626 days later, I can share insights that I've learned since then and that need to be corrected in the video: - Merge collectors are NOT responsible for the "F1-style" exhaust sound. That sound is created by putting multiple inflection points in series (along with the other commonly known factors). However, merge collectors do enhance the smoothness of the exhaust sound as mentioned in the video, thanks to their gradual pressure wave reflection. - There's a new contender for the best-sounding production car ever made: the GMA T.50. - I assume that BMW didn't use baffle collectors for a broad usable powerband. In theory the "baffle"-style collector causes stronger reflections at a narrower rpm. But reality is more complex. As one Formula 1 engineer has put it: "The collector ... performs various functions, not all of which are fully understood." I believe BMW chose this collector style primarily for cost-effectiveness and easier mass production, especially considering when the original inline-6 M5 engine was designed and built, particularly when compared to the complexity of merge collectors. - My S13 with M120 swap and BMW M5 headers didn't produce "F1 sounds" due to the varying segment lengths between the equal-length headers and Y-pipe(s). However, its "raspy" sound was a result of BMW's baffle-style collectors. - Regarding the wild claim "6-into-1 headers lose horsepower": Actually, combining more cylinders into a single collector might increase power due to stronger pressure wave reflections in a "low impedance" environment (within the hot collector). While I'm not aware of any direct back-to-back testing, even some Formula One engineers seem to speculate that "more pipes are joined together = more power." - The statement "The more cylinders joined by equal-length pipes, the better the sound" is false at least unless additional inflection points are added before the final collector. This crucial detail wasn't known to me (or apparently anyone else) when the video was released. While other factors like firing order sequence also play important roles, I hope it's not required to specifically point that out. - Sequential Firing Order: This is NOT essential for achieving the "musical" exhaust note. After testing various exhaust configurations, I believe the sound difference compared to a non-sequential header might be noticeable but subtle. I assume the effect becomes more pronounced as more cylinders join in the collector. Regarding performance: Sequential firing order should positively impact power output, with the effect amplifying as more cylinders are combined. Unfortunately there hasn't been any back to back testing yet, as far as I'm aware of. - While the stock M120 engine with its 12-into-1 header doesn't outperform Pagani's sound, this could be achieved with one "minor" exhaust modification: adding a single inflection point per pipe before the collector would do wonders. No engine modifications would be necessary. - Regarding Tim's planned 2022 event: Although he did participate, the car wasn't competition-ready. Instead, he attended as an exhibition entry with a running, but poorly-sounding Mercedes SL. The rest of the video still seems to be valid, especially the bit about the McLaren F1 not being able to hit the high note. But if you would add three Y-pipes, it would it would start to sound a lot more like the GMA T.50. You can find more details about my exhaust sound research on this youtube channel.
New video: November, 25th
626 days later, I can share insights that I've learned since then and that need to be corrected in the video:
- Merge collectors are NOT responsible for the "F1-style" exhaust sound. That sound is created by putting multiple inflection points in series (along with the other commonly known factors). However, merge collectors do enhance the smoothness of the exhaust sound as mentioned in the video, thanks to their gradual pressure wave reflection.
- There's a new contender for the best-sounding production car ever made: the GMA T.50.
- I assume that BMW didn't use baffle collectors for a broad usable powerband. In theory the "baffle"-style collector causes stronger reflections at a narrower rpm. But reality is more complex. As one Formula 1 engineer has put it: "The collector ... performs various functions, not all of which are fully understood." I believe BMW chose this collector style primarily for cost-effectiveness and easier mass production, especially considering when the original inline-6 M5 engine was designed and built, particularly when compared to the complexity of merge collectors.
- My S13 with M120 swap and BMW M5 headers didn't produce "F1 sounds" due to the varying segment lengths between the equal-length headers and Y-pipe(s). However, its "raspy" sound was a result of BMW's baffle-style collectors.
- Regarding the wild claim "6-into-1 headers lose horsepower": Actually, combining more cylinders into a single collector might increase power due to stronger pressure wave reflections in a "low impedance" environment (within the hot collector). While I'm not aware of any direct back-to-back testing, even some Formula One engineers seem to speculate that "more pipes are joined together = more power."
- The statement "The more cylinders joined by equal-length pipes, the better the sound" is false at least unless additional inflection points are added before the final collector. This crucial detail wasn't known to me (or apparently anyone else) when the video was released. While other factors like firing order sequence also play important roles, I hope it's not required to specifically point that out.
- Sequential Firing Order: This is NOT essential for achieving the "musical" exhaust note. After testing various exhaust configurations, I believe the sound difference compared to a non-sequential header might be noticeable but subtle. I assume the effect becomes more pronounced as more cylinders join in the collector. Regarding performance: Sequential firing order should positively impact power output, with the effect amplifying as more cylinders are combined. Unfortunately there hasn't been any back to back testing yet, as far as I'm aware of.
- While the stock M120 engine with its 12-into-1 header doesn't outperform Pagani's sound, this could be achieved with one "minor" exhaust modification: adding a single inflection point per pipe before the collector would do wonders. No engine modifications would be necessary.
- Regarding Tim's planned 2022 event: Although he did participate, the car wasn't competition-ready. Instead, he attended as an exhibition entry with a running, but poorly-sounding Mercedes SL.
The rest of the video still seems to be valid, especially the bit about the McLaren F1 not being able to hit the high note. But if you would add three Y-pipes, it would it would start to sound a lot more like the GMA T.50.
You can find more details about my exhaust sound research on this youtube channel.
That's all the comments we need. Thanks to everyone who has contributed something of value.
More videos of that Mustang with the 8-in-1 header: www.youtube.com/@trackdayclassics