R300 noise

[richcurry]

Hi All,

First (long) post after rejoining the Caterham fold so be kind 🙂

I picked up a 2002 K series R300 on roller barrels (technically a Supersport R as it was converted) last week and I'm enjoying getting acquainted with it. My intention is to do a few track days over the summer with a couple currently on the radar - Croft (105 static and 97 drive by) and Donington (98 driveby only, no static). The car isn't the quietest and I'm concerned that I'll be pushing the limits on both days - the car has no cat but a decent sized silencer 660mm x 140mm diameter which is repackable (nothing in the history to suggest what it is but shown in the pic).

Bearing in mind that I'm about 2 hours from the nearest circuit so popping out for a quick noise test isnt really viable, are there any steps I can take to quieten things down? Things that have crossed my mind....

Check the exhaust packing is still there and re-pack if required

Get hold of a SuperTrapp type bolt on silencer, there's also Decibel Slayer but the tailpipe on my car has almost no straight section so I don't think that'll fit

Install an airbox to calm down the iduction noise, ideally something I can install for trackdays and remove for road use, any suggestions? I see Piper Cross do a PX600 replacement box or there's the (spendy) Reverie option. I'll probably pop a wanted ad up for an airbox in case anyone has one sat on a shelf in their garage. 

Put a bigger silencer on - RaceCo seem to be to popular choice but like a shiny carbon air box, this is a fairly big ticket upgrade.

I realise not knowing how loud it is makes this difficult but looking for any ideas especially from members with similarly spec'd cars for avoiding trouble with the noise police. 

Cheers

Richard

[rgrigsby]

It's very hard to say what result you will get, however based on experience I'd be very surprised if you have an issue at somewhere like Donnington Park. Your exhaust looks like it's a reasonable size, as long as it's been repacked recently, I think you'll be fine.

Induction noise can be an issue on some K's, however if you don't have a bonnet cutout it's SuperSport R spec again I don't think that will be an issue.

It's all very subjective until you can get to a noise meter, where abouts are you?

FWIW the Raceco exhausts are a great upgrade, they will make a difference to the noise level. I'm running one of their big 950mm silencers on by 250bhp Duratec, at Cadwell Park last week my car was 97dB at 5000rpm on the static test.

[richcurry]

Hi,

Thanks for the insight, good food for though - there’s nothing in the history about what exhaust it is or whether it has even been repacked so I’ll start by opening it up for a look and go from there.

I'm near Ilkley in West Yorkshire so Croft is my “local” circuit, that said, Harewood is down the road, they might be worth a call and see if I can get it checked at an event?

The RaceCos certainly look like a nicely engineered piece of kit and obviously do the job from the numbers you’re getting on an R500!

Thanks again 👍🏻

[Colin_T]

exhaust noise probably be ok as looks to be a fair size silencer.

intake noise be more likely out the two to trip the sound meters over the edge, if it even does…

I’d look at trying to get some kind of sealed cold fed airbox as it’s certainly worth looking at anyway, not just for noise but for performance benefits too. I done some back to back testing on my R500 k with and without the cold air ducting up to the airbox and saw significant gains (between 9 and 14bhp) and considerably more consistent figures between runs as the air temps were more consistent. 
 

You may even discover the R300 to be ok noise wise compared to the R500, as the revs aren’t as high, the cams aren’t as “over-lappy” so won’t have as much induction bark. 

for some kind of reference:

I have the R500 airbox, and Raceco silencer and have not been black flagged yet. Even on a brands evening session where the db limits are lower. 

personally I do a few laps at 7k…. If no flag I go to 8k… still no flag I’ll go full beans 9k.

They give you one chance to fix the issue, so you can “fix” it by just shifting 1000rpm sooner and going back to where you wasn’t flagged off. Obviously you’d prefer to be able to use everything the cars got but worst case at least this way you won’t go home early and can still enjoy your day.

additionally I’ve always found to be well under on static testing. 

[Tom_Arundel]

Are they NS2R tyres?   If so they will be `interesting ` on track......Get some heat in them before `giving it some` ....

[richcurry]

Messed up the quote 🤦🏻‍♂️

 

Edited June 3 by richcurry

[richcurry]

On 01/06/2024 at 09:37, Colin_T said:

exhaust noise probably be ok as looks to be a fair size silencer.

intake noise be more likely out the two to trip the sound meters over the edge, if it even does…

I’d look at trying to get some kind of sealed cold fed airbox as it’s certainly worth looking at anyway, not just for noise but for performance benefits too. I done some back to back testing on my R500 k with and without the cold air ducting up to the airbox and saw significant gains (between 9 and 14bhp) and considerably more consistent figures between runs as the air temps were more consistent. 
 

You may even discover the R300 to be ok noise wise compared to the R500, as the revs aren’t as high, the cams aren’t as “over-lappy” so won’t have as much induction bark. 

for some kind of reference:

I have the R500 airbox, and Raceco silencer and have not been black flagged yet. Even on a brands evening session where the db limits are lower. 

personally I do a few laps at 7k…. If no flag I go to 8k… still no flag I’ll go full beans 9k.

They give you one chance to fix the issue, so you can “fix” it by just shifting 1000rpm sooner and going back to where you wasn’t flagged off. Obviously you’d prefer to be able to use everything the cars got but worst case at least this way you won’t go home early and can still enjoy your day.

additionally I’ve always found to be well under on static testing. 

Thanks Colin,

I’m looking for an airbox for it, using it over the weekend, it’s not mega noisy when giving it some so I think it’ll be ok unless the meters are very inconveniently placed. 
I previously had a de-cat Roadsport racer and never had an issue with that, so I think I just need to try it.

i did check the packing and it’s all there, some of it is going a bit black but it’s not breaking down .

[richcurry]

On 01/06/2024 at 13:57, Tom_Arundel said:

Are they NS2R tyres?   If so they will be `interesting ` on track......Get some heat in them before `giving it some` ....

Hi Tom

They are NS2Rs - not my choice and I’m not that impressed on the road to be honest
Might see if I can get a set of R888s for it before the first day 👍🏻

[JosephlFudge]

If it helps, my R300k on roller barrels noise tested at Goodwood a few weeks ago at 96db static. 
I can also vouch for the R888r’s having run ns2r’s I can notice a big improvement. 
 

Joe

[JosephlFudge]

I’m also running no cat, looks to be exactly the same spec as yours. 
 

 

[richcurry]

6 hours ago, JosephlFudge said:

If it helps, my R300k on roller barrels noise tested at Goodwood a few weeks ago at 96db static. 
I can also vouch for the R888r’s having run ns2r’s I can notice a big improvement. 
 

Joe

Thanks Joe, are you running an airbox or just the Pipercross filter?

[John Vine]

My old 1.8K Supersport-R never tripped noise meters at tracks like Brands, Donington, and Castle Combe.

I think the fact that the air filter was entirely under the bonnet helped, plus it had a fat 7" R500 silencer.

JV

[JosephlFudge]

No airbox, just the pipercross filter. 

[Lucy]

Hi Richard, 

I have just received a call from the previous owner of this car Steven M, he has advised that when the car was in his possession he never experienced any issues with noise limits, even at castle combe. Hope this helps slightly. 

kind regards

Lucy, Admin Team

[richcurry]

20 hours ago, Lucy said:

Hi Richard, 

I have just received a call from the previous owner of this car Steven M, he has advised that when the car was in his possession he never experienced any issues with noise limits, even at castle combe. Hope this helps slightly. 

kind regards

Lucy, Admin Team

Thanks Lucy, 

Thats great news, thanks for letting me know 👍🏻

Richard