hi, im a professional diesel engine mechanic and can easily explain what youre hearing.
Most italian/european sports cars (with the exception of Mercedes in the past 3 years because American customers) have machined their crankshafts as "flatplane" cranks. Flat-plane cranks, no matter what firing order they have, will always alternate from bank to bank. This yields optimum exhaust scavenging and thus doesn't require the more complex header primaries that have to cross over from one bank to the other. Due to their design they don't need huge counterweights, which is why they rev up so quickly. The downside is that they suffer from secondary vibrations and have lower torque.
Americans typically machine closer to if not dead-on a crossplane crank or cruciform crank. the four crank pins are positioned in two planes, offset by 90 degrees. Typically the two outer pins are perpendicular to the outer and the two end pins are in one 180-degree plane. exhaust gas scavenging isn't as efficient as with a flat-plane crank, but that sound is worth it. This design necessitates larger counterweights to achieve a proper engine balance. The result is that you don't have the secondary vibration problems associated with flat-plane cranks. But they also don't rev as fast or as high. pick crossplane when you want torque imo.
I personally understand that a euro flat-plane crank is superior in its efficiency and power for racing, but the crossplane sound just melts my cold American heart when i hear it.
Thanks for summarizing the main points of the article so concisely.
The article also points out that GMs LT6 flat-plane V8 for the Corvette Z06 has a sound different from the F355, this apparently being deliberate design choice made by choosing which harmonics to emphasize in the exhaust system.
You say that flat-plane engines do not require the complex header primaries that have to cross over from one bank to the other, but AFAIK typical road car and truck V8s do not have such headers[1]. Would the purpose of such headers be to give a cross-plane V8 scavenging about as good as a flat-plane one, all else being equal? In that case, would the cross-plane engine lose most of its distinctive sound?
I would be interested in hearing the difference between otherwise comparable flat-plane and cross-plane V8s at the same RPM.
Not the one you were responding to, just a car nerd.
You say that flat-plane engines do not require the complex header primaries that have to cross over from one bank to the other, but AFAIK typical road car and truck V8s do not have such headers[1]. Would the purpose of such headers be to give a cross-plane V8 scavenging about as good as a flat-plane one, all else being equal?
Yes, but as you point out deployments of this technique are limited due to packaging, cost, and even other performance parameters. See the GT40 “bundle of snake” headers for an example.
For a notable example of the other performance parameters, exhaust header lengths are tuned to the powerband of the engine such that shorter headers are more efficient at higher RPMs and longer headers at higher RPMs. This can even get into resonant effects as with intake runners. It’s difficult to design cross bank headers short enough to suit modern high-rpm engines, with the exception of the “hot-V”, exhaust inside intake outside, concept deployed on German V8s from BMW, Mercedes, and Porsche on the 918 (though the latter is a flatplane crank).
In that case, would the cross-plane engine lose most of its distinctive sound?
It additionally talks about the unusual pattern used in modern voodoo engines in the Ford Mustang (which is also mentioned in the article). The video is very similar to this article.
That's an excellent video and helped me understand a lot. Another great video is this one from a guy who created Engine Simulator which not only simulates the physics but the sound of engines as well. In this video he covers the difference between flat and cross plane engines: https://youtu.be/NBBwva3NZ6o
Yes, a crossplane V8 with Flowmasters is probably one of the most unmistakably American sounds. I find the high-revving import sound far less enjoyable; it's smoother but the high pitch is fatiguing.
On the other hand, I also like the sound of two-stroke diesels.
I live in the US and have the same preference as far as cars go, but I literally cried happy man tears the day that I got my four-cylinder Honda bike (with a flat-plane crank) and listened to it as I wound it out in first gear. There's definitely room in this wonderful world for both :-)
I think that you should mention that this is specific to 90 degree v8 engines - other engine designs can have similar crankshaft / firing order trade offs but would not be described as “flat plane” or “cross plane”.
Hi, I’m a longtime student of the American culture and I think the primary reason why Americans love it so much is because it temporarily masks their tinnitus and not because it melts their cold hearts.
Approximately 10 percent of the U.S. adult population — over 25 million Americans — experience some form of tinnitus. And an even larger percentage is suffering from hearing impairments.
Broken mufflers and loud engines mask the tinnitus sounds and finally they can relax. This is also the reason why they prefer to hang their Freeways in the air, in the middle of the city. And why their cafes are unbearably loud with the sound of refrigerators competing with the loud music.
Americans like it because when you sit in a big V8 and smash the accelerator it jolts you forward and pins you in the seat while the engine is roaring like a lion. It's fun, like going down a hill in a rollercoaster. That's really all there is to it. Hearing it makes you think of the fun yourself.
this is actually a really great comment. Mercedes is pivoting to the crossplane kinda for this reason (the american market.) it makes a V6 sound like a V8, keeps their engine design euro spec compliant, and helps deliver torque which their twelve SUV lineup desperately needs considering most weigh in at over two short tonnes. crossplane also helps mask turbo whine which most red-blooded americans associate with their massive trucks, not sport SUV offerings.
Mercedes is running cross-plane cranks in their V6 engines because V6s are cross-plane out of necessity. That applies to all engines with cylinder counts which are not exponents of 2.
A "dinky", "small-displacement", "underpowered" European or Japanese sports car will do the same job. There are many replacements for displacement. The American preference for big, heavy vehicles with big, heavy engines is just aesthetic.
You can't get the sort of low end torque with a turbocharged i4 that you can with a large displacement V8 even if they both have the same peak horsepower. More low end torque give a better throttle response and different characteristics than more high revving engines.
Who says Americans hate electric cars? Teslas are selling quite well here.
But you have to realize America is enormous--its over 2600 miles to drive end to end. Our highway system and infrastructure isn't setup to completely replace gas or diesel with electric for long term trips. It's getting much better, but I suspect reluctance to get an electric car in the US primarily comes down to cost and range anxiety.
I'm not sure if this is a joke or not. I know lots of young people, myself included, who don't have tinnitus and also like V8s or V-twins motorcycles in my case.
Comments
hi, im a professional diesel engine mechanic and can easily explain what youre hearing.
Most italian/european sports cars (with the exception of Mercedes in the past 3 years because American customers) have machined their crankshafts as "flatplane" cranks. Flat-plane cranks, no matter what firing order they have, will always alternate from bank to bank. This yields optimum exhaust scavenging and thus doesn't require the more complex header primaries that have to cross over from one bank to the other. Due to their design they don't need huge counterweights, which is why they rev up so quickly. The downside is that they suffer from secondary vibrations and have lower torque.
Americans typically machine closer to if not dead-on a crossplane crank or cruciform crank. the four crank pins are positioned in two planes, offset by 90 degrees. Typically the two outer pins are perpendicular to the outer and the two end pins are in one 180-degree plane. exhaust gas scavenging isn't as efficient as with a flat-plane crank, but that sound is worth it. This design necessitates larger counterweights to achieve a proper engine balance. The result is that you don't have the secondary vibration problems associated with flat-plane cranks. But they also don't rev as fast or as high. pick crossplane when you want torque imo.
I personally understand that a euro flat-plane crank is superior in its efficiency and power for racing, but the crossplane sound just melts my cold American heart when i hear it.
Thanks for summarizing the main points of the article so concisely.
The article also points out that GMs LT6 flat-plane V8 for the Corvette Z06 has a sound different from the F355, this apparently being deliberate design choice made by choosing which harmonics to emphasize in the exhaust system.
You say that flat-plane engines do not require the complex header primaries that have to cross over from one bank to the other, but AFAIK typical road car and truck V8s do not have such headers[1]. Would the purpose of such headers be to give a cross-plane V8 scavenging about as good as a flat-plane one, all else being equal? In that case, would the cross-plane engine lose most of its distinctive sound?
I would be interested in hearing the difference between otherwise comparable flat-plane and cross-plane V8s at the same RPM.
[1] https://en.wikipedia.org/wiki/Crossplane#Sound
Not the one you were responding to, just a car nerd.
Yes, but as you point out deployments of this technique are limited due to packaging, cost, and even other performance parameters. See the GT40 “bundle of snake” headers for an example.
For a notable example of the other performance parameters, exhaust header lengths are tuned to the powerband of the engine such that shorter headers are more efficient at higher RPMs and longer headers at higher RPMs. This can even get into resonant effects as with intake runners. It’s difficult to design cross bank headers short enough to suit modern high-rpm engines, with the exception of the “hot-V”, exhaust inside intake outside, concept deployed on German V8s from BMW, Mercedes, and Porsche on the 918 (though the latter is a flatplane crank).
Yes
I found this video to be an excellent explainer on the differences between cross and flat plane cranks: https://www.youtube.com/watch?v=RcyMoZoqkPA
It additionally talks about the unusual pattern used in modern voodoo engines in the Ford Mustang (which is also mentioned in the article). The video is very similar to this article.
That's an excellent video and helped me understand a lot. Another great video is this one from a guy who created Engine Simulator which not only simulates the physics but the sound of engines as well. In this video he covers the difference between flat and cross plane engines: https://youtu.be/NBBwva3NZ6o
The engine simulator was discussed on HN too: https://news.ycombinator.com/item?id=32423102
Thanks for the yt link. So that's what 11mpg sounds like.
Re: Ford Mustang [1]
[1] https://www.pocket-lint.com/cars/news/ford/131151-ford-admit...
Yes, a crossplane V8 with Flowmasters is probably one of the most unmistakably American sounds. I find the high-revving import sound far less enjoyable; it's smoother but the high pitch is fatiguing.
On the other hand, I also like the sound of two-stroke diesels.
I live in the US and have the same preference as far as cars go, but I literally cried happy man tears the day that I got my four-cylinder Honda bike (with a flat-plane crank) and listened to it as I wound it out in first gear. There's definitely room in this wonderful world for both :-)
There's this youtube channel (William Moser) that makes different firing-order engine sound simulations using an analog circuit of some kind
crossplane: https://www.youtube.com/watch?v=vpswVBOC8lk
flatplane: https://www.youtube.com/watch?v=5r7X9L8_pS4
I think that you should mention that this is specific to 90 degree v8 engines - other engine designs can have similar crankshaft / firing order trade offs but would not be described as “flat plane” or “cross plane”.
Thanks, this reply is better than the article's
Hi, I’m a longtime student of the American culture and I think the primary reason why Americans love it so much is because it temporarily masks their tinnitus and not because it melts their cold hearts.
Approximately 10 percent of the U.S. adult population — over 25 million Americans — experience some form of tinnitus. And an even larger percentage is suffering from hearing impairments.
Broken mufflers and loud engines mask the tinnitus sounds and finally they can relax. This is also the reason why they prefer to hang their Freeways in the air, in the middle of the city. And why their cafes are unbearably loud with the sound of refrigerators competing with the loud music.
Americans like it because when you sit in a big V8 and smash the accelerator it jolts you forward and pins you in the seat while the engine is roaring like a lion. It's fun, like going down a hill in a rollercoaster. That's really all there is to it. Hearing it makes you think of the fun yourself.
this is actually a really great comment. Mercedes is pivoting to the crossplane kinda for this reason (the american market.) it makes a V6 sound like a V8, keeps their engine design euro spec compliant, and helps deliver torque which their twelve SUV lineup desperately needs considering most weigh in at over two short tonnes. crossplane also helps mask turbo whine which most red-blooded americans associate with their massive trucks, not sport SUV offerings.
Mercedes is running cross-plane cranks in their V6 engines because V6s are cross-plane out of necessity. That applies to all engines with cylinder counts which are not exponents of 2.
A "dinky", "small-displacement", "underpowered" European or Japanese sports car will do the same job. There are many replacements for displacement. The American preference for big, heavy vehicles with big, heavy engines is just aesthetic.
You can't get the sort of low end torque with a turbocharged i4 that you can with a large displacement V8 even if they both have the same peak horsepower. More low end torque give a better throttle response and different characteristics than more high revving engines.
So why do most Americans hate or at least dislike electric cars then? Which does the same, even more so?
Who says Americans hate electric cars? Teslas are selling quite well here.
But you have to realize America is enormous--its over 2600 miles to drive end to end. Our highway system and infrastructure isn't setup to completely replace gas or diesel with electric for long term trips. It's getting much better, but I suspect reluctance to get an electric car in the US primarily comes down to cost and range anxiety.
Teslas have great acceleration too!
Why do you think Americans suffer from tinnitus more than other nationalities?
Maybe longtime students of the American culture speak very loudly.
Because of all the loud cross plane exhausts.
I'm not sure if this is a joke or not. I know lots of young people, myself included, who don't have tinnitus and also like V8s or V-twins motorcycles in my case.