H I, I have a s reg 1.8 sport I have a home made induction kit drawing in cold air, veryf ree flowing, and a full stainless exhaust, no mid box. I’m considering making a straight pipe to replace the cat . I’m wondering whether the ecu and injectors will be able to provide the extra fuel to keep it stoichiometric, don’t want it lean and melting things! Anyone done this and what kind of gains were achieved?
doing full geometry setup soon as iv just made my own tracking kit, I’m a race engineer, so if anyone wants a proper fast road or custom setup, camber and toe, let me know. I’m on the Wirral…
I run a 93 import no cat and a full stainless system inc a 4into2 into 1 stainless manifold and as far as I know no alterations to ECU [ or at least I havent done any thing ]passes mot ok on emmisions [last week ]
I understand that 1998, S reg on was the cut-off, certainly was for my Caterham.
My MOT man seemed to be under the impression that any car found to be on the public road without a cat when one should be present could have their cars confiscated and crushed. Not sure I believe him but I would make some serious enquiries before I contemplated removing mine.
Any one with better factual info to offer would be appreciated.
If a car can pass the MOT emissions without a cat it makes me wonder why cats are mandatory for new cars or whether the limits set for the MOT test reflect the standards manufacturers have to abide by.
Of course cats do eliminate some of the other noxious emissions but that effectiveness is not measured at MOT time. It begs the question of whether they are really effective or beneficial in the long term.
Even if it passes an MOT it would breach construction and use regs it is the same reason DPF removal and fitting aftermarket HID’s are illegal. Although, if you took it all the way increasing the noise level of your exhaust is as well…the final one is more the EU than anything.
Something I copied when I was researching the legality of de-cating my '91 UK BRG Limited Edition (which incidentally I did legally according to the rules below).
On the emissions thing. Most Eunos roadsters will not have an SMMT code so only need a basic test and may not need a Cat even if originally fitted. See below a letter I had from VOSA as a reply when I requested confirmation from them.
Spark ignition cars first used on or after 1 August 1992 are subject to a Basic Emissions Test (BET) regardless of whether a catalytic converter is fitted or required. In the event that the BET is failed, it becomes necessary to reference both the MOT Inspection Manual, Section 7.3 and the In Service Exhaust Emission Standards for Road Vehicles publication (Emissions book). The MOT Inspection Manual is available on-line at http://www.motinfo.gov.uk/htdocs/ and the Emissions book athttps://www.gov.uk/government/uploads/system/uploads/attachment_data/file/194133/Emissions_17th_Edition.pdf
For vehicles first used between 1 August 1992 and 31 July 1995, if there is an exact match for the vehicle in the Emissions book, then a full cat test must be carried out. Where this is the case, the vehicle must have a catalytic converter fitted or it will fail, regardless of the result of the emissions test.
If there is not an exact match in the Emissions book, then the vehicle will be subject to a non-cat emissions test (two gas test). Where this is the case, the vehicle is not required to have a catalytic converter fitted for MOT purposes, regardless of whether one was originally fitted.
I am unable to provide an answer specific to a particular vehicle as you have not provided any details of such. However, assuming you have the relevant Vehicle Identification Number (VIN), you can easily check for yourself using the link to the Emissions book and referencing page 70 of Section 1 (page 86 of the pdf). The Mazda VDS number is the 4th to 9th digits of the VIN.
Thanks for responses guys. I have little doubt that ur right about the legality of not running a cat on a 98 car, but let’s just assume that isn’t an issue, I was only using the decat pipe on a track day say…has anyone found noticeable gains over just having a cat back system? Obviously a n/a engine needs to retain adequate back pressure if I don’t want to lose all the low down torque etc for road use. But the stock manifold and sensible diameter pipe should suffice, my main worry was under fuelling however.
by the sound of it, de cat hasn’t caused any issues for anyone? So its more a question of whether its worth the time/money when my aim is to gain a couple horsies!
I agree totally that our cars must comply with the Construction & Use Regulations. It would be illegal and irresponsible not to do so. However the MOT test only covers certain aspects of a car. The testers are not checking full compliance with the C & U Regs, just certain items, so theoretically it is possible for a non complying car to pass the MOT test.