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To preface, I would grade my exhaust knowledge with a "B-". I know what the major components are and what they do, but I don't know if and when certain exhaust parts became mandated or introduced over time.

I love how a throaty late-60's/early-70's muscle car exhaust sounds. Gnarly, a bit raspy, yet throaty and with some oomph. But when I hear most current muscle cars - 90s and on - the exhaust is mostly deep and loud, with little of the raw or explosive sound that the classic cars have. The classic muscle cars sound very similar to an inboard/outboard boat engine, where the contemporary muscle cars rarely achieve that note.

A few examples to describe what I notice... (site won't let me post more than 2 links, I posted the most representative examples of what I'm describing)

Classic sound

1970 Charger - 40 sec

Current Sound

2014 Mustang - 20 sec

  • I understand straight pipes make it louder
  • I understand bigger cams stagger the rhythm of the revolutions

Is there anything inherent that causes the discrepancy in exhaust note? Or do modern manufacturers and modern aftermarket performance companies prefer the "newer" sound?

  • 1
    This is really not that easy. The most cars have some special exhaust sound, made by special formed metal sheets inside. You need a lot of calculations with a lot of factors and then a lot of tries, to made the sound you like. That is why some akrapovic exhaust systems may cost 20k$. – Watsche Sep 26 '14 at 6:51
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    The emission norms and noise pollution regulations have changed a lot since the good old days. And because of that, the designers have to implement bigger mufflers and heavier and more advanced catalytic converters to keep the same under check. Switching to an FFE will certainly make it a lot more louder and perhaps like a 1970 charger. And like @Watsche mentioned, its complicated mathematics, trigonometry, algebra, geometry and you name it, goes into shaping the exhaust for the desired torque at the desired rpm. You could also consider custom/hand made exhausts. Good question btw.. Cheers!! – You_Shall_Not_Pass Sep 26 '14 at 8:28
  • Well...they still sound a hell of a lot better than a V6 or god forbid 4 banger. – malcom Z Aug 6 '17 at 3:05
  • Yes it’s defiantly the camshaft that makes the engine rumble – Erin Burke Jun 3 at 6:22
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It has very little to do with the exhaust system and much to do with the mechanics of the engine. All modern muscle cars have aluminium blocks (vs cast iron), round exhaust ports (vs rectangle), and completely different timing set ups than 60s cars have. The firing order makes a big difference because nobody fires 2 in a row on the same side of the engine anymore. Thus engines have much better balance now and are smoother sounding. It's also one of the reasons red lines are so much higher. The thin walled aluminium blocks and heads resonates sound much differently than cast iron did and even things like 6 bolt mains change engine resonance through the block giving you a tighter tinny sound. Of course just like air blowing over valves in a trumpet the shape of the combustion chambers and round exhaust ports changes the exhaust note too. In short the only way to get the 60s sound is with a 60s car.

For what it's worth I have tried nearly everything to get my LS1 Miata to sound like a real muscle car!

  • We all love the miata.. <3 – You_Shall_Not_Pass Sep 26 '14 at 11:35
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    Isn't the LS1 firing order 1-8-7-2-6-5-4-3? Seems to me that twice in the order it fires on the same side (2-6 and 3-1). While it is a very simplified version, I agree with most everything else you've. Even the Ford Coyote engine fires 1-5-4-8-6-3-7-2. – Pᴀᴜʟsᴛᴇʀ2 Sep 26 '14 at 13:26
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    Opps brain fart! I had to go back though my exhaust notes to remember. The SBC firing order created harmonic vibration in the center of the crankshaft. Warren Johnson figured this out in his pro stock cars years before GM addressed it. The new firing order eliminates that and is a smoother running engine. Not unusual to see LS1s with cross hatching marks in the cylinder walls well over 100,000 miles. Don't forget Ford numbers there cylinders Right bank: 1, 2, 3, 4 Left bank: 5, 6, 7, 8 and GM is Right bank: 2, 4, 6, 8 Left bank: 1, 3, 5, 7. Thanks for the catch! – Jim Stainer Sep 27 '14 at 11:31
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You may be able to get close to what you want by installing a stainless steel exhaust (as opposed to the standard mild steel). It will give you a more raspy sound. In addition, deleting the center resonator/muffler and adding a freeflowing sports rear box with a large tip (diameter should be larger than the diameter of the pipe coming from the cat) would help too. Just keep in mind that deleting the resonator will make the exhaust resonate in the cabin at certain RPM (usually around 2700 to 3000RPM). It may be annoying.

As folks have said, the shape, profile and materials have changed, so you'll never get to 100%, but you can come close. FYI: Porsche uses butterfly valves in the modern 911's (or at least until 2001 when I learned about it) exhaust to mimic the sound of the classic 911's like the Super 2000, 2.7RS, etc. So it's not like you're the first person to want to do this.

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What your ears may be detecting is the camshaft specifications. In the sixties the flat tappet camshafts were the norm. To get a better picture on how a camshaft works look up "how stuff works/camshaft. Looking at the cam spec graph you will see there is a time when the exhaust valve is not fully closed and the intake valve is on its way open. This is the cams overlap, in part -LSA(lobe separation angle). The duration and overlap between different camshaft designs will give the exhaust a different sound and change the engine characteristics. Older cams needed to increase the duration and overlap to gain higher lift. Now modern car engines with fuel injection can't tolerate much overlap without throwing codes, running poorly and failing emissions. Cars of the 60s that had that great sound was due, from my experience, to the flat tappet cam which had a longer duration and greater overlap. With the advent of the roller lifter, engineers could now put steeper lobes and higher lifts into the cam but if you would tried to do that with a flat tappet cam the edge of lifter would dig into the lobe. Today's cars run with shorter duration, less overlap but very high lifts giving great performance! But without those long durations and large overlaps you lose that muscle car sound we crave.

1

I'm not a mechanic or a car expert, but like John said, that choppy, banging idol you hear from the old school muscle cars mostly has to do with the cams and the timing. Big-duration cams and uneven timing gives you that sort of popping, clangy badassness that everyone loves. If you had push-rod flat-tapet cams, maybe some longer duration and lift, you're gonna get that badass choking sound, like it's rough but mean and powerful sounding. I love that sound too. Plus, if you add open headers or straight pipe, that's where it really starts to sound raw. Not to mention if you have a big-displacement and high compression.... ooohhhh you're cookin' now. The modern muscle cars do the ooposite... they gotta have exhausts, they are fuel-injected, have more even timing, and have less-radical cams with less overlap. Not that it's bad for performance, it's just bad for the sound that us proud, primitive car-lovers need. So bottom line is, big block, high compression, big cam and open headers=you lose your hearing. Hope that helps!

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