De-catting a 325i E36
Discussion
I've recently picked up a 1992 J reg 325i
I was wondering if it would be worth me removing the cats to gain a little bit more power, as I understand pre August 1994 cars don't need them to pass the MOT. Is the process just as simple as cutting them off and replacing them with 2 sections of straight through pipe?
Does anyone know what the likely power, torque and MPG gains would be like?
I was wondering if it would be worth me removing the cats to gain a little bit more power, as I understand pre August 1994 cars don't need them to pass the MOT. Is the process just as simple as cutting them off and replacing them with 2 sections of straight through pipe?
Does anyone know what the likely power, torque and MPG gains would be like?
sniff petrol said:
I've recently picked up a 1992 J reg 325i
I was wondering if it would be worth me removing the cats to gain a little bit more power, as I understand pre August 1994 cars don't need them to pass the MOT. Is the process just as simple as cutting them off and replacing them with 2 sections of straight through pipe?
Does anyone know what the likely power, torque and MPG gains would be like?
Your's requires the CAT for MOT, it's either August 1992 that the compulsory ACT came in or Jan 1993, can't remember which. I was wondering if it would be worth me removing the cats to gain a little bit more power, as I understand pre August 1994 cars don't need them to pass the MOT. Is the process just as simple as cutting them off and replacing them with 2 sections of straight through pipe?
Does anyone know what the likely power, torque and MPG gains would be like?
Just pulled this off from here: http://www.motester.co.uk/mot-qanda.html
EMISSIONS WITHOUT CAT
I own a Honda CRX Civic Del Sol 1992 K reg and I am having a stainless steel exhaust built and fitted. The fitter has said to me because the car is a 1992 model and the law that governs the catalytic converters for the MOT came into effect in 1993, the car does not fall into this law, and I could remove the cat and it would still pass the MOT. Is he correct or will it fail the emissions Test. Thanks, Ben.
Your fitter is not quite correct. The MOT regulations say nothing about a vehicle having a catalytic converter. They merely set emission levels which have to be achieved if the vehicle is first used after a specific year. Certainly some cars with every efficient engines could achieve the required emission levels without a catalytic converter. However in your case, if your vehicle’s year is before the break year, then should the cat be removed, in all probabilty it should not affect the MOT. – MOTT
EMISSIONS WITHOUT CAT
I own a Honda CRX Civic Del Sol 1992 K reg and I am having a stainless steel exhaust built and fitted. The fitter has said to me because the car is a 1992 model and the law that governs the catalytic converters for the MOT came into effect in 1993, the car does not fall into this law, and I could remove the cat and it would still pass the MOT. Is he correct or will it fail the emissions Test. Thanks, Ben.
Your fitter is not quite correct. The MOT regulations say nothing about a vehicle having a catalytic converter. They merely set emission levels which have to be achieved if the vehicle is first used after a specific year. Certainly some cars with every efficient engines could achieve the required emission levels without a catalytic converter. However in your case, if your vehicle’s year is before the break year, then should the cat be removed, in all probabilty it should not affect the MOT. – MOTT
This is a 190bhp version presumably? Perhaps if they made both cat and non-cat versions that will tell you something. I believe that for the similar capacity 2.5 cossie Merc, a non-"KAT" version like mine is 150KW or 204PS, while a KAT version is 143KW or 194PS, so it looks like you might gain 9 or 10 bhp, however I'm not certain if there may have been other differences between the KAT and non KAT versions when it comes to these Mercs.
For the 2.6 Merc the difference is 5KW, about 7bhp.
Wonder how much power there is to be freed from one of these 325s as 190 is a good figure already. What RPM is max power at?
For the 2.6 Merc the difference is 5KW, about 7bhp.
Wonder how much power there is to be freed from one of these 325s as 190 is a good figure already. What RPM is max power at?
Pentoman said:
This is a 190bhp version presumably? Perhaps if they made both cat and non-cat versions that will tell you something. I believe that for the similar capacity 2.5 cossie Merc, a non-"KAT" version like mine is 150KW or 204PS, while a KAT version is 143KW or 194PS, so it looks like you might gain 9 or 10 bhp, however I'm not certain if there may have been other differences between the KAT and non KAT versions when it comes to these Mercs.
For the 2.6 Merc the difference is 5KW, about 7bhp.
Wonder how much power there is to be freed from one of these 325s as 190 is a good figure already. What RPM is max power at?
According to the handbook it makes 192 bhp @ 5900 rpm and 181 lb/ft @ 4200For the 2.6 Merc the difference is 5KW, about 7bhp.
Wonder how much power there is to be freed from one of these 325s as 190 is a good figure already. What RPM is max power at?
It had a replacement SH engine less than two years ago and it seems like a good'un. Would be nice to get a nice round 200 bhp.
te, so whipping it off will help a lot. If it's as clean as a whistle you might find no difference.
See if he'll swap them for a set of 328i headers. The 2.5 has old skool cast sausage headers, the 2.8 has tubular. According to the wise sages on the internerd it's a worthwhile change, but you probably need to fiddle with the intake a bit and play with the maps to get the best of it all.
Just to update I spent this afternoon taking the cats off and replacing the section with some straight through pipes. The car produces a lovely rasp now that adds to the induction noise from the big cone filter, I put the induction kit on first and it seems to make a bit of difference to the power high up in the rev-range, seems faster revving over about 3000rpm. The de-cat to be honest doesn't seem to have made any difference to the power or running of the engine, just noise as the only silencer is the large back box. If I wasn't getting £80 for my old cats from the scrapyard then I wouldn't have bothered.
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