Anatomy of an Ansa (cutting open a 308 exhaust)

Looks terribly restrictive, right? The exhaust has to make all sorts of horrible twists and turns to get out. It looks pretty much like the internals of a most OEM mufflers.

BUT...

Re the dyno tests I referred to earlier, we did a test that showed a pair of OEM mufflers on a totally stock factory performance car produced seven MORE HP than a pair of these with no "obstructions" to the exhaust flow: https://www.autoaccessoriesgarage.com/img/group/main/31/3156_1_lg.jpg

So what the eye sees as 'correct' and what the engine needs for optimum performance can be quite different!

 

Mike, Does that holds true on a turbo cars you've dyno'd?

 

Unfortunately, I can't recall ever doing a different muffler test on a turbo motor. My gut feeling is that a turbo motor would be less influenced by different mufflers because its going to generate whatever boost is dialed into the waste gate regardless of muffler configuration but since we never actually tested that, my assumption may be wrong.

Sorry I can't provide any useful info!

 

The ANSA on my GT4 developed a rattle shortly after I purchased the car. I cut it open (had been opened and welded shut at some point previously) and found about a third of the solid center divider had broken off and was bouncing around inside. I didn't weld it back in place, just removed it and closed the muffler back up. Big mistake, the resonance was horrendous, it made not just my teeth rattle but my whole body vibrate.

I wouldn't get too critical of OEM mufflers, they have a completely different set of design criteria than "maximum flow".

 

Check this out. I like this racing muffler..... (7) Ferrari 308 GTB 9200RPM dyno KMS MD35 / throttle body kit 400+hp - YouTube

 

One thing is sure, the whole exhaust "line" : manifold + intermediary pipes (no cats on "Euro" 3x8s) + mufflers is incredibly HEAVY.
I have the standard exhaust factory OEM muffler from my 328 GTB on a shelf, and I got the opportunity to buy a set of good second hand OEM manifolds and intermediary pipes (the rear OEM one on the car cracked two years ago and had to be welded)
(so I now have a complete spare exhaust "line" should I decide to have the car fitted with aftermarket mufflers, manifolds, etc...)

I don't have a scale big enough for them at home, but the weight of the OEM manifolds seems unbelievable; I mean, battleship weight.
Pretty sure any good quality aftermarket stainless steel manifolds (Tubi, Larini, etc...) must be several kilograms lighter...

Rgds

 

I have often thought of putting an electric baffle values at two of the four tips to control the noise levels at low revs.

 

Having played a brass wind instrument, I always thought it must be trial-and-error with tube runs and bendings to create the optimal sound of an exhaust. It might be a fun exercise to tinker with various configurations - on a bench.
Though I suspect there's software implementations to mimic the flow, pressure points, pitch, etc.

 

Well, having played a brass instrument you've perhaps heard, like I did, about the old story (Legend? Truth?) that in the old days, they asked organ builders to be there in the workshop at the moment the exhaust was built? Someone was holding a saw and cut small lengths of the tubes until the organ builder said that the note was right...

Rgds

 

It's possible.

I toured Steve Dinan's shop during the heyday of Dinan Engineering (an American BMW tuner). Despite being a performance tuner (even building the BMW Daytona Prototype engines), they made no secret that they were designing exhaust systems focused on sound. I recall that, for a particular car, they had a muffler/silencer which had pipes that could be slide in and out to determine the proper internal lengths to get the right sound.

It seems to me that an organ builder would just be someone with an opinion about what sounds good. It seems to me that engine noise is a cacophony of sounds; not something really with a pitch like a musical instrument.

(An interesting bit of gossip is that we spotted a Ferrari engine tucked in a corner on an engine stand. They said it was "for a boat." Uh huh, sure.)

 

Check out the inner opening on my Ansa tips? It is about an inch......can this be good for performance?
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Slightly off topic but I noticed it was mentioned numerous times that glass wool was used inside the mufflers. Would the same material have been used in the manifolds as well? I recently stripped off the sheeting and insulation from my manifolds and I was wearing a respirator while doing the work as I've heard/read that it was asbestos that was used. I washed down the whole work area to try and capture as much of the dust as possible. So, did they use asbestos or was it glass wool? It was very powdery and not stringy/flaky. By the way, a lot of people have said that this stuff eventually vibrates out from the sheet covering over time. I can assure anyone that both of my manifolds were jammed solid with the stuff from manifold flange to outlet flange. Looks like not a spec of the crap ever came out of mine (photos show that I pulled out the majority of stuff to reveal the manifold inside. Two typical shopping bags full). I'm glad to be rid of all of this and plan on ceramic coating them instead.

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Why did you decide to remove the insulation/sheet metal? It appears it was in good condition - not rotting out or anything.

 

FWIW- I noticed the collector diameter of the Euro headers are slightly larger than the US version.

 

Sure of that? Not confusing the 2 valve engine manifolds (carbed cars and 2 valve injected) which are round in section, and the four valve engine manifolds (QVs and 328), which are oval in section, and therefore larger?

Rgds

 

I have a set of QV US and Euro headers. They are different sizes

 

The US is smaller. The exhaust gaskets at the collectors for US and Euro have differnt part #'s as well. I have mistakenly ordered the wrong one in the past.

 

When I took the cover off of mine, I had the material test for the same concern. The lab said it was fiberglass.

 

I did exactly the same thing to my exhaust headers... here's the outcome!
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Looks nice but seems like a lot of trouble/expense for something that can only be seen from under the car and has no operational benefit...

 

Well, at least it won’t rattle