What is with the sound big V8s make? Why is it so distinctive?

[Noriaki]

What is with the sound big V8s make? Why is it so distinctive?

Ok I thought it was just a function of having a big block....but the other day I heard a viper (8L counts a big block) revving way up (a little past redline I think), and it screams really nice, but it just doesn't have the same sound as a 426 Hemi or a Ford FE...or even the smaller block Vette and Mustang engines of today.

 

[amnesiac]

Part of it is the exhaust, you can get totally different sounds out of the same car depending on what kind of exhaust system you have.

 

[JohnnyKnoxville]

Viper is a V-10

 

[Goldfish]

I think he meant 8.0 Litres.

 

[RaoulDuke]

there's just more combustion going on, and as amnesiac the exhaust has a lot to do with it too

 

[Noriaki]

I know the Viper is a V10
That was my point.

The 7L V8s of the late 60s (Chrysler Hemi, Ford FE, etc) make a great sound, a nice low rumble.

I thought it was because of the big block, but an 8L V10 viper doesn't really rumble, it screams. So obviously it's not becuase of the big block.

 

[SSP]

Maybe cause the Viper runs at a higher RPM then the old big blocks?

 

[snakesnfrogs]

firing order, timing, exhaust system all play a part in the way it sounds

 

[TimberWolf]

"Big cams" - long duration and alot of valve overlap for the cam lobe timing profiles are common to big bore cylinders using a longer crankshaft stroke. Although ignition timing and exhaust tube / muffler flow add to the effect, cams are the biggest physical influence.

A V-10 design seeks to combine displacement ("There's No Substitute For Cubic Inches&quot with the volumetric efficiency inherant to shorter stroke and smaller bore, and will have significant differences in camshaft profiles and lobe timings. Short stroke / small bore is why a V-10 rev's higher.

An added visceral benefit to the big block V-8 is that "Cha-WAAHH" sound as the carb secondaries open up (while you're being squashed into your seat) . . .

 

[mAdD INDIAN]

The firing pattern of V8s are different than the V10 and such, give them the charastic sound.

 

[Viperoni]

It's not only the camshaft profile and firing order, but also the headers and the way they come together (many different types)
plus if there's a crossover pipe....too many factors.
But when you get them moderately right, OOOOOH they sound awesome

 

[smartt]

Because big V8s have a larger opening in the bottle. So you make more of a gulping sound when drinking it.

 

[Cyberian]

<< &quot;Big cams&quot; - long duration and alot of valve overlap for the cam lobe timing profiles are common to big bore cylinders using a longer crankshaft stroke. Although ignition timing and exhaust tube / muffler flow add to the effect, cams are the biggest physical influence.
>>



Timber Wolf
I understand how volumetric efficiency can be increased by cam lift and dwell. Size, number and location of valves as well as length, tuning and polishing of intake runners would also make a difference.
I'm not sure I see how a longer stroke would affect it.

 

[Triumph]

Did somebody ask to hear a V8?

 

[TimberWolf]

Cyberian:


<< I understand how volumetric efficiency can be increased by cam lift and dwell. Size, number and location of valves as well as length, tuning and polishing of intake runners would also make a difference. >>


Cam lobe lift, duration, and overlap can have a dramatic effect on volumetric efficiency, relative to the RPM range the engine is intended to be running at. High-compression big blocks generally have greater intake / exhaust overlap to improve starting and low RPM performance by &quot;bleeding off&quot; a bit of compression. That's not particularly efficient, but it's a necessary compromise for all-around drivability.

A longer crankshaft stroke means it takes more time to decelerate, reverse direction, and accelerate the piston through it's linear travel during each phase of the firing cycle. For a naturally aspirated engine, that results in an (initially) low signal to, and slow response from the intake plenum on the induction stroke for a cylinder.