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Where to get a catalytic converter? (5g 2.2VTI)

Engine/Gearbox questions and discussion
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wurlycorner
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Where to get a catalytic converter? (5g 2.2VTI)

Post by wurlycorner » Wed Mar 13, 2024 6:26 pm

Scott560 wrote:
Wed Mar 13, 2024 2:46 pm
but there isn't really a test for it being blocked
You can use an IR temp reader to check temp differential front-rear of the cat.
If it's free-flowing, there shouldn't be much difference. If it's blocked, rear will be significantly cooler.

If it's a pre and post O2 sensor car (ludes aren't so this comment is effectively just wasting the internet - sorry!) you can pop the sensors out and put a pressure gauge in their place to check the pressure either side - same as temp, shouldn't be enormous difference unless blocked.

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Where to get a catalytic converter? (5g 2.2VTI)

Post by stinkypaul » Mon Jun 03, 2024 5:34 pm

chris_rd92 wrote:
Wed Mar 13, 2024 2:56 pm
I had a feeling that might be the case, yeah I do still have the heat shield. I'm starting to consider the option of replacing the entire downpipe as well as the cat, however there is a complication here too... A while back I fitted a full powerflow catback system which I got cheap second hand, but it turned out to be for a JDM model, so it was slightly too short to reach my cat. As my downpipe/flexi was a little worse for wear, I decided to have that cut and lengthened instead, which in turn moved my cat further rearwards to meet the powerflow system.

So here is the new question, can I just buy a JDM H22A5 downpipe with a new cat to fit my current exhaust?
Appreciate you've probably got this sorted now, but that's similar to my situation. To make everything fit I have a downpipe from one model, a cat from another and a cat-back stainless design for a different model again. Fit's perfect though :)

Measuring is tricky. I have the following on file for when I needed to last replace my downpipe. (I know that's nerdy). However when I next need to change or fix it, I'll either have custom parts made or weld it myself.

BM70450 845mm lambda before the flexi, pipe before and after flexi is long, hanger after flexi (H22A2) * (£55, available) 93 - 96

BM70496 660mm Lambda after flexi. Pipe before and after flexi is short, hanger after flexi (H22A5)

BM70630 730mm Lambda after flexi and close to flange. hanger after flexi (H22A5, H22A2)

BM70404 880mm lambda before the flexi, pipe before and after flexi is long, hanger after flexi

--- Cats ---

BM90784 392mm ** 97-01

BM90790 252mm

BM90723 357mm * 93-96

I think I went for the BM70450 and BM90784 which worked for me, but you'll have to measure up your pipe.

The stock cat flange bolt holes didn't quite match up to my stainless cat back, I had to open up the holes on one side.

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Where to get a catalytic converter? (5g 2.2VTI)

Post by vanzep » Mon Jun 03, 2024 7:01 pm

link to oem cat sizes for 4th and 5th gen in knowledge base on forum:

kb/viewarticle?a=6
1996-2000 1993 EG9 Blue Civic 1.6 Vti - Traded in against the BB4
2000-2019 1994 2WS BB4 Milano Red JDM Prelude Si VTEC LSD

2015 on > 1991 4WS BB1 Phantom Pearl Grey JDM Prelude Si VTEC LSD
2021 ON > 1998 2WS BB6 White Pearl JDM Prelude Si VTEC

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Where to get a catalytic converter? (5g 2.2VTI)

Post by chris_rd92 » Fri Jul 11, 2025 11:39 am

Hi all just reviving this thread again as I'm finally doing something about this!

My exhaust is falling apart so I'll be booking the car in soon for a full custom stainless system made to my specs. As it's a daily driver I want it to be relatively tame and MOT friendly.

I'm still looking at cats and front pipes on 'cats2u', and this has got me confused. The are 3 cats and 2 pipes listed for my car (1997 2.2vti H22A5 BB8) that all look slightly different and vary massively in cost.

Cats :

https://www.cats2u.co.uk/honda/31643-ho ... a6003.html

https://www.cats2u.co.uk/honda/7148-hon ... 90784.html

https://www.cats2u.co.uk/honda/7149-hon ... 0784h.html

Front pipes :

https://www.cats2u.co.uk/honda/3005-hon ... 70496.html

https://www.cats2u.co.uk/honda/3177-hon ... 70630.html

Could anyone please tell me which cat and front pipe are the ones to suit my car? I may have the front pipe custom made in stainless when I have the rest of the system done, but this all depends on costs and I'd like to have the cheap option as a backup.

Thanks all!

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Where to get a catalytic converter? (5g 2.2VTI)

Post by stinkypaul » Fri Jul 11, 2025 6:33 pm

It's probably

BM90784 (your first link )
And
BM70450 which you don't have listed.

But here's the thing, seeing as you are getting the rest custom made you could use BM70630 (your second front pipe link) they all fit together they are just different lengths. Brackets are a bit different but not a major obstacle.

If you want the same as you have now you'll need to measure what you have and compare to the specs in your links.

If the budget will stretch I would get a custom front pipe and sports cat as well. The BM/ cats2u cats are pretty bad but I think they are the only off the shelf option, at least for reasonable money. They are restrictive and they catalyse for only a short time. I've had a few and junked them. I tried a cheap sports cat but that fell apart after a few weeks. So now I use a test pipe and just put the cat on for MOT.

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