![]() To accommodate this, the collector for a 90-degree crank motor must be larger than for an “all-other-things-being-equal” flat-crank motor, thereby losing some low and mid-range torque. This gives the engine that inherent “American V-8” exhaust burble, but also causes a “crowded” condition in the collector when two exhaust pulses, separated by only 90 crank degrees are trying to exit through the collector. The problem is that for a conventional 4-1 exhaust header, the separation between two firing (or exhaust) impulses is 90 crank degrees in each collector versus 180 crank degrees for a flat crank engine. So what’s the problem with these 180 degree headers? Some racing and high performance engines including Ferraris use a flat-plane crank to optimize the intake and exhaust processes, accepting the additional vibrations. The purpose of the 90-degree crank is to minimize vibrations inherent to “flat-plane” cranks. Most modern V-8s have what is known as 90-degree cranks (aka crucified cranks, bent cranks, cross-plane cranks) wherein the cylinder firing order is such that two cylinders on each bank fire consecutively as opposed to alternating banks. ![]() What was the purpose of these tangled spaghetti-like devices? Those beautiful works of art built by English craftsman on the Lola-designed chassis where two tubes from each bank of the V-8 are crossed over the engine to collect in 4-1 collectors with opposing tubes. Many of you have seen the so-called “bundle-of-snakes” headers on the infamous Ford GT40s of the late sixties, but you might wonder. ![]()
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