When the LS1 was released into the wild back in 1997, it soon became apparent that the intake manifold was one of the chief obstructions to obtaining ultimate performance. Various companies took a stab at producing replacements, building them from sheetmetal and other materials, but none of these proved to be the magic bullet required for an all-around power gain.
When the LS6 was rolled out for the '01 model year, LS1 guys (and gals) finally had their wish granted. The LS6 intake was a direct bolt-on that looked stock, was priced reasonably, and provided a solid performance improvement across the rpm band. This intake instantly became the unit of choice among LS1 engine builders, performing admirably on heads/cam combinations and even on fairly stout stroker motors. But once the combination got really serious, it too became a bottleneck.
With the introduction of the LS2, the cycle started over. Though it utilizes a large, 90mm throttle body, the LS2 intake quickly becomes a restriction once the engine's air demands increase due to modifications. This was exactly the case with D6C. Though modifications to this point have been rather mild, the added breathing capability of the LG Motorsports X1 cam and long-tube headers, plus the 3-inch Stainless Works exhaust system, left the stock intake manifold as the engine's most restrictive component.
FAST's LSX intake manifold was introduced a few years ago and went on to become the standard for big-inch and forced-induction mills. Turns out it works pretty darned well on the LS2, too. In fact, the LSX has shown an uncanny ability to produce a 20-plus-horsepower increase over both the LS1 and LS2 intakes in most combinations. And unlike sheetmetal manifolds, which typically make all their power at high rpm, the FAST unit boosts power across the board, with no loss of driveability or low-rpm torque. It is truly a no-downside install.
The dyno sheet shows a gain...
The dyno sheet shows a gain across the board; approximately 20 rwhp and 20 rwtq were the maximum numbers. That brings D6C's running totals up to 450 rwhp and 441 rwtq!
The LSX achieves this impressive performance by increasing plenum volume some 25 percent and utilizing longer, tapered runners to improve both high-rpm horsepower and off-idle torque. Of particular interest is the intake's three-piece construction, which allows disassembly for the purpose of interior porting. Additional material is even cast into the runners for this very reason. FAST was also thinking ahead far enough to incorporate witness marks to give the porter a wall-thickness reference. Another feature of the modular design is the ability to change the top shell in order to accommodate either a 78 or a 90mm throttle body. Pretty clever.
The FAST manifold is constructed of Amodel polymer, which is 30 percent stronger than the stock manifold's material and is also phenolic. This means it does not become a power-robbing heat sink as underhood temperatures rise. FAST also incorporated nitrous-oxide-injector ports, making a direct-port nitrous injection a relative snap. Lastly, an optional burst panel is available for nitrous or boosted applications.
While there is little argument among enthusiasts as to whether the FAST intake makes power, some C6 owners have stayed away from it based on the argument that "you have to cut up the car" to make it fit. It's true that the installation is not a strictly bolt-on affair and does require that a clearance hole be cut in the cowl. Fortunately, FAST makes the job significantly easier by offering a C6-specific kit that supplies everything needed to cleanly modify the cowl area.
You should expect installation to take three to four hours, less if you are as fleet of tool as LG Motorsports' man Sean Burt. He knocked it out in under three, even with the pauses required for photography.
So while the FAST intake may not be for everyone, even cars with limited power upgrades can benefit greatly from its installation. If you've got a strong stomach for modifications and an even stronger appetite for power, here's your next speed part!
LSX 90mm Intake Manifold
LSX C6 Corvette Map Sensor
LSX C6 Corvette Firewall
LSX to LS2 Fuel Rail Adapter Kit
Relieve fuel-system pressure...
Relieve fuel-system pressure using the Schrader valve at the end of the fuel rail, then disconnect the fuel-supply line from the rail itself. Have a rag or two handy to catch any escaping fuel.
Remove the four bolts fastening...
Remove the four bolts fastening the fuel rail to the manifold and disconnect the fuel-injector harnesses. You can then remove the rail and the injectors as a single unit.
Disconnect the vacuum harness...
Disconnect the vacuum harness from the throttle body (shown) and the passenger-side valve cover. It may then be removed from the car.
Now you can disconnect the...
Now you can disconnect the MAF harness from the sensor.
Next, remove the induction...
Next, remove the induction system. In this case, the upper portion of the Vararam is on its way out. The filter housing and scoop can be left in place.
The intake-manifold bolts...
The intake-manifold bolts can now be removed.