Muscle car sound

"BugEyedBimmer - back in the Saddle Dakota Leather" (bugeyedacura) 12/20/2013 at 20:18 • Filed to: None

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What gives classic muscle that distinctive sound? You know the one, deep and burbling, but also vaguely metallic. No modern car sounds that way.

IDROVEAPICKUPTRUCK > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 20:28

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A quick guess would be:

-No cats

-Simple mufflers

-Carbs

Burt > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 20:28

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Testicles. Massive testicles.

Deal Killer - Powered by Focus > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 20:28

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Cubic inches, no emission controls and a simple air intake.

BugEyedBimmer - back in the Saddle Dakota Leather > IDROVEAPICKUPTRUCK 12/20/2013 at 20:30

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Must be the carbs. Modern V8s don't sounds like that even without their emissions equipment.

IDROVEAPICKUPTRUCK > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 20:31

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Might also have something to do with lower compression ratios

BlazinAce - Doctor of Internal Combustion > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 20:31

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My guess would be the intake, carbs, cams and exhaust.

Hermann > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 20:35

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Muscle car sound recipe, take your notebooks:
1 Carburetor
1 pinch of heavy steel
4 gallons of fuel rambling about and being transformed into sound instead of power
2 tea spoons of cam tuning

Some engines get very similar sounds today, but nowadays you can't make inefficient engines anymore.

desertdog5051 > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 20:39

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Large displacement and no restrictions would be my guess.

Arch Duke Maxyenko, Shit Talk Extraordinaire > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 20:41

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Large bore and stroke, 90 degree V8's, primary and secondary butterflies and sometimes multiple carbs, no cats, aggressive cams, high compression.

If only EssExTee could be so grossly incandescent > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 20:44

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Lots of displacement, fairly unrestricted exhaust, and of course crossplane cranks.

GhostZ > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 21:03

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Most of the comments before this one is not entirely true. While yes, certain exhaust systems, carburetors, and large displacements contribute to the sound, those are not unique to muscle cars . That distinctive burble actually comes from a Cross Plane Crank and non-evenly distributed firing orders.

Its most obvious in the Mustang, where the firing order does not alternate left-right-left-right on the exhaust, starting with the 289:

Notice how cylinders 4 and 2, and 7 and 8, fire from the same side right after eachother. This causes a "double" firing from that exhaust pipe, giving it that distinctive burble. Here's a picture for example:

The next change, closely related, is a Cross-Plane crank rather than a Flat-Plane crank. A cross plane crank allows cylinders to fire at 90 degrees from eachother. This effect is more noticeable at lower RPMs where the gaps between firings are more pronounced. It looks like this:

Instead of the crank pins being split into two gruops ("top" and "bottom", 180 degrees apart) the crank is split into 4 groups, with 2 sets opposing eachother. This changes the way the engine revs and "evenness" of the exhaust firings.

A Ferrari V8, with firing order 1,5,3,7,4,8,2,6, doesn't overlap and has a flat plane crank.

Every other aspect of the engine noise, such as exhaust settings, carbs, compression ratio, etc. can be changed and are not exclusive to older American V8 engines. For example, most V8 engines are hydraulic overhead valve units. However, some American V8s (such as Ford's modular, I think) retain their odd firing orders while being a DOHC unit. Plus, many muscle cars on the track used solid roller cams, which can change the sound a well. The cam profile has a huge effect as well, but all of those things can be changed whether its a Ferrari or a Ford engine. The crank angle and firing order are the real source of that unique sound.

Skif6996 > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 21:07

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I would say the cam plays a significant role in this. Big lope gives it that muscle car rhythm.

GhostZ > Hermann 12/20/2013 at 21:08

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Most muscle cars that were built for real performance (and not cheap engines for consumer use) could 95HP/liter and decent gas milage on 95 octane. Numbers basically similar to a modern N/A Porsche 911. They weren't as reliable, but they were as efficient.

They aren't fuel efficient by today's standards, but not necessarily "inefficient" in terms of mechanical ability.

Bandit > BugEyedBimmer - back in the Saddle Dakota Leather 12/20/2013 at 21:14

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Big cam, simple exhaust, low revs, and the whine of a blower.

matt > GhostZ 12/20/2013 at 21:14

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I came to the comments expecting at least one in depth detailed explanation.

Wasn't disappointed.

Who needs sway bars anyway > GhostZ 12/20/2013 at 22:26

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One thing to add is the cam that goes with the firing order. The lopping cam duration is another thing that give the distinctive sound.

BugEyedBimmer - back in the Saddle Dakota Leather > GhostZ 12/21/2013 at 08:31

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Dude. Thank you so much. How did you learn all that?

GhostZ > BugEyedBimmer - back in the Saddle Dakota Leather 12/21/2013 at 09:01

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YEARS OF WASTED TIME RESEARCHING CAR STUFF

Philbert/Phartnagle > GhostZ 12/23/2013 at 21:48

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Yep, what you said, this is a great explanation. You did an excellent job and I'm impressed with your knowledge. Thanks!

If you've ever driven a car with an old 302 and really listened to it and felt its vibrations with that firing order, then get into a newer 5.0 (302) HO engine car, you can easily tell what a firing order change can do for an engine.