Streetlegal Posted June 23, 2015 Share Posted June 23, 2015 So my stock air box won't fit with my FMS FMIC kit and I wanted some feedback on my thoughts. I did some searching around and found someone who basically did what I was thinking of doing. Since you have to rescale the MAF if you changed to a larger size etc would it be possible to cut out the MAF housing of the stock air box and make an intake using that MAF tube? This way the MAF still has the same area and shouldn't mess with it, I think. Here's a thread I found on nasioc http://forums.nasioc.com/forums/showthread.php?t=1546717 I would be doing it cleaner than this but I just wanted to know if the concept would work or if it would screw with the MAF. I figured I would ask before I cut up my stock intake box. Link to comment Share on other sites More sharing options...
ras06LGT Posted June 23, 2015 Share Posted June 23, 2015 The flow characteristics across the MAF are also critical. The stock airbox is designed to have as smooth of flow as they can get (while balancing noise and other things). Doing what the NASIOC link did will create more turbulent flow across the MAF with the filter being so close to the sensor. Also, he's now created a very nice hot-air-intake out of the nice factory cold-air-intake. If you decide to go this route I would try to get the MAF as far from the filter as you can to provide the smoothest air flow you can. Also, you'll need an update to your tune, but with a FMIC you are probably already going that route anyways... Link to comment Share on other sites More sharing options...
FJuan Posted June 23, 2015 Share Posted June 23, 2015 You might be better off with a CAI and get it tuned. My wife's balls are delicious. Link to comment Share on other sites More sharing options...
Streetlegal Posted June 23, 2015 Author Share Posted June 23, 2015 The flow characteristics across the MAF are also critical. The stock airbox is designed to have as smooth of flow as they can get (while balancing noise and other things). Doing what the NASIOC link did will create more turbulent flow across the MAF with the filter being so close to the sensor. Also, he's now created a very nice hot-air-intake out of the nice factory cold-air-intake. If you decide to go this route I would try to get the MAF as far from the filter as you can to provide the smoothest air flow you can. Also, you'll need an update to your tune, but with a FMIC you are probably already going that route anyways... Well I knew the flow characteristics are important but I was hoping that the straighteners inside the MAF tube would be enough to not have to mess with it. I know his isn't the greatest but I just was referring to the same concept. If I were to be able to achieve a laminar enough flow would that allow me to not have to rescale my MAF? I know I'll have to mess with the tune a little when I put the FMIC on but I was hoping to not have to rescale the MAF. Granted it's not a huge deal if I have to. It was just a thought. I would much rather build something for my car than pay for one when I know I have the capability of making it. Do you think something along the lines of this would work? Filter down in fender where other CAI sit -> 8-12" of aluminum (or another plastic I have at work) piping -> silicone coupler -> MAF section -> silicone coupler (maybe 45° or something) -> turbo inlet tube Link to comment Share on other sites More sharing options...
cryo Posted June 23, 2015 Share Posted June 23, 2015 Keep in mind the setup will be laggy in response and fueling will be inconsistent with the fmic and no tune. Honestly I would say its worth getting a proper "flow tested" intake kit with your frontmount and a proper tune to take advantage of the mods. The tip in settings after changing to a frontmount can and normally will create an issue as the car trys to anticipate adding fuel to compensate for airflow much like an accelerator pump on a carbureted car. without changes in that area you will run richer than target as you mash the throttle which kills your torque output. just my .02 Dave [sIGPIC][/sIGPIC] Providing unmatched customer service and a Premium level of Dyno/E-tuning to the Community cryotuneperformance@yahoo.com facebook.com/cryotuneperformance. Link to comment Share on other sites More sharing options...
heiche Posted June 24, 2015 Share Posted June 24, 2015 maf scaling is so sensitive that you should change it even when swapping in an aftermarket air filter. so much larger changes like hacking out the maf sensor tube definitely require rescaling. if you're thinking of doing that then you might also consider using a Spectre Air Flow Sensor Mount #8705. some advance auto stores carry them, and for only $15. Here's the DIY intake I ended up putting together. This is shown without the sheetmetal "cold airbox". BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT Link to comment Share on other sites More sharing options...
Streetlegal Posted June 24, 2015 Author Share Posted June 24, 2015 Keep in mind the setup will be laggy in response and fueling will be inconsistent with the fmic and no tune. Honestly I would say its worth getting a proper "flow tested" intake kit with your frontmount and a proper tune to take advantage of the mods. The tip in settings after changing to a frontmount can and normally will create an issue as the car trys to anticipate adding fuel to compensate for airflow much like an accelerator pump on a carbureted car. without changes in that area you will run richer than target as you mash the throttle which kills your torque output. just my .02 Dave I planned on adjusting the tune for the FMIC but I was hoping to not have to rescale the MAF and be able to utilize existing pieces I have. I just have a hard time justifying a $2-300 piece of pipe that I can make myself for almost nothing. Especially since I plan to go rotated eventually which would make me have no need for the intake I just bought anyways. maf scaling is so sensitive that you should change it even when swapping in an aftermarket air filter. so much larger changes like hacking out the maf sensor tube definitely require rescaling. if you're thinking of doing that then you might also consider using a Spectre Air Flow Sensor Mount #8705. some advance auto stores carry them, and for only $15. Here's the DIY intake I ended up putting together. This is shown without the sheetmetal "cold airbox". Yea that is pretty much what I was thinking of doing but keeping the stock MAF tube. I do appreciate the feedback from you guys so I hope I don't come off in a way seeming like I know it all Link to comment Share on other sites More sharing options...
cryo Posted June 25, 2015 Share Posted June 25, 2015 While making all the needed changes to accommodate the fmic the scaling for a different intake should be a piece of cake. I understand you not wanting to shell out money for the intake kit but as heiche mentioned you can make your own kit for pretty cheap as well rather than hacking up the stock box. I personally think rescaling the maf is needed if ANY changes are made to the air intake system *I have seen something as simple as removing the snorkus cause odd turbulence and require rescaling at idle. Some people don't realize that the Helmholtz snorkus is actually designed to smooth flow and make it quieter while it ends up catching some debris as well. Obviously this is not your issue but figured I'd mention it as well. https://en.wikipedia.org/wiki/Helmholtz_resonance Hope that helps but obviously its up to you, just make sure to look at a log or two after the changes to make sure you didn't decrease overall flow ability in the hopes of increasing it. Dave [sIGPIC][/sIGPIC] Providing unmatched customer service and a Premium level of Dyno/E-tuning to the Community cryotuneperformance@yahoo.com facebook.com/cryotuneperformance. Link to comment Share on other sites More sharing options...
Streetlegal Posted June 25, 2015 Author Share Posted June 25, 2015 While making all the needed changes to accommodate the fmic the scaling for a different intake should be a piece of cake. I understand you not wanting to shell out money for the intake kit but as heiche mentioned you can make your own kit for pretty cheap as well rather than hacking up the stock box. I personally think rescaling the maf is needed if ANY changes are made to the air intake system *I have seen something as simple as removing the snorkus cause odd turbulence and require rescaling at idle. Some people don't realize that the Helmholtz snorkus is actually designed to smooth flow and make it quieter while it ends up catching some debris as well. Obviously this is not your issue but figured I'd mention it as well. https://en.wikipedia.org/wiki/Helmholtz_resonance Hope that helps but obviously its up to you, just make sure to look at a log or two after the changes to make sure you didn't decrease overall flow ability in the hopes of increasing it. Dave Thank you for the heads up. I didn't think that just the snorkus would make enough of a difference. I knew about the helmholtz stuff, pretty cool actually, especially when utilized in exhaust to cancel drone. So would you suggest I change the intake first and get that all dialed in and then do the FMIC? I'll probably go the route of heiche and use that tube section for the MAF. I'll rescale my injectors and whatnot first so I can keep the stock intake then switch. Link to comment Share on other sites More sharing options...
heiche Posted June 25, 2015 Share Posted June 25, 2015 please see this post for more info on the Spectre MAF tube. My scaling turned out to be quite a bit different than his, but it seems to be different for every combo, unless it's totally stock BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT Link to comment Share on other sites More sharing options...
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