Noise level

[nuf_said]

I know it sounds great, but I was wondering how loud my exhaust is. I have access to a dB meter (and bloke who knows how to use it) but, is there a standard method of measurement? Perhaps there is a standard distance from the car and a standard revs etc. How do they measure it at the race tracks where there is a noise limit?

Nuf_said

[Grease Monkey]

SVA is something like 50cm at 45° to the tailpipe at the same level, held at 3/4 max power RPM, ie around 3000 - 3500rpm.

SVA limit is 101, most tracks require under 100..

[route66]

Originally Posted by Grease Monkey

......SVA limit is 101, most tracks require under 100..

Not at the recent RAF Marham track day

[nuf_said]

Originally Posted by Grease Monkey

SVA is something like 50cm at 45° to the tailpipe at the same level, held at 3/4 max power RPM, ie around 3000 - 3500rpm.

SVA limit is 101, most tracks require under 100..

Thanks Grease for the fast reply - exactly what i needed.

:thumb:
Nuf_said

[Grease Monkey]

Cribbed from the SVA Manual....


Procedure and Standards

1. Check the exhaust system is complete, is fitted with a silencer and is secure to the vehicle. NOTE: The following assessment must be completed even in cases where the exhaust system is holed/leaking due to deterioration.

2. Position the vehicle on an unobstructed test site (concrete or asphalt) which covers a rectangular area the sides of which are at least 3 metres from the vehicle sides, front and rear. Ensure the engine is at normal operating temperature. Using a sound level meter of ‘Type 1’ (as defined in BSEN 5969 or IEC651) to the manufacturers instructions, carry out a static noise check. NOTE: This check may be carried out following the emission test. Place the microphone

• at the height of the exhaust outlet, or a height of 200mm, whichever is the higher
• at an angle of 45° to the exhaust outlet in the direction which gives the greatest possible distance between it and the vehicle contour
• at a distance of 500mm from the exhaust outlet.

NOTE: If the exhaust has several outlets which are not more than 300mm apart and which are connected to the same silencer, the microphone must face the outlet closest to the vehicle contour or the highest above the ground. In all other cases, separate measurements must be taken, the highest recorded being the test value.

Run the engine at a constant speed of 3/4 of its maximum power speed eg. the speed at which maximum power is produced is 6,000 rpm, therefore the test is conducted at 4,500 rpm. Check the level of sound emitted. NOTE: Where the engine maximum power speed is not available, the test may be carried out at 2/3 engine maximum design speed.

Reason for Failure

1. An exhaust system

• incomplete
• not fitted with a silencer
• mounting or component insecure
• mounting of inadequate strength to support the weight of the system.

2. The measured sound level is more than 101 db(A).

[nuf_said]

Thanks again Grease - excellent stuff.

Can we add extra marks for how many blokes with daft grins on their faces we attract during the test?

Nuf_said

[rsk289]

Worth noting - with this in mind, I quoted max power as 2,800 on my SVA application. Examiner didn't bat an eyelid, just asked me to run it up to 2,100 for the test.
It passed.

[nuf_said]

Tested the exhaust today (Sunday) at 3500 and 3800 revs just as Grease's post suggested - and it was exactly 100dB(A) - so that's alright then! 100 beautiful decibels.

[wilf]

Rather quiet then?

[nuf_said]

Heck, is that quiet? Does Leicester enjoy even more dBs from yours? :thumb:
Nuf_said.