Best after market exhaust for 3.2

[GTV6SA]

What is the best aftermarket exhaust for 3.2 Ti,anyone put Autodelta end boxes compared to Regazzon,wizard or Novitec

[Stu159]

Hi GTV6SA,

I have no idea, but I'd also be interested to know 

It used to claim an increase in horsepower on the Auto Delta description on their webpage, but it doesn't any longer.

Cheers
Stu

[V AR 164]

Someone I know who has a 159 V6 just got custom muffler deletes made up with larger chrome tips fitted.

He came on a club run a few months back and I was astounded how good it sounded. A deep sounding note with no annoying rasp.
He did mention there was a little bit of drone, but I assume that could be solved by putting in place a small hot dog resonator instead of a straight pipe.
Personally I wouldn't spend heaps of cash on brand name mufflers alone if you just want some extra sound. No real gains are to be had unless you go for a full cat back system or header back system.
Best bet would be to go down to your local exhaust shop and get them to try out different mufflers and cater it to your taste.

Andrew.

[GTV6SA]

Anyone put a mille miglia exhaust system on their 159 3.2 , costs and results?

[GTV6SA]

Ended getting Lambros to build a SS catback exhaust system with 2 new mufflers and 4" tips, now sounds what a V6 Alfa should be with a deep low growl.

[Stu159]

Hello SA,

Thought I might add to this thread, as I've now read on x 2 different UK forums that the most restrictive cat's in the 159 system, are the ones at the manifolds. I'm no mechanic, not even close, but thought I should pass this on as it slightly contradicts what I wrote earlier, from information I'd been given. Downside is that fitting headers is an engine out job apparently, so this would be where the "cost of doing so" advice would apply 

Wizard are looking to have headers available for the V6 in their summer, this year. Hopefully they'll be a more realistic price than the ones on offer from AutoDelta

Cheers
Stu

[GTV6SA]

I have been following the comments on A.O forum as well and speaking with the local Aus
Autodelta rep, I was also told that the biggest gains for HP is the catless header manifolds.Fom muboen experience in forced induction, it is really important for efficient exhaust scavenging to get rid of gasses, this can be done by equal length headers that are cc'd to make sure the volume is equal, ceramic coated headers also improve efficiency and even  the joint where the headers merge into 1 pipe.One problem with a transverse V6 ,it is very difficult   to have equal length headers on each bank due to the engine configuration without major redisign of the whole exhaust.

[Ascari32]

Scavenging, in the classic sense can only really be performed on an engine where the valve timing allows cross - flow from inlet tract to exhaust system/manifold. Unfortunately, the 3.2 JTS engine has static valve timing angles which inhibits cross - flow, given the inlet valve opens at 11.5 deg. Atdc, but the exhaust valve has closed at 9.0 deg. Atdc.

These angles appear to have been chosen to promote internal EGR to comply with emissions regulations. It also results in gutless low end torque as no charge air enters the cylinder until the piston is 11.5 degrees into its induction stroke.

So, as someone pointed out, choose an exhaust which caters for your tastes in sound as the cost of fitting a performance exhaust system can't really be justified without addressing valve timing, manifold cats and secondary cats under the car.

For those that are interested, I have detailed the work I undertook in these areas in "Enigmatic 159"


foot note - corrected valve timing angles. 

[Stu159]

Hi Ascari, your post reminded me of information I'd read on a UK Alfa performance tuning house website. Seems they take this into account with their remap?
http://www.autolusso-penrith.co.uk/remaps.html

Cheers
Stu

[Ascari32]

Quote:- "your post reminded me of information I'd read on a UK Alfa performance tuning house website. Seems they take this into account with their remap?"

The company you refer to has a fine reputation and are well established.

However, the physical angles of the camshafts are dictated by the grind of the lobes and their position is fixed with respect to the crankshaft via the timing chain system. The internal bias of the springs within the "Phasors"/camshaft rotors ensures, whenever the engine is switched off or the driver lifts off the throttle, the pressure exerted on the camshafts will always - repeat - always, return/rotate the camshafts towards their internal end - stops. In the case of the Inlet camshaft, 11.5 degrees After Top Dead Centre and the Exhaust camshaft, 9 degrees After Top Dead Centre. No software modifications can change this.

There are several reasons for this:-

1. When the engine is switched off - starting the engine is done with the valve timing creating very little compressive load, greatly assisting the engine in firing up. The ECU also knows exactly what position this dynamic valve timing system is in, as the angles are locked by the rotor pins.

2. With this particular engine - direct injection and it's ability to use lean/ultra lean burn techniques, at tick over, the valve timing remains at these preset angles which prevents "Hunting": Camshaft Flutter due to oil pressure anomalies; as the camshaft "Lock - Pins" remain in - they do not release until the ECU opens their respective Solenoid Valves. This function is embedded within the Core ECU program for VVT management I believe. To modify this would be very dangerous - mechanically and that is why it is fixed - non adjustable.

3. Using Stratified Charge techniques, enables extremely lean burn mixtures when the driver lifts off the throttle. I.e, the AFR returns to that figure set at tick - over/low load.

A high compression ratio is not normally associated with lean mixtures as engines can be very quickly destroyed due to pre - detonation. However, the stratified charge, forming a cylindrical charge; richest at the centre and weakest at the circumference, ensures the cylinder bores/walls are cooled by the intake of air rotating around the walls and helping reduce the temperature of the exhaust valves and piston crowns, such that under normal/correct operation, the "Anti-knock" devices are never invoked. Camshaft angles and Piston Crown design play an important role in this. This is particularly important with manifold Catalytic Converters such as those fitted to the 3.2 JTS engine, the intention of which being to raise their temperature very quickly to achieve "light - Off", for proper conversion.

4. The 3.2 JTS valve timing covers a maximum range of 50 degree advance of the inlet camshaft and a 50 degree of retard of the exhaust camshaft; from their static positions, a huge range!!!!!!!!! I remain convinced the system was never designed by Alfa Romeo - it is far too sophisticated for a first attempt at quad cam VVT chain driven system, although I do believe it was designed "In - House".

With such angles, comes the real possibility of stuffing a valve into a piston crown - this is an interference engine. Modifying inlet valve timing, beyond the scope of the embedded software program, could well create pressure which at the very least could blow cylinder head gaskets and in worst case - crankshaft failure.

I believe the scope of software changes in limited to AFR and Ignition Advance/Retard. Nothing can be done about valve timing angles, without changing the camshafts. My camshafts have modified the valve timing to 0.5deg. BTDC, inlet valve opens, 23 deg. ATDC, exhaust valve closes; Static Angles. There was no other way of ridding this engine with 2.5deg. NVO -negative valve overlap. Interestingly, although my engine ticks-over; solidly, still at 750 rpm, it sounds meaty - powerful. No doubt I will have to have the AFR adjusted, although I am happy with the economy. However, it appears clear, there is a preset AFR when the camshafts are locked - rotor pins in. This is evidenced by virtue of the fact, if I apply the throttle lightly as I pull away, even before the clutch engages, there is a very slight dip in revs.

But, coming off the throttle at speed, the camshafts rotate swiftly back to their "Static positions" and the engine offers very little drag. When however, the camshafts finally do get back to their static positions, the ECU seem to apply the AFR figure to the charge. And the slight difference results in an even lesser amount of drag offered by the engine. Which is why I believe I shall have to uprate the brakes.

5. Finally, the VVT System, Valve Timing/Camshafts, along with the Piston Design and both the Manifold Cats and the Twin Cat under the car are integral to the 3.2 JTS achieving the highest ratings category - 5, I believe, for emissions. Along with the obvious safety features and superb platform/chassis, this monumental car, deserves respect. We will never get so much again from Alfa Romeo, at such a relatively low price. Best Alfa for forty years; IMHO.
       

[Ascari32]

Hi Ascari, your post reminded me of information I'd read on a UK Alfa performance tuning house website. Seems they take this into account with their remap?
http://www.autolusso-penrith.co.uk/remaps.html

Cheers
Stu

Hi Stu,

I believe the remapping relates to Diesel engines, not the 3.2 JTS.

With the 3.2 JTS engine, exhaust gases cannot get into the inlet tract as the inlet valve remains closed until 11.5deg. ATDC. So the piston is already on it's induction stroke and for 2.5deg., NVO ensures both inlet and exhaust are closed. This partial vacuum pulls unburnt HC's + some oil past the rings, into the combustion chamber.

The highest content of pollutants are between the ring/piston and cylinder bore interface area and they are normally the last to exit the cylinder via the exhaust valve. By adopting this approach, Alfa seem to have generated internal EGR. So these pollutants do not pass into the exhaust system and then out into the environment, but remain within the cylinder to be reburnt along with the incoming charge. It is said to be very effective and pollutants are almost completely destroyed.  It also reduces the density of the charge because these components are hot and expand, reducing the inrush of air through the inlet valve - creating lean burn conditions.

That some oil makes its way past the rings is a small price to pay for upper cylinder lubrication - assisted by the spray jets in the sump. It is probably the reason for a 112,000 mile engine having cylinder bores which looked like the block had just come from the manufacturer.

 

[Stu159]

Hi Ascari,

Probably a good time for me to slot in another quote from a previous post of mine in this thread "I'm no mechanic, not even close" 
Regardless, it's all an interesting read. On that link to the U.K. tuning house, they note they install some sort of plate to offset the EGR gases, not that they do it with a remap. The remap is part of the process. There's not a lot of info there, but I'm sure someone such as yourself would find it interesting.

Thanks for taking the time to put all of this down. I love my 159 also, so I'm always interested to learn as much as I can about it and I'm sure I also speak for others in this forum in this regard

All the best
Stu

[Ascari32]

The plate blanks off the EGR valve which normally returns some exhaust gases to the inlet tract. Being hot, they also reduce the density of the charge. Without blanking it off, build up of crud can accrue in the inlet tract and also on the EGR valve itself. Indeed the plate seems to have come about as EGR valves were failing, regularly. I only changed the valve once in 170,000 miles, so maybe I was lucky. It is a practical solution lots of diesel owners have adopted.

[Ascari32]

What is the best aftermarket exhaust for 3.2 Ti,anyone put Autodelta end boxes compared to Regazzon,wizard or Novitec

Just inputting some further details, wrt end boxes.

The ones I have just fitted are dreadful at the moment. I shan't say who makes them - yet as it would be unfair until all processes have been gone through.

However, fitting a Supersprint centre section: stainless steel, shifted the droning at 2500 rpm from the central resonator, to the rear boxes. Believing the Alfa Boxes could not cope, I bought the ones now fitted. Brilliant over 3000 rpm - terrible below.

However, further investigation leads me to believe the central cat has now completely failed. Having removed the manifold cats in favour of Autodeltas and changed the valve timing courtesy of new camshafts, it seems like the exhaust gas pressure, in conjunction with the heat has destroyed the Ceramic twin cats.

I know Ceramic cats have a lower working temperature, but the 3.2 JTS software advances the exhaust camshaft when ever the driver lifts off the throttle. This for instance, enables cat "Light - off" temperatures to be maintained when a driver comes from cruising speeds to urban/traffic jam conditions. So there is still a lot of energy in the exhaust gases which are being discharged early into the manifold/exhaust system.

I am informed by authoritative figures that this can cause sintering of the Ceramic Honeycomb, which, although Ceramic is a good thermal insulator, it is incredibly thin walled. The excess heat can cause the precious washcoat to be stripped and channels can block/collapse.

So it appears, I have no choice but to fit a Metallic Catalytic Converter in replacement to Alfa's Twin Cat. Whilst still believing the droning is a function of the "Reed" formed by Alfa's Cat Output, it would appear, this aside, it's days would be numbered in anycase.

Lesson learned! No cylinder head temperature reduction - always an issue for me - unless the manifold cats are removed. No real performance benefit unless the camshaft timing is altered. And no real benefit from both of these, unless a free flow exhaust system is fitted. And if one is going to undertake these changes, the Alfa twin cats are too restrictive to remain, aside from their apparent inability in coping with increased temperatures.

Caveat Emptor!

PS:- choose whatever rear boxes suit your tastes and stay away from all else - unless you have very deep pockets. The performance improvement is stunning, but I'm not sure the cost can be justified. But it kept me out of trouble and it was purely an exercise in seeing how good this much maligned engine - here in UK - could be! And it is a fabulous engine in my opinion.


     

[Stu159]

Hi Ascari, I've recently had the centre cats removed completely and the OEM muffler replaced + the rear OEM cats replaced with high flow aftermarket custom fit out. There are no droning sounds and it has a nice growl under revs, especially at high points. Not sure if it sounds as good as a Busso, but I'm yet to be outside the car to hear it. It's quite loud on warm up, when cold, but outside of that, all good. Very noticeable pick up in throttle response.

Cheers
Stu