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The mkiv Supra Owners Club

Screamer pipe regs


paul21uk

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not illegal as far \s im aware, there are no regs that say the exhaust gasses must be exhusted at the rear of the car
As far as I'm aware, exhaust gasses have to pass through a cat for the system to be completely legal.

 

Theoretically speaking, you could make a completely legal one by plumbing it back into your exhaust system, but it's quieter than purely externally venting ones. You could probably get away with an external one as long as you were quiet around police, but I'm fairly certain that unless you pair it with the exhaust system, you'd get pulled for it at some point.

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The filth have it in for cars like supras round my way always get tugged for " roadside checks" so wanna keep it 100 % legal in the noise aspect

As far as I'm aware, exhaust gasses have to pass through a cat for the system to be completely legal.

 

Theoretically speaking, you could make a completely legal one by plumbing it back into your exhaust system, but it's quieter than purely externally venting ones. You could probably get away with an external one as long as you were quiet around police, but I'm fairly certain that unless you pair it with the exhaust system, you'd get pulled for it at some point.

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where are you? I never have any problems with police with my exhaust and I'm in EA, doubt they could get much out of the screamer on a roadside check, no where near enough load. Quiet exhaust and screamer, sorted.

In Boston mate sweet well I shall do it and sees what happens

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Having ridden bikes with race pipes for years the MOT testers discretion on noise is what counts. For a bike if the pipe has 'not for road use' stamped in it then obviously it would not be in his interest to pass it, if it has no markings then there is no visual reason to fail it. He will check for emissions and leaks and can fail on these but not on noise, unless the MOT tester personally feels it is too loud.

 

They have no decibel meters etc so its purely down to the tester discretion.

 

The other side is what Mr Plod thinks, he will note it has no road markings, no baffles and sounds very loud and will make you retest at a MOT station. Of course in this time your pipe will miraculously grow baffles or maybe change size, shape and colour :)

 

With a screamer pipe, unless it was leaking or giving off excessive noise which under MOT conditions it may not then there should be no reason to fail in accordance with the regulations. However, under MOT the tester will rev the car hard as part of the MOT emissions test and you wouldnt want the thing to be howling its head off giving rise to a fail.

 

I believe the official line is:

With the engine running assess subjectively the effectiveness of the silencer in reducing exhaust noise to a level considered to be average for the vehicle.

It will then fail if the exhaust system is in a condition, or of such a type, that the noise emitted from the vehicle is clearly unreasonably above the level expected from a similar vehicle with a silencer in average condition.

 

Its all very vague and subjective!

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Really? "Fast idle" is hardly revving it hard. :)

 

A screamer pipe wouldn't fail an MOT because the wastegate won't be open.

 

Mr Plod is a different matter...

 

 

The MOT tester will rev the car as it is part of the emissions:

 

The MOT testers manual states that for vehicles first used before 1st August 1979 the compression ignition engine emissions test is put at either 2500 engine rpm OR half of maximum engine speed whichever is the lower.

 

For vehicles first used after 1st August 1979 if the engine checks are satisfactory and having removed any oil temperature probe, raise the engine speed to around 2500rpm, or half the maximum engine speed if this is lower, and hold for 30 seconds to fully purge the inlet and exhaust system. Raise engine speed slowly to maximum to check the operation of the governor. Once the engine speed has stabilised or if it becomes clear that the governor is not working, release the pedal, return to idle and stop the engine.

Prompt the meter to carry out a zero check.

Insert the probe fully and securely, in line with the gas flow. Restart the engine.

Following the meter prompts, depress the accelerator pedal quickly and continuously but not violently, to reach full fuel position in less than 1 second

 

With this I was suggesting that there may......just may be a situation where noise then becomes an issue. As most people with screamers have no problems then its unlikely but still possible the MOT tester could get over excited.

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The MOT tester will rev the car as it is part of the emissions:

 

The MOT testers manual states that for vehicles first used before 1st August 1979 the compression ignition engine emissions test is put at either 2500 engine rpm OR half of maximum engine speed whichever is the lower.

 

For vehicles first used after 1st August 1979 if the engine checks are satisfactory and having removed any oil temperature probe, raise the engine speed to around 2500rpm, or half the maximum engine speed if this is lower, and hold for 30 seconds to fully purge the inlet and exhaust system. Raise engine speed slowly to maximum to check the operation of the governor. Once the engine speed has stabilised or if it becomes clear that the governor is not working, release the pedal, return to idle and stop the engine.

Prompt the meter to carry out a zero check.

Insert the probe fully and securely, in line with the gas flow. Restart the engine.

Following the meter prompts, depress the accelerator pedal quickly and continuously but not violently, to reach full fuel position in less than 1 second

 

With this I was suggesting that there may......just may be a situation where noise then becomes an issue. As most people with screamers have no problems then its unlikely but still possible the MOT tester could get over excited.

 

Wastegate wont be open under any MOT situation dude, you would need a lot more load on the engine to open it.

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