V6 question

[t/a 6.6]

Ok so i have a big question having to do with the exhust note, or sound, that a v6 engine produces.
why is it that a 3.8 liter v6 from ford as well as the Buick 3.8 liter sound so much more like a v8, (it has more of a low rumble) than say a 4.0 v6 form ford, or a dodge 3.2 litter v6?

does it have anything to do with the fact that the 3.8 liter v6's are 90 degree blocks, while the 4.0 is a 60 degree block?

[drdisque]

the 3.8 is a pushrod engine, the modern 4.0 ford is SOHC. I'm not familiar with a dodge 3.2, but the dodge 3.5 is DOHC. That will greatly affect the sound. There's also bore and stroke differences. I believe a car that gets its displacement from long stroke will sound deeper than an engine that gets it by large bore.

There's also the matter of valve timing and mufflers. Some exhausts are just tuned to sound differently.

[maxwedge]

Different firing orders in the various engines also change the exhaust note.

[MagicRat]

Originally Posted by t/a 6.6

does it have anything to do with the fact that the 3.8 liter v6's are 90 degree blocks, while the 4.0 is a 60 degree block?

IMO that's it. The 60 deg V6 pushrod engines I have built/owned sound different than my 3800 series Buick engines just as you describe here, even though they are mechanically very similar.

[curtis73]

True, but the 90* V6s mentioned have offset cranks, meaning the firing order is evenly distributed just like a 60*.

Most of it is exhaust construction. Part of it is cam duration, compression, and other engine factors. Put a dynomax exhaust on all of them and they'll sound remarkably similar. Any difference at that point could be attributed to cam timing, difference in exhaust length/curves, exhaust ports/manifold configuration, etc.

[Polygon]

Exhaust note can be affected by a number of things:

Displacement
Firing order
Intake & manifold
Exhaust & manifold
Head design
Valve timing & lift
OHC vs OHV

I'm sure I'm forgetting something. My point is that there are a lot of variables that affect exhaust note. Here is a good example. My GTC has a 2.2L I4 SOHC. It has an intercooled Garrett T3 with an exhaust that goes from 2.5" to 1.25" and has a cat right after the downpipe and the muffler at the tail end of the car. Stock it had a low burble thanks to the turbo but it was VERY subdued. I have changed the exhaust to a full 3" mandrel bent system with the muffler right after the cat. People that here it don't think it's a four cylinder. Also, I'm sure it will change when I put the 3" downpipe, swing valve, header, intake, head work, and the new turbo and intercooler. All those things will change the note. Here is how it sounds right now:

http://www.synapsepc.com/Hosting/Ima...04/exhaust.mp3

Had I put the muffler at the back instead of right after the cat it would have sounded different.

Originally Posted by drdisque

but the dodge 3.5 is DOHC.

Actually, in the mid 90's the 3.5L was a SOHC with 24 valves per cylinder. Later they changed it to DOHC.

[curtis73]

What always fascinated me was why a V8 with dual exhaust doesn't sound like two 4 cylinders idling side by side. Just goes to show how there are tons of variables.

[Moppie]

Originally Posted by Polygon

Here is how it sounds right now:

http://www.synapsepc.com/Hosting/Ima...04/exhaust.mp3

Thats a might fine sounding tractor you got there son.

[Polygon]

Originally Posted by Moppie

Thats a might fine sounding tractor you got there son.

LOL, you're the first person that didn't like it.

[Steel]

Originally Posted by curtis73

What always fascinated me was why a V8 with dual exhaust doesn't sound like two 4 cylinders idling side by side. Just goes to show how there are tons of variables.

Unless its a flat-crank V8, like lotus, ferarri and such.

[Moppie]

Originally Posted by Polygon

LOL, you're the first person that didn't like it.

Hey, didn't say I didn't like it




The Lotus V8 has to have one of the oddest exhaust notes.
The idle sounds like two out of tune 4 cylinders, each with a mis fire on a different cylinder.

[Steel]

<3 flat crank v8's. Probably the only engine i'd consider swapping into a 7.

[Polygon]

Originally Posted by Moppie

Hey, didn't say I didn't like it




The Lotus V8 has to have one of the oddest exhaust notes.
The idle sounds like two out of tune 4 cylinders, each with a mis fire on a different cylinder.

LOL, nice!