I've been fascinated with venturi boosters since I first installed them in the bores of my dad's Tillotson carbs in 1975. He went out and set the APBA kilo record in APBA FS class.
Since the good old days, Mercury Carb Stacks have simply been copies of the stock air box plate, and the venturi booster effect had long been forgotten on the V6, until now!
Modern variable velocity stacks, where intake runners change length based on throttle position are commonplace in other motorsports. Trumpet-shaped curves, with tuned lengths, allow for laminar flow, where the air can travel more smoothly and faster.
The length of the stack determines the torque curve in the RPM range. Longer stacks give more torque at higher RPM, while short stacks produce added torque at lower RPM. Even common blow guns have venturi ports on the nozzle to draw additional air volume without taxing the compressor.
Learning from these common but missed industry developments, Buckshot Racing #77 has created a unique set of Boost Stacks for the Mercury V6 with impressive mid-range and peak power.
We employed a top velocity stack engineer (with credentials from the FIM) to create our unique fixed two-tier boost stack system that tricks the motor into believing the stacks are moving as air flow increases!
We tested multiple shapes and designs on an air flow-bench, then did some dyno testing on the single cylinder to iterate versions, finally tested on a load wheel and acceleration runs in the tunnel boat.
By creating the additional front-tier venturi booster, we've seen velocity increase as the cross-section decreases. The airflow is more inviscid, laminar, and further driven by the pressure drop around the bridge. The energy and increased speed come from reduced static pressure.
We finalized on a Fused Carbon Fiber Onyx Laminate (approved for racing in MotoGP) to create these complex shapes, but retain the strength of aluminum, the toughness of steel, and resistance to Petrochemicals.
Our Onyx Carbon Boost Stacks have a 50% better strength-to-weight ratio and are 40% lighter compared with 6061 aluminum.
Each kit includes 3 sets of Boost Stacks, bolts, and Allen wrench for a clean install.
Each stack takes 28 hours to produce on an industrial-grade 3D printer to infuse the micro-carbon fibers.