Cat replacement

Author
Discussion

sapper

Original Poster:

1,017 posts

143 months

Monday 11th February
quotequote all
I’m looking to put a CAT back in below the turbo , pretty sure I can get one to fit but will a 200 cell be sufficient.
Anybody out there that knows about catalytic converters?

Dominic TVRetto

1,269 posts

119 months

Monday 11th February
quotequote all
I've just had a replacement cat core put inside my N/A y-piece - 100cell. Theoretically allows higher flow than a 200 like-for-like, but needs heating up more in order to work as effectively - as I understand it.

With a turbo I assume you will see higher exhaust temps, so long at the cat is as near as possible to the turbo, so this heating issue may not be such a problem.

So perhaps a 100-cell core might be a better solution for you? Worth a thought anyway...

HTH

sapper

Original Poster:

1,017 posts

143 months

Monday 11th February
quotequote all
Thanks Dom
I’ll go for the 100 cell
I can also get a lean map ready for MOT test.

Dominic TVRetto

1,269 posts

119 months

Monday 11th February
quotequote all
I'd look a little further into it, as cats aren't cheap - so make sure you get it right.

I'd double check what the EGT will be post-turbo, especially depending how far away you will have to site it - I'd like to think it would still be hot enough, but best check to make sure.


QBee

16,300 posts

82 months

Tuesday 12th February
quotequote all
Watching with interest, as the same mod crossed my mind too. Next question is where to site it, and how to fit it?
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sapper

Original Poster:

1,017 posts

143 months

Tuesday 12th February
quotequote all
QBee said:
Watching with interest, as the same mod crossed my mind too. Next question is where to site it, and how to fit it?
I put my car on the lift last night and I’m measuring today.
Hoping to find space below the turbo

QBee

16,300 posts

82 months

Tuesday 12th February
quotequote all
sapper said:
QBee said:
Watching with interest, as the same mod crossed my mind too. Next question is where to site it, and how to fit it?
I put my car on the lift last night and I’m measuring today.
Hoping to find space below the turbo
Photos would be brilliant - I am seeing Mat Smith in the next few days and would like to show him for an extra opinion, given that they get pretty hot.

spitfire4v8

2,741 posts

119 months

Tuesday 12th February
quotequote all
I made a removable cat up once for a car that was going to the continent .. fitted it at the side of the sump .. I'm not sure you'd get one under the turbo that's going to be of any use. In any case, the turbo will take a lot of heat from the exhaust gas so if you're expecting to pass emissions then use tricks with thermal lagging and ecu tweaks to get the exhaust gas as hot as poss ..

sapper

Original Poster:

1,017 posts

143 months

Tuesday 12th February
quotequote all
https://www.ebay.co.uk/itm/Universal-100-Cell-High...

Think of using something like the above.
Under the turbo there is just enough room but I like the idea of alongside the sump as fitting would be easier.

sapper

Original Poster:

1,017 posts

143 months

Tuesday 12th February
quotequote all
spitfire4v8 said:
I made a removable cat up once for a car that was going to the continent .. fitted it at the side of the sump .. I'm not sure you'd get one under the turbo that's going to be of any use. In any case, the turbo will take a lot of heat from the exhaust gas so if you're expecting to pass emissions then use tricks with thermal lagging and ecu tweaks to get the exhaust gas as hot as poss ..
Which cat did you use? Did you use flanged pipe or U clamps?
I’ve got 3 maps available, currently no3 is set up for unleaded low Ron (continental use) I was thinking of getting it to run lean come MOT time. 1st map is full fat 2nd is eco run so it’ll be trial and error but fitting the cat could be enough. Unfortunately I don’t know enough about it yet so any advice welcome.

sapper

Original Poster:

1,017 posts

143 months

Tuesday 12th February
quotequote all
QBee said:
Photos would be brilliant - I am seeing Mat Smith in the next few days and would like to show him for an extra opinion, given that they get pretty hot.
Anthony there is 300mm available alongside the sump with 30mm either side of the exhaust.
So 20-25mm useable space. Exhaust is 75mm and there is a high flow cat on eBay that is 100mm wide. So basically will it be enough.

https://www.ebay.co.uk/itm/Universal-3-100-Cell-Hi...

GreenV8S

26,647 posts

222 months

Tuesday 12th February
quotequote all
sapper said:
1st map is full fat 2nd is eco run
Why do they need to be different?

spitfire4v8

2,741 posts

119 months

Wednesday 13th February
quotequote all
GreenV8S said:
sapper said:
1st map is full fat 2nd is eco run
Why do they need to be different?
Hi Peter .. only because the RV8 enjoys a richer mixture to run at its smoothest, but good economy mixtures well into the 15sAFR start to impact on the perception of smoothest, with occasional small weak mix misfires a possibility and also a small degradation in the way the power delivery follows small throttle inputs for accuracy. Weak mix engines just aren't as sharp to the throttle as a richer mix engine. It's a fun car, so you want the main map to be a great driving/feeling map, but also many people do long journeys, so eeking out a few mpg can be important.
So I do a smooth running map in slot1, and a weaker map in another slot which will run weak on cruise, but in certain situations might impact on the smooth driving.

Also I implement fuel shut off on overrun on the eco map, but don't on the normal running map as that can sometimes cause a slight stutter coming back on the throttle from overrun situations.
Both my pervious BMW and my current Ford both have a tendency to be a bit aggressive on the overrun on/off fuelling .. coming down a motorway incline especially can be a series of small lurches felt through the car as the fuel is shut off, then re-introduced, then shut off as the rpm change slightly on the descent. On my daily driver I wish I could turn the overrun fuel cut off but I can't.
With 3 maps you have that option.

There's 3 maps slots in the emerald so that's why it's done this way smile

sapper

Original Poster:

1,017 posts

143 months

Wednesday 13th February
quotequote all
sapper said:
Anthony there is 300mm available alongside the sump with 30mm either side of the exhaust.
So 20-25mm useable space. Exhaust is 75mm and there is a high flow cat on eBay that is 100mm wide. So basically will it be enough.

https://www.ebay.co.uk/itm/Universal-3-100-Cell-Hi...



spitfire4v8

2,741 posts

119 months

Wednesday 13th February
quotequote all
Mick, you could do worse than give these guys a call .. not far from you

http://www.bmcatalysts.co.uk

QBee

16,300 posts

82 months

Wednesday 13th February
quotequote all
Thanks for the pics, Mick. Much appreciated.

sapper

Original Poster:

1,017 posts

143 months

Wednesday 13th February
quotequote all
spitfire4v8 said:
Mick, you could do worse than give these guys a call .. not far from you

http://www.bmcatalysts.co.uk
Thanks I’ll do that