Aftermarket intake manifold support for the LS platform has exploded on the scene in the last few years. Among the front runners in performance and innovation are the folks at FAST. The intake manifold, like any other flow-based performance adder, must be tuned like a wind instrument to work at the frequency and target rpm for each given application. In yesteryear, intake manifolds were cast, single-piece designs that had pre-determined flow characteristics.
In order to change the induction harmonics of a given engine it was common practice to swap the whole intake. Tuning a cast-aluminum intake requires the care and understanding of a master-porter to work their magic with a tungsten carbide burr. In the digital age, composite materials have largely replaced the metallic forbearers of intake construction. The modular design, and lightweight construction of the FAST LSXR and LSXRT manifolds begged for further tuning authority. FAST has brought that kind of power to the fingertips of tuners everywhere.
FAST has developed and dyno-proven one of the first solutions to making the LS intake manifold truly modular. It’s interchangeable interior runner lengths are optimized to suit the needs of builders who can be slotted into one of three levels of performance — primarily defined by operating rpm-range. “The original goal was to maximize power throughout a standard 2,500-6,000 operating band. Hence the runners needed to be as long as could be packaged inside the LS space constraints for proper wave tuning, especially in the mid range,” explained Brandon Flannery of FAST.
The FAST LSXR 102 mm manifold is already a prolifically popular upgrade, but with the additional tuning possibilities of intake horns the applications expand exponentially. The possible permutations that arise from three different profile horns, potentially mixed and matched, over two base manifolds makes for a huge number of potential combinations.
“We first ran each set of runners in both the low and high top FAST manifold. Then we started trying different ‘dual plane’ style setups — those are cool in that they do exactly what you would expect with the torque curve splitting the difference in the two other tests. With some more work on individual cylinder tuning we might see improved results,” said Billy Godbold of FAST.
The three different length runners are defined as Standard, High Horsepower, and Race. Each of these levels push the rpm band and horsepower gains a little further out until you are in the extreme territory north of 9,000 rpm. Starting with the standard; a long length runner will provide the best low-end characteristics like torque, throttle response, and general streetability while serving both stock and mildly modified engines.
The middle of the range in interchangeable runners is the high-horsepower horn, this purple color-coded runner features a mid-length design and a straighter path for incoming charge air. The shorter length starts to increase the harmonic frequency at which the engine performs its best, pushing the power band gains above 6,000 rpm. These middle-of-the-road runners are best suited to moderately modified, high-power and torque engines that are driven with some zest.
The final offering from FAST is the most extreme of the lineup. The racing-red intake runner is the shortest and straightest design, maximizing the outer limits of flow characteristics. This air horn is for the fringe players who demand every bit out of their LS platform at extremely high rpm operation. Horsepower gains of around 30 hp at in excess of 9,000 rpm means these runners are only for applications where extended high-rpm operation is expected.
The testbed engine featured on the dyno in this video is a 6.0-liter LS7 with a stock crank but Lunati H-beam rods and pistons. FAST looks at this breakthrough in tuning ability as a window into other realms of aftermarket support. With the industry trend leaning toward screamer engines, other facets of parts will follow suit. “If we can improve one component, like the intake, it then inspires us to alter the other components. Once we have a manifold that is set up to go to 9,000 rpm, we can then design a camshaft to compliment it or make upgrades to elements of the fuel system. Operating in the 9,000 rpm range safely opens up a new realm of possibilities and package options,” foreshadowed Godbold.
We are excited to see the potential that these interchangeable runners represent, in time it’s likely that more and more modularity will be built into parts. For more information on the FAST LSXR and LSXRT interchangeable intake runners check out their website, and look for a follow-up video covering the ability to mix and match different runners.