Cat Convertors on Gran Sport

[Geofflyn]

Hi folks
Can anyone tell me what's so special about these cats that makes them so expensive? Reason I ask is I have some misgivings about what's been put on my car as part of the compliancing process when it arrived in Australia. Cats seem to range in price from a couple of hundred to the mega dollars from Eurospares or Maserati. Thanks Geoff

 

[conaero]

When you look at what they are, they are stupidly priced. All they are is a can with a honeycomb mesh inside:

What happens is the hot exhaust gasses heat up the honeycomb to red hot, then any unburnt fuel in the exhaust is burnt off. This is bad in 2 ways (for the driver)

1st, the restriction of the honeycomb increases back pressure which in turn chocks the engine as it cant get the fuel/air mixture in and out of the head quick enough.
2nd is that it burns all the unburnt fuel off in the exhaust gasses, which stop the V8 popping and cracking on the overrun, which those of us with Larini DeCats will hold testament to.

You have three options with regards to the Secondary cats:
1. remove them and have a bypass made or buy the Larini De Cats pipe
2. cut open the existing cat and replace the honeycomb material
3. Cut the cats out and weld in an aftermarket/generic cat

This all relates to the secondary cats under the car, the header cats are more difficult to sort but I think Larini do have an option. Best Call David at Larini to discuss or ping him out an email.

 

[adam01]

If i may add (and pls step in to correct) the material inside the OEM cats on a Masa is ceramic which in more prone to break up if it receives a decent wack. Once damaged, irrepairable

 

[conaero]

I have heard the brake up thing too, can get sucked back up into the engine and blow the engine too. Did not know they were ceramic, although I do know cats do contain precious metals.

 

[Geofflyn]

Thanks everyone that's really helpful. If I understand correctly I shouldn't be concerned about Masratis cats being removed as they are potentially problematic anyway. As far as being concerned about what's been put on the car the concerns that maybe I should have are:
Cheap local/generics that may not have a long life
Overly restrictive and diminishing performance. I would imagine in this case there is the increased likelihood of the cats overheating as well.
Have I got this right?
Thanks again everyone
Geoff

 

[adam01]

Thanks everyone that's really helpful. If I understand correctly I shouldn't be concerned about Masratis cats being removed as they are potentially problematic anyway. As far as being concerned about what's been put on the car the concerns that maybe I should have are:
Cheap local/generics that may not have a long life
Overly restrictive and diminishing performance. I would imagine in this case there is the increased likelihood of the cats overheating as well.
Have I got this right?
Thanks again everyone
Geoff

Geoff

Havent heard where imported cars have their cats changed - if they were u would have paid a lot more for the service as each is $6k+. If they stripped the cats, complier would be risking their license

If damaged, should hear a rattle like marble sound in which case u would need to take action
OEM cats whilst restrictive will perform adequately but not optimally compared to Larininbut should not overheat (unless there is prolonged high speed driving)

 

[Geofflyn]

Thanks Adam, they were definitely replaced and I questioned why as my understAnding is that the compliance rules require them tobe replaced if the car is 6 years old and mine isn't. Reason given was they were "line ball". However they are nit required to put on OEM cats so they could have done the replacement for as little as $500 each. We should chat offline as it's an Aussie centric issue so don't want to bore Matt too much with it. I must try and get hold of the detailed compliance requirements.

 

[rotorheadcase]

The standard cats are 400 cell and there are two on each side primary/secondary. A single 200 cell cat on each side will meet Oz emission requirements. I'm not sure where the lambdas are on the GS but even if they are downstream of the primaries, 200 cell cats should not have any CEL issues.

Have been quoted $1000 to replace both pairs of OEM cats with a pair of 100 cell cats and austectic stainless tubing fully installed. Estimated at freeing up around 15-20 hp

Regards,

Neil

 

[Geofflyn]

Thanks Neil I think I need to stick it on a hoist to see exactly what's been done as all the compliance certificates says is that two cat convertors have been replaced. Doesn't sound like I should be concerned other than why they needed replacing at all. Cheers Geoff

 

[Geofflyn]

Meant to ask what are lambdas?

 

[rotorheadcase]

Err... Aka O2 sensors. They monitor the ratio of air/fuel in the exhaust gases to continuously provide feedback to the fuel control unit.

Neil

 

[conaero]

Indeed, a bit more....they sit pre and post cat so monitor the O2 content of the exhaust both pre and post the cat, send the data back to the ECU, combined with other info such as the MAF (air flow meter) the ECU adjust the fuelling for optimum performance.

If the pre and post readings are the same it throws up an CEL (Check Engine Light) as the cat is not working or, more commonly, the sensor has packed up.

 

[rotorheadcase]

Interestingly the 3200 only has sensors before the primaries I think and temp sensors after. Perhaps the 4200s and GS have less restrictive cats as a result of having two sensors on each side.

My exhaust guy was surprised to see two pairs of cats on a high performance car but it is after all 10 years old.

Neil

 

[conaero]

Well, that takes us back to why they are in there does it not. Alot of us have always suspected that Ferrari are at the root of alot of these restrictions so the cars dont compete with theirs.

 

[conaero]

I completely removed my secondary cats with the Larini de cat pipes and never had any issues and still sailed through the MOT, so they are completely surplus to requirement.

 

[MAF260]

Possibly something to do with the strict US emissions as well?

 

[conaero]

Maybe, but I like conspiracy theories, they are more fun!

 

[Geofflyn]

Maybe, but I like conspiracy theories, they are more fun!

I am in your camp Matt. Makes sense for Ferrari to keep Masers a notch down anyway they can.
Thanks for all the feedback.....another night of learning for me. Cheers all

 

[abyss]

Geoff, Lambdas sensor is a little sensor plug into the cat to get all the reading to ECU.

 

[abyss]

Ops. Delayed response.