Discussion
Just an afternoon chat for the geeks to show how clever they are and the pedants to spit darjeeling all over their Daily Mails:
If we accept (and we do, we do*) that a 3 cylinder petrol internal combustion engine bears a passing audio resemblance to a 6 cylinder version, then why does a 4 pot not sound like an 8?
* based upon empirical research taking into account the opinions of at least three gentlemen with a trace of cracked crude oil in their physiologies
If we accept (and we do, we do*) that a 3 cylinder petrol internal combustion engine bears a passing audio resemblance to a 6 cylinder version, then why does a 4 pot not sound like an 8?
* based upon empirical research taking into account the opinions of at least three gentlemen with a trace of cracked crude oil in their physiologies
I didn't say V6 - and fully expected the dissent on the general principle!
However, MrsC currently has a courtesy VW with an IL3 on the drive, which I just drove for a few miles, and if you wind it up it sounds distinctly related to a 6 - probably a straight 6 then, if you like. Not identical, you understand, just that it does vaguely have that characteristic sound.
A friend had a different IL3 as a courtesy a while back and we noted the same thing then.
However, MrsC currently has a courtesy VW with an IL3 on the drive, which I just drove for a few miles, and if you wind it up it sounds distinctly related to a 6 - probably a straight 6 then, if you like. Not identical, you understand, just that it does vaguely have that characteristic sound.
A friend had a different IL3 as a courtesy a while back and we noted the same thing then.
doogz said:
Attym3 said:
C8PPO said:
If we accept (and we do, we do*) that a 3 cylinder petrol internal combustion engine bears a passing audio resemblance to a 6 cylinder version
First time I've ever heard that?If you look at engine harmonics and balance (I wouldn't recommend it as it's boring at the best of times), an I6 is the most naturally balanced engine configuration you can have. Whilst a 3 pot can indeed sound a bit like an I6, I'd generally say it's got more of a Flat 6 gruffness to it. A friend of mine who's an NVH engineer could probably tell you why that is (likely due to harmonic interference patterns etc), but it's much easier to answer the second question about an I4 and V8.
The sound of a 'traditional' V8 with a crossplane crank as found in Big and Small Blocks is created by the firing order giving uneven exhaust pulses. A small block Chevy engine fires as:
1-8-4-3-6-5-7-2
If you split that in to exhausts 1 and 2 that gives you:
1,2,1,1,2,2,2,1
That's what gives you the classic 'potato, potato, potato' of an old muscle car as the uneven pulses of exhaust gas meet in the silencer.
A flat plane Ferrari V8 on the other hand actually sounds almost identical to an I4 and has the firing order:
1-5-3-7-4-8-2-6
Giving pulses:
1,2,1,2,1,2,1,2
In a common single silencer, this gives even pulses (or the same pulses an I4). The only differences are down to exhaust tuning, and in the case of a Ferrari engine, high revs. A high revving I4 can actually sound very similar to a flat plane V8.
A Cosworth BDA for instance:
http://www.youtube.com/watch?v=3hRybKOEwqI
Equally, some I6s can sound very similar to a V12 and, many V10s and I5s sound similar.
So in answer to the question, it's actually a cross plane V8 that's the odd one out and is the only one that doesn't really sound like it's inline relative.
The sound of a 'traditional' V8 with a crossplane crank as found in Big and Small Blocks is created by the firing order giving uneven exhaust pulses. A small block Chevy engine fires as:
1-8-4-3-6-5-7-2
If you split that in to exhausts 1 and 2 that gives you:
1,2,1,1,2,2,2,1
That's what gives you the classic 'potato, potato, potato' of an old muscle car as the uneven pulses of exhaust gas meet in the silencer.
A flat plane Ferrari V8 on the other hand actually sounds almost identical to an I4 and has the firing order:
1-5-3-7-4-8-2-6
Giving pulses:
1,2,1,2,1,2,1,2
In a common single silencer, this gives even pulses (or the same pulses an I4). The only differences are down to exhaust tuning, and in the case of a Ferrari engine, high revs. A high revving I4 can actually sound very similar to a flat plane V8.
A Cosworth BDA for instance:
http://www.youtube.com/watch?v=3hRybKOEwqI
Equally, some I6s can sound very similar to a V12 and, many V10s and I5s sound similar.
So in answer to the question, it's actually a cross plane V8 that's the odd one out and is the only one that doesn't really sound like it's inline relative.
ArosaMike said:
If you look at engine harmonics and balance (I wouldn't recommend it as it's boring at the best of times), an I6 is the most naturally balanced engine configuration you can have. Whilst a 3 pot can indeed sound a bit like an I6, I'd generally say it's got more of a Flat 6 gruffness to it. A friend of mine who's an NVH engineer could probably tell you why that is (likely due to harmonic interference patterns etc), but it's much easier to answer the second question about an I4 and V8.
The sound of a 'traditional' V8 with a crossplane crank as found in Big and Small Blocks is created by the firing order giving uneven exhaust pulses. A small block Chevy engine fires as:
1-8-4-3-6-5-7-2
If you split that in to exhausts 1 and 2 that gives you:
1,2,1,1,2,2,2,1
That's what gives you the classic 'potato, potato, potato' of an old muscle car as the uneven pulses of exhaust gas meet in the silencer.
A flat plane Ferrari V8 on the other hand actually sounds almost identical to an I4 and has the firing order:
1-5-3-7-4-8-2-6
Giving pulses:
1,2,1,2,1,2,1,2
In a common single silencer, this gives even pulses (or the same pulses an I4). The only differences are down to exhaust tuning, and in the case of a Ferrari engine, high revs. A high revving I4 can actually sound very similar to a flat plane V8.
A Cosworth BDA for instance:
http://www.youtube.com/watch?v=3hRybKOEwqI
Equally, some I6s can sound very similar to a V12 and, many V10s and I5s sound similar.
So in answer to the question, it's actually a cross plane V8 that's the odd one out and is the only one that doesn't really sound like it's inline relative.
Is your day job writing odd one out questions for have I got news for you?The sound of a 'traditional' V8 with a crossplane crank as found in Big and Small Blocks is created by the firing order giving uneven exhaust pulses. A small block Chevy engine fires as:
1-8-4-3-6-5-7-2
If you split that in to exhausts 1 and 2 that gives you:
1,2,1,1,2,2,2,1
That's what gives you the classic 'potato, potato, potato' of an old muscle car as the uneven pulses of exhaust gas meet in the silencer.
A flat plane Ferrari V8 on the other hand actually sounds almost identical to an I4 and has the firing order:
1-5-3-7-4-8-2-6
Giving pulses:
1,2,1,2,1,2,1,2
In a common single silencer, this gives even pulses (or the same pulses an I4). The only differences are down to exhaust tuning, and in the case of a Ferrari engine, high revs. A high revving I4 can actually sound very similar to a flat plane V8.
A Cosworth BDA for instance:
http://www.youtube.com/watch?v=3hRybKOEwqI
Equally, some I6s can sound very similar to a V12 and, many V10s and I5s sound similar.
So in answer to the question, it's actually a cross plane V8 that's the odd one out and is the only one that doesn't really sound like it's inline relative.
(good post btw!)
gavgavgav said:
Is your day job writing odd one out questions for have I got news for you?
(good post btw!)
A sideline I'd not considered :P(good post btw!)
My only excuse for that knowledge is that the automotive engineering modules in my degree were one of the few bits I found interesting! I also intended on going in to engine development originally but have now ended up effectively as a software engineer working on ABS, traction and Stability Control!
C8PPO said:
Just an afternoon chat for the geeks to show how clever they are and the pedants to spit darjeeling all over their Daily Mails:
If we accept (and we do, we do*) that a 3 cylinder petrol internal combustion engine bears a passing audio resemblance to a 6 cylinder version, then why does a 4 pot not sound like an 8?
* based upon empirical research taking into account the opinions of at least three gentlemen with a trace of cracked crude oil in their physiologies
Yep, it gave a great deal of entertainment to us when we noticed the 3 cylinder Micra engine sounds remarkably similar to my mates 370Z when it was thrashed hard. If we accept (and we do, we do*) that a 3 cylinder petrol internal combustion engine bears a passing audio resemblance to a 6 cylinder version, then why does a 4 pot not sound like an 8?
* based upon empirical research taking into account the opinions of at least three gentlemen with a trace of cracked crude oil in their physiologies
Disco You said:
Who cares how 3 cylinder cars sound? In my experience you can't hear the sound of the engine over your teeth clattering together from the distinctive "1 cylinder missing" bone-shaking.
ever driven a modern three cylinder car? I rather enjoyed hooning around in my mother's 107!ArosaMike said:
A sideline I'd not considered :P
My only excuse for that knowledge is that the automotive engineering modules in my degree were one of the few bits I found interesting! I also intended on going in to engine development originally but have now ended up effectively as a software engineer working on ABS, traction and Stability Control!
Beats designing headlights I suppose...My only excuse for that knowledge is that the automotive engineering modules in my degree were one of the few bits I found interesting! I also intended on going in to engine development originally but have now ended up effectively as a software engineer working on ABS, traction and Stability Control!
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