R500 SV - noise levels with foam airbox

[Walton]

Hi

A mate is in the process of buying an R500 SV. It only has the foam air filter (instead of the quiet carbon one), but CC reckon it'd pass drive-by regs as the bonnet hasn't got a cut-out like the narrow-body R500.

Has anyone got experience of running the foam filter on an R500 SV at places like Bedford?

[thequietone]

Absolutely no experience of the SV but I cant see a bonnet making that much difference. Would probably be as noisy as an S3 with the airbox on. Purely guesswork though.

[CatMatt7]

K-series or Duratec?

My k-series R500 is currently coming in at 100db and is one of the more noisy R500's I have come across. This could be cured with a Raceco exhaust, but currently funds don't permit.

As for Bedford, you may have a little work to do as they are quite strict, so I am told.

Worth speaking to Ammo at Raceco if you are worried about it being too loud

[RoyH]

My R500K was measured at 105 db at Bedford (and no, i didnt get onto the track!).

You could start with a bigger/longer silencer. Racecos are the best in the business on a Caterham, but for cost reason I went for a silencer by Goodfabs. I have yet to have it noise tested though.

If that doesnt suffice, and you didnt want to have to shell out for a carbon airbox and a cut-out on your bonnet, try a Bernard Scouse airbox. Or get one of Oily's modified Scouse airboxes; you dont need to hack about with the bonnet if you go down this route.

[Walton]

Cheers, it's a Duratec.

Exhaust shouldn't be an issue as it's Caterham's quieter track-day version (which has been fine for me at Bedford aside from when it lost it's packing).

Given the bonnet clearance, wouldn't a carbon box fit without mods?

Rich

[edb49]

I've got a Raceco exhaust, but it didn't make any difference in noise. Basically going from the Caterham track day exhaust with catalyst to Raceco exhaust and no catalyst kept my noise the same (98db @ 4.5k rpm), but lets the car breath a bit better to give 5% more power. (Measured by timing acceleration runs.)

If you have the foam filter in the SV, doesn't that get rid half the point? E.G. You're sucking in under-bonnet air which is going to be quite warm on the track. Having it covered by the bonnet will make a big difference to the noise produced by it.

[Dave J]

a good new exhaust is only better then the one you are replacing it with. If your present exhaust is functioning with a healthy ammount of fill then it will do the job.

one option for underbonnet is to line the inside face of the bonnet near the filter with a sound absorbant material. I tried this using underlay once and it realy did reduce the noise.

I'm now on a duratec and the induction is a lot quieter.

dj

[Yellow 7]

I fitted a homemade air box and cold air splitter.
That did the trick.














The splitter works well - I had to richen up the fuel map a couple of clicks higher up the rev range under load!

Edited by Yellow 7 on Friday 24th September 15:32

[edb49]

That looks like a good solution, shame Caterham don't build it like that in the first place!

[Yellow 7]

Yeah the Redtop is very noisy without!

[MadHatter7]

roy why do you say Raceco are the best ?

[geeeforce]

hi

i would'nt worry about the noise from the air intake.... you wont here it over the noise from the dry clutch and sequential gearbox....

Its a great car,fastest thing ever..... but sound like a bag of bolts.