Carbon air box (R500) unable to fit under bonnet

[griggsy2]

Morning,

Wonder if anyone else has had this and solved the issue.

For trackday noise reduction I have bought the carbon airbox with cone filter under the bonnet. However, once fitted, the cut out in the bonnet sits on the neck of the box meaning I am unable to close it.

Not sure but I believe I have either longer trumpets with the raceline DHTBs or a spacer pushing them out. Rather than change that I think the only other option is to extend the hole in the bonnet by an inch or so to allow it to close.

Anybody else had this and solved it?

Cheers,
Lee

[CR500Dom]

A picture is worth a thousand words 😉

And have you got the carbon bathtub back plate too or are you trying to mount it on a flat backplate ?

[griggsy2]

I annoyingly didn't take any pictures at the weekend but the below shows the current filter sitting quite high to others I have seen. Would say I have the carbon bathtub (if that's what it's called), about 2 inch depth that the box connects to. Certainly not flat.

[Dave J]

need more pictures, of the engine from above without Bonnet and the airbox you have purchased.

there are several variants of throttle bodies / inlet manifolds / airbox / backplate mountings all originally designed for either k series or duratec.

[griggsy2]

Fair play, will sort some pictures out tonight.

This is the airbox:
http://caterhamparts.co.uk/product.php?id_product=...

DHTBs are raceline versions.

[GreigM]

That car originally had a different carbon airbox on it:
http://www.caterhamparts.co.uk/product.php?id_prod...


which fit through the hole like this:

Edited by GreigM on Monday 26th September 12:00

[Dave J]

as the R500 was running roller barrels, they are shorter than the direct to heads you have. This results in the face of the bodies are closer to the bonnet line by more than 2". I don't see that your going to be able to instal the airbox you have bought unless you cut the bonnet, but then the actual filter will probably then clash.
see the airbox on a R500 below - it was always a tight fit on a real R500.

http://4.bp.blogspot.com/-B7A3vkYfNj8/U5JVbwEqbUI/...

[griggsy2]

Thanks Greig, that saved me some photos.

Alas that airbox will not knock the noise down far enough for me, hence the contained effort I bought. Aimed to add some further noise reduction on the outside and see then how I get on.

Dave, re the filter on the end, it's certainly tight but think I can solve that with a bit of modification, the carbon elbow however is the main issue.

Sounds like a bonnet cut... Anybody done that (well) before

[GreigM]

griggsy2 said:

Alas that airbox will not knock the noise down far enough for me, hence the contained effort I bought. Aimed to add some further noise reduction on the outside and see then how I get on.

It got on to Oulton, Spa, Croft, Donnington with that configuration - where are you going that is looking for quieter?

[griggsy2]

Was at an MSV Brands day with a 92db driveby, seemed to be reaching 97db with the open filter.

Garage chum in an R500 I met that day (struggling with noise limits too) had the enclosed version which knocked off 2-3db, and the one you show below which only knocked off 1db.

Given the above it would leave with me another 3-5db to find on the enclosed unit which I hoped to manage through external sound deadening, amongst other things.

Had to keep to 6000rpm limit to stay at 92db (with repacked exhaust so not that), got second black flag when pushing to 7000rpm

What drive by levels were the track days you used to attend?

[GreigM]

It is very variable depending on the circuit and exactly where the meters are. The car is substantially louder without the airbox. Oulton is also a 92db drive-by and it had no problems with it. I genuinely doubt you'd get it much quieter at the intake side with the other airbox.

FYI the car had the airbox fitted when it was sold to 7s&Cs

Edited by GreigM on Monday 26th September 16:04

[griggsy2]

I saw a previous picture of the car with the box on and specifically asked if they had it, "No". I said in that case maybe the previous owner held on to it, "Likely".

Will keep my eyes open for one in classifieds, can't justify the cost of a new one (£440) on Caterham parts just to test.

Edited by griggsy2 on Monday 26th September 16:43

[Dave J]

that's cos they sell for £300 second hand ....

[MikeE]

Don't you just need to replace the carbon bathtub backplate with a flat one to pull the airbox fixing well inside the bonnet. I had the Raceline DTHTBs on my 2.3l with the cone filter and it all fitted under the bonnet fine.

Don't know where you are butI have a spare unused backplate in the garage you could try.

[griggsy2]

Thanks Mike!

I could, and I expect you are correct, but I believe the mapping was done to take advantage of the extra space provided by the bathtub which freed up quite a bit of extra performance from the engine. I appreciate I will bugger that up a bit anyway by adding the box but aim was just to use that for track days and switch back and forward with the foam filter.

If I can avoid a more permanent adjustment I would like to. Annoying thing is the driveby level is not so easy to test short of going on track and seeing how it goes, unless anybody else has found a decent method.

[griggsy2]

After a while I decided to buy a new bonnet to use on track days and cut an extension in order to use the carbon box whilst keeping the bath tub.

A dremel, few files, some masking tape and some bravery later, jobs a good'un!

Just need to get the bonnet sprayed to colour match and striped.

Edited by griggsy2 on Monday 20th February 09:20

[Oysterman]

Any use?

[griggsy2]

Looks nice but all done now with new bonnet whilst maintaining the bathtub

Edited by griggsy2 on Thursday 13th April 08:59