FORGE Intake (CAI) - Full Write Up: Buying/Fitting/Results

Iggu

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After reading every thread on the subject and a few PMs to people who'd already bought one I decided on a Forge CAI about 3 weeks ago. It came yesterday, fitted it this morning, have driven it round this afternoon. It is, in my opinion, an absolutely essential item to have on your S3. Here's the full write up for those interested:

1. Buying
2. Fitting
3. Results / Conclusion

1. Buying
The price from Forge themselves was £241. Damian at DPM offered me a good discount on this (I won't quote it here but contact him if you decide on this route) but I found a brand new unopened one on eBay for £120 without looking too hard. With £15 p&p it was delivered a couple of days later in perfect, unopened condition. The seller I bought from was Barry 3-2-1 but there were a couple on eBay at similar prices.

2. Fitting
Tools needed: Torx 20 screwdriver (£4 B&Q), 24mm deep 12 point socket (£5 B&Q), jack stands, wrench. The instructions from Forge are cack - they are for a LHD Golf MkV which doesn't have all the same parts as the S3. Here's how I did it:

i) Unclip the spring clamp from the original intake and the 2 Torx screws
on the front edge:

DSCF2563.jpg

DSCF2564.jpg


ii) Then unclip the MAF sensor with a flathead screwdriver and undo the clips on the turbo inlet pipe:

DSCF2566.jpg

DSCF2567.jpg


iii) This step is not in the instructions because the S3 has a DV valve located in a different place from the Golf which they are based on. Unclamp the DV hose and keep the spring clamp safe:

DSCF2568.jpg


iv) Then remove the engine cover. YOU MUST RUN THE ENGINE UNTIL ITS HOT before you attempt this ******. I found the front left corner came away the easiest, then the front right and then the back edge was a doddle. Getting the first one loose is not easy but its like opening a jam jar: it comes loose all in one go just as you think your head will explode.

v) This is the worst bit. Turning yourself into Harry Houdini for a few minutes, you have to get your pliers/wrench down to the other end of the plastic turbo inlet pipe which will now be swinging free after you unclamped it earlier in step ii). Here a picture (bit shaky as I was swearing loudly at this point). Took me about 20 mins to finally get it off - its just tricky to get your fingers down there !

DSCF2572.jpg


vi) This bit is also not in the instructions. Fit the pipe plus 2 silicone connector pipes to the turbo inlet as follows:

DSCF2575.jpg


vii) Then fit the heatshield - you'll need to undo the existing plastic engine mounts using the 24mm socket, put the heatshield down and then put the engine mounts back to pin it in place. Dead easy.

viii) Then jack the car up and take off passenger side front wheel. Then use a Torx 20 to undo all the screws from the wheel liner and four more underneath. This is the fun bit. Connect the cone filter to the crooked silicone tube (with jubilee clips) and with one hand feed the cone up through the wheel arch and into the engine bay leaving the silicone pipe resting just next to the DRL bulb changing unit. You need one hand underneath the car and one hand in the engine bay - help if you're an octopus with long arms or if you can get someone to help you at this point.

DSCF2582.jpg


ix) Then you can fix the main pipe to the turbo inlet pipe (step vi) and the engine mountings using the Allen bolt provided.

x) Finally connect the silicone pipe coming from underneath the car to the main pipe which is heading down towards the DRL unit. I had to use a bit of lube at this point to get the silicone pipe onto the main pipe - don't forget you are still mounting the car at this point with one arm underneath and one arm over the top. Not easy but lube made it much easier. Obviously don't get any lube on the INSIDE of anything !! Tighten all jubilee clips. Done. Have big beer.

3. Results / Conclusions

NOISE: Its not as noisy as I thought - certainly not as burbly or "wah wah wah" as the old K&N cone filter on my Corrado. But there is a great whooshing sound as the air comes in and lots of hisses and hushes on the overrun. Its subtle though. PERFORMANCE - well: I could not have been more shocked. It almost feels like its been mapped again. Rabbit222 has posted a thread showing a "with/without" dyno readout which shows the Forge CAI gives serious extra power: I can back that up fully. You will feel the difference in the first drive and I'm guessing as the ECU gets used to all that extra air there might be more to come. My old K&N was a purely cosmetic mod offering great sound - make no mistake this is a performance mod.
Overall - for £120 this must be the best value mod you could get. Even if you don't find one on eBay it is worth the £240 EASILY. Do not delay. And if you're worried about fitting - I have the mechanical skills of a goat and managed the whole thing in 2 hours.
 
good write up... cant wait to get mine now.
 
Well done mate! I'm glad that you have fitted the kit and have seen the results for yourself....definitely is a must have mod for any guy wanting that little bit extra out of their S3.

Enjoy bro!
 
As a few of us have been saying for a while, a full intake on the S3 REALLY opens it up!:)

Glad your pleased with it mate!!

Exhaust next then?:eyebrows:
 
Nice write up. i didn't realise it was so low down. Is it not at risk of getting really wet?
 
Went to have supper and while thinking about this thread I realised something....you never mentioned anything regarding the heatshield. Was your kit supplied with one? Mine(heatshield) started rattling recently so I removed it...need to get it fitted soon though as the heat that builds up below the heatshield is hectic!
 
Nice write up. i didn't realise it was so low down. Is it not at risk of getting really wet?

Yeah that's why they say not to drive in extreme wet weather... someone on here posted a link to some sock looking thing to cover filters with that helps keep water out, anyone got a link?
 
Hey bud, awesome write-up. Do you have a funny idle sometimes. Or the revs hanging as you let off the throttle?
 
Cheers for the comments. I've ordered one of these waterproof socks to stop the wate from getting to it:
http://www.racinglab.com/injen-hydroshield-x1035.html
but to be honest it is well protected by the undercar floor liner. Unless you literally submerge the car in a pool I can't see a major risk (but for a few extra quid I'll befitting the sock for piece of mind anyway.)

I fitted the heatshield Ok and there is a rattle when I lift off the throttle - the kit came with a funny looking rubber edging strip which I couldn't work out. I think I know what its for now :redface:. I'll be fitting that today to stop the metal on metal rattle from the heatshield.

Only drove it for a few miles yesterday so haven't noticed funny idles or the revs hanging yet. Not sure if I undertand the hanging revs thing properly - but it sounds like a GOOD thing ! Or am I misunderstanding ?

The engine cover will not fit back on - but as jonnyc said somewhere else: who cares wht the engine bay looks like unless you drive with the bonnet open ? :). If the TT-S cover fits with a Forge I'll get one but otherwise I'm not too bothered.

Itching to get in the car now and go for a spin - that's the sig of a good mod !

Next up: Milltek turboback exhaust (but need to save some pennies for that one !)
 
Sorry to give you all the bad news: the TTS engine cover does not fit.
The pins are different in shape and dimension and they are positioned in different places than the S3 cover. Plus, they are 3 instead of 4 (on the part facing the front of the car there is just one pin in the middle instead of two).
The easiest way is to buy an aftermarket cover..

For the funny idle (revving akwardly between 750 and 850 rpm) and the hanging revs, I had the same problem. It sorted out to be a small oil vapour bleed valve that sits under the engine cover that needed to be changed (all under warranty).

Cheers!
 
Nice write up mate.. Certainly not for me though with the mileage I do.. One big puddle and game over!!!
Would be very interested to see a before and after dyno to see if it does actually give anymore power (seen it sooo many times before).. Get yourself back to Prosport Mr.... lol
 
Howdy bread-o - mine did that stock, and still does that.

My A3 also did that.

It's part of Audi's software to help make the car drive "smoother", they hang the revs for a little bit during gear changes apparantly.
 
It's part of Audi's software to help make the car drive "smoother", they hang the revs for a little bit during gear changes apparantly.
It really depends how long it "holds" the revs...

A certain "slowness" in dropping the revs is due to the software, it does so in order to burn all the residues of fuel so to produce less pollution. This behaviour is not nice driving on the track where you need the engine brake as soon as you release the accelerator. If you can have your map custom fitted and you disable the "slowness" il will drop instantly and emit a series of bangs (unburnt fuel going in the exhaust and exploding beacuse of the high temperature of it).

If it "holds" the revs for too long (if it does so it is impossible no to notice it) it is a problem and you should have it investigated by your dealer.
 
It's part of Audi's software to help make the car drive "smoother", they hang the revs for a little bit during gear changes apparantly.

It becomes more evident when fitting the intake. I initially thought that my MAF was playing up but soon realised that it was due to the intake....its been a while actually since it last happened.
 
It really depends how long it "holds" the revs...

A certain "slowness" in dropping the revs is due to the software, it does so in order to burn all the residues of fuel so to produce less pollution. This behaviour is not nice driving on the track where you need the engine brake as soon as you release the accelerator. If you can have your map custom fitted and you disable the "slowness" il will drop instantly and emit a series of bangs (unburnt fuel going in the exhaust and exploding beacuse of the high temperature of it).

If it "holds" the revs for too long (if it does so it is impossible no to notice it) it is a problem and you should have it investigated by your dealer.

Very interesting - I drive quite a bit on track and have noticed this (you have to use the brake pedal to compensate for the lack of engine breaking) but never knew why it was. Not sure I'd want to disable this if exhaust popping is the result - bit naff IMO.
 
It becomes more evident when fitting the intake. I initially thought that my MAF was playing up but soon realised that it was due to the intake....its been a while actually since it last happened.

Do you think the ECU "learns" to cope with all the extra air and adapts over time ? It probably thinks the car has moved to the North Pole the amount of cold air the Forge throws in its mouth !
 
Do you think the ECU "learns" to cope with all the extra air and adapts over time ? It probably thinks the car has moved to the North Pole the amount of cold air the Forge throws in its mouth !
THe first thing that comes to my mind is that, given the extra amount of air the CAI sucks in, when you release the accelerator pedal, there will be more unburnt fuel to burn, therefore the ECU keeps the throttle a bit open for a tad more time... Hence the increase time before the rpm drop...
 
Very interesting - I drive quite a bit on track and have noticed this (you have to use the brake pedal to compensate for the lack of engine breaking) but never knew why it was. Not sure I'd want to disable this if exhaust popping is the result - bit naff IMO.

I see your point, but the popping will occur only when you pass from full throttle to zero instantly at hi rpm's, not whe you are cruisin' around and gently lift your foot to smoothly shif up a gear.:whistle2:
 
Do you think the ECU "learns" to cope with all the extra air and adapts over time ? It probably thinks the car has moved to the North Pole the amount of cold air the Forge throws in its mouth !


Yes the engine ECU will adapt itself to the way you drive and the way the engine operates at certain speeds and loads.

When you delete the fault code memory then all the adapts get cleared so the ECU has 'learn' it all again.
 
I drove through a 'puddle' that was about 18-20 inches deep on Monday afternoon (and about 30 metres wide). Glad the airbox on the A3 is so high up. With one of these I'd have got wet feet!

Good write up though.
 
Do you think this is better than the carbon speed CAI, with a pipercross air filter? whould be interesting to see the difference in the 2, I went Carbonspeed to keep the intake high due to wet roads around Reading!
 
Excellent write up mate,glad you're as impressed as i am with mine!

Just a couple of things though,watch out for the jubilee clips working loose,i thought i did mine up tight,maybe it was the heat of the engine that softened the hoses yesterday - i had to give them a few good turns to tighten everything. Also,the bolt which connects the alu pipe on the right to the top of the engine keeps working loose! I've got a longer one,spring washers,and still it works its way free. A smear of threadlock should hopefully stop that,i'll report back to you guys....a long drive down to Suffolk from Yorks,then back home followed by a trip down to Devon should give some feedback! And some nice twisty steep roads to unleash the hammer map:happy:
 
I drove through a 'puddle' that was about 18-20 inches deep on Monday afternoon (and about 30 metres wide). Glad the airbox on the A3 is so high up. With one of these I'd have got wet feet!

That's why you buy one of these - as used by rally drivers in the Kielder Forest. Sort of a water-repellent jonnybag for your Forge. Dry as a bone in here !

DSCF2585.jpg
 
They make the shield in various sizes, which one did you get? Was it the one in the link you posted or another size?
 
be interesting to see if the bag has any effect on performance, surely it can't breathe as easily with it on. :think:
 

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