Which design uses tapered runners angled more directly toward the cylinder head to improve airflow at high RPM?

• A. Cross-ram
• B. Tunnel ram
• C. Plenum
• D. Fuel injection manifold

Answer: (B)

When you want airflow to stay strong at high RPM, the path the air takes from the plenum to each cylinder is everything. The tunnel ram does exactly that by using long, straight runners that taper toward the cylinder head ports. This design keeps air moving fast as it enters each cylinder, with minimal turbulence from bends, which helps boost top-end horsepower. The air is fed through a central plenum between the banks, and each runner is aimed directly at its port, preserving velocity all the way to ignition.

Cross-ram setups use shorter runners that cross between banks and often involve more turns to reach the ports, which can reduce velocity at very high RPM. A plenum-style manifold focuses on even distribution across cylinders and a broad RPM range rather than optimizing velocity at high speed. A fuel-injection manifold concerns how fuel is delivered rather than the geometry of air runners, so it doesn’t inherently optimize high-RPM airflow in the same way.

So, the design described—tapered runners angled directly toward the cylinder head to improve high-RPM airflow—is the tunnel ram.