FTO exhaust level noise test

After scoring a 122dB and a 117dB on two separate NCT (national car test) exhaust noise tests, I decided to test the exhaust myself as I felt these two readings were too high. A score of over 99dB means your car is too loud for the road and it will not receive the legally required (in Ireland) certificate of road worthiness.

What you see/hear in the clip.

1. Firstly you can see the background noise level in the car park I used is 58.7 dB (dBA). The whining noise you can hear is a water pressure tank for an apartment block.

2. I start the car. You can now see that the car at idle produces approx 72dB

3. I rev the car to 3800 - 4000rpm 4 times. The sound meter records a maximum reading of 101.4dB. The NCT say they only revved my car to between 3500-3800rpm to produce 122dB and 117dB. Seems highly unlikely given how far below this level my own results are with a higher rev.

4. I then revved the car to 5500 to 6000rpm (not required for NCT test) to produce a louder reading to see if I could produce near 117dB or 122dB range. The maximum reading was only 107.6dB

While my own test verified that my car is indeed over the 99dB limit, it was only over by less than 3dB. I have already shown that the NCT test has an error rate of 5db+ as my car was tested twice by them on two different days and produced 122dB on the first test and 117dB on the second test.

Microphone was set up 50cm from exhaust outlet and at approx 45 degree angle as per NCT test instructions.

Category:

Autos & Vehicles

Tags:

• NCT
• test
• exhaust
• noise
• decibel
• FTO
• loud

[shanenorberg]

Why didnt you test in it a more quiet area ?