Noise reduction with extra can

[stevefoster]

Well, we did a test using a 4" side exit can

added onto my 5" existing one.

 

Static test only the results are below.

Engine 2.0l standard VX XE.

Lift indicates the dB when holding 4500 and

lifting off the throttle still measuring.

Move indicates the dB when the measurer turned

away from the sound source and then the rpm was

wound down.

All measurements were made at 0.5m & 45 deg angle.

No parked cars or walls were near.

The sound meter was a Phil's digital type costing around

£70.

 

5" only (FAST) dB

RPM lift move

4500 100.7 99.5

 

With extra 4" (FAST) dB

RPM lift move

4500 98.9 96.6

 

Improvement dB

lift move

1.8 3

 

 

5" only (SLOW) dB

RPM lift move

4500 97.7 98.7

 

With extra 4" (SLOW) dB

RPM lift move

4500 96.8 96.6

 

Improvement dB

lift move

0.9 2.1

 

The induction noise was 99dB! (twin 45's)

 

Does anyone know if the noise tests at circuits

are done in Fast or Slow mode?

 

Lifting off gives higher final reading!

What do the test marshals do?

 

Next test is to borrow a nearly new 5" can and

try that (thanks Phil). My 5" can has done 4

years of service.