Has anyone tried gutting the cats on their V12V?
Since the O2's & pre cats are in the manifolds, I don't forsee any code issues.
How necessary are the secondary cats or are they just for extra emissions cleaning?
Thanks ahead of time for the replies.

 

In theory it should not throw a check engine, but some claim you need at least 100 cell the guarantee no CEL. It will get significantly louder just FYI

 

I think RSC has 100 cell sport cats for sale. I'd do that before gutting the stock cats. Alternatively, you could replace the manifolds. Don't hold me to these numbers because I'm going from my memory (which is pretty poor), but that mod increases bhp by about 40-50 bhp and reduces weight by something like 75 lbs. The stock manifolds look like something out of a tractor from the 1950s.

 

Why are you wanting to gut the cats.? You do realize that the emission equipment on all new cars is an extremely fine tuned system. I bet if you gut the cats you will loose horsepower unless you pay someone to remap the engine computer parameters.

 

I wasn't aware that there was an aftermarket header for the V12V. By the looks of the factory set-up a decent set of exhaust headers with extended O2's to after the factory cats would probably provide the best bang for the buck (as well as sound).
On just about every high performance vehicle out there, removal of the pre-cats provides at least 18 - 20 hp.
I don't know how sensitive the tuning parameters are on the Aston's, but the use of spark plug anti-foulers to extend out the secondary O2's has worked well for my Viper and ZR1.
If anyone knows of an existing header supplier for the V12V, please chime in.
Thanks Racer_x!

 

Hi Dan, the factory cats are down stream from the secondary O2's, so I can't see how the tuning parameters would be affected. Based on the design, there are no other electronic sensors after the exhaust manifolds. The only other item downstream would be the exhaust bypass valve, but of course this is a vacuum actuated system like the ZR1 & ZO6 corvette.
Removal and plugging of the vacuum lines provides a permanent bypass on the exhaust without pressing the sport button (I already tried it, and it works well). I'm not sure if the vacuum pump is utilized for any other components, but if the exhaust is the only item a guy could save a few pounds removing the vacuum pump as well. This winter, I will probably trace all of the vacuum lines and see if removal of the pump is feasible.
I know I might get flamed for wanting to try a number of performance mods on an Aston Martin, but I'm a rodder at heart.

 

The 200 cell V8 cats, which are more restrictive, only provide about 20 bhp. The 40-50 bhp figure is headers and cats, I believe. Bamford Rose (UK) makes headers now, but I don't think you can get them in the US yet. You can learn about them from the PistonHeads forum. RSC expressed an interest in producing their own V12 headers, but I don't think they've done the design work yet.

 

Thanks for the reply Racer_X! I'll try giving Bamford a call.
It looks like there should be more than ample room for long tube headers. The only big question would be the parameters for the O2's, and wether tuning would be required.
It looks like the factory manifolds dump directly into the pre-cat set-up, and then branch off towards the secondary cats. This design has got to be really restrictive on power. Minor intake & exhaust changes should realistically bring the V12 into the high 500 hp range.
I'm not looking for major power increases, but more for efficiency increases. High engine efficiency usually provides better power & less fuel consumption.

 

From what I understand, no tuning is required, just a lot of time to install the headers. The OE headers are pretty restrictive, and really heavy. Just look at the difference between the OE headers and BR headers:
.

 

Racer X, have you added headers and changed the exhaust to your V12V? If so, what was your experience and how much power did it ad? How much weight did it cut off?

 

We're not ready to sign off yet, but there are a set of RSC headers in existence somewhere out there just doing some extended testing...

 

Nope. I considered it, but decided not to do it, at least not for the time being. I might give them a try next year.

 

I spoke with Mike at Bamord; he told me that they are getting 72 bhp gains with headers & high flow cats. That would theoretically bring the V12 vantage into superlegerra territory.
I wasn't aware that RSC was working on long tubes for the V12V, I would be very interested in a set if this is the case.
Let me know how the development goes, or if you need a guinea pig.......

 

What did Mike say about selling to the U.S. market?

 

Mike said that they're not quite ready to deal outside of the UK yet.
I know they would have a market in North America if they do decide to breakout. Their long tube design is definitely a work of art.
Looking at the RSC design vs. the Bamford design, I would think maintaining the smaller diameter primaries in 304 stainless would probably provide the best increase in volume while remaining the original V12 tone. An increase in the secondaries pipe diameter would probably deepen the sound and reduce the raspiness.
Power levels should be similar, but sound style between the two designs will be slightly different.
Mike verified that the V12V ECU is highly adaptive, and there is no necessity for re-tuning with long tube headers. This would explain the excellent power increases (72 hp) with headers and cats alone.
I think that the V12V will probably be a good contender in the horsepower wars.
I hope RSC will complete their testing soon!