K&N Intake Kit

Hi All So having read a few articles on the topic and decided to splash out and put a K&N Cold Intake Kit on my 99 C2 3.4 Cab. I ordered through these guys and 3 days later a huge box arrived. http://www.potn.co.uk/p1529035.htm Having played around with cars a bit in my youth I decided to fit it myself. The hardest part was "parts identification" from the huge bag of bits that came in the K&N kit. After 15 mins swearing sat at the kitchen table I'd worked it out and started the build. Most of the work can be done away from the car as you have to construct the kit. This takes about an hour to get it right and tightened up nicely. My electric screwdriver and a small adjustable spanner was all that was really required for this part. Next part was to remove the original airbox from the car. that's pretty straightforward and then the new box is installed. Car has to be drilled in one spot by the bonnet catch to provide extra strength to the fixing. Only issue I had with fitment onto the vehicle was the butterfly clips that were provided in the K&N box didn't seem big enough to go around the throttle linkage so I re-used the one of the standard Porsche airbox and that was fine. 2 hours after staring I was done and the engine was running without any warning lights which was great. Took it out on the road yesterday and the change was really noticable. Firstly the pull up from 3,500 to 7,000 rpm seems much quicker (noticably). The literature quotes 23 bhp average on their dynos and whilst I'm always very sceptical of these claims you really can feel extra pull where as if it was 5hp you would never notice the difference. The biggest change though is the noise. When it comes on cam at 4,000 OMG it sounds amazing. There is a roar all the way to the red line. The stereo gets drowned and all you can hear is the glorious sound of the Flat 6. If you were anywhere near Epping Forest yesterday you would have heard me! If this sounds like the sort of thing you would like to achieve on your 996 and for £270 and 2 hours of your time I can highly recommend this. If you want to know any more let me know. pickersm

I fitted one of these kits to my Carrera and took it off before selling it to get the turbo. It definitely improved the throttle response and the sound was a nice improvement. Very worthwhile mod. For the record (and advertisement purposes ) I stiil have the kit. If anyone is interested in a mutually beneficial arrangement just mail me.

AndrewM Pm sent TB

I don't want to pi55 on people's fires but I'd love to see this in a real world dyno. I had the K&N on my C4 and although the WOT sound is amazing any percieved power increase is really "sounds faster so must be faster" logic. There are frequent threads about K&N over on the US forums with no proof other than manufacturers claims. The K&N doesn't actually seal its self within the engine bay unlike the OEM or EVOMS. It's not so much Cold Air Induction as Warm-Engine Air induction. The spoiler is also there not to force air into the engine compartment for the K&N but to aid stabilization at speed. You need a wing with additional air rams for that like the GT3 has. And then that has a massive scoop to the cone filter sealed from the engine heat. I have the EVOMS and revised plenum together with more free flowing exhaust parts and my dyno result was only 9.8bhp above stock. How K&N do 23bhp with their meccano approach I don't know... I'm not knocking the throttle response though, you do get a marked improvement on that which may help with the perception on improved power... £270 is still not much for the increase in smiles you get at 4krpm... :thumb:

Thanks for the info Pickersm. It's interesting as I've been looking into this area myself recently. I'm after improving the noise, so I've been reading about various CAI and associated mods as well as potential mods to exhausts (I've ruled out the PSE because I don't believe they're worth their new inflated price, and, well, I'll never want to switch the thing off anyway!). When it comes to intakes, the performance gains do seem to be argued over again and again, but this really isn't my primary goal anyway (it'd just be a nice bonus). So if we're just talking about noise improvement, what real benefit is offered by the £300ish K&N kit over the $10 airbox mod on Renntech? http://www.renntech.org/forums/index.php?showtopic=14765 To be fair, it's not clear from that thread whether the mod can performed on the stock airbox...

I did say sceptical Stuart and I agree it's a big claim and maybe improved throttle response isn't indicative of more hp but just allowing the engine to breathe better i.e. stopped choking the amount of air getting in. Noise is excellent though and worth it for that alone. Waiting for drier and warmer weather to drop the roof and go tunnel blasting! Not sure Storm. Didn't strike me as making a huge difference to be honest - i.e. a very minor mod.

here here, for the K&N mod boys...!!!!! sound is just great past 4000...

+1 I fitted my K&N after a few days of ownership and didn't really notice any power hike, but a crisper throttle and that sound was enough, especially with the PSE. Awesome!!!

I'm intrested Andrew how old was the k & n before you took it off also how much do you want for it? Regards Lee

Take standard airbox, delete the internal anti-phase Helmholtz resonator cavity, bung up aperture, ideally fit smooth silicone tubing in lieu of standard Y-pipe. Optionally fit free-flow panel filter for better breathing (remembering to wrap in newspaper overnight to wick excess oil from cloth to avoid MAF contamination). See here: http://911uk.com/viewtopic.php?t=46801&postdays=0&postorder=asc&highlight=airbox&start=20 Personally, I don't see a surface area advantage to the cone filters. There is some debate on laminar flow characteristics, but the plastic and wire "screens" in the standard airbox "straighten" the flow from a panel filter anyway. The other advantages to a standard airbox solution are a sealed airbox-snorkel arrangement that, with a GT2 or GT3 fixed wing and ram-air scoops and at speed, forces partially pressurized FRESH COLD EXTERNAL air through the system. Some other open systems don't or can't seal (or even attempt to) the snorkel or other pure cold air channel. Instead bleeding warm (or hot) engine bay air.

Many thanks GT4 - That's clearer a lot up I think. I had a number of questions, but most have been answered by that thread and your post above. However, some still remain, if you wouldn't mind indulging me... To get it clear in my mind - 1) Installing a replacement hose makes the air flow easier because it's a smoother design and because a muffler that exists in the OEM hose isn't present. This also accounts for the increase in noise. 2) The OEM (Y-shaped) hose connects to the airbox at two points - the second point being a bypass pipe (I'm sure I'm wrong here). 3) The replacement hose only connects at one point - the supplied alloy plug should be used to block of the remaining hole in order to prevent debree etc. entering. 4) Extra benefit can be gained by removing the Helmholz resonator cavity, as this allows takes up valuable post filter air space. 5) If you do this you'll need to manufacture a 'bung' of some sorts as the alloy cap will be too small to fit in the resulting hole. Either the orange cap, or the bits of plumbing you listed. Is that pretty much correct? You've said the filter is optional. So I can really stick with the stock filter? I'm just double checking as mine were only replace about 200 miles ago. What advantage is offered by the K&N kit? Is it just because the cone shaped airfilter allows even greater airflow? Thanks, Mike

The OEM pipe is "ruckled" as it is a concertina design. There is no "muffler" as such, there is a spur (one leg of the "Y") that goes to an (anti) resonance cavity to cancel intake resonance. Plugging access to the helmholtz resonator is the primary noise objective. Use of a smooth pipe aids airflow, and hence I guess at least throttle response, if not outright performance. Not a "bypass" - just a cavity/chamber. It goes nowhere. Interestingly, on 997 airboxes, this resonator chamber is "valved" to close by vacuum actuators to improve performance and noise outside drive-by noise speeds. Correct. Apart from aesthetics and to remove a nice pocket to collect water and road debris, you actually don't need to plug the helmholtz cavity. That is with replacement hose. You can cheat and using standard "Y-pipe" just plug the cavity. But I would be scared the plug might work loose and get sucked up the Y-pipe and into the throttle body. Correct. Both the total post-filter air (available for instantaneous intake, prior to low pressure induction acting across panel to draw in higher rate of air flow upon acceleration) is enhanced, and additionally the full surface arear of the panel is unihibited and flow smoothed. (with cavity in place almost 1/3rd panel surface is covered/restricted and air flow forced inefficiently around the cavity box) Correct. There is some debate on the efficacy and (MAF oiling) risks in using an oiled filter panel vs nice new paper one (after all, the GT2,3 and Turbo all use a paper filter). However, used properly a sports filter WILL de-restrict air flow. Which is a good thing! As for Cone vs Panel, as per my previous reply, surface area to surface area comparisons show no real advantage (assuming comparable material - ie paper vs paper or cloth vs cloth etc) - especially once the additional 30% is fully liberated by cavity removal. The only advantage is the possible laminar flow characteristics. As mentioned, the standard airbox includes TWO stages of air straightening prior to the cylindrical tube (intake pipe) anyway. The downsides to cones can be warm air intake (erm,the opposite to the intended CAI) if badly designed enclousures are used and any lack of continuity with snorkel will drive ram air effect (fixed wing scoops etc) to zero.

PS - thanks for reminding me. My car has been in storage since 11/11/09 and I need to hoover/clean the K&N panel filter before I re-commission in March.

No problem GT4, I'm always happy to help! Seriously though - thanks for the enlightenment! I'm off to buy a hose! Expect a question in a week or so asking for more detail on your plumbing solution :thumb:

No worries, I sell the plumbing kit for: Two plastic washers Low rise nut (1 3/4 inch) Internal sealing cap - solvent fix type (1 3/4 inch) Screw-to-solvent adapter coupling erm ... plus ... Dozen grollings (flushed) Length of copper flange pipe Two jamborees and seven nipples (greased) Five olive-spantles, jigged and onioned (12 mil) Metre of fleeling wire (coaxial) Twenty UJs An embarrassed parping couplet (male and female) Two rolls of spowling tape (double-sided) Six sheets of gruddock paper (non-parkinised) Four felching pens (or frotting pencils) One bevelled spill-trunion. -------------------------------------------- £158.74 + Delivery + VAT