Hi guys,

Ive got an MK indy with a zx12 bike engine and I really struggle keeping under the noise limits at brands. They now give you one chance and if you're pulled in again, you're sent home. Bit of a pain in the bum, especially with a revving bike engine.

What have other people done to their cars to reduce sound and is there a particular exhaust configuration or product that anyone recommends? I noticed a lot of the Caterhams have a box on the side and another behind the car, with the pipe routing under the rear axle.

I don't mind building a new exhaust but be handy to see what other people have done rather than using trial and error.

Thanks
Stu

put an extra silencer on it for track days or get the noise reducing muffler insert or decibel slayer to bolt onto the exhaust.

One of the problems with right hand tracks is the exhaust exits on the left and they measure on the outside.

Take it out the back or baffle, I am trying with a 28" long silencer down the entire side.

Make sure the induction is also quiet, this can be far worse than the exhaust then added together puts you over the limit so box in those throttle bodies!

Is there a particular silencer that people use or are people just using whatever?

My induction is pretty loud as my air filter is out the bonnet. It was under the bonnet but wanted fresh air. One solution would be to build an air box, like the bike would have had.

It wasn't too bad a couple of years ago at Brands but now they are super strict and i tried putting things inside the exhaust but didn't help for long.

Standard Suzuki can works a treat! Although I have a few options to try at blyton!

what pipe have you used to route the pipe under the car? my existing system is stainless but if i weld it wig my mig welder, it'll be just normal steel which would look a bit crap.

Not sure what you mean? The pipe doesn't go under the car on mine it's pretty much straight out the back

My MK has a Blade engine with a Blade silencer and still exceeds track noise limits. Therefore, I assume that Honda Fireblades cannot take part in bike track days. Secondly I have just got in from Brands where today they had historic racing which was superb. However, the Derek Bell Trophy included historic F1 cars etc and the noise they made was ear splitting and far exceeded the noise of any track day car I've heard, therefore, why do track days have such low noise levels?

My exhaust exits on the nearside, as with most kitcars so surely if it's to route to the rear, it would have to then go under the rear axle to come out the rear?

The noise limits at brands are a real pain. My JCW MINI exceeds the limits so my kitcar doesn't have much chance. Every time I go there on a track day I see so many people struggling with the noise limits and moaning that the same limits at other tracks don't get them pulled in. I think they struggle with the nearby houses (close to the GP track) complaining of noise levels which is why the GP track rarely has test/track days.

Race days don't have the same noise limits but do have a curfew so sometimes they have to end the day short if it overruns.

A couple of weeks ago I saw a number of caterham's with the two box setup, one on the side and one on the rear so as I see, that's got to be worth a try.

Mines a rear engine, so very quiet a short run for the exhaust (see pic)so it's pretty loud with my shirt can on, but the standard Suzuki one is pretty quiet, picked it up for £25 happy days!

Ah that makes more sense. That's going to be pretty loud! Looking good though!

Haha normally I have the short can on ( http://i399.photobucket.com/albums/pp73/phil_bucket_photo/R1ot%20rebuild/E5C3F176-3356-4523-89BB-C670BE9DBECE.jpg ) yeah it's pretty loud. Have a play about with different cans it's amazing why difference it makes. The annoying thing is, the quieter it is the bigger effect on the performance.

If you're having issues at Brands (Indy?), don't even think of going to Combe or Goodwood.

I fitted many mufflers, airbox combinations until the BEC was acceptable at most 'noisy' circuits.... but it was all still a bit risky (especially on the drive-by). I then bought an old MX5.

Drive-by was the main issue. The STV's will kill the induction noise (and to some extent the exhaust noise) on a 3/4 static test, but wide open past the drive-by meters and it's a black flag.

When I got kicked off of brands a few months back it was the drive by limit i breached.

The issue with brands, and as far I can see this is the only MSV circuit affected, is that they have maintained the 101db stactic limit but lowered the drive by limit from 98db to 94db.

This meant for me that I static blow 99db but dont drop enough on the drive by to stay under 94db. Which is silly really. They said i would be at the limit with my 99db static limit but just ignored them as I have never had trouble.

Regarding noisey historic F1 at the weekend. Circuits are allowed certain number of noisey days and weekends a year. Its up to them to choose when and how they use them.

I went to historic bike racing there about 5 years ago. They were so loud that most people had ear defenders or fingers in their ears. It was ridiculous.