Which induction kit / CAI / Air filter to go for???

I'm interested in improving the induction on my stock 996 C4S but there are several options available. Firstly, An induction kit,several different makes including K&N and EVOMS V-Flow, these replace the panel filter for a cone filter and the stock hosing for silicon hosing from the filter to the plenum inlet, including the MAF mounting flange. But how effective are these kits, and which is the best one to go for. Another option (cheaper) is the add the Cold Air Induction modded listed on design911 (about £60) which claims mid range performance increases, better responsiveness and a better exhaust note. What does this mod do that a full induction kit doesn't and vice versa? Is the later part of the induction kit (after the MAF mount) exactly the same as the cheaper CAI mod and so the only difference is the filter being used (panel or cone)? Whilst on the subject of filters, which is the best to go for panels or cones, does one type have an advantage over the other? Finally, which make of filter is commonly thought to be the best? K&N or BMC? At the moment I'm interested in the K&N induction kit, but only if this system has similar or better flow characteristics than the CAI listed below (£60). But if this isn't the case and if the cone filter doesn't provide much of an advantage, then I'd be interested in the cheaper CAI plus a high-flow performance panel filter (about £120 in total). Can anyone comment on this set-up? So in summary, which set up would give the best improvements in responsiveness, power gains and exhaust note; a complete induction kit or a cheaper CAI added to a high-flow panel filter? Which kits and filters are the ones to go for and which are the ones to void? I'm planning on replacing the inlet plenum, the exhaust system (currently stock) and having a remap done eventual although it'll be an ongoing project). Apologies for the length of this post and the long-windedness of it!!! Thanks in advance for your advice and help Regards Jacko Here are some links to the products I have been describing: K&N Induction Kit Link: http://www.design911.co.uk/fu/prod761/Air-Induction-Kit-for-Porsche-996-1999-2005/ EVOMS V-Flow Induction Kit Link: http://www.evoms.com/marketplace/ViewProduct.asp?Now=5%2F10%2F2010+9%3A55%3A23+AM&ProductID={CA5A72B6-30B7-498B-9754-430D699F6DF6}&OrgID={CA5E16BC-D877-4137-8237-7EB9084DD3D8}&ParentID={5E2B4978-7CC3-48CF-885D-D00B3D65FC7C}&Curr={5E2B4978-7CC3-48CF-885D-D00B3D65FC7C} CAI Link: http://www.design911.co.uk/fu/prod765/Cold-Air-Induction-Kit-Porsche-996-C2-C4-1997-2004/

I have the cai with a k and n panel Does little by way of go but does a bit for sound Buy the evoms I'd say

Just fitted my KandN induction kit last week and it sounds f@cking brilliant. At about 4000rpm the noise just starts to roar and the again at 5.500rpm it goes off again. Best £260 ive spent!! Only took about 1.5 hoirs to build and fit.

My Turbo came with the Evoms kit... I'm happy... has a nice sound and although I haven't driven another to compare, the Porsche chap at the service centre who deals with them all the time and has driven mine reckons it has a little more squirt over a stock one... Kiwi

couldn't agree more !! :thumb:

Have a read of these... http://www.911uk.com/viewtopic.php?t=51575&postdays=0&postorder=asc&highlight=air&start=0 http://www.911uk.com/viewtopic.php?t=51335&highlight=air :thumb:

Mine's not the one in the link with the cone filter mine is a k and n panel in the standard air box with a silicone hose and a plug.it is sold as a cai though. It would take about 3 minutes to fit so it's clearly not the same kit that you guys have got.

Can anyone tell me why some of these induction kits say for 'manual only', while others make no such claim. Is there a fitting that is different on some of the kits? The Porsche filter boxes appear to be the same. TB

The Manual / Tiptronic stipulation for these kits appears to based on US spec vehicles which have to have some form of "smog pump" on the Tiptronic oil reservoir. This takes the form of a breather or vacuum line to the side of the US spec Y-pipe. (RoW Y-pipes have no additional tapping point). The US system is designed to suck any lubricant vapours from the Tiptronic transmission system and pass into engine for high temperature burn-off and subsequent catalysis to low HC "harmless" gasses. Hence, for RoW, systems are transmission independent. There are also a number of "illegal" (certainly in CA.) venting solutions if US Tip owners really want to fit these kits, but the kit manufacturers cannot be seen to promote them.

I guess the point of an induction kit is two fold: 1) Noise 2) Performance NOISE The noise is increased (improved?) by the removal of the standard airbox Helmholtz resonator (this is a noise cancellation method using anti-sound resonance of the natural air pulses into the throttle body during cylinder induction) AIRBOX TOP AND RESONATOR The methods for this are Helmholtz resonator and/or spur negation via "Orange Cap" mod or Schnell/Fab Speed etc Helmholtz removal and/or capping. The "Orange Cap" mod just blocks the resonator mouth, leaving the resonator cavity in the airbox top and the "Y" tube spur. This is not very efficient as the resonator box still restricts the filter panel. The spur still causes venturi turbulance AFTER the airbox straightener! "Y" TUBE In the FabSpeed/Schnell solutions a nice slippery silicone tube replaces the standard "Y" pipe, which also improves efficiency of induction and completely removes the Helmholtz spur and resonator cavity, thus increasing post-filter side air capacity and reducing turbulence/restriction across filter panel surface area. The noise is also increased by complete removal of the standard airbox, a la EVOMS and K&N 57-7000. These systems not only remove the Helmholtz resonator, but by using a "naked" cone filter outside of an enclosed airbox the induction roar is much greater. They also replace "Y" tube with smooth plastic/metal tubing. PERFORMANCE Performance is increased by greater airflow (density and speed). The performance filters tend to be oiled cloth (which, if not wicked of surplus oil, will dirty or damage the MAF) and are designed to allow more air through than paper filters. The actual per surface area flow charcteristics are very close when clean, but paper start to block almost immediately. One thing to be aware of is how much total filter surface area is offered. I do not know how the cone filters compare with the panel filters, but suspect they may be less. However, the cone filter will intrinsically offer better laminar (less turbulent) flow. The panel filter needs the post filter air-straightener to streamline the flow. Some people discuss removing the straightener THIS MUST NOT BE REMOVED - firstly the air will be more turbulent, secondly any large particles somehow getting past filter panel (either ill fitting or panel missing etc) will not get stopped prior to throttle body and engine ingestion! STRAIGHTENER (there is a finer metal mesh begind this grid) The biggest downside to the EVOMS and K&N is the possible sealing issues with the cone assembly cradle: if it fails to seal correctly (and I have fundamental concerns they ever will) the filter will draw in low density warm engine bay air. (EVOMS to a lesser extent as it is of better design/manufacture) The CAI systems (Schnell/FabSpeed) still use the sealed external snorkel for high density cold air. Additionally, on vehicles with fixed rear spoilers (GT3, GT2 style) the external scoops leading to the snorkel push ram-air effect positive air pressure into the airbox. As the cone filter systems are not sealed units, this feature is not available to them. FabSpeed/Schnell: EVOMS/K&N:

Thanks for the info, I thought that was the case. Nice write up :thumb: TB

yes, I took apart my box today to check the filter and when it was off I am thinking what could I do to increase airflow. I am thinking the same, if I cap the small box and then the little branch pipe, the box is still in postion. Could I remove the little box and just plastic blank off the hole? any ideas? good and bad about doing this.. I ama plastic injector and could easy re-create it, just wondering if actually removing the hole that the small box sticks through this would mean no box inside the filter housing and caping of the small branch off pipe?

right after having a really close look I am thinking of doing this.. 1. remove this completely. http://img205.imageshack.us/img205/9730/iphone2008020920099.jpg[/img] Now cut here so I am left with the top part that goes through the airbox. So I just attach eveything as it was, surly this is better as it gets more airflow than any mod available such as capping this and changing the pipe? Or am i missing something, just this way keeps just about everything and the only mod is the small little box that I think is a kind of noise reduction.

NO!!! If you do not blank off that branch then you will be allowing lots of unmetered air into the throttle body, bypassing the MAF. You can remove the resonance box, but make sure you blank the hole in the airbox and plug the branch pipe.

oh i see, thanks richard. I have blanked off the hold now, and now going to blank the branch pipe, does it have to be near the top or can i blank the branch at the bottom using the current jub clip and a bottle top?