I hate the stock airbox, so - 2.4i intake
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    1. #1
      Junior Member lunalolvo's Avatar
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      I hate the stock airbox, so - 2.4i intake

      I've had to venture below the airbox a few times now in my S40 2.4i. Now I may be clumsy, but every single time this blasted thing has been the hardest part of the repair by miles.

      Most recently I was heading under there to take a look at a sticky starter (which seems to have solved itself for now). I did what avenger09123 suggested - cut off the leftmost "arm" holding the box, which was a hugely helpful maneuver, I was able (just) to remove the box without shifting the engine.

      Though I got the box out, I severed a coolant hose doing so (my fault), and was generally fed up with its bulk and how tricky you had to be with it and everything around it to coax it out.

      Enough was enough for me, so in the interests of serviceability and not noise, MPG, power, or any other dubious claims that come with an intake:



      This is a Spectre 9833 inline air box with two silicone elbows (trimmed a little), a Spectre 87051 MAF mount which seems to have our stock MAF tube's inner diameter (simpler than the similar Spectre 9405 kit), and a bookshelf bracket holding the ECU (subject to improvement, hopefully). Other things include a 3" coupler and a 10mm breather filter, which clamps around the breather line with the OEM 90 degree elbow removed from it. Also: sink strainer mesh before the MAF tube to emulate the pre-MAF mesh in the OEM box. It's a good hint from a member on here, from the Cheap Mods thread I believe. I had a lumpy idle and hesitant acceleration before doing that, silky smooth now.

      Notable things:
      Oiled gauze air filters are notoriously less than ideal. I'm using foam as a pre-filter (oiled lightly with foam-specific stuff) to hopefully shore up the filtration a bit on both the airbox filter and the breather filter. You can see it on the breather filter, I did something very similar with the one inside the airbox.

      It's quiet until 4k RPM! This is why I chose the relatively small diameter airbox - didn't want any din from an oversized one. Ironically in my case it's quieter than the stock setup at low RPM, as the "elbow" going to the snorkel was rattly in my S40. Per Spectre, the CFM rating (of the box, not just the filter itself) should be well over what's needed for the 2.4i, and I'm certain I haven't lost any appreciable amount of power.


      Figured I'd share an inexpensive way to throw together a very simple intake for the 2.4i. No codes so far, but I'll update with developments if there are any.
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      Last edited by lunalolvo; 01-11-2020 at 10:16 AM.

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    3. #2
      Member jondevieonS40's Avatar
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      makes oil changes so much easier!
      2008 S40 T5 AWD ("Shadow") |ELEVATE 3" Intake, 2.5" Charge Pipe, Intercooler, Torque Mount, ECU Mount, TCV, Turbosmart CBV, Turbosmart Actuator, stage 3 APC Tune, 3 Stickers (5HP)ea||ClockWorkCalibrations Custom 3" Exhaust||EuroSportTuning 3" downpipe.||CF Cone Filter||De-Badged||custom Mesh Grill||Intercooler Cut out||Porsche 911 Throttle body upgrade||18" Enkie PDC Wheels wrapped in 225/45/18 Sentury UHP||M3 Spoiler|| 8k Morimoto HID Kit|| White LED Fog,City,trunk light|"embody God, then go crazy"

    4. #3
      Junior Member lunalolvo's Avatar
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      Quote Originally Posted by jondevieonS40 View Post
      makes oil changes so much easier!
      I never had an S40 with the early airbox resonator, so I can't say I've ever had trouble with oil changes. I did have a lower engine cover with the hole in the wrong spot though, had to hack away my own oil drain hole - that was fun

      I can finally get to the transmission fluid dipstick without taking off the ECU cover to make enough space for my hands - that's an upgrade for sure

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    6. #4
      Member EngTech's Avatar
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      Sure Seems - these - 2.4 with Natural Breathing - would Benefit - Most from Lower Intake Porting & Cams . .
      Matching that Upper Better to Lower "Ported Unit" seems would be 15HP .. then Cams 10HP so Combined 28HP . .
      Sure would be Rev Happy . .

      Pop lower unit on E-bay for $50. and Ship it to Me ~ I'll Port it for $325.00 it's really easy - "DIY" Bolt On

      ps: Have to take a Look at Exhaust Manifold ~ Make it into Header ..
      ** V50 AWD - Handling & Performance Tweaks = New Stance / VW CC - Handling Tweaks - Testing & Porting - Intake Mods
      A Garden Gate will Last You a Life Time . http://s261.photobucket.com/user/Eng...0Trim%20%20etc

    7. #5
      That is awesome dude. I never considered in an IN-LINE air filter, that's awesome.

      That filter is fine, the 2.4i only pulls 165 CFM at 6500RPM if you account for stroke, RPM, and volumetric efficiency, so you'll be fine on a filter that size.
      Last edited by avenger09123; 01-11-2020 at 02:01 AM.
      2006 Volvo S40 AWD T5 M66 - Dusty Rusty
      2012 Subaru Outback 2.5i CVT - Slowmobile - CAI only, Powerstop Rotors+Pads.
      1996 HD Electra Glide - Big Bertha - 10:1 Wisecos; EV13 Cam: Ultima Digital Ignition; Buell Head Conversion; E85 Carb Tuned;

    8. #6
      Member jondevieonS40's Avatar
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      Quote Originally Posted by EngTech View Post
      Sure Seems - these - 2.4 with Natural Breathing - would Benefit - Most from Lower Intake Porting & Cams . .
      Matching that Upper Better to Lower "Ported Unit" seems would be 15HP .. then Cams 10HP so Combined 28HP . .
      Sure would be Rev Happy . .

      Pop lower unit on E-bay for $50. and Ship it to Me ~ I'll Port it for $325.00 it's really easy - "DIY" Bolt On

      ps: Have to take a Look at Exhaust Manifold ~ Make it into Header ..
      If anyone spent that much money on a 2.4i i think id, actually i spent about that much on my old 2.4i in odd-ball accessories so i guess its not that crazy lol
      2008 S40 T5 AWD ("Shadow") |ELEVATE 3" Intake, 2.5" Charge Pipe, Intercooler, Torque Mount, ECU Mount, TCV, Turbosmart CBV, Turbosmart Actuator, stage 3 APC Tune, 3 Stickers (5HP)ea||ClockWorkCalibrations Custom 3" Exhaust||EuroSportTuning 3" downpipe.||CF Cone Filter||De-Badged||custom Mesh Grill||Intercooler Cut out||Porsche 911 Throttle body upgrade||18" Enkie PDC Wheels wrapped in 225/45/18 Sentury UHP||M3 Spoiler|| 8k Morimoto HID Kit|| White LED Fog,City,trunk light|"embody God, then go crazy"

    9. #7
      Member EngTech's Avatar
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      Porting Increases volumetric efficiency

      Turbo's are getting 11-12Hp to say 14Hp on Lower Unit Depending on Tune ~ that a Motor that's Being Assisted Via ~ Turbo .. volumetric efficiency .. is way Lower on on Vac Pump ~ Normal Motor ..
      Any Improvement in Going to achieve Higher Results , seeing 2.4i already has Header style Exhaust - Now the Front of the Motor needs to be Un_Corked ..
      Matching the Upper & Lower Unit and Ported Lower Unit ~ 15Hp..

      ( 2400cc / 2 ) x 6000rpm/1728 = CFM 254.254

      Then Take Cu. Ft. Min. 254.254 x .85 volumetric efficiency = 216 C. F. M

      216 CMF could be Bumped Up to .92 or More with Porting 234 CFM through Motor ..so approx 3.75 Cu. ft. Per Cly. ( Increase )


      ps: Exhaust Header - Looks pretty good - I'd maybe do Port Match to the Gasket as on Turbo Motors the Exhaust Flange is under sized .080 & Shifted .060 . .
      Most Likely the ~ 2.4i Exhaust Ports in Head aren't Aligned any Better to Manifold Exit ~
      Last edited by EngTech; 01-11-2020 at 10:27 AM.
      ** V50 AWD - Handling & Performance Tweaks = New Stance / VW CC - Handling Tweaks - Testing & Porting - Intake Mods
      A Garden Gate will Last You a Life Time . http://s261.photobucket.com/user/Eng...0Trim%20%20etc

    10. #8
      Junior Member lunalolvo's Avatar
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      Quote Originally Posted by avenger09123 View Post
      That is awesome dude. I never considered in an IN-LINE air filter, that's awesome.

      That filter is fine, the 2.4i only pulls 165 CFM at 6500RPM if you account for stroke, RPM, and volumetric efficiency, so you'll be fine on a filter that size.
      Yeah, and I'm hoping foam doesn't restrict it too much - I really don't trust the bare filter on its own. I have 1/4" 30PPI stuff on there which I suspect won't be enough, so I may bump it to 60PPI later on. Planning on doing a UOA on the setup as is and seeing what comes up.



      Photo was being weird on some browsers, I think I fixed that

    11. #9
      Member EngTech's Avatar
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      PORTING WOULD Bring may more then Cold Air ~


      ( 2400cc / 2 ) x 6000rpm/1728 = CFM 254.254

      Then Take Cu. Ft. Min. 254.254 x .85 volumetric efficiency = 216 C. F. M

      216 CMF could be Bumped Up to .92 or More with Porting 234 CFM through Motor ..so approx 3.75 Cu. ft. Per Cly. ( Increase )


      ps: Exhaust Header - Looks pretty good - I'd maybe do Port Match to the Gasket as on Turbo Motors the Exhaust Flange is under sized .080 & Shifted .060 . .
      Most Likely the ~ 2.4i Exhaust Ports in Head aren't Aligned any Better to Manifold Exit ~
      ** V50 AWD - Handling & Performance Tweaks = New Stance / VW CC - Handling Tweaks - Testing & Porting - Intake Mods
      A Garden Gate will Last You a Life Time . http://s261.photobucket.com/user/Eng...0Trim%20%20etc

    12. #10
      Member EngTech's Avatar
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      Just trying to Demonstrate Improving ~ volumetric efficiency ~

      Ported.jpg
      ** V50 AWD - Handling & Performance Tweaks = New Stance / VW CC - Handling Tweaks - Testing & Porting - Intake Mods
      A Garden Gate will Last You a Life Time . http://s261.photobucket.com/user/Eng...0Trim%20%20etc

    13. #11
      Quote Originally Posted by EngTech View Post
      Just trying to Demonstrate Improving ~ volumetric efficiency ~

      Ported.jpg
      Cool graphic. I accounted for 60% VE since 80% and above was usually forced induction vehicles and he's got a 2.4i
      2006 Volvo S40 AWD T5 M66 - Dusty Rusty
      2012 Subaru Outback 2.5i CVT - Slowmobile - CAI only, Powerstop Rotors+Pads.
      1996 HD Electra Glide - Big Bertha - 10:1 Wisecos; EV13 Cam: Ultima Digital Ignition; Buell Head Conversion; E85 Carb Tuned;

    14. #12
      Junior Member 80sGuy's Avatar
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      Quote Originally Posted by jondevieonS40 View Post
      makes oil changes so much easier!
      Never an issue with oil-changes on the 2.4i, only the 2.5 Turbo where you'd have to remove part of the front duct/snorkel for clearance to the oil filter.

    15. #13
      Member EngTech's Avatar
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      2.4I is pretty Good seeing it has 4 Valve Head and Medium Header with 11:1 Compression ,so more Like .88
      But there are Improvements to be Had , as Described . .

      I went back through the Calu. using more Acute Numbers : 228 Cfm @ 6000 Rpms
      Ported would be Up around 242 Cfm ..


      Author of Formula _ says Turbo Motors today are 100% or More as to Recovery of Waster Energy being used to Pressurize Intake .. I don't see it this Way has As the Turbo's are Very Restrictive
      Hence Cutting Back of the Exducer Wheel and Opening up Waste Gate some ~ allow ~ a Lot more Top End - Higher Spin on Turbo also .. - When I Port the Turbo Manifold I also Open up - Internal Passage way to Main Exhaust Scroll


      Porting the Lower Unit and Matching the Exhaust Manifold Plate ( S. Steel ) probably SS409 as those do get Rusty ~ Port & Ceramic Coat on that would be 1 step ..
      Better step would be Matching Up and Streamline Lower Intake Manifold - Taking out all the Casting Web , Major Roughness . . Steps between the Mating Surfaces - has to be at Least 16Hp / 12 ft. lbs Tq. in there .. Dan
      Last edited by EngTech; 01-12-2020 at 12:05 PM.
      ** V50 AWD - Handling & Performance Tweaks = New Stance / VW CC - Handling Tweaks - Testing & Porting - Intake Mods
      A Garden Gate will Last You a Life Time . http://s261.photobucket.com/user/Eng...0Trim%20%20etc

    16. #14
      Junior Member lunalolvo's Avatar
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      Some interesting points:

      Per the Amazon customer Q&A page, the filter box can be oriented both ways, with the cone facing incoming air, or facing the throttle body. There is some CFM benefit to the latter, and that's how I originally installed it (by mistake).
      I've since flipped the box so the filter cone points towards incoming air (the prefilter was wrapped around the cone, so for now that's really the only valid orientation from a filtration standpoint).

      Throttle response is a bit more similar to stock than with the filter reversed (less jumpy)
      Induction "honk" can be heard sooner than with the filter reversed. It's not loud to start, just a tone difference. Now starts at ~3k, as opposed to ~4k with the filter reversed.
      I may wrap the prefilter on the inside of the cone and reinstall it reversed just so it's quieter in the future, but I'm keeping it as is for now.
      Last edited by lunalolvo; 01-12-2020 at 05:37 PM.

    17. #15
      Member EngTech's Avatar
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      What No Electric Fan to Boost Air Flow ?

      What CFM is rated for ?

      How many Sq. Inches of Air Filter ?

      Anyone running 70mm Throttle-body ?

      Aren't there any other wireless throttle bodies ? sure seems someone would have come up with Nice set up
      by now , seems VW 2.5 5 cly. has more support . .
      ** V50 AWD - Handling & Performance Tweaks = New Stance / VW CC - Handling Tweaks - Testing & Porting - Intake Mods
      A Garden Gate will Last You a Life Time . http://s261.photobucket.com/user/Eng...0Trim%20%20etc

    18. #16
      Junior Member lunalolvo's Avatar
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      365 CFM forward, 427 reversed per the guy from Spectre one of the buyers spoke to.

      Can't imagine that the throttle body is a bottleneck for the 2.4i (don't think the Porsche one bolts up) nor is the stock intake.

      I have a 2.5 Golf, and would spend probably $2k+ to get an appreciable horsepower gain - intake, intake manifold, exhaust, tune. Even so, it might only make the 200 mark. Lots of noise, still not much power. At that point why not buy a t5?

    19. #17
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      Lunalovo, it sure looks like the engine will be a lot easier to work on. Do you have any worries about ECU cooling? The stock airbox seems to have some ducting across the ECU cooling fins.
      Mark

      "New-to-me" V50 Back from the dead.

    20. #18
      Junior Member lunalolvo's Avatar
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      Quote Originally Posted by mf70 View Post
      Lunalovo, it sure looks like the engine will be a lot easier to work on. Do you have any worries about ECU cooling? The stock airbox seems to have some ducting across the ECU cooling fins.
      The Simota kit uses a similar placement and claims no issues. I believe a member on here had overheating issues with a DIY setup that were resolved by moving the ECU closer to the battery cooling duct. Someone else preemptively made an extra hole in that same duct, so there are options.
      Last edited by lunalolvo; 01-14-2020 at 11:09 AM.

    21. #19
      Junior Member lunalolvo's Avatar
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      Somewhat related update:

      I've had super low idle LTFT values related to: https://forums.swedespeed.com/showthread.php?401201 , https://forums.swedespeed.com/showth...uns-great-2-4i

      As I had disconnected the crankcase breather from the airbox and it now has its own filter, I had a bit of flexibility to mess around with the left over vacuum line "elbow". Usually the vacuum ejector valve only is sold in a full assembly (~$100), and some others (around the $40 mark) are used on P2s and may or may not be a direct fit. Audi/VW P/N 058133753B ($8 aftermarket on Amazon!) is remarkably similar, with the top and bottom nibs reversed: the top one is thick, the bottom thin. The breather line is a direct fit. With some hose trickery and home depot clamps it can be made to fit:

      Idle LTFT has gone from -17% to just around +5%, which is to be expected with a CAI. The OEM valve I had removed wasn't clogged, but it was letting air go in both directions, so it had failed.
      Last edited by lunalolvo; 01-19-2020 at 06:12 PM.

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