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V6 350 Stock Cat Cells


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thank you Colin.

do you know how many cells have the single cat? (i.e. 600, 400 …)?

I would like to understand how many the stock cat is different from a sports cat (200 cells)

Edited by Gigliosa
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I would like to compare the stock cat with sports cat. In Italy some lotus motorsport workshops propose ever to decat, but I'm not convinced to do this, and I would like to evaluate an improvement with sport cat, because I do every year 25-30 track-day sessions (25min each session).

My main trouble is that with decat, the comnpression chain from motor to exhaust exit will change, and this change will influence the software setup of the ECU (not only O-gas), interfering with the excellence of sport and race ecu lotus setup.

I would like to undestand if with a sport cat I may improve the safe of the engine, because I do many track-day per year.

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36 minutes ago, Gigliosa said:

My main trouble is that with decat, the comnpression chain from motor to exhaust exit will change, and this change will influence the software setup of the ECU (not only O-gas), interfering with the excellence of sport and race ecu lotus setup.

Correct.  De-cat is not recommended on supercharged engines.  Sports cat will work well.

Dave

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1 hour ago, Gigliosa said:

I would like to compare the stock cat with sports cat. In Italy some lotus motorsport workshops propose ever to decat, but I'm not convinced to do this, and I would like to evaluate an improvement with sport cat, because I do every year 25-30 track-day sessions (25min each session).

My main trouble is that with decat, the comnpression chain from motor to exhaust exit will change, and this change will influence the software setup of the ECU (not only O-gas), interfering with the excellence of sport and race ecu lotus setup.

I would like to undestand if with a sport cat I may improve the safe of the engine, because I do many track-day per year.

Yes definitely a Sport Cat will improve matters and as Dave said best not to decat.

Ive used both a Komotec and 2bular 200 Sports Cat and can confirm it is a step up from the awful Toyota ones 

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I had an involuntary de-cat a while back. Car ran fine whilst I was waiting for Lotus to decide what the problem was. They examined the engine data and without any fuss replaced them FOC. If it eventually happens again I will go for 200 cell cat.

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On 19/11/2021 at 17:54, Hangar 111 said:

Correct.  De-cat is not recommended on supercharged engines.  Sports cat will work well.

Dave

 

On 19/11/2021 at 17:17, Gigliosa said:

I would like to compare the stock cat with sports cat. In Italy some lotus motorsport workshops propose ever to decat, but I'm not convinced to do this, and I would like to evaluate an improvement with sport cat, because I do every year 25-30 track-day sessions (25min each session).

My main trouble is that with decat, the comnpression chain from motor to exhaust exit will change, and this change will influence the software setup of the ECU (not only O-gas), interfering with the excellence of sport and race ecu lotus setup.

I would like to undestand if with a sport cat I may improve the safe of the engine, because I do many track-day per year.

I don't quite understand why decat could damage the engine or supercharger.

Do you mean without the restriction in place (decatted), the charger boost will alter and the stock ECU will not able to coop with that? 

 

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I have heard a lot about OEM cats being fragile.  What exactly does that mean?  Do they tend to shatter / break into pieces or sth?  Would like to know if anyone has experienced this first hand.

I had a full Larini de-catted system before and I opted to switched back to full OEM.  I didn’t like the full de-catted exhaust sound and it was way too smelly.  But now I’m a bit nervous if the OEM cats are made of glass.

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@KIMUTAKU - yes, the OEM cats are known to fail (on track).  When this happens they break apart and chunks get blown further into the exhaust system.  That is best case... these OEM cats sit very close to the cylinder heads!  Why didn't you just install a sports cat in your Larini setup; added benefit of additional power, less smell (but not completely gone), and no worries about the OEM cats breaking into pieces.

Edited by Kristof Thys
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On 24/11/2021 at 14:25, Hangar 111 said:

I think the point of "improving the safety" is that you are replacing the standard ceramic cats near head, which are known to be a bit fragile.

With SC engines you can lose boost in the valve overlap if you free the exhaust too much - we have seen it back to back on the dyno.

Dave

What I dont understand here is why there are so many dealers selling decat exhausts and the option for a racecat if full decat is this bad for the engine. None of them (except komotec) is offering remaps, so are tubular, larini etc all selling stuff that might damage the engine or loose power due to their products, while they call those exhaust “engine saving kits”? 
also the cupr is catless, but this a different map off course. 
 

could you explain further? Because I’ve spoken to a bunch of parts dealers and all tell different versions. Most say it is best to delete cats entirely for better flow, some say the engine gets lean, some say the engine is self learning and its not a problem. 
i have no clue who to follow….

so not saying you are incorrect, just saying I dont follow whats what

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On 19/11/2021 at 09:54, Hangar 111 said:

Correct.  De-cat is not recommended on supercharged engines.  Sports cat will work well.

Dave

Hi Dave, can I just confirm I understand you correctly please - it is OK to use new headers and delete the original cats "as long" as you also include, say a 200CEL sports cat - so you end up with one cat still?

I did that on my NA and it was superb, I'll be doing it next year on my Evora 410 as long as it is not likely to damage anything.

Thanks

Alcohol. Sex. Tobacco. Drugs. Chocolate.  Meh! NOTHING in this world is as addictive as an Evora +0. It's not for babies!    

The first guy to ride a bull for fun, was a true hero. The second man to follow him was truly nuts!   

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16 hours ago, royz_garage said:

Because I’ve spoken to a bunch of parts dealers and all tell different versions. Most say it is best to delete cats entirely for better flow, some say the engine gets lean, some say the engine is self learning and its not a problem.

Everyone will have a different version for whatever product they are trying to sell you.

The ECU does, like all modern vehicles, have long and short term fuel trims, up to, let's say +/- 20%.  So a standard car lives somewhere in the middle of that scale.  It's there to allow for different conditions, such as fuel quality, inlet temperatures (and therefore ambient temperatures), planting your foot down under load, etc.  Put some dodgy fuel in, you might need, maybe 10%?  Take it on track and show it a good time, another 10%?

Now fit some new hardware.  You're probably going to need some more fuel for all that extra air you are moving.  So your new baseline now might be +10%.  Now you've only got 10% left to play with.  You might get lucky and the ECU can run things OK with less trim available.  You might not.  It might be fine until you do that hard drive on the hottest day of the year and you could only get standard unleaded fuel.

Why wouldn't you remap to make the most of the expensive hardware you've just purchased for your expensive car?  Or leave it luck.  Just one of those things that only you can decide.

We know that the upgrades that we sell are tested and proven.  I don't know about any others.

Dave

16 hours ago, C8RKH said:

Hi Dave, can I just confirm I understand you correctly please - it is OK to use new headers and delete the original cats "as long" as you also include, say a 200CEL sports cat - so you end up with one cat still?

Yep, that's a fine plan.  I'd always recommend remapping, as per reasons above.

Dave

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Thank you. Much appreciated. Just such a damn shame you are so far away lol....

Edited by Bravo73

Alcohol. Sex. Tobacco. Drugs. Chocolate.  Meh! NOTHING in this world is as addictive as an Evora +0. It's not for babies!    

The first guy to ride a bull for fun, was a true hero. The second man to follow him was truly nuts!   

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51 minutes ago, Hangar 111 said:

Everyone will have a different version for whatever product they are trying to sell you.

The ECU does, like all modern vehicles, have long and short term fuel trims, up to, let's say +/- 20%.  So a standard car lives somewhere in the middle of that scale.  It's there to allow for different conditions, such as fuel quality, inlet temperatures (and therefore ambient temperatures), planting your foot down under load, etc.  Put some dodgy fuel in, you might need, maybe 10%?  Take it on track and show it a good time, another 10%?

Now fit some new hardware.  You're probably going to need some more fuel for all that extra air you are moving.  So your new baseline now might be +10%.  Now you've only got 10% left to play with.  You might get lucky and the ECU can run things OK with less trim available.  You might not.  It might be fine until you do that hard drive on the hottest day of the year and you could only get standard unleaded fuel.

Why wouldn't you remap to make the most of the expensive hardware you've just purchased for your expensive car?  Or leave it luck.  Just one of those things that only you can decide.

We know that the upgrades that we sell are tested and proven.  I don't know about any others.

Dave

Yep, that's a fine plan.  I'd always recommend remapping, as per reasons above.

Dave


 

Sounds good. Its not that I dont want this or that, just trying to understand whats what and I like to understand my car.

 

appreciated that a professional takes time to share real info on a forum👌🏻👊

my logic was that when placing a new intake your text is true as you indeed have better ingoing airflow, but when removing something that blocks flow like a cat it releases the potential of more airflow through the pipe, but as the engine doesnt know that it is not there anymore, it will spit out exactly the same and you dont benefit from it, but you loose the potential engine damaging oem cats(which a remap could fix.)

so for instance one could just take the oem manifolds, weld in a pipe instead of the cat and back on the road for 200 euro’s and than you didn’t get more power, but also lost the risk of damaging the cats/engine

to avoid a cell some sell these lambda blockers which make the ecu think there still is a cat. 
 

I owned 2 Ariel atoms supercharged and decatted both, which is factory supported and actually gained a little top end power and on one it lost a little low end, other one didn’t. 
 

dont get me wrong here, I’ll probably drive stock and than opt for 475 komotec kit or sell the car, but I know a lot of guys just want to get rid of the manifolds only and dont want to pay for sportcats, y-pipes, remaps etc.

 

Edited by royz_garage
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1 hour ago, royz_garage said:

so for instance one could just take the oem manifolds, weld in a pipe instead of the cat and back on the road for 200 euro’s

I think many of us would be interested to understand how that goes. Do let us know if you do it.

However, at that point, unless yours is a federal (US) car would that not mean that you had removed the only two cats on the whole exhaust system (i think only the US cars got the 3rd cat in the exhaust)?  So how would that work for emissions?

Alcohol. Sex. Tobacco. Drugs. Chocolate.  Meh! NOTHING in this world is as addictive as an Evora +0. It's not for babies!    

The first guy to ride a bull for fun, was a true hero. The second man to follow him was truly nuts!   

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13 minutes ago, C8RKH said:

So how would that work for emissions?

Simple. It wouldn't (in the UK anyway).

1 hour ago, royz_garage said:

as the engine doesnt know that it is not there anymore

It does!  The lambda and MAF sensors tell it.

If you remove a blockage there is more going through the whole system.  If there's more gas going out, there'll be more gas coming in.  Engine is essentially an air pump after all.

Dave

Edited by Hangar 111
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22 minutes ago, C8RKH said:

I think many of us would be interested to understand how that goes. Do let us know if you do it.

However, at that point, unless yours is a federal (US) car would that not mean that you had removed the only two cats on the whole exhaust system (i think only the US cars got the 3rd cat in the exhaust)?  So how would that work for emissions?

Obviously it would be “not good” for emissions, but that being said, put in the  co spacers and the engine will think it still has a cat. This should avoid a cell being throwed and in my country if there isnt a cell/mil code on the obd they dont do the emissions test with the sniffing machine, if they do you’ll have to swap out the manifolds every 2 years for MOT. 
 

assuming Dave is correct you will have the risk of damaging the engine. 
probably dealers tell different versions of the same truth. Dave seems to be smart and on the safe side, others might say go ahead the ecu will correct it, both are correct, its just how much “risk” is one willing to take. 

I guess best is remapping, but there really arent any mappers except for komotec who really rather sells a complete package incl mapping. 
 

feels a bit like “if you want to get rid of the cats, please buy a complete kit or nothing at all”

so thats probably what I end up with

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It's not a binary approach; just do the sensible thing.  Don't weld pipes in restrictive manifolds but get good aftermarket headers.  If you want to run with or without sport cat is your choice: like you say, it will work with just 2 "post cat" O2 simulators on the lambda sensors.  DixieV6 ran his car for +4 years that way, including a good CAI (with air straightener).  However, this setup does drone with the OEM back box.  Come 2y inspection time, swapped the straight pipe with a sport cat.

I am running headers and a 100-cell (not 200-cell) cat for over 2 years now, with same type of CAI and straight pipes internally in the customised back box. 

 

Neither of us have had any issues, both cars on stock tune.  At WOT I am seeing on my wideband O2 AFR's 11:1's where when stock I was at 10:1's fcuk rich at WOT.  Long term fuel trims are at +3.5 IIRC.  So all good.

Dave IS correct that on a SC application, freeing up the exhaust too much might decrease low & mid range power.

 

 

EDITED to add: you say "swapping" the headers/manifolds over IF they use the sniffer at inspection...  one extra reason to get decent headers: swapping the decat pipe with the sport cat will be 100x easier than swapping manifolds once.

 

Edited by Kristof Thys
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2 hours ago, Hangar 111 said:

You're a man of means ;)  Get it transported down here!

Dave

@C8RKHI know a man in Scotland who can help, covered trailer and everything...

@Hangar 111Dave, when do you reopen in New year? I have just had a new toy delivered from Scotland, but it needs a service.

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2 minutes ago, Gashead1105 said:

@Hangar 111Dave, when do you reopen in New year? I have just had a new toy delivered from Scotland, but it needs a service.

(Hi Will, just to confuse, this is my new account)

We're back on 4th Jan - drop Marianne a line to discuss scheduling, it's not too bad for January at the moment.

Dave

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