IMM Focus: Automotive:Manifold magic strikes aftermarket

Molded air intake manifolds have knocked metal into the back seat among OEMs. Now they are taking the enthusiast aftermarket by storm thanks to innovative design and an aggressive material choice. No, it’s not nylon.

You’ve read about injection molded air-intake manifolds many times in the pages of this magazine over the years. They provide an excellent way to remove weight and improve engine performance, as witnessed in stand-out projects such as GM’s Northstar engine and the recent SPE award winner for BMW.

Until this point, plastic manifolds appeared only on production vehicles. Now, the automotive aftermarket is chiming in for the first time with a replacement for the stock nylon manifolds on LS1 and LS6 engines for Corvettes, Camaros, and Firebirds. Fuel-Air-Spark Technologies (Fast), a seven-year-old aftermarket OEM, recently introduced the LSX manifold, molded of polyphthalamide (PPA—Amodel A-6135HSL from Solvay).

The LSX is a three-part design that is bolted together onto the engine. Typically, the shells of plastic air-intake manifolds are bonded by vibration welding. However, auto enthusiasts who want to tweak engine performance are looking for something that can be easily disassembled. Hence, the three-shell design concept was born.

Prior to its first shipping on Jan. 2, the LSX had already received twice the amount of orders anticipated, appearing well on its way to motor sport enthusiast fame. Original annual volumes were projected at 1000, then 2000; currently, the estimate is 4000. The LSX retails for $800.

Bringing this product to market was Managed Programs LLC (MPI; Rochester Hills, MI) and Keith Wilson of Wilson Manifolds (Ft. Lauderdale, FL)—both of whom performed design and engineering—and Composite Performance Technologies (CPT; Rochester Hills, MI), a Tier One supplier to the automotive aftermarket business.

Speeding Up Production

Dan Agnew, president of CPT, tells IMM that the team was able to bypass the prototype tooling stage by outsourcing cast urethane models made in silicone tools from a service bureau that can deliver them in two to three weeks. “We used the models to validate performance on engine dynos and actual vehicles before final production design,” he explains, “and then went directly to production tooling.”

One of the factors that makes this rapid manufacturing timetable possible is the expertise CPT has on staff. “All of our design engineers know how tooling works,” Agnew says, “so we don’t design anything that can’t be molded.” Early supplier involvement meetings also helped design both parts and tools for manufacturability. Another key variable is the strong relationships CPT has built with key tooling companies and molding suppliers. LSX molding is done by custom molder Valtech (Rochester, NY). Two of the three P-20 tools contain elaborate slides (obviously).

Essentially, CPT is treating low-volume production like a high-volume prototype program. “We’ve eliminated the prototype stage, going directly to tools that will easily produce the number of parts anticipated for many years of production,” Agnew says. “We keep the tooling costs down, make use of production molding equipment and time rather than dedicated cells, and in the end, it keeps the parts affordable for our customer.”

Why PPA?

Until the LSX hit the streets, aftermarket performance intakes had been produced solely in sand-cast aluminum at a weight of about 26 lb. By comparison, the LSX delivers 25% more airflow and weighs only 11 lb. Aluminum also heats up intake air, which reduces power, while plastic acts as an insulator.

But why the switch from nylon to PPA? According to Agnew, strength and stiffness were the determining factors. Under high heat and humidity, the tensile strength of this specific PPA grade is 20% greater than nylon 6, and also higher than nylon 6/6. “The pressure in a normally aspirated manifold is less than the surrounding atmosphere,” says Agnew, “but a turbo or supercharger will boost that pressure to 1.5 or 2 atm. The added strength is very important.”Flex modulus for the PPA material also beat nylon by 20% for greater stiffness, and PPA better resists tensile creep over time, which provides security against air leakage at the gaskets. Chemical resistance to gasoline, oils, and coolants was another requirement PPA met.

Added Varoom

Improved performance with the LSX is a marriage between material and design. Wilson and MPI increased airflow by 25% over stock manifolds, and made the runners longer to maintain low-end torque for drivability.

MPI estimates that the LSX will add 20 hp to the 360 generally available from the V-8s it is designed to fit, if no modifications are made. “The three-piece design makes additional tweaking doable for the competent enthusiast,” MPI’s design engineer Tim Collins adds. “Being able to look down the runner at the intake valve, for example, simplifies the job of port matching, which can account for 50 additional hp in a normally aspirated engine.”