Vanquish Gen 2 Which Cats to Delete?

[Nick-n1cz7]

Hi all,

I am thinking of deleting my second cats to increase sound in lower Rev range but not sure whether to delete primary based upon risk to engine according to BR or secondary. Don’t want to delete both. Any thoughts? Thanks all

[8Tech]

Very much a consideration on budget.

Ideally, remove primaries and retain secondaries but this is around 8 times the cost of removing the secondaries and keeping the primaries.

Removing the primary cats eliminates the small possibility of cat failure and ingestion which will save many, many thousands in replacing the engine though.

Your cash, your risk.

[Nick-n1cz7]

Thanks for the response, to be honest I don’t know the cost of replacing the primary only the secondary, circa 1100 AM Dealer.

Other thing is I can’t find much chatter about primary cat failure and engine destruction.

[AdamV12V]

Nick-n1cz7 said:

Thanks for the response, to be honest I don’t know the cost of replacing the primary only the secondary, circa 1100 AM Dealer.

Other thing is I can’t find much chatter about primary cat failure and engine destruction.

The secondaries can be deleted for about £800 at an AM dealer if you haggle a bit. Less if you go to an Indi...

The primaries using the QS manifold is about £8500 at an AM dealer, again less if you go to an Indi, or use somebody like BR who will do a chop job on your existing manifold for you, cutting out the primaries and rewelding in clear pipes. Around £3000 for that.

The cat ingestion thing gets a LOT of coverage on forums, far more than it probably deserves, but if you are that 1 in 1000 owner who it happens to, then it is terminal on the engine.

The best bang for the buck is to delete the secondaries really.

[SHIFTY]

I purchased secondary cat pipes and new gaskets from AM Grange for just over £600 genuine AM parts as fitted to Vanquish S.

I swapped mine myself and required jacking up (one side only), remove under tray, unbolt existing cats (8 bolts) insert new cats and gaskets bolt up, lower car all in less than one hour.

Would say using a lift about 1/2 hour to complete, so £500 for fitting from AM dealer is extortionate and they are already making a profit from selling the cats.

[JJbing]

AdamV12V said:

The secondaries can be deleted for about £800 at an AM dealer if you haggle a bit. Less if you go to an Indi...

The primaries using the QS manifold is about £8500 at an AM dealer, again less if you go to an Indi, or use somebody like BR who will do a chop job on your existing manifold for you, cutting out the primaries and rewelding in clear pipes. Around £3000 for that.

The cat ingestion thing gets a LOT of coverage on forums, far more than it probably deserves, but if you are that 1 in 1000 owner who it happens to, then it is terminal on the engine.

The best bang for the buck is to delete the secondaries really.

I’ve got secondaries and was going to get primaries for my vanquish, however, the noise produced in my opinion, doesn’t suit the car at all. More Ferrari / lambo.

[AdamV12V]

Do you have a clip of the QS (or other make) primary manifolds? Im struggling to find anything online really. Plenty of clips for V8’s but seeming not V12’s?

[Nick-n1cz7]

Thanks for the feedback all, much appreciated and thank you for taking the time to respond.

The AM dealer quote is from Aston Martin Nottingham, not the best of quotes by the sounds of it.

I will have to re assess the situation and look at delete of primary cats.

I don’t want the sound to be too intrusive either way.

[Sydney V8V]

Using BR headers without primary cats , increases power , sound and better fuel range if used with ECU update , and saving engine.

[M5MarkM]

Nick-n1cz7 said:

Hi all,

I am thinking of deleting my second cats to increase sound in lower Rev range but not sure whether to delete primary based upon risk to engine according to BR or secondary. Don’t want to delete both. Any thoughts? Thanks all

Not your origonal question I know, but I had Vanquis and a Vanquish I deleted secondary cats and replaced rear box, both times with Larini and I was very happy with results..

[Nick-n1cz7]

Thanks Mark, I’m told there’s lots to read about primary cat failure but I’m still looking doesn’t seem to be a hot topic

[Nick-n1cz7]

Just found this quote below from 8Tech on another topic, I think it’s a valid point IMHO

I would also like to hear how the failure of a catalytic converter, downstream of the cylinder in the flow of the exhaust gasses manages to go against that not unsubstantial flow, and reverse up the manifold getting into the cylinder.

I am aware of certain sellers offering performance exhaust manifolds without cats that are supposed to prevent this happening, but has anyone actually suffered this fate, and not just being told so by the manifold seller? A tubular manifold, correctly designed and without cats will certainly offer a notable increase in performance but I just cant see the cat ingestion arguement.

[SHIFTY]

There is mention in another recent thread of someone who had cat ingest problem see "Vanquish Coil Pack replacement"

[AdamV12V]

Cat ingestion is rare - very rare. Don't get too scared by what people say, but it can happen. It is caused by misfires that are not fixed promptly, as the owner who either doesn't notice them or doesn't realise how potentially significant they could be, and keeps on driving. Then fuel goes onto the cats and breaks them down and they start to disintegrate. I'm not sure how the dust then gets sucked back into the engine, but clearly it does.

So as long as you have your ears and eyes on alert for misfires and deal with any promptly without driving far once it happens, you can mitigate the issue almost entirely - for free!

That said the V12 engine is otherwise pretty bomb proof, so I think that this in its armour, is why it probably gets more press than it deserves.

To be clear this is not a problem exclusive to the Aston V12. Any engine with primary cats in the manifold, so close to the engine can potentially suffer from this issue.

Anyway, I really don't think its reason alone to get the primaries removed, but if you are considering other options like stripping right down to the bare min cats, (which would be a single set of 200 cell), then those are only available as secondaries, so that would be a reason to do new (or a cut job) manifolds and primary delete.

If you just want more noise and a splash of power to boot, at a sensible cost, then secondary deletes is the way forward for sure.

Edited by AdamV12V on Monday 10th May 12:46

[LTP]

AdamV12V said:

Cat ingestion is rare - very rare. Don't get too scared by what people say, but it can happen. It is caused by misfires that are not fixed promptly, as the owner who either doesn't notice them or doesn't realise how potentially significant they could be, and keeps on driving. Then fuel goes onto the cats and breaks them down and they start to disintegrate. I'm not sure how the dust then gets sucked back into the engine, but clearly it does.

The actual failure is the fuel reaching the surface of the cat and then being detonated by the hot exhaust gasses from the other cylinders. This then breaks down the surface of the ceramic in the cat can. The reason the abrasive ceramic dust thus created can get drawn back into the engine is the V12 uses an internal EGR system, with a large valve overlap so exhaust gases are drawn in from the headers at the start of the induction stroke - if those exhaust gases are full of ceramic dust from the catalyst then goodbye engine. Mike from BR has a good video on this.

AdamV12V said:

So as long as you have your ears and eyes on alert for misfires and deal with any promptly without driving far once it happens, you can mitigate the issue almost entirely - for free!

Except it can be difficult to detect a misfire when it's only one cylinder with eleven others and a flywheel working hard to keep the idle pretty smooth

AdamV12V said:

To be clear this is not a problem exclusive to the Aston V12. Any engine with primary cats in the manifold, so close to the engine can potentially suffer from this issue.

Again, not entirely true. If the V12 uses external EGR so it doesn't have a large valve overlap, or if they use metal cores in the cats rather than the cheaper ceramic there wouldn't be a problem

Edited by LTP on Monday 10th May 13:43

[AdamV12V]

LTP said:

[

AdamV12V said:

To be clear this is not a problem exclusive to the Aston V12. Any engine with primary cats in the manifold, so close to the engine can potentially suffer from this issue.

Again, not entirely true. If the V12 uses external EGR so it doesn't have a large valve overlap, or if they use metal cores in the cats rather than the cheaper ceramic there wouldn't be a problem

True - I dont disagree with anything you've put. Just to be clear on my last para however, I wasn't saying all other engines with primary cats in the manifolds will suffer from the problem. I used the words "can potentially", meaning some may, but not all.

Anyway I think we are on the same page.

[Jon39]

Apologies if this video has already been referenced, but if not, it might be helpful.

https://m.youtube.com/watch?v=mcBtHj60BJ8

[Nick-n1cz7]

Thanks for all the input folks, very much appreciated.

It is clearly a topic of debate and I wish you all the very best of good fortune for happy motoring