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Exhaust Note/ Proposition



the buick 3.8 and its 3800 descendants are based on the old buick V8's, those same buick v8's licensed to range rover....

our high angularity SII (short deck) 3800's have very fast piston acceleration/deceleration rates at the TDC/BDC points, this makes for a sharper, more staccato exhaust pulse wavefront.

our headers inducing a timing disparity put two of those staccato pulses next to each other, and depending on rpm, give us the "3800 Blatt".... a lower perceived pulse frequency....

Turbo buicks (3.8) have a similar issue with their under engine crossover headers.

turbo is best muffler, having turbo merge equidistant from the ports helps lots too.

3.8/SI 3800's will always have a more pleasant exhaust note with the lower angularity of the tall deck buick 6's

seriously....listen to an open DP SI 3800 L67 (94/95)...and then listen to a SII L67 (97+)
 
I had thought so. Lol regardless, the most recent iteration of the 3800 requires extensive modification in order to sound any form of pleasant.
 


Turbocharged400sbc said:
our high angularity SII (short deck) 3800's have very fast piston acceleration/deceleration rates at the TDC/BDC points, this makes for a sharper, more staccato exhaust pulse wavefront.

our headers inducing a timing disparity put two of those staccato pulses next to each other, and depending on rpm, give us the "3800 Blatt".... a lower perceived pulse frequenc

3.8/SI 3800's will always have a more pleasant exhaust note with the lower angularity of the tall deck buick 6's
Click to expand...
Good. Thanks for that.

The V8 minus 2 thing, maybe you were thinking the GM 4.3. I've heard them piped alotta ways. The Tumblebeast (my Blazer) keeps on rumblin' on worn out stock exhaust.
 
Article #1http://www.caranddriver.com/features/this-is-why-various-engine-types-sound-so-different-feature

And copy of a post from another forum:
"Exhaust harmonics are dependent on a couple of factors including intake pulses and valve sizes. However the main factor involved is the pulse timing. An air pulse exiting the cylinder head creates a shock-wave that travels down the exhaust path and is follwed by a mometary vacuum pulse.

V8 and 4-cylinders have pistons that rise up in perfect pairs at the exact same time. That explanes the deep note that you get from since they perfectly sinc exhaust pulses together. V6s on the other hand, usually have offset or split crank-pins to even out the firing sequence. So pistons are slightly off-sinc which in tern causes the exhaust pulses to slightly off. This leads to more raspyness because of gaps in the air-pulses.

Exhaust design utilizes one of three designs to control exhaust sound. The first type (and most common) is absorbsion. These mufflers use sound absorbstion material and internal channels to smother out noise. Although quiet, they are restrictive and they are the least desirable of the three/

The second type is deflection style mufflers. Mufflers of these type use internal baffles to bounce sound waves back at the incomming pulses and cause them to nullify each other. Flow-master (AKA choke-master uses this design)

The last, and best of the bunch are the "resonator" type. Resonators fall into one of two catagories. The first is "helmholtz" and the second is mesh type.

The mesh type mufflers are what you usuallt hear on the rice burners. They utilize a flow-through design with a baffled pipe that passes through a cavity that is either filled with fiber-glass or stainless mesh to act as a silencer. "Cherry bomb" mufflers fall into this catagory.

The "helholtz" resonator uses a unique bulb shaped chamber which causes incomming air to suddenly expand over its inner surface area. As it enters the larger part of the bulb the shock wave slows down a bit. As the next shock-wave enters the chamber, the first wave exits through the other end, and speeds up as it leaves the bottle-neck. Both shock-waves mesh and causes the waves to mesh into one-another. A resonator gives a rich deep tone to your exhaust note while getting rid of unwanted "raspy" harmonics. That unique sound that you hear from a G35 can be attributed to this type of exhast design.

There are a few other factors like exhaust legnth, temperature and thermal expansion rates, but thats really the jist of it."

Full thread for the above post here: http://www.fullthrottlev6.com/forums/showthread.php?59714-What-determines-your-exhaust-note-tone
 
It might be really cool. There's probably enough room under there for the J pipe "bubble" thing. I'll probably look into the cost after my stockers rust off ..and everything else is fixed. Lol

Good stuff.
 


That's the Biggest problem that people don't understand about why a 3.8 (which was based on the 215 Buick). (and 4.3 for that matter as far as raspyness) sound so raspy is the pulses are not evenly spaced since the rod journals are split. This is what gives the raspyness to the sound. I have heard people say that splitting the exhaust into different banks will help, it will not it won't make any difference. I used to have people tell me that running a 350 with single exhaust would make it sound like crap and would sound "twice as fast since both banks are fed into 1 pipe" This was even in a car rag (Hotrod, Car Craft one of those) and I was running a Torque Technologies 3" exhaust system but I only ran the right side through a single 3" 3 chamber flowmaster it sounded just like any other 350 out there with dual exhaust. I also added later an Edelbrock TES system that mated to the same system and other than the normal header ping you get it sounded just like any other V8.

The piping isn't going to make any difference with the exception of adding a Helmoltz resonator which is application specific and requires a hell of a lot of math or Dumb Luck to make work properly. The original dual exhaust straight pipe sound clip is only because of the bends and the primary length being more equal. There are also several bends that are in there that we cannot see, I can still hear the rasp, though it's not nearly as bad as these cars sound.
 
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The two banks of exhaust need to be of equal length BEFORE they merge together. That is the single biggest ingredient in making the 3800 sound good. Everything else you place downstream is fine tuning, but the foundation for good sound is laid by making sure your header secondaries are of equal length, or as close to it as possible. That is why turbo 3800's sound better than non turbo cars, and why 3800 powered Holden Commodores can sound good to great. The factory system in our cars has the front bank of exhaust travel through the crossover before merging with the rear bank. This creates uneven pulse collision, which boosts nasty sounding odd-order frequencies, and creates turbulence which we hear as rasp when revving. It's all about the equal length secondaries, which in a front wheel drive car is not easy to achieve... but also not impossible. I know because I built the one in the above link. The red GTP is mine.
 


NSTGP1 said:
The two banks of exhaust need to be of equal length BEFORE they merge together. That is the single biggest ingredient in making the 3800 sound good. Everything else you place downstream is fine tuning, but the foundation for good sound is laid by making sure your header secondaries are of equal length, or as close to it as possible. That is why turbo 3800's sound better than non turbo cars, and why 3800 powered Holden Commodores can sound good to great. The factory system in our cars has the front bank of exhaust travel through the crossover before merging with the rear bank. This creates uneven pulse collision, which boosts nasty sounding odd-order frequencies, and creates turbulence which we hear as rasp when revving. It's all about the equal length secondaries, which in a front wheel drive car is not easy to achieve... but also not impossible. I know because I built the one in the above link. The red GTP is mine.
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This doesn't hold water as there were tons of 3.8 RWD's made way back when and unless they had stock exhaust sounded just as raspy. I had a couple of guys in high school that had equal length headers and dual exhaust on their cutlass with 3.8's in them. They were raspy as hell, really turned me off of the V6 at that time until we really started seeing GN's and T-Types, and the TBird SC and Cyclone/Typhoon. We also had guys with 4.3L engines in everything from full size trucks to S10's and G- bodies and every kid in the country ass town that I grew up in had dual exhaust on them and a couple of friends had headers on the 4.3. They all sounded like crap with the same staccato idle and raspyness that offset pinned cranks cause. And how many 3.8 Camaros have you seen with headers and full exhaust that sounded just as raspy? If you say that it's because they merge into single exhaust than that would be totally off since V8's have merged for years. V8's in FWD applications still sound like V8's whether it's the Northstar or the LS4 it doesn't matter. It's all in the firing order because of he crank. Also you say:

" but the foundation for good sound is laid by making sure your header secondaries are of equal length, or as close to it as possible. That is why turbo 3800's sound better than non turbo cars,"

Well that's kind of odd since turbo cars don't have equal length leading to the turbo, the turbo just acts as a dampener to the sound as it converts pulses into slower flowing gasses.

Any V6 with offset rod journals and funky firing orders are going to sound like that. Really that's all there is to it. The only way to dampen it is to muffle it whether it's a turbo or by canceling sound.

One of the mechanics at my friends shop has a S-10 Blazer he is building for his son it has a 4.3L in it and he is running log manifolds and dual exhaust through a crossover to 2 flowmasters. It sounded like crap. The last time I had visited the shop that came guy was working on the truck again but this time it sounded different. I asked about it and he had run a pipe from one muffler to the other so that it basically had 2 inlets. This gave it a nicer tone and it wasn't nearly as bad as before.

Jeff
 
J57ltr said:
The piping isn't going to make any difference with the exception of adding a Helmholtz resonator which is application specific and requires a hell of a lot of math or Dumb Luck to make work properly.
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I'm going to say that the math was less of a factor in that 3800 exhaust build.

I started doing the math on a variant of the Helmholtz. I stopped when my resonator length was 7 feet. The Helmholtz design requires a complex equation. Factors of which are mainly givens, but you need to know things like the engine's frequency, speed of sound, fluid dynamics, etc. That's a little harder.

A person could straight pipe a 3800 with equal length ten foot or 3 foot exhaust.. it's still going to have the same inherent "problem(s)."
 
The difference between designing one for speaker enclosures (for boosting instead of cutting) is that the movement of air is cyclical instead of in one direction and pulses. This is the main issue with it that's why I said it's a lot of math or dumb luck 7' huh? I knew it would be large. What size pipe did you use for the calculations? If you use smaller pipe you can usually drop the length. As diameter increases then so does the length for the same frequency.

Jeff
 
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