Inlet Manifolds for the Modern Age – Brendan Baker @EngineBuilder

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Today’s aftermarket intake manifolds offer engine builders many options, but choosing the right one for your build is more than just finding the biggest one.

When Vic Edelbrock Sr. bought a 1932 Ford Roadster as his first project car in 1938, it was a turning point in his young company’s history. Vic Sr. ‘s entry into the world of “hot rods” led to the design and manufacture of the first Edelbrock intake manifold, and thus the hotrod age began. 

Edelbrock Sr. knew the engine’s top end was about moving air and fuel to the combustion chamber as efficiently as possible, and a good design had the potential to unlock horsepower. He came up with the first performance intake for Flathead V8s with a 180-degree dual-plane design. The rest, as they say, is history.

Today’s aftermarket intake manifolds offer engine builders many options, but choosing the right one for your build is more than just finding the biggest one. Experts say it is essential to match the head and intake to your application and intended use, i.e., rpm range. 

If your customer is an occasional drag strip competitor, but mainly drives his showpiece to the local diner for car club nights, you may want to choose an intake that’s good for the street and reasonable on the strip (or from stoplight to stoplight). Today’s performance components blur the lines between street and racing more than ever, so engine builders must know how to read between the lines for their customers.

High-performance intake manifolds should have smooth contours and gradual transitions between segments. The design and orientation of the intake manifold is a significant factor in the efficiency of an engine. Major contour changes can invoke pressure drops, resulting in less air (or fuel) entering the combustion chamber.

While there are several manifold styles from which to choose, each design has some compromise to consider. Take, for instance, the dual-plane manifold. It has consistently been recognized for its performance from idle to 5,500-6,000 rpm. This manifold has been a mainstay for OEMs because it produces excellent drivability. The cylinder runners are grouped and separated by 180-degrees of crank rotation and split a plenum. There are two small separate plenums, and the runners are usually long, with each one feeding four opposing cylinders of a V8 engine. 

One thing to keep in mind when choosing an intake is that air velocity affects throttle response as well as low-end torque. That’s why cylinder heads with port runner volumes that are too large may not perform as well as the stock cylinder head.

Turbulence helps route air into the cylinder more efficiently and promotes better air and fuel mixture for better combustion. Turbulence can also cause air and fuel separation in the combustion chamber, which you can better get an idea of what’s causing the fuel to separate by wet flow testing.

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Categories: Engine, Engineering

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