Modified cars and the MOT
Discussion
Noobish question -
I have never modified a car before but have wondered what happens when it comes to the MOT?
Imagine upgrading a GTi with a massive turbo and uprated injectors for example. Wouldn't the car be producing more emmisions that a stock version? So Mr MOT tests it and finds the emmisions are way too high for "a GTi", so it would fail the MOT, right? Similarly, if you transplant a V6 engine into an MR2, wouldnt the MOT assessor expect the emmisions of a smaller 2.0 4-pot?
It's probably a simple answer, but how do you get around these issues?
I have never modified a car before but have wondered what happens when it comes to the MOT?
Imagine upgrading a GTi with a massive turbo and uprated injectors for example. Wouldn't the car be producing more emmisions that a stock version? So Mr MOT tests it and finds the emmisions are way too high for "a GTi", so it would fail the MOT, right? Similarly, if you transplant a V6 engine into an MR2, wouldnt the MOT assessor expect the emmisions of a smaller 2.0 4-pot?
It's probably a simple answer, but how do you get around these issues?
Ok, so it takes into acount Hydrocarbons as part of the measurement. Hydrocarbons could be unburnt fuel, right?
So what about a highly modified Evo running anti-lag? Wouldn't this be throwing more hydrocarbons out of the exhaust pipe than a standard Evo?
Also, would you expect 4.5 litre Cerbera engine to produce the same amount of hydrocarbons as a 800cc hatchback? I just find that surprising.
So what about a highly modified Evo running anti-lag? Wouldn't this be throwing more hydrocarbons out of the exhaust pipe than a standard Evo?
Also, would you expect 4.5 litre Cerbera engine to produce the same amount of hydrocarbons as a 800cc hatchback? I just find that surprising.
the emisions test is also based on what the car is registered as, so for ur mr2 if it was still registered as a 2.0 but you managed to get a v6 in it then yes the emmisions would be high, if however you registered it properly (as would be illegal not to) the emmisions would be ok, presuming the engine in is good order.
FreeLitres said:
Noobish question -
Imagine upgrading a GTi with a massive turbo and uprated injectors for example. Wouldn't the car be producing more emmisions that a stock version? So Mr MOT tests it and finds the emmisions are way too high for "a GTi", so it would fail the MOT, right?
Yes it would fail if they are way too high but cars are tested in the first instance by year not model.Imagine upgrading a GTi with a massive turbo and uprated injectors for example. Wouldn't the car be producing more emmisions that a stock version? So Mr MOT tests it and finds the emmisions are way too high for "a GTi", so it would fail the MOT, right?
FreeLitres said:
Similarly, if you transplant a V6 engine into an MR2, wouldnt the MOT assessor expect the emmisions of a smaller 2.0 4-pot?
No.We're supposed to test to what the engine is, well that's the idea with age so for instance if you have a brand new car and fit a 1980 engine, providing you can prove it's a 1980 engine we would test to those standards. Although I've never come across it before the same would apply to fitting a larger engine but of a similar age to the original
Edited by jagracer on Sunday 26th July 18:53
I see what you are saying about percentage of emission, rather than absolute volume.
The thing that confuses me is that I can practically smell the petrol coming out of a TVR when they drive past. Do TVRs really release the same percentage of petrol vapour out of their exhaust pipes as a basic Corsa?
The thing that confuses me is that I can practically smell the petrol coming out of a TVR when they drive past. Do TVRs really release the same percentage of petrol vapour out of their exhaust pipes as a basic Corsa?
FreeLitres said:
I see what you are saying about percentage of emission, rather than absolute volume.
The thing that confuses me is that I can practically smell the petrol coming out of a TVR when they drive past. Do TVRs really release the same percentage of petrol vapour out of their exhaust pipes as a basic Corsa?
Probs a de-cat lol. Sometimes we have 15 year old cars come in which are 'cleaner' burners than 3 year old cars. The emissions test goes on what came 1st; the engine or the car. The thing that confuses me is that I can practically smell the petrol coming out of a TVR when they drive past. Do TVRs really release the same percentage of petrol vapour out of their exhaust pipes as a basic Corsa?
no, and jagracer wil confirm this, but...
my understanding is that the emissions allowed are different for different cars
the mot test just confirms emissions are within correct limit for that model / age of car
a pre-cat TVR will smell different from a car with catalytic converter...
and i'm sure if you modify your car, and it fails the emissions test, there are things you can do to rectify the situation
so what mods are you actually planning?
my understanding is that the emissions allowed are different for different cars
the mot test just confirms emissions are within correct limit for that model / age of car
a pre-cat TVR will smell different from a car with catalytic converter...
and i'm sure if you modify your car, and it fails the emissions test, there are things you can do to rectify the situation
so what mods are you actually planning?
Edited by deeen on Sunday 26th July 19:10
Ok, so I think I have this now...
So if I transplant a pre-cat TVR engine into a brand new Fiesta, it would have to be tested as a pre-cat TVR, rather than a Fiesta... Not that I am planning on doing this of course!
As for my mods - nothing planned for my current car (3.0 X-Type). Any more power will likely strip the delicate chocolate transfer box. For my next car though, supercharging a S2000 could be of interest.
So if I transplant a pre-cat TVR engine into a brand new Fiesta, it would have to be tested as a pre-cat TVR, rather than a Fiesta... Not that I am planning on doing this of course!
As for my mods - nothing planned for my current car (3.0 X-Type). Any more power will likely strip the delicate chocolate transfer box. For my next car though, supercharging a S2000 could be of interest.
deeen said:
no, and jagracer wil confirm this, but...
my understanding is that the emissions allowed are different for different cars
Yes and no. There is a basic emmission test (BET) for specific years that every car should pass e.g. a 2003 Range Rover will have the same emission test as a 2003 Clio. However if the car fails the BET then it can be tested against the manufacturer specific data for that particular model. A car that fails the BET but passes the specific one is probably gonna fail the next year though.my understanding is that the emissions allowed are different for different cars
FreeLitres said:
Ok, so I think I have this now...
So if I transplant a pre-cat TVR engine into a brand new Fiesta, it would have to be tested as a pre-cat TVR, rather than a Fiesta... Not that I am planning on doing this of course!
As for my mods - nothing planned for my current car (3.0 X-Type). Any more power will likely strip the delicate chocolate transfer box. For my next car though, supercharging a S2000 could be of interest.
Well in theory you would test for the age of the TVR engine regardless of whether it has cats fitted or not but the onus is on the presenter to give written proof of the age of the engine.So if I transplant a pre-cat TVR engine into a brand new Fiesta, it would have to be tested as a pre-cat TVR, rather than a Fiesta... Not that I am planning on doing this of course!
As for my mods - nothing planned for my current car (3.0 X-Type). Any more power will likely strip the delicate chocolate transfer box. For my next car though, supercharging a S2000 could be of interest.
A car is initially given a basic emission test, if it fails that, as in the case of some TVRs we can then do a full cat test for which we have tables of emissions which are often more lenient. There is another thread similar to this at http://www.pistonheads.com/gassing/topic.asp?h=0&a... if you can be arsed wading through it.
Edited; fish981 beat me to it.
Edited by jagracer on Sunday 26th July 19:27
jagracer said:
FreeLitres said:
Ok, so I think I have this now...
So if I transplant a pre-cat TVR engine into a brand new Fiesta, it would have to be tested as a pre-cat TVR, rather than a Fiesta... Not that I am planning on doing this of course!
As for my mods - nothing planned for my current car (3.0 X-Type). Any more power will likely strip the delicate chocolate transfer box. For my next car though, supercharging a S2000 could be of interest.
Well in theory you would test for the age of the TVR engine regardless of whether it has cats fitted or not but the onus is on the presenter to give written proof of the age of the engine.So if I transplant a pre-cat TVR engine into a brand new Fiesta, it would have to be tested as a pre-cat TVR, rather than a Fiesta... Not that I am planning on doing this of course!
As for my mods - nothing planned for my current car (3.0 X-Type). Any more power will likely strip the delicate chocolate transfer box. For my next car though, supercharging a S2000 could be of interest.
A car is initially given a basic emission test, if it fails that, as in the case of some TVRs we can then do a full cat test for which we have tables of emissions which are often more lenient. There is another thread similar to this at http://www.pistonheads.com/gassing/topic.asp?h=0&a... if you can be arsed wading through it.
Edited; fish981 beat me to it.
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