Precat removal
Discussion
Does anyone know how much removing the precats does to the emissions readings on a Griff 500?....I was wondering about removing mine as my manifolds are off at the moment as I’m refurbing the chassis. I’m a little concerned about removing them as I was reading a few days ago about the proposal of emissions being tightened up at MOT’s.
Removed the pre-cats on my Griff 500 when I first had it. You will find that there is no detrimental effect in doing so, they are only there to reduce emissions on initial start up until the main cat has reached operating temperature. When removed there is a noticeable reduction in under bonnet heat, the noise is virtually no different, but the engine did seem to run smoother (maybe a placebo effect). Also no effect on the MOT readings.
I have an ear drium that plays up at certain frequencies and around 2800-3500 revs I notice it after pre cat removal, a drone sort of thing, nothing like a sleeved exhaust but it’s still audible even with a Catted Y piece so no ill effects but on a long drive it’s noticeable if you are used to the fully Catted car.
Most might not notice it maybe and some will prefer that sound but if you don’t like those resonation’s it will get on your wick if you like to do long distance touring.
I think someone said it releases about 5 hp which I think sounds fair as mine defo felt slightly more urgent without the per cats in.
But then I can’t drive with the windows fully closed, I always have the drivers window open about a inch, pressure inside the car and resonation can knock you about and tire you out very quickly or it does me. Open the window and it neutralises and my ears are fine!
Is this just me or do others feel this?
It might just be that I like hearing the exhausts
Most might not notice it maybe and some will prefer that sound but if you don’t like those resonation’s it will get on your wick if you like to do long distance touring.
I think someone said it releases about 5 hp which I think sounds fair as mine defo felt slightly more urgent without the per cats in.
But then I can’t drive with the windows fully closed, I always have the drivers window open about a inch, pressure inside the car and resonation can knock you about and tire you out very quickly or it does me. Open the window and it neutralises and my ears are fine!
Is this just me or do others feel this?
It might just be that I like hearing the exhausts
das2000m said:
Does anyone know how much removing the precats does to the emissions readings on a Griff 500?....I was wondering about removing mine as my manifolds are off at the moment as I’m refurbing the chassis. I’m a little concerned about removing them as I was reading a few days ago about the proposal of emissions being tightened up at MOT’s.
Where is the info about emissions being tightened? they can't tighten the test for cars already made, you can't expect a car designed to meet one set of limits to be able to magically meet a stricter set if that isn't what it's designed to do ... are you sure it's not just new limits for new cars when they become testable?
Most regulations aren't changed retrospectively (seatbelts, reflective number plates, rear fog lamps etc), you're right but they were tightened slightly for diesel cars in May 2018.
Instead of having to meet the limit of 1.5 l/min, all diesel cars registered after 1st July 2008 have to meet the 'plated' value if there is one. For my run-around Swift DDiS, it means at MoT time it has to be below 0.5 l/min in the smoke test rather than the previous limit. It only just made it this year (not being driven enough!).
It was all part of the Mot test overhaul in 2018:
https://www.driving.co.uk/car-clinic/guide-new-mot...
Petrol cars are not seen as the devil's fuel, yet, and no TVR ever had a DPF fitted so you should be OK.
Instead of having to meet the limit of 1.5 l/min, all diesel cars registered after 1st July 2008 have to meet the 'plated' value if there is one. For my run-around Swift DDiS, it means at MoT time it has to be below 0.5 l/min in the smoke test rather than the previous limit. It only just made it this year (not being driven enough!).
It was all part of the Mot test overhaul in 2018:
https://www.driving.co.uk/car-clinic/guide-new-mot...
Petrol cars are not seen as the devil's fuel, yet, and no TVR ever had a DPF fitted so you should be OK.
I read the article somewhere online, it was saying something about testing the emissions to what the cars were when new minus a small percentage to allow for engine wear etc.
It seems that the majority of people think that removing the precats is a good idea with the downside being potentially having a droning noise. One of the cats should be easier than the other to remove as it has slipped forward a little so must be slightly loose.
It seems that the majority of people think that removing the precats is a good idea with the downside being potentially having a droning noise. One of the cats should be easier than the other to remove as it has slipped forward a little so must be slightly loose.
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