airbox modding 2.8 V6

[quattrostyle]

I had a look at the airbox of my cabriolet 2.8 and thought it could do with a bigger inlet. It's now in the region of 50 mm.

What I need to know, will for example an 3'' inlet ruin the driveability? I know the 10 by 10 cm. hole in the airbox of my ex 90 quattro did. Sounded lovely but was rubbish in the lower revs.

[david]

i think that will improve the air intake,checkout my 5" airbox on my rs2

[quattrostyle]

I had a look at yours, but I guess things are different when it comes to NA engines

[Rusty]

Get a spare one and cut it up

[quattrostyle]

so no BTDT's then? Will cut it up then, need at least some sound from that engine.

[Error404]

I drilled a load of holes in the cold side of my old 2.8cq'sd airbox, it sounded sweet and no drop in low end torque

[quattrostyle]

nice

now need to get me a 3'' bass port

[andy10v]

I think there is some info of Mances about modding the airbox, lots of mods on his site.

[Rusty]

Aye, get a 20mm drill and drill the cold side, chop off the front and get a nice cold air pipe to feed it. If it's not to oyur liking then I'm sure that V6 airboxes aren't too expensive so you can do something a little more refined...

[Nj]

I did something similar in my 3.0 at haven't noticed any drop in low end torque. see towards the end of this thread http://www.audifans.net/ftopic-28701-30.html
I assume it's ok to link to another forum?

[quattrostyle]

thx guys.

I won't get mad with a 20 mm. drill that's not my cup of tea. I'll order a nice 3'' bass port and install it neat. Will also modify the trim behind the headlight to fit the bigger inlet.

Ow and need someone from the UK that can help me out shipping 2 lambda probes over for my cabriolet. The ebay seller won't ship overseas.

[istoo]

the throttle body is the restrictive part of the 2.8. bore up the smaller bore. But your right they are pretty choked. holes in the air box will just make a bit more noise tbh. There was more proven increase from RAM air but i have seen that argument go round and round. A good BMC carbon can will give you noise and some genuine improvement.

Standard TB

Modified TB

Have a read round that site its a fairly easy job to do yourself, the primary aperture is the only aperture till 4000 odd rpm which you can imagine is very restrictive, increases i saw were circa 30% more air at lower speeds and 10% at higher revs. If you have an auto apparently makes a very notable difference to throttle response.

Next to check is which age is your 2.8, the earlier cars had a 2.5 in MAF the latter had the 3". The 3" gives you a good bit more cfm's. These can have quite a bit of material removed to get he cfm rates up, ie imrpove your throttle response significantly.

The Mance workshops can be found here

http://www.justboring.com/audi/images/

Get reading... Mance aka onepissedoff90 on the amercian audifans is the guru for the 2.8 12v, builds pikes peak cars i beleive. He used to do a service for his own xTBs but not sure if that still stands, or if you can find him. You can do it yourself and it makes a lazy engine a bit more spritly!
And if you want to read, check out fast28's SC thread on audifans.net.

[quattrostyle]

wow quite some info there, didn't know the TB looked like the 5-pot one. My cabriolet is a '93 example.

I'm not looking for more power really, just a bit more noise instead. But if it's not that much work it will be worth inverstigating.

[istoo]

TB isnt a lot of work. the airbox will give you more noise. Although my 2.8 was a 93 as well but i opted to go for a full stainless system at the time which made it a bit throatier purely as my wife did say, its very quiet, which i interpretted as... make it louder!

[quattrostyle]

hehehe and that was what the wife meant?

Yeah I informed about a custom stainless exhaust for my cabbie too, but it was €850,- so I bought a near perfect OEM exhaust for €180,- and I really like it being quiet. But some noise when going WOT ain't bad