Different exaust sounds for different types of cars

[Stallion]

Why is it that a Chevelle sounds so much different than a Civic? I know, they are totally opposite, but provided you have the same exact exaust on both, I'm sure they still won't have the same tone. Why is that? Why do newer cars have that "whiny" sound, while our old muscle has that nice rumbly roar to it?

I first thought that it might be the engine displacement, where as my 350 is a lot bigger than those 1.9L (or whatever the imports are throwing in there). But, a newer Corvette also has a 350 and they still don't sound like my '78.

Can anybody shed a little light and reasoning on this?

Thanks!

Stallion

 

[atmmac]

I always wondered the same thing. Possibly Carburetion?


-Andy

 

[bossvette]

perhaps its the cats or the fact most don't run true duals

 

[Stallion]

I have a cat and I don't run true duals.

 

[Edmond]

While true that they are 350's, that's pretty much the only similarity. Different engines will rev differently and sound different at the same RPM's. LIke the ZR-1's, I can't explain it but they sound different. The LS1's have a distinct sound and you can spot them quite easily. I think anything before the LT1's have that "classic" small block sound. But that's just me. Maybe my ears are funny from years of guitar playing.

 

[JohnZ]

Factors affecting exhaust sound include:

Displacement

Number of cylinders

Firing Order

Compression Ratio

Camshaft specifications

Exhaust manifold design

Exhaust pipe diameter

Presence/absence of resonators

Presence/absence of catalytic converter(s)

Muffler design/size/packaging/flow capacity/attenuation strategy

Regulatory "pass-by" noise test requirements

Etc.........

 

[Stallion]

Wow, thanks for the list, John. I didn't know that there were that many factors that went into the sound. Very interesting, though. Thanks again, buddy!

 

[bossvette]

Regulatory "pass-by" noise test requirements

I'll bet this is the biggie

 

[Stallion]

I'll bet this is the biggie

Unfortunately, it probably is. Okay, fuel economy, I understand why they have to bother us about that. But noise...? I mean, cmon. Who are we hurting?

 

[atmmac]

stallion dude pull that cat OFF! Make sure you dont need to pass emissions first though! =)

-Andy

 

[Stallion]

Dude, I still have to pass emissions. But I am looking into getting Historic Plates.

 

[Muffman]

Like JohnZ said - all of those factors.

First of all - only a V-8 sounds like a V-8. No other number of cylinders can duplicate that sound. This is why even a V-10 sounds funky, no matter what you do to the exhaust (I think a V-10 sounds more like a straight six). Plus on an OE application, it has to pass a drive-by dBA (decibel) requirement. On Fords, the requirement is 80 dBA @ 70 MPH. That's why the 2003 Cobras sound so crappy with the OE exhaust on them. Ford restricts the exhaust flow to achieve the objective. Plus, different motors produce different sounds. A lot of late models have multiple catalysts per bank, or pre-cats before a main cat, etc. The more cats, the more engine sound gets knocked out before reaching the mufflers. Today's cats flow very freely - I think it's a waste of $$ to attempt to upgrade to "performance" cats. None of the aftermarket converters are built as well as the OE units either - the OE's have 80,000 mile durability built into them minimal. Eliminating the cats on an after-'96 vehicle is trouble because of the sensitivity of the O2 sensor feedback from the downstream O2's. You can't just yank them out like you could on an OBD-1 vehicle.

To make the cars quieter, it usually means restricting the muffler flow, which in turn robs valuable HP & torque. This is why the aftermarket exhaust upgrades are so important & popular. Even on vehicles like diesel pickups & gas pickups, there is an instant advantage to exhaust upgrades. Like put a good performance cat-back on your Chevy pickup, & bolt-on 2-3 MPG! Plus, the engine will run a little cooler & may last a little longer. Think of it this way: With a restrictive exhaust, the engine turns into a pump trying to muscle spent exhaust past the restrictive mufflers and restrictive pipe diameters. By installing a free-flow system, you are allowing the motor to operate more freely when everything escapes easier - it's pretty simple.

-Eric
www.classicchambered.com