Air box for K Series DTHTB 's

[Jason Plato]

I'm looking for an air box that will fit on the K series DTHTB's . Idealy mounting between the trumpets and throttle bodies rather than "hanging" from the ends of the bell mouths ,

similar to the set up on Steve Broughtons Jade .

 

I've seen a carbon box on the Brooke-Kensington ( www.brooke-kensington.co.uk )web site but this was more than £500 gulp!!.

 

Anyone any ideas ???????...........Pleeeeeeese ??

 

PS: Its a sad state of the country when you have to silence a Caterham at both ends !!!

 

Dave

 

Edited by - Dave J on 7 Jan 2001 20:41:53

[CHRIS CLARK]

'phone a friend!!!

[Peter Carmichael]

I just spent a day driving a Honda S2000.

 

Had a look under the bonnet at the 240bhp VTEC and it had a simple plenum arrangement which didn't seem to be dimensionally much different to the k-series item. It might be fun to retrofit the k-series plenum onto my big engine and see how much power I lose and how much the noise comes down by.

 

Admittedly the Honda's throttle response did not have the crisp edge that I am used to.

 

Power delivery was peakier than my k-series too, with everything waking up at the VTEC cross over near 7000rpm and gutless before.

 

The steering that everyone complains about is worth describing. The car needed to be chucked into the corners - passenger disliked this, so I had to moderate the corner entry speed *a lot*. The car could not be adjusted to a wider line on the throttle - you needed to apply a steering correction. This made it feel very clumsy. It is close, but not quite there.

[murph7355]

Are you sure there's room for one without putting a hole in the bonnet? Or are you not worried about the latter?

 

If you have to cut a hole, wouldn't the fact that the box is outside the bonnet negate any noise reduction gains?

 

I know some of the guys with Elise conversions have made air boxes so perhaps theirs would fit with a suitable hole or some slight mods? Check out Dave Andrew's site or the se7ens list for more info.

 

Maybe you could try some sound insulating foam around strategic areas under the bonnet. I'm sure I've heard of others doing similar with some success...

 

C7 AJM

[Rob Walker]

It makes a lovely noise Dave. Just lag the inside face of the bonnet with thick felt carpet underlay directly infront of the bellmouths/filter. It works well, I have never had a problem and did six days at Castle Combe last season. If you still want to go down the airbox route contact Bernard Scouse his e-mail address is on DVA`s website. Ask him nicely and he will make ya one.

 

 

[Jason Plato]

Peter ...... so you dont know where I can get one ??

 

Andy & Rob .... The box would have to fit under the bonnet , I'm realy doing it to ensure the coldest possible air is going to the engine , I know it sounds the dogs bollocks but performance "may" be improved still further with a box ( 200bhp ?? ) .

 

Every little helps !

 

later

Dave

:-)

[murph7355]

I think you'll be lucky to get one to fit - what size trumpets are you using?

 

40mm jobs give a bit more room than 90mm (obviously), but I'm still not sure there's much (enough) to play with.

 

I've made some child-like sketches of where one might go but gave up on the thought of taking it further as it looked like going nowhere. I'm also sure the Elise one won't fit. But giving Bernard a call may get you accurate dimensions you can start to work with.

 

What power are you at already? I doubt it'll give anything noticable in terms of extra power.

 

The felt underlay thing sounds good though. I might try this if I get hassle at track days when I finally get on track again (velcro it in so I can be loud on the road and quiet on track maybe...why does this sound a about f?).

 

C7 AJM

[Mike Bees]

Through a combination of DIY work and other people's favours I have an interchangeable airbox/sausage filter system (They both fit onto the same backplate). So for noise-sensitive venues (Combe and Goodwood) I run the airbox, and elsewhere I run with the sausage filter. The airbox makes a *big* difference to the amount of intake noise. I haven't got a cold air feed to it at present, just a cone filter on the end of the airbox. It all fits under the bonnet, just, but it took a lot of fiddling about.

 

The airbox is the same as the one in the pics on Dave Andrews' website, http://members.aol.com/_ht_a/kenginemod/kairbox.jpg

 

Back-to-back tests with/without this airbox on a ~200bhp Elise showed that the airbox cost 10-15bhp at the top end. It also slows down the throttle response making the engine much less of a joy to 'blip'.

 

Mike

[murph7355]

Crikey.

 

Looks like I won't bother with the quiet circuits for track days then.

 

C7 AJM

[Mike Bees]

I think the downsides are a feature of this particular airbox design, rather than of airboxes per se. It had to fit into a very small space!

 

Mike

[Jason Plato]

Oh dear Mike , your info has changed my mind , with my 185 - 190 bhp I could be loosing a similar amount of power to that elise . :-( .

Do you notice a difference in throttle response etc in your engine ??

What db are you recording mike with / without the box ? .

 

Cheers dave

 

 

 

[Mike Bees]

Only when blipping from idle, it's much slower to blip with the airbox in place. I'm hoping to do a back-to-back power run on the rolling road sometime before the season starts to see exactly what the airbox is doing for me.

 

It doesn't affect static noise tests ('cos they're taken so close to the exhaust) and I don't have any drive-by figures.

 

Mike