comp XFI Series camshaft. The Phaser Limiter will limit the range of camshaft movement from 62 (stock) to 22 crank degrees, thus requiring VVT program tuning. This kit contains the special tools to safely disassemble the cam phaser and install the cam phaser limiter block.
15. With the cam phaser kit tools installed, the phaser was safely disassembled to install the limiter block. The limiter block will mechanically limit the camshaft movement, making it safer when running a big cam and helping to prevent valve-to-piston contact at high rpm.
16. Here, the limiter block is put into place inside one of the cam phaser control chambers. The slotted end went in first. Then the phaser was reassembled and ready to go.
17. Notice the oil pump and dry-sump pan are missing. It’s the only way you’ll be able to reinstall the timing set with the modified cam phaser gear. All the block, timing cover, and oil pan surfaces were cleaned up. Then we applied Permatex Ultra Grey RTV silicone to replicate the look and the way GM sealed up those parts.
18. To reinstall the oil pump (and then the oil pan), it’s necessary to drop down the engine cradle and front suspension. Notice the American Racing Headers tubes from our first test. The missing oil pan is evident, but the disconnected oil lines for the dry sump tell you this Stingray has the Z51 package.
19. This engine apparatus was fabricated for future C7 cam swaps. It will hold and support the engine for when the engine cradle and suspension have to be lowered for clearance to remove the oil pan.
20. We didn’t want to buzz the motor over 7,000 rpm with the stock valvesprings and risk floating valves or possible piston-to-valve contact, which could be catastrophic. The cam card recommended using PN 26918 beehive springs. Comp suggested we try its new conical valvesprings for serious valve control at the high rpm (7,000) we intended to spin the LT1 during dyno testing. Here we’re removing one of the stock springs.
21. The beehive-type valvespring (left) was a major breakthrough in valvespring technology back in the 1990s. Now the conical valvespring (right) is the latest breakthrough in valvespring development. Notice the decreasing diameter of the conical spring from the bottom to the top. The conical design reduces mass for less parasitic loss, improved rpm stability, while decreasing dynamic spring oscillations. The springs we’ll be using (PN 7228-16) have a spring rate of 438 lb/inch, a seat load of 136 pounds at 1.800 inches, and an open load of 412 at 1.170 inches. Comp’s own testing of these springs has shown better valve control for more power over the traditional beehive and cylindrical springs.
22-23. Here’s a look at the stock beehive (left) and the conical springs (right). To perform the spring swap, these parts were necessary—Lightweight Tool Steel Retainers (PN 1772-16), Spring Seats (PN 4680-16), and a Shim Kit (PN 4752) to set the springs at an installed height of 1.800 inches for the proper load pressure at each valve. To set the intake spring height, we used the 0.045-inch spring seat, 0.060-inch shim, and a 0.015-inch shim. For the exhaust, we used the same 0.045-inch spring seat and 0.060-inch shim but used a 0.030-inch shim for a tiny bit more spring pressure on the exhaust valves. We coated the springs with Comp’s Valve Train Assembly Spray (PN 106) to protect them during initial start-up.
24. We fed the dry-sump oil system with Joe Gibbs Driven LS30 synthetic 5W-30 oil. Joe Gibbs Racing developed the Driven line of lubricants for the high-performance race and/or street engine. The Driven LS30 synthetic oil we’re using is ideal for the LS and LT1 engine that is naturally aspirated or with a power-adder. Driven claims its LS30 delivers industry-leading shear stability and HTHS-bearing oil film thickness. Additionally, there are higher levels of zinc (ZDDP) to deliver proper anti-wear protection for high-output engines with aggressive valvetrain designs.
25. The LT1 looks bone stock unless you notice the headers. Out back, the lopey sound comes courtesy of the new, more aggressive cam. It is just awesome hearing the tones going through the headers, cross-pipe, and out the stock mufflers. A proper break-in is very important for new valvesprings. We let it idle and varied the rpm between 1,000 to 1,800 rpm until the engine reached normal operating temperature. We let them cool down to room temp. This can help eliminate early breakage and prolong spring life.
26. On the dyno, the Stingray strut its stuff—to the tune of 450 rwhp at 6,400 rpm on Tune Times’ Mustang chassis dyno. That’s a gain of 37 rwhp for the LT1. Comp’s newly designed LT1 cam and conical valvesprings delivered the top-end power we desired. The new deeper breathing cam was inhaling so much more air, there was a major restriction in the stock air intake, causing a power loss across the power curve between 3,800 to 4,800 rpm. At this point, we knew a high-flow air intake system would be very beneficial to the heavier-breathing engine. This is a perfect example in which one modification needs another for optimum results.
27. The dyno graph shows the bone-stock baseline with the headers and the Comp cam. It’s easy to see how the headers increased power all across the dyno pull. The cam swap shows a slight (5-7hp) loss from 3,800 to 4,800 rpm, then starts to pull strong right through 6,600 rpm when we lifted. With the stock air cleaner restricting airflow, we knew a high-flow air intake system would help the cammed-up LT1 produce more power all along the power curve.
28. The high-flow cold-air intake system from Halltech (Stinger CKN) not only looks cool, it smoothly enabled the cammed-up LT1 to inhale/breathe much more easily. The Stinger air intake will bolt on a bone-stock C7 without any required tuning, but with the cam, tuning is required. Matt performed his dyno-tuning magic after ace technician Justin bolted on the Stinger.
29. Here we can see how the Halltech Stinger cold-air intake allowed the LT1 to inhale better, thus producing more power throughout the power curve. Matt tells us the throttle response, low-speed driveability, and fuel economy have increased tremendously. The C7 realized a whopping 21-rwhp and 11-lb-ft gain from the Stinger air intake. Fifty-eight more rear wheel horsepower is quite a bit from two modifications.
Dyno and Dragstrip Results
|M/T Drag Radials||1.68||11.47/119.32|
|Comp Cam, Springs||413/4800||450/6400|
|Halltech Air Intake||424/4900||471/6100|