free hit
counters
Federal Exhaust and Track Noise Limits - Induction/Turbo/Manifold/Exhaust - The Lotus Forums Jump to content
Sign in to follow this  
Fred Basset

Federal Exhaust and Track Noise Limits

Recommended Posts

I'm just about to book a track day with a 100db limit. My 02 has a Federal Exhaust, just wondering if anyone has been through noise tests at UK circuits and passed with one of these exhausts.

Cheers

Fred

Share this post


Link to post
Share on other sites

Upgrade today to remove Google ads and support TLF.
I'm just about to book a track day with a 100db limit. My 02 has a Federal Exhaust, just wondering if anyone has been through noise tests at UK circuits and passed with one of these exhausts.

Cheers

Fred

What's the track - some are a lot more strict than others? 100dB sounds (excuse the pun) like Castle Combe. If not, is it a 3/4 max rpm @ 0.5m static test or drive by?

I haven't used the federal exhaust but from my experience with straight through exhaust pipes you can expect 105dB static, Lotus sports exhaust 103dB and stock exhaust 96dB. Having stock cats, sports cats or no cats doesn't really affect it - a big cat gives a boomier sound, no cat gives a raspier sound but the noise level is roughly the same.

The Lotus sports exhaust is basically two solid U-bends, one for each bank, in the exhaust housing. The stock exhaust is similar except it has a balancing pipe between the two U-bends which works by using one bank to cancel out the sound waves from the other and vice versa. My understanding of the federal exhaust is that it is two straight through pipes with this balancing pipe. If so I would expect the noise to be somewhere between the Lotus sports exhaust and stock exhaust.

So I'd say you'll be borderline in which case it depends on the track and how strict they are.


May: DON'T hit it with a hammer!

Clarkson: Why?

May: Cause it's the tool of a pikey.

Share this post


Link to post
Share on other sites

At one point Maplin were doing a cheap Db reader. Might be worth a look on their site to see if they are still doing it. Give you an idea and not cost the earth??

Cheers


Alan Croft

2000 V8 GT

87 Turbo Esprit HC

2000 Elise Sport 160

Share this post


Link to post
Share on other sites

First off, a sincere congrats on wanting to take your Esprit to a track. It's well worth it!

However, buying a budget noise meter doesn't tell you a thing. I've been through two and my second one is accurate, but only because I now know from experience that it underreads by 6-7dB! And the thing is, the circuits who don't care have equally useless noise meters - e.g. Brands Indy. During the day there's supposed to be 105dB limit but I was never tested. So I went along to an evening session (101) and they tested me at 109 (way over what it was), and still let me on the track!

But if you go to say Bedford or Donington they can give you an exact static reading which corresponds to their drive by reading - and they're measured exactly. The instructor at Bedford said they have four drive by meters along the 3.5 (now 4) mile GP circuit and every time one pops they have to file a report to the local council!

Okay, the bad news - Casle Combe are *really* strict on their noise. If you fail it is gutting. I've been there twice, first at Donington and then at at Bedford. Donington was quite funny. Turned up (with Lotus sports exhaust), failed noise miseralby, given second chance and disconnected the wastegate bleed valve to limit boost to 5psi and still failed. Spent the rest of the morning trailing round exhaust shops, etc, but to no joy. Went back and after some gentle persuasion (the marshalls didn't give a toss about noise) let me out if I stayed in fouth gear (which I did apart from the Adelaide hairpin - V8 has brillaint pickup).

Bedford though was another story, in there by 9am, out at 9.30am and no return. It is so gutting to psyche yourself up to a track day and then be told to go home!

Since then I've now got the stock silencer - bizarre, my car is gradually reverting back to stock in every way!

Whereabouts do you live? Castle Combe is ambitious if your exhaust is at all lairy. But there's plenty of other circuits who don't care - that way you can get a feel and if you're enjoying it you can think about scaling down the decibels. Personally I was a bit disappointed at first when I went back to the stock exhaust but now I couldn't car less - barryboys hate sublety :)


May: DON'T hit it with a hammer!

Clarkson: Why?

May: Cause it's the tool of a pikey.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...