Exhaust Manifolds & Headers Flashcards

What is 'exhaust scavenging'?

Answer: Using exhaust pulse energy to help draw fresh gases into the cylinder

Exhaust scavenging uses the negative pressure wave created by an exhaust pulse to help pull fresh intake charge into the cylinder, improving volumetric efficiency.

Which type of header is best suited for maximizing low-end torque in street performance applications?

Answer: Shorty headers

Shorty headers are less disruptive to low-RPM exhaust scavenging characteristics, making them better suited for street driving where low-end torque is prioritized.

What sealing component is placed between the exhaust manifold and the cylinder head?

Answer: Exhaust manifold gasket

An exhaust manifold gasket seals the joint between the manifold and cylinder head, preventing exhaust gases from leaking and causing noise or damage.

What symptom commonly indicates an exhaust manifold leak?

Answer: Ticking or popping sound from the engine bay that diminishes as the engine warms up

A cracked or leaking exhaust manifold often produces a metallic ticking sound when cold that may reduce as the metal expands and partially seals the crack once warmed up.

What is the purpose of ceramic or thermal coating applied to exhaust manifolds?

Answer: To retain exhaust heat inside the pipes, improving flow velocity and reducing under-hood temperatures

Thermal coating keeps exhaust gases hotter inside the manifold, maintaining gas velocity for better scavenging, while also reducing underhood radiant heat.

What is a 'collector' in the context of performance exhaust headers?

Answer: The section where individual primary tubes merge into a single outlet

The collector is the funnel-shaped section at the end of an exhaust header where all individual cylinder tubes merge into one pipe, which then connects to the rest of the exhaust.