R300 noise...

[don777]

Hi All,
Picked my new car up a few days ago. It had just had a top end rebuild and I wasn't able to give it the full beans for 200 miles or so. This brought me nicely to the door of Bedford West circuit yesterday for a track day with Lotus-on-Track. Unfortunately I failed the drive-by noise limit by .5dB (yes that is a decimal point not a piece of dirt on the screen). I didn't realise noise meters were that accurate, mine certainly isn't.

I just passed the static test at 100.7 (101 limit) and the drive by was 88 (limit was 87.5).

So I need to get something done before Goodwood next Saturday!

I'm taking it back to Caterham to see if they have a bigger can for me (it's totally standard at the moment). I realise that it has a lot to do with induction noise but hopefully just a couple of dB off will cure it.

1. Do you think one of the bigger Caterham cans will help? (they seem to think it would)

2. Has anyone used a 'Supertrapp' as a temporary fix for trackdays?

3. And also does anyone know what the drive by limit for Goodwood is (on a 98dB static day)?

Thanks.

[casbar]

I have an R300 engine, running a Caterham 4:2:1 system with a 7 inch race can, mine measures 97 db.

Would struggle at Bedford, but been ok at other tracks

[jimmyslr]

Bigger can would help certainly. I suggest a Raceco can rather than a Caterham one. If you do a bit of Blatchat research, you'll see many who opt for Raceco. It's titanium so very light and also about the quietest around. Not cheap at >500, but great kit; I have one. It will take a few weeks though so no good in short term.

I have found Goodwood similar to Bedford on drive-by, but I think their static is lower and you'll struggle. Static shouldn't matter much as it's not the one the council uses. I have been thrown off Bedford once, but never Goodwood. At Goodwood they wave at you and then advise that you short change past the meters. V sociable.

[Bafty_Crastard]

Rebuilt top end……not a new car???

Might be you just need to re-pack the silencer

Bafty

[rubystone]

repack the silencer first. Dave Jackson also had some success with turning the silencer round so that the pipe exited under the car . He claims it worked and didn't heat up anything underneath. It's the sort of thing I'd try if all else failed! Raceco will take some time to sort - Ammo generally likes to measure up the car first - the reason why I still haven't done anything about mine!

[don777]

casbar said:

I have an R300 engine, running a Caterham 4:2:1 system with a 7 inch race can, mine measures 97 db.

Would struggle at Bedford, but been ok at other tracks

Have you been to Goodwood? that's good news if you have.

Bafty_Crastard said:

Rebuilt top end……not a new car???

Might be you just need to re-pack the silencer

Bafty

Sorry, meant new to me. It's 3 years old roughly.

I had them re-pack the exhaust before I picked it up, so that route is 'exhausted'

I think I'll try the bigger 'race' can that Caterham do and that hopefully will do the trick. I rented a noise meter from Book-a-track so at least I can check it out before Goodwood on Sat.

Has anyone used a Supertrapp? Might consider it just to get me through on Sat.

[Bafty_Crastard]

See..........[url]www.r300.net/index.php?name=PNphpBB2&file=viewtopic&t=670[/url]

Bafty

[casbar]

Sorry haven't done Goodwood. Always stuck to Oulton, Cadwell, Anglsey plus Euro tracks.

Although I am going to try Coombe in Jul

[don777]

Bafty_Crastard said:

See..........www.r300.net/index.php?name=PNphpBB2&file=viewtopic&t=670

Bafty

There's a huge difference between 88dB (from the above link - R300 with 7" race can) and Casbar @ 97 dB (R300 with 7" race can)

I realise the weather conditions on the day make a bit of a difference but not that much. I think Casbar, yours sounds about right to me.

Oh well, I'll find out on Wed. Caterham are going to put an 'old style' race can on, whatever that is?? but they assure me it'll be quieter.

[murph7355]

Also, how's your induction set up?

[don777]

Looks like a standard foam filter over the roller barrels. It did have a huge Carbon Fibre induction manifold leading down to a scoop under the radiator (like a R500??) but it kept hitting every tiny bump on the roads so that got removed. It also woke the dead.

[murph7355]

don777 said:

Looks like a standard foam filter over the roller barrels. It did have a huge Carbon Fibre induction manifold leading down to a scoop under the radiator (like a R500??) but it kept hitting every tiny bump on the roads so that got removed. It also woke the dead.

A decent airbox should help mute the induction noise.

Was it fitted properly? Were there any breaks in it?

You can get airboxes that end in a cone type filter places higher up than the Caterham spider scoop.

Does sound like your exhaust should be the first thing to have a go with, but induction noise can affect readings wildly.

[Bafty_Crastard]

If you are no longer using the ReVerie induction kit I would sell it as it, as cost around £1K new

[url]http://public.fotki.com/clik/caterham[/url]

Bafty

Edited by Bafty_Crastard on Tuesday 20th February 23:15

[don777]

Bafty_Crastard said:

If you are no longer using the ReVerie induction kit I would sell it as it, as cost around £1K new

[url]http://public.fotki.com/clik/caterham[/url]

Bafty

It didn't look like that, so I'm not sure what kind it was. The actual intake was right underneath the radiator, and was very very low. I asked them to replace it, and I got quite alot in return, such as cat bypass, new tyres, new seats etc.

I've just got back from picking my car up. They've put a secondhand 7" race can on it. I did a static noise test on it before and after...101.5dB before and 94dB after. That'll get me through the static test at Goodwood and hopefully the drive-by will be down too (seems to be less noisy at high rpm, even though the induction hasn't changed). I've kept the other exhaust set-up for loud road blasting.

I've got to say the service at Caterham has been absolutely top-notch, I'm really impressed.

I'll let you know how I get on at Goodwood, thanks for the help.

[cuzza]

Hi Don,

I was at Bedford in the Orange Roadsport - sorry to see you get chucked off, your car didn't sound that loud compared to some of the Honda powered Elises to me but I guess with your exhaust being on the same side as the noise meter after turn one didn't help.

Glad you seem to have it sorted now - have fun at Goodwood

[don777]

Thanks, I think it was just a case of bad luck that day.