Exhausting Measures
Yes that’s right everyone; if, in the officer’s opinion, your exhaust is too loud they do have the right to simply green sticker your car. If they do this, you must take your car to a VTNZ testing station where you will have your exhaust noise measured with a decibel meter, and possibly failed if the reading is above the not properly imposed limit of 85dB.
It is, however, the method of conducting the initial test that raises question marks. The current proposal is for the officer to have the owner of the car raise the engine speed to half of the red-line limit, then release the throttle, and then perform a series of short bursts on the throttle and then decide if they think it’s too loud.
This is where the problem lies. Now, we all know that this is open for error, and that this method of testing by the police is neither accurate nor reliable. There are certain considerations that need to be addressed when carrying out a test for any noise level, be it exhaust noise, stereo noise or traffic noise.
In the case of an exhaust level test, it is imperative that the test be carried out in a flat, open area with few, if any obstructions present to rebound the noise back into the measuring device, which in this case is the untrained ear of a police officer. This means there should be no traffic noise, like a motorway for instance, no concrete buildings, like a testing station, and no other distractions which could lead to false or inaccurate reading.
Now we all know that these are the guidelines for accurate noise testing, but will they be followed in a fair and unbiased manner? We think not, so along with the generous help of Tony Johnson and his colleagues from the LWTA we decided to run a fair and proper exhaust test of our own, and this time the exhausts would be measured according to the proper guidelines.
A large, flat open car park on Auckland’s North Shore was chosen for the testing to take place. It was nice and sheltered, with little wind and no real surrounding objects that could reverberate the noise back into the decibel meters. We arranged a large assortment of vehicles to test including a Harley Davidson, plenty of old T-Bucket V8s and a good range of Japanese cars with both modified and unmodified exhaust systems.
Also of much interest to us was a spankers Ford Falcon XR6 Turbo with less than two grand on the clock. This was going to prove interesting, considering that part of the new law change deems any exhaust other than standard is illegal due to the likelihood that it will be louder than that fitted by the factory, and thus exceed the 85dB limit. Would the standard exhaust on this brand new factory car read above 85dB? The method of testing was simple.
The car was driven up to a sectioned-off area by the owner, and left running with the hand brake on. The decibel meter was raised to the level of the exhaust pipe exit point, where it was supported by a trolley jack, and then turned outwards on a 45-degree angle at a distance of approximately 500mm. A reading of the car’s idle noise level was first taken and recorded.
Following this the owner of the car was asked to increase the rpm of their car to half the factory red-line limit, and told to hold that engine speed steadily until asked to stop, and a further reading taken. A third reading was taken to measure the noise of the exhaust when the throttle was suddenly lifted and the engine was left to decrease its rpm back to idle speed. Finally, a reading was taken of the noise level when the engine rpm was rapidly increased to above the 50 per cent red-line limit.
The results were to prove interesting, to say the least. The V8s were first up to the line, with all comers easily eclipsing the 85dB limit, most even from idle speed. The big block assortment was excellent, ranging from old Ford coupes, to Chevy Impalas, and a newish 5.7-litre SS Commodore sedan.
The Japanese cars followed on from here, and all but three failed to stay under the 85dB limit at cruise level rpm. It’s hardly surprising, though, that of the three which passed, one was an R33 facelift Skyline with a stock standard exhaust, the other was also an R33 Skyline with a standard quiet JASMA (Japan Auto Sport Muffler Association) approved exhaust, and the last was a Lancer Evo VI, with a great fat plug-in silencer stuck up the Blitz tailpipe which, upon its removal, saw the dB reading shoot up to 98!
Now we here at NZPC understand that it’s a sensible idea to have a law of sorts in place, but the current proposal is draconian to say the least. Australia has sliding limits of up to 96dB, and Japan’s limit is 95dB, as it is in California, USA. Why should we have to cop 10 fewer decibels because of a few complaints over the last few months?
Surely New Zealand could simply follow the likes of our closest cousin, Australia, and set our limit at around 95dB as well? We asked a few of the attendees on the day, including owners of both Japanese cars and older V8-powered numbers, and here’s what some of them had to say when asked about how realistic the new law is.
‘The decibel level should be raised to realistic level, with a correct testing method put in place.” We couldn’t agree more. Or what about this one for a fair comment? “You can’t have someone say, ‘I think it’s louder than it should be, therefore it’s illegal’.” Not a truer word was spoken, we think. In fairness to the officer doing the testing, there was the following quote; “What’s being laid down for them isn’t easy to follow,” which is also probably quite true. So why not introduce a more sensible law?
A law that has an unbiased uniform authority for measuring exhaust noise, not to mention a more realistic maximum dB rating. Back to the XR6 T. there was much raising of eyebrows when this car crawled up to the measuring spot, as there had been some rumours that the car would officially fail the test were it to be measured properly. As with the other cars the Falcon was revved to half its maximum limit, and held steady.
The exhaust was measured at an officially illegal 88.9dB! This means that the exhaust on this vehicle is deemed too loud to be on the road. What’s worse is that when the car was spiked to only 3500rpm the reading jumped to around 103dB. Of course, the driver of this vehicle probably wouldn’t be pulled over because the system looks standard, and is standard, so they would avoid the long arm of the law.
But for all you drivers out there with expensive stainless after market systems with five-inch tips, beware, because it is you who they will be targeting. Forget the fact that there are other cars out there just as illegal as yours, even ones straight off the showroom floor.
To be fair though, the V8 owners who were at the car park that day are up in arms just as we are, for they too are officially breaking the new law, and with their rather eye-catching T-Bucket coupes they may have some difficulty, too. Then there’s the issue with noisy trucks and buses, which only goes to show that unfairness rules the roost in the current ruling authority.
So what next, then? Well who really knows, in fact we wonder if even the legislative authorities know where to go from here. When there are responsible groups of people such as us conducting our own set of true tests to prove the hopelessness of the proposed ruling, what can they do?
All we, as motoring enthusiasts, can ask for is that a sensible ruling will be put in place where people will not be pulled over simply to entertain the egos of newly trained officers. We need a more realistic limit imposed, and a far more accurate and reliable testing method to boot.
Results
Below is a list of some of the cars that attended the meeting, with the decibel reading at a cruising speed – half the red-line limit of the engine.
1990 Harley Davidson FXRS – 109dB (spiked to 135dB)
1933 Ford Coupe – 96dB
1961 Chevy Impala – 106dB
1996 Subaru Impreza WRX STI – 98dB
1992 Nissan Skyline GT-R – 95dB
1999 Holden Commodore SS 5.7 – 93dB
1993 Rover 220 GTi – 98dB
1989 Mazda Familia GT-X – 99dB
1966 Chevy Malibu – 97dB
1934 Chevy DC – 94dB
1993 Honda Integra VTi-R – 92dB
1991 Nissan Skyline GT-R – 105dB
1957 Chevy Bel Air – 99dB
2002 Fraser V6 – 116dB (idle 103dB)
1998 Nissan Skyline GTS 25T – 84dB
1997 Nissan Skyline GTS 25T – 82dB
2003 Ford Falcon XR6 Turbo (Std car) – 88dB (spiked to T03dB)
1989 NZPC Project VTEC – 96dB
Source: Performance Car