PhilT Posted August 28, 2005 Share Posted August 28, 2005 OK, so after reading lots of posts whether high flow intakes make any difference or not I decided there was only way to prove it. With the help of a friend who runs a fabrication shop I made up a MAF adapter pipe, fitted it with a cone filter and slapped it in. The results were way more than I expected, she pulls harder now for sure, and I know some people will say its only my butt dyno, but I have no doubts, it's so obvious when you hit the gas. The other benefit, which actually I like more than the extra zoom zoom, is the sounds that now comes from the turbo. You can clearly hear it spool up, almost like an aircraft, then let of the gas and psssst, the BOV lets you know it's working loud and clear. I have no other mods, in fact I have removed the intake for now as I want to put some fins into it to smooth out any turbulence, the same as is fitted to the stock airbox, and get a permanent bracket to hold it in place. I should have my AP fitted tomorrow, so once I get used to that the intake will go back on and see how it fares. Attached are a few pics of the intake, not pretty, but works good. Double Award Winning Legacy GT Wagon Link to comment Share on other sites More sharing options...
ShaggyGT Posted August 28, 2005 Share Posted August 28, 2005 I hope you have a way to check your A/F ratio with that thing installed. That MAF plate looks pretty thick and if there is any more air getting past the MAF sensor than with the stock intake then you will be running very lean without knowing it. By having the MAF sensor sit higher in the intake unmetered air can get past the sensor and the ECU will not compensate for it. What you have is pretty similar to a BIG MAF housing, which can not be ran on the stock ECU safely. -Matt Link to comment Share on other sites More sharing options...
PhilT Posted August 28, 2005 Author Share Posted August 28, 2005 The ID of the aluminum tube is exactly the same as stock, the centre of the MAF is also exactly in the centre of the tube, as is stock. Although I say it's a DIY job, it was very precisely fabricated. Double Award Winning Legacy GT Wagon Link to comment Share on other sites More sharing options...
mwiener2 Posted August 28, 2005 Share Posted August 28, 2005 I'm sorry, but unless you run back to back dyno runs.........your ass is grass My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
ShaggyGT Posted August 28, 2005 Share Posted August 28, 2005 Nevermind you missed my point.... Link to comment Share on other sites More sharing options...
PhilT Posted August 28, 2005 Author Share Posted August 28, 2005 Nevermind you missed my point.... Sorry, I must have. By higher in the intake you mean above centre or closer to the turbo ? No air can get past the sensor. I'm not being sarcy, you have a valid point and I want to understand it. Double Award Winning Legacy GT Wagon Link to comment Share on other sites More sharing options...
ShaggyGT Posted August 28, 2005 Share Posted August 28, 2005 Kinda hard to explain it actually, but I will give it a shot. If the sensor in the stock MAF housing was almost hitting the bottom of the housing and now it is an inch or more away from it you will indeed be getting unmetered air. I attached a quick picture I made to show you what I mean. -Matt Link to comment Share on other sites More sharing options...
firedawgs Posted August 28, 2005 Share Posted August 28, 2005 Ok, Prove everyone wrong. Go get a dyno completed including A/F ratios. The results will shut up many. Or better yet have one of us data log it. Updated my vBGarage: Link to comment Share on other sites More sharing options...
PhilT Posted August 28, 2005 Author Share Posted August 28, 2005 Kinda hard to explain it actually, but I will give it a shot. If the sensor in the stock MAF housing was almost hitting the bottom of the housing and now it is an inch or more away from it you will indeed be getting unmetered air. I attached a quick picture I made to show you what I mean. -Matt Ok I know what you meant now. The centre "eye" of the MAF sensor is exactly in the centre of the pipe on the stock piece, as it must be for the venturi to meaure the flow correctly. It basically measures the air pressure before and after the venturi, and calculates the flow rate from that. Using the tube diameter, and a temperature sensor in there, it can then calculate the Mass Air Flow in lbs/min or whatever units it uses. I have not changed any dimensions from the stock setup, so have no reason to think that it is inaccurate. But as Firedawgs says, I should get a dyno run done, with A/F measurement. If I can prove it's OK and the gain is actual and not just in my butt, then I'm sure I could sell a few Double Award Winning Legacy GT Wagon Link to comment Share on other sites More sharing options...
rao Posted August 28, 2005 Share Posted August 28, 2005 Since I don't know anything take this with a grain of salt , but the sensor measures the mass of the air by determining how much the heated wire element is cooled. The potential problem with intakes is that if the flow through the tube is changed, the sample that the actual sensor sees can be diffeent (think of the air flowing through the tube mostly along the bottom, or the side, etc.) and that can give a different reading than stock for a given true air flow. The diameter of the tube is critical because the ratio of the tube size to the sample size must be kept consistent. The "Big MAF" set-ups just place the sensor in a larger tube so that the ratio is increased and the MAF reads a lower voltage for a given aount of air flow. Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
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