Exhaust Question

[prova]

Bit despondent today. Took the Alfa into an exhaust workshop and found both my centre muffler and rear are stuffed. $300 to sort it out (pretty reasonable I thought but not an expense I had budgeted for). Up on the hoist I noticed the car has a small front 'muffler' close to where the single exhaust starts. My car is an 85 2.0 GTV is this a catalytic converter? Regardless of what it is can this be removed without too many issues/etc. Any opinions greatly appreciated.

[scuzzyGTV]

i replaced my centre muffler with a "hotdog" which will give a bit better flow (had to tell when the original baffle had broken) & made it sound much sexier!
not sure what the general concensus is, so i'd be interested to see what other options/opinions are.

[Mat Francis]

Pretty sure that front one is indeed a muffler, not a cat. Could be wrong though.

For a similar price i had a system made up a couple of years ago. One large muffler where the center muffler sits and one at the rear of the car, after it goes over the driveshaft. Sounds good and is pretty quiet, 2 inch pipe the whole way. (It actually sounds a whole let better after i smashed the crap out of the center muffler rallying it a few weeks ago, not sure why but not complaining  )

Younger brother's Alfetta runs what i think is the standard exhaust, except it has a hotdog in place of the rear muffler. Sounds bloody good but far too loud for me to live with everyday.

For a standard car i wouldn't go any bigger than 2 1/4". I think it starts to sound too droney, and there is nothing to be gained in terms of performance.

[prova]

Thanks for the speedy replies guys. My pipe work is sound so I will be keeping that stock just the two main mufflers are stuffed. My thoughts at the moment are - ditch the front small muffler (about 20cm long and fat) and two new mufflers - could they both be 'straight thru' designs or would this be to loud? Maybe just the rear straight thru as you suggested Mat or as Scuzzy suggested maybe the centre is a better option?

Has anyone fitted two 'straight thru/hotdog' style mufflers before - if so I would love to hear your advice - thanks again guys!

[116gtv]

G'day,
To answer your q's, its not a cat, it can be removed without problems if you dont have an originality fetish..

[prova]

Thats good news - off she comes then!

[MD]

The small front "muffler" is not a muffler. It's a resonator and is intended to end the tuned length of the factory fitted system. It should remain.

[prova]

Sounds important then! She stays! Unless someone else sways me with an alternative view - I am easily swayed!

[Sheldon McIntosh]

Don't sway away from MDs advice.

[Mat Francis]

MD; any chance of further explanation? I gather by removing it the flow of gasses will be upset, having some form of adverse effect right the way back through the engine?

I'm also guessing that fitment of extractors would have another effect, (hopefully not a negative one), and consequently the resonator would become redundant, given that the airflow has been modified before it would reach the resonator?

[MD]

mat,prova.

Even a factory exhaust system,especially Alfa ones are part of a compromise for road tuning. This is to achieve as early torque as possible and mid rev torque at worst. To do this, there are basically three stages  of a street car exhaust system. The primaries (headers) the secondaries(engine pipe) and the balance of the exhaust to satisfy
legal constraints for noise.

The combination of the first and second stages together with their respective bore and lengths form a "tuned " length that delivers this target torque as previously stated. For the tuned length to have a specific length, the resonance needs to end somewhere. It does so at the resonator. So this little black duct helps you get the factory intended torque band. If you remove it you are upsetting the resonance length of the second stage.

For other torque bands at different RPM ranges, different bores and lengths of pipes are called for but the principle remains when it comes to the end of the tuned length.It can be a muffler or a resonator but it needs to be located at the end of the tuned length. Fitting a "hot dog" where the resonator is or in place of it is quite ok. However do not simply by pass it with a piece of exhaust pipe as the gases are not expanding when they need to.

I hope that clarifies the reason why these seemingly useless things are installed.

[prova]

Great info and insight MD. Could a possible solution be to replace the front reasonator with a hotdog style muffler, omit the centre muffler and obviously keep the rear?

Maybe I am just complicating things - go simple and fool proof - keep the reasonator and just replace the knackered mufflers maybe one of them with a straight through design. I will probably get the work done tomorrow afternoon so thanks for all the input!

[116gtv]

Point taken, Mike. Although practically I cant say i've noticed any difference after deleting the resonator on a stock Alfetta, other than a slight increase in exhaust note..

[prova]

Good point Martin. I wondered in real terms if the removal of the reasonator would actually make a noticeable difference. I think tomorrow its going to be a gut feeling decision on these matters I will let you know how it turns out.

[116gtv]

fwiw- a hotdog with only one muffler would be too loud for me... for a road car..