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Thank you for this profound insight. Contributions like yours make this site what it is.
And some need to grow a sense of humor..... lighten up a little.... this thread was getting to be an obsession on the whole exotic sound thing, and how to go to great lengths to get it. The whole 8-into-1 thing was a bit over the top.
I agree that the rumble comes from unequal timing. But, if the primaries are all equal length, then why would the exhaust pulses arrive at the merge with unequal timing? The arrival time of each pulse only depends on the length of the tube between the exhaust valve and the collector.
Uneven timing of the pulses. You have two pulses closer together in timing than the others as two cylinders fire back to back each side instead of alternating sides each pulse.
When each bank empties into its own header collector, one collector gets its pulses like- "BAM.... BAMBAM...… BAM", and the other one might be "BAMBAM.... BAM.... BAM". The short-coupled exhaust blasts will affect the sound differently than the single ones. Combine all this and you have the typical skewed-crank exhaust beat. Argue against it all you want, but the results are well-known!
When each bank empties into its own header collector, one collector gets its pulses like- "BAM.... BAMBAM...… BAM", and the other one might be "BAMBAM.... BAM.... BAM". The short-coupled exhaust blasts will affect the sound differently than the single ones. Combine all this and you have the typical skewed-crank exhaust beat. Argue against it all you want, but the results are well-known!
You're not wrong, but you're also not talking about the same thing that spanks13 and I were talking about. I was responding to spanks13's claim that a flat-plane crank is necessary. And also to his claim that equal length headers are not necessary and not used in 180-paired exhausts.
As counterexamples to those claims here are two builds with cross-plane cranks and equal-length 180-paired headers:
You're not wrong, but you're also not talking about the same thing that spanks13 and I were talking about. I was responding to spanks13's claim that a flat-plane crank is necessary. And also to his claim that equal length headers are not necessary and not used in 180-paired exhausts.
As counterexamples to those claims here are two builds with cross-plane cranks and equal-length 180-paired headers:
As for me, whether you want to call me obsessing or not is a matter of opinion. Looking like I'll get back to my equal length tri-y's & make them merge sharply into 1 when I get to a stopping point with what I'm actually physically working on right now, which is this.
american V8's sound the way they do because of manufacturer packaging. having headers joining from just one engine bank is our common way of doing things is ONLY because of packaging. it is actually preventing potential power. the 8 into 1 IS on the right track of how to get exotic sound. but could also be 8-4-2-1, but, the first 8 into 4, there would be cylinders on opposing engine banks that need to join up. there fore, packaging on an affordable mass production american car makes this impossible. and equal length is only hinting at it. YES they need to be equal length, BUT they also need to have the correct measurment of length for the specific engine. if the length hits a wave "valley" then there is no "added power" but if the length times up with a exhaust wave peak, then power can be made. combine this philosophy with the intake ports, and boost can be made in an NA engine. this is how F1, indy, opererate. F1 has variable intake ports on the fly, which keep the boost through the rpm range, or else this effect only takes place through a narrow rpm band.
this is "in a nutshell", theres a lot more factors. and also the collector at the end of the header is very important. and if this is done correctly, then any exhaust after the collector is indifferent to the engines performance.
the flat plane sounds more exotic because it changes the firing order. so more consecutive engine combustion pulses are together on the same side. so the traditional american v8 one sided header will have more consecutive engine combustion pulses going through it.
Last edited by drivinsidewayz; Jan 27, 2019 at 12:35 AM.
Reason: added to it
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