V5 information.(dB(A)).

[mileshawk56]

04' MGZT KV6 auto - on my v5 under "vehicle details" at entry U. " Sound level" U.1 stationary ( dB(A)) shows 82. At U.2 engine speed(min-1) 4875. At U.3 drive-by (dB(A)) shows 74. Anyone with the same engine/vintage Rover 75 who can check the same entry and the (dB(A) recorded. Reason for asking? wife complains on noise level. Thanks for your time. Chris.S.

[macafee2]

FWIW, no help to the OP but :-
My understanding of noise and a db reading is that you need to know the frequency of the wave of the noise.
If memory serves me right, a 0db sound generated at 300hz, 800hz and 1.6khz will seem not to be of the same volume, loudness, to us humans

macafee2

[Matt_75]

Originally Posted by mileshawk56

Anyone with the same engine/vintage Rover 75 who can check the same entry and the (dB(A) recorded.

I've checked the V5 for our KV6 75s and that section is blank, so can't help there I'm afraid. Is it tyre, wind, engine or exhaust noise that's the problem? One of our cars has a factory style silencer fitted, the other a cheap aftermarket one. The difference in noise is massive, the cheap aftermarket is so much louder and drones a bit on the motorway. I'll be changing it for a quality one in due course...

Originally Posted by macafee2

FWIW, no help to the OP but :-
My understanding of noise and a db reading is that you need to know the frequency of the wave of the noise.
If memory serves me right, a 0db sound generated at 300hz, 800hz and 1.6khz will seem not to be of the same volume, loudness, to us humans

This video explains it quite nicely: https://youtu.be/Is_wu0VRIqQ?si=iuhRzI2YRmOBO5uj

[macafee2]

Originally Posted by Matt_75

I've checked the V5 for our KV6 75s and that section is blank, so can't help there I'm afraid. Is it tyre, wind, engine or exhaust noise that's the problem? One of our cars has a factory style silencer fitted, the other a cheap aftermarket one. The difference in noise is massive, the cheap aftermarket is so much louder and drones a bit on the motorway. I'll be changing it for a quality one in due course...



This video explains it quite nicely: https://youtu.be/Is_wu0VRIqQ?si=iuhRzI2YRmOBO5uj

I do like the Tom Scott videos

macafee2

[SD1too]

Originally Posted by mileshawk56

04' MGZT KV6 auto - on my v5 under "vehicle details" at entry U. " Sound level" U.1 stationary ( dB(A)) shows 82. At U.2 engine speed(min-1) 4875. At U.3 drive-by (dB(A)) shows 74. Anyone with the same engine/vintage Rover 75 who can check the same entry and the (dB(A) recorded.

I have a Rover 75 KV6 and my Certificate of Conformity has these figures:

Stationary 84 dB(A)
Drive-by* 70 dB(A)

* The engine speed is not declared.

If your wife is inside the car as a passenger then I'd say that the noise level she perceives has more to do with the omission of Rover soundproofing on the MG ZT range for a sportier experience.

Simon

[roverbarmy]

The carpets on Cowley cars were supposedly thicker than those on later cars. My personal observations would agree with that on the two 75's that I owned, the early car was quieter despite being a V6.

[mileshawk56]

Thank you all for your help- now we have a bit of sunshine I hope to get under the vehicle and have a poke around- I thinking it maybe "induction noise" ie its noticed when accelerating a moderate amount, Im wondering if the Shannon tube has gone awol, the noise is about passenger side of centre line engine bulkhead. Its not an easy investigation as my wife in unfortunately deaf so picks up sound differently to hearing people but if I can source the sound I can hear we have achieved some thing. I realise there are various differences R75/MGZT in suspension etc which could account for some aspects of noise transmission,its a bit a rabbit hole!! Chris.S