Why do most exhausts go 4-2-1?
Discussion
Hi all,
Trying to understand a bit more about fluid dynamics, and exhaust design.
The question I have is, why do most 4 cylinder exhausts join together into one pipe, which is the same diameter as the four pipes going into it? What would happen if you had all four cylinders with separate pipes to the rear of the vehicle.
Also, backpressure, this gets spoken about a lot but many sources I have read on the internet claim that backpressure is a complete myth, anyone shed any light?
Trying to understand a bit more about fluid dynamics, and exhaust design.
The question I have is, why do most 4 cylinder exhausts join together into one pipe, which is the same diameter as the four pipes going into it? What would happen if you had all four cylinders with separate pipes to the rear of the vehicle.
Also, backpressure, this gets spoken about a lot but many sources I have read on the internet claim that backpressure is a complete myth, anyone shed any light?
Backpressure is a myth, people get it confused with exhaust tuning.
The exhaust gasses come out in pulses, and between each pulse is a low pressure area, so a decent exhaust manifold will attempt to get the tube sizes and resonation to work out that as an exhaust valve opens, it meets a low pressure pocket at the manifold.
When people fiddle too much with exhaust sizes, they can lose the tuned pulse effects, and lose power.
The exhaust gasses come out in pulses, and between each pulse is a low pressure area, so a decent exhaust manifold will attempt to get the tube sizes and resonation to work out that as an exhaust valve opens, it meets a low pressure pocket at the manifold.
When people fiddle too much with exhaust sizes, they can lose the tuned pulse effects, and lose power.
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