Decatting? And MOT results!

[wurlycorner]

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

Plus higher compression pistons.

Jdm and UKDM both came with cats, so it's nothing to do with the difference I'm afraid. Although JDM cat is physically shorter than UKDM.

[vanzep]

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.

same as Pushki i have a 94 BB4
its is decatted with plm manifold and 2.5" system

emissions results from last years MOT

CO 0.61%
HC 163 ppm

decatting - you do have a slightly better flow on the exhaust and the note is slightly louder - might only add 2 or 3 bhp - i doubt it will add anything more than that - the oem exhaust system for the BB4 is very well designed so hard to improve on by much

[Merlin]

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

Anyone with a BB4 goes through a non-CAT test (Pushki, Vanzep, me etc...) and the non-CAT test is much less strict.

It has nothing to do with the car being JDM or not. In order to put the car though a CAT test the chassis number must be on the MOT testers database, BB1's were both UK and JDM so it is on the database, but the BB4 (only JDM) is not on the database. The 4th gen JDM BB4 is the only H22 Prelude that can go though a non-CAT test, all others are meant to go through a normal test.

http://www.ludegeneration.co.uk/wiki/in ... sions_Test

[Vtecmec]

all others are meant to go through a normal test.

And pre-August '92 cars are exempt too; though i believe it is the engine manufacture date that is relevant, not the car, H22's have a date mark on the cylinder head.

My CO results were 0.275 without a cat.

[alinton]

Interesting, I must inquire here if my BB4 should go through a non-CAT test.

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

Anyone with a BB4 goes through a non-CAT test (Pushki, Vanzep, me etc...) and the non-CAT test is much less strict.

It has nothing to do with the car being JDM or not. In order to put the car though a CAT test the chassis number must be on the MOT testers database, BB1's were both UK and JDM so it is on the database, but the BB4 (only JDM) is not on the database. The 4th gen JDM BB4 is the only H22 Prelude that can go though a non-CAT test, all others are meant to go through a normal test.

http://www.ludegeneration.co.uk/wiki/in ... sions_Test

[RattyMcClelland]

So they should do the same with a bb6 prelude. But they won't.

[Merlin]

And pre-August '92 cars are exempt too

True, but you'll struggle to find many 4th gens that are pre-August '92.

So they should do the same with a bb6 prelude. But they won't.

It is because JDM 5ths are registered after 1995 so must go through a CAT test regardless of it being on the database or not.


My BB4 was a fair bit higher on emissions but the engine is far from standard and it idles around 1.1K rpm.

CO2 - 1.06%
HC - 640ppm

[Vtecmec]

True, but you'll struggle to find many 4th gens that are pre-August '92.

Aye, not many of us left.

[jjmartin349571]

Just checked my log book for the 4th gen, vehicle declared manufactured 1991

Moot point though as it's a BB4 anyway, plus it failed the non-cat equipped emissions test last time it was in

[Vtecmec]