Ram-air intake system

What are those forward facing scoops or ducts on the hood of muscle cars?

Have you ever wondered, what are those forward facing scoops or ducts on the hood of muscle cars? The classic air intakes on the Pontiac Firebird is the finest example of such Ram-air intakes. These are generally found in high-performance racing cars, SUVs, trucks and motorcycles to add the engine power. Ram air is an engine intake system, which is specially designed to increase the static air pressure inside the intake manifold of an IC engine. It can be achieved with the help of dynamic air pressure created by the motion of the vehicle. To be precise, getting more air inside the intake means more air-fuel mixture, which results in more power. Whatever be the intake system, the primary goal is to achieve more power output from the engine.

How it works

Actually, ram-air intake is a hybrid system that works in between the naturally aspirated and forced induction system. As the intake air gets compressed before it reaches the inlet manifold and thereby increasing the power. The system can boost the power from 5 to 15 bhp in total, depending on the engine capacity. As this system increases the volumetric efficiency of the engine, the conventional carburettors have to be replaced or modified. Because the carburettors rely on pressure drop to draw the fuel through main-jet and the pressurized ram-air could damage this venturi effect.

The ram-air intake relies hugely on the vehicle speed. At lower speeds, the intake air can't reach the throat of the scoop to get compressed. Therefore, it is more effective at a minimum speed range of 50 kmph or even higher.

How it can be made

This system can be made out of plastic, rubber, metal, composite materials, fiberglass or even with Kevlar. The intake air box of the system should have a size to complement to the engine and opening mouth or hose must be large enough to breathe sufficient air in all driving conditions. The power delivery can be varied from time to time, depending on the engine speed.

The basic ram-air intake consists of a plastic tube leading to a conical air filter placed exposed from the engine. Such intake system always has added sound due to the absence of covering.

The ram-air intake and cold air intake system works under different parameters. The cold air system works by bringing the cold air inside the inlet valve while ram air works by bringing air at a faster speed and thereby deriving more fuel. Neither the cold air or ram-air intake system can boost the performance as that of a forced induction systems like super chargers and turbo chargers. However, ram-air intakes are less complicated, least expensive and more reliable at times. So one could easily opt for ram-air intake system without spending much sum.

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