Decatting? And MOT results!

alinton · Post by **alinton** » Sat May 02, 2015 4:11 pm

Benefits, or lack thereof of decatting a 2.2 VTEC?

Or any experiences please?

Last time I did it to another car I gained 30hp. Mind you, that was a TVR Cerbera 4.5 V8.

Ta

A

Post by **Drax** » Sat May 02, 2015 5:23 pm

lol you aint gonna gain 30bhp decatting a lude, maybe 1-5bhp. always a good little cheap gain in my experience, plus makes any exhaust system a smidge louder. only downside is emissions testing, quite often depending on the gen and facelift lude you have, you may need a "friendly" mot tester

or the ability to put the cat back on for the test

alinton · Post by **alinton** » Sat May 02, 2015 9:40 pm

Is that all you get? I knew I wouldn't get 30!

Although I guess with the cat being 18 years old there the possibility it's a bit blocked anyway, so might be restrictive. I'd be interested to know what the emissions would be without it.

The car had its NCT yesterday (Irish equiv of the mot) and the emissions were very good, CO was 0.03% at low idle and 0.04% at high idle. HC was 43 and 41 ppm respectively.

The car did fail though, because the break fluid was less than half full, the rear arb drop links are worn and the left headlight is slightly low!

EvilDmen · Post by **EvilDmen** » Sun May 03, 2015 12:06 am

I had a resonated decat on mine and just swapped it out for my new cat come MOT time.

20 mins and 6 bolts, go for MOT and then 20 mins and 6 bolts when I get home.

I have both for sale if you're looking? £40 each or £70 for them both.

Edit.

Just seen you have a 4th gen. D'oh! Sorry they won't fit.

Post by **RattyMcClelland** » Sun May 03, 2015 12:55 am

How the hell do you guys get under the car to remove it?
I havnt figured that out yet and can never get enough leverage to remove the bolts.
Mot is £100 to "pass it".

But cheaper than failing and cheaper than garage removing the cat and vice versa.

'92 Si VTEC · Post by **jjmartin349571** » Sun May 03, 2015 12:04 pm

RattyMcClelland wrote:How the hell do you guys get under the car to remove it?
I havnt figured that out yet and can never get enough leverage to remove the bolts.

My thoughts exactly, some of those bolts are right up in the exhaust tunnel!! Even with long extensions with wobbly ends it's not a job I'd want to do. I've got a whole exhaust + decat still waiting to go on for this very reason

quarkhimself · Post by **quarkhimself** » Sun May 03, 2015 12:57 pm

as far as i know my 4g is decat. i had no problems with emissions , i can try and find the MOT emissions sheet. performance wise ukdm is 185hp and jdm 198hp, so that's probably the difference between cat and decat

Post by **RattyMcClelland** » Sun May 03, 2015 1:45 pm

quarkhimself wrote:performance wise ukdm is 185hp and jdm 198hp, so that's probably the difference between cat and decat

Plus higher compression pistons.

Post by **Pushki** » Sun May 03, 2015 1:59 pm

My 1994 4G BB4 Prelude has a de-cat.
As it's an import the BB4 doesn't appear on their emissions list therefore it goes through as a 'Non-catalyst equipped vehicle'.

Results

CO = 0.72 % (Pass = max 3.50 %)
HC = 157 ppm (Pass = max 1200 ppm)

When I fitted the de-cat I did notice the revs were slightly more responsive and the exhaust sounded a little meatier.

I've never had it on a dyno, so it could all be psychological.

alinton · Post by **alinton** » Sun May 03, 2015 2:14 pm

Those figures wouldn't pass here, the max CO is 0.5%.

I don't believe the crowd that do the tests here make any reference to whether the vehicle is JDM or not. Still I might get a decat pipe and try it out, would be interesting to test it with the cat gone and see what difference it was making.

They did tell me that the results they got from my car were extremely good for a car of its age. The guy was very impressed with everything about it, what it failed on are insignificant and easy to fix.