Running with no backbox, under 105 dB?

[robins]

I'm doing the Bedford trackday on Friday, the backbox has just fallen off of my car. Will it be quiet enough to stay under the 105dB static/drive by noise limit they have at Bedford? Car is standard with a cat and renault centre section. I'm running out of options within the timeframe and don't want to throw away money on a pants exhaust.

 

[Dave..]

The middle exhaust hanger won't be enough to support the centre silencer and cat, I'd be more concerned about what little you have left, falling off completely. Just buy a new exhaust.

 

[jaysjetski]

i dont think they would let you run as the car isnt safe with exhaust emissions coming into the car. just get it sorted. its wednesday tomorrow. get a overnight courier to deliver one thursday and get it fitted.

 

[drhowser]

I very much doubt you'll get through sound testing with no back box!!

 

[robins]

It's ran fine for a good 250 miles, no problems with fumes or rattling around. There is 1 less hanger but no backbox to support. The manifold and centre rubber normally support the weight of the centre box and cat anyway, the centre rubber just isnt very good at supporting the side to side movement and the rotational movement of the centre section. The amount of 172s is see driving around with their back box twisted because it is not correctly joined to the mid section - they are in the same boat as I am regarding exhaust support. I'm just worried about the noise limits tbh, there must be some racers running some pretty open systems, didn't Burp run with just a sport cat at the end of the mid section?

 

[Dave..]

Pikey as f**k.

...and how you've done 250 miles on just the centre mount I'll never know.

 

[robins]

haha, well if you have a quick look and a think - that little mount doesn't have to do much at all. Anyway the Magnex of shame sitting in the corner is looking like it may have to be fitted.......

 

[Fletcher]

When my backbox fell off I lost quite a bit of power. I'd not want to do a track day without one fitted!

 

[jaysjetski]

this is taken from http://www.trackdays.co.uk/car_track_day_guide/ which covers bedford track

Does my car have to be roadworthy?

In most cases yes definitely, If your car has a MOT then that's fine. The car has to be of a safe standard.


i think the back box being of is classed as been unsafe as i said above.


and the dB limit is 101 not 105. http://www.trackdays.co.uk/tracks/bedford.htm

 

[robins]

this is taken from http://www.trackdays.co.uk/car_track_day_guide/ which covers bedford track

Does my car have to be roadworthy?

In most cases yes definitely, If your car has a MOT then that's fine. The car has to be of a safe standard.


i think the back box being of is classed as been unsafe as i said above.


and the dB limit is 101 not 105. http://www.trackdays.co.uk/tracks/bedford.htm

First useful answer, thank you!

Think you're right about them possibly seeing it it as unsafe if they do spot it. It's not really worth the risk of being kicked off I guess. I saw that noise rating too but on this day they say its 105 dB for some reason????? http://www.clubmsv.com/car-home/event-details.aspx?productid=388


I have got a backup plan, its just not a very pretty one.......

 

[TimR26]

No way will you pass the noise test without a backbox. When mine fell off it was stupidly loud just driving 50 miles down to Ktec to get a stealth fitted. Don't know how you've done 250 miles you must be deaf by now!

 

[robins]

pardon? ha

stick to 68mph and it hits a quiet spot. Has done wonders for my fuel economy 42mpg! But the rest of the time it is pretty redonkulous.

Took the father for a ride in the clio and he reconed it was a fair bit quieter than his race car which just passes the 105 dB static test. Its a 1.8L VHPD K-series running with just a blue-flame bike titanium back box.

105 dB is pretty loud.

 

[jaysjetski]

have u tried an mot station? they may have a db tester so that would answer your question. to be fair just shove a cheap universal box on for now then its sorted for friday.
then you can get something better fitted. or just get it done now,let the engine breather better which will be better on the track anyway!

 

[Fred@BTM]

bedford is 101db i believe