Question about intakes with regards to the stock MAF housing
Jul 15, 2010, 11:46 AM
#1
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Thread Starter
Question about intakes with regards to the stock MAF housing
I've been searching for a few hours, reading up on this as much as I can, and I have yet to find an answer. I've searched the forums here, the "other" Evo forum, and the Cobb tuning forum and have yet to find a real answer.
My setup - basically I'm running an 08 X GSR with the Perrin Stage III kit on it, which includes the AP with the Perrin III tune, and the Perrin FMIC, downpipe and exhaust. I don't currently have the Perrin intake. (When I ordered all of the Perrin stuff I already had AP so I didn't buy the whole "kit" because it also comes with an AP. I just bought the components of the kit individually and forgot the filter on the order).
When I made the order someone from Perrin called me and asked if I wanted the whole kit and thought I'd forgotten to order the AP. I told them I already had it, so all was cool. He asked me if I had any existing modifications on the car short of what I was getting from them. I told him I had an intake, and he told me to take it off. What I'd done is just put a cone filter with a 3" inlet on the stock MAF housing with a T clamp. I'd been running this setup with the Cobb Stage 1 93 SF map for a long time with no adverse effects.
He told me that panel filters were ok to run with the Perrin tune, but not any other intake. This is where my question comes in.
I've noticed that most intake systems for the Evo X replace the stock MAF housing with a larger one, so it would make sense that if the ECU thinks that a given amount of flow over the sensor, with respect to the size of the stock MAF housing, that an equation can easily translate that number to a total incoming air flow value.
If the size of the MAF housing gets larger, but the MAF sensor stays the same and the ECU isn't adjusted to compensate for the larger MAF housing, more air will be entering the intake side than is expected, thus creating a leaner condition. To me, this makes sense.
If the size of the MAF housing stays the same, but the filter on the "cold" side of the MAF housing is changed, then the MAF calibration in the ECU should be able to stay the same since the MAF housing didn't get any larger. This would mean that the calculation can stay the same (no tuning) - correct?
If my thought process is not totally wrong on this, then the following questions arise:
1.) I can see why Perrin recommends that the intake be stock, since an aftermarket intake could potentially replace the MAF housing with one 10% larger, 20% larger, etc. This is a variable and unknown to them, obviously. BUT - if the MAF housing stays the same, then running a cone filter on the stock MAF housing (or any other intake which doesn't modify the MAF housing) should be ok, correct?
2.) If they can say that any drop-in panel filter works with the tune, and drop-in panel filters can flow much differently (some not very well, like stock, and others very well, like Works), wouldn't this reinforce the idea that putting a cone on the MAF housing or putting an intake that doesn't change the MAF housing and only modifies things on the "cold" side of the MAF housing be acceptable? How would adding a cone to the cold side of the MAF be any different than adding a high flow panel (like the Works panel), which is acceptable?
I'm really looking for a technical explanation here, more than anything to kill my curiosity on the subject.
Anyone got any ideas? Does this make sense or am I totally off the reservation on this one?
My setup - basically I'm running an 08 X GSR with the Perrin Stage III kit on it, which includes the AP with the Perrin III tune, and the Perrin FMIC, downpipe and exhaust. I don't currently have the Perrin intake. (When I ordered all of the Perrin stuff I already had AP so I didn't buy the whole "kit" because it also comes with an AP. I just bought the components of the kit individually and forgot the filter on the order).
When I made the order someone from Perrin called me and asked if I wanted the whole kit and thought I'd forgotten to order the AP. I told them I already had it, so all was cool. He asked me if I had any existing modifications on the car short of what I was getting from them. I told him I had an intake, and he told me to take it off. What I'd done is just put a cone filter with a 3" inlet on the stock MAF housing with a T clamp. I'd been running this setup with the Cobb Stage 1 93 SF map for a long time with no adverse effects.
He told me that panel filters were ok to run with the Perrin tune, but not any other intake. This is where my question comes in.
I've noticed that most intake systems for the Evo X replace the stock MAF housing with a larger one, so it would make sense that if the ECU thinks that a given amount of flow over the sensor, with respect to the size of the stock MAF housing, that an equation can easily translate that number to a total incoming air flow value.
If the size of the MAF housing gets larger, but the MAF sensor stays the same and the ECU isn't adjusted to compensate for the larger MAF housing, more air will be entering the intake side than is expected, thus creating a leaner condition. To me, this makes sense.
If the size of the MAF housing stays the same, but the filter on the "cold" side of the MAF housing is changed, then the MAF calibration in the ECU should be able to stay the same since the MAF housing didn't get any larger. This would mean that the calculation can stay the same (no tuning) - correct?
If my thought process is not totally wrong on this, then the following questions arise:
1.) I can see why Perrin recommends that the intake be stock, since an aftermarket intake could potentially replace the MAF housing with one 10% larger, 20% larger, etc. This is a variable and unknown to them, obviously. BUT - if the MAF housing stays the same, then running a cone filter on the stock MAF housing (or any other intake which doesn't modify the MAF housing) should be ok, correct?
2.) If they can say that any drop-in panel filter works with the tune, and drop-in panel filters can flow much differently (some not very well, like stock, and others very well, like Works), wouldn't this reinforce the idea that putting a cone on the MAF housing or putting an intake that doesn't change the MAF housing and only modifies things on the "cold" side of the MAF housing be acceptable? How would adding a cone to the cold side of the MAF be any different than adding a high flow panel (like the Works panel), which is acceptable?
I'm really looking for a technical explanation here, more than anything to kill my curiosity on the subject.
Anyone got any ideas? Does this make sense or am I totally off the reservation on this one?
Last edited by i64X; Jul 15, 2010 at 11:51 AM.
Jul 15, 2010, 12:30 PM
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I've been searching for a few hours, reading up on this as much as I can, and I have yet to find an answer. I've searched the forums here, the "other" Evo forum, and the Cobb tuning forum and have yet to find a real answer.
My setup - basically I'm running an 08 X GSR with the Perrin Stage III kit on it, which includes the AP with the Perrin III tune, and the Perrin FMIC, downpipe and exhaust. I don't currently have the Perrin intake. (When I ordered all of the Perrin stuff I already had AP so I didn't buy the whole "kit" because it also comes with an AP. I just bought the components of the kit individually and forgot the filter on the order).
When I made the order someone from Perrin called me and asked if I wanted the whole kit and thought I'd forgotten to order the AP. I told them I already had it, so all was cool. He asked me if I had any existing modifications on the car short of what I was getting from them. I told him I had an intake, and he told me to take it off. What I'd done is just put a cone filter with a 3" inlet on the stock MAF housing with a T clamp. I'd been running this setup with the Cobb Stage 1 93 SF map for a long time with no adverse effects.
He told me that panel filters were ok to run with the Perrin tune, but not any other intake. This is where my question comes in.
I've noticed that most intake systems for the Evo X replace the stock MAF housing with a larger one, so it would make sense that if the ECU thinks that a given amount of flow over the sensor, with respect to the size of the stock MAF housing, that an equation can easily translate that number to a total incoming air flow value.
If the size of the MAF housing gets larger, but the MAF sensor stays the same and the ECU isn't adjusted to compensate for the larger MAF housing, more air will be entering the intake side than is expected, thus creating a leaner condition. To me, this makes sense.
If the size of the MAF housing stays the same, but the filter on the "cold" side of the MAF housing is changed, then the MAF calibration in the ECU should be able to stay the same since the MAF housing didn't get any larger. This would mean that the calculation can stay the same (no tuning) - correct?
If my thought process is not totally wrong on this, then the following questions arise:
1.) I can see why Perrin recommends that the intake be stock, since an aftermarket intake could potentially replace the MAF housing with one 10% larger, 20% larger, etc. This is a variable and unknown to them, obviously. BUT - if the MAF housing stays the same, then running a cone filter on the stock MAF housing (or any other intake which doesn't modify the MAF housing) should be ok, correct?
2.) If they can say that any drop-in panel filter works with the tune, and drop-in panel filters can flow much differently (some not very well, like stock, and others very well, like Works), wouldn't this reinforce the idea that putting a cone on the MAF housing or putting an intake that doesn't change the MAF housing and only modifies things on the "cold" side of the MAF housing be acceptable? How would adding a cone to the cold side of the MAF be any different than adding a high flow panel (like the Works panel), which is acceptable?
I'm really looking for a technical explanation here, more than anything to kill my curiosity on the subject.
Anyone got any ideas? Does this make sense or am I totally off the reservation on this one?
My setup - basically I'm running an 08 X GSR with the Perrin Stage III kit on it, which includes the AP with the Perrin III tune, and the Perrin FMIC, downpipe and exhaust. I don't currently have the Perrin intake. (When I ordered all of the Perrin stuff I already had AP so I didn't buy the whole "kit" because it also comes with an AP. I just bought the components of the kit individually and forgot the filter on the order).
When I made the order someone from Perrin called me and asked if I wanted the whole kit and thought I'd forgotten to order the AP. I told them I already had it, so all was cool. He asked me if I had any existing modifications on the car short of what I was getting from them. I told him I had an intake, and he told me to take it off. What I'd done is just put a cone filter with a 3" inlet on the stock MAF housing with a T clamp. I'd been running this setup with the Cobb Stage 1 93 SF map for a long time with no adverse effects.
He told me that panel filters were ok to run with the Perrin tune, but not any other intake. This is where my question comes in.
I've noticed that most intake systems for the Evo X replace the stock MAF housing with a larger one, so it would make sense that if the ECU thinks that a given amount of flow over the sensor, with respect to the size of the stock MAF housing, that an equation can easily translate that number to a total incoming air flow value.
If the size of the MAF housing gets larger, but the MAF sensor stays the same and the ECU isn't adjusted to compensate for the larger MAF housing, more air will be entering the intake side than is expected, thus creating a leaner condition. To me, this makes sense.
If the size of the MAF housing stays the same, but the filter on the "cold" side of the MAF housing is changed, then the MAF calibration in the ECU should be able to stay the same since the MAF housing didn't get any larger. This would mean that the calculation can stay the same (no tuning) - correct?
If my thought process is not totally wrong on this, then the following questions arise:
1.) I can see why Perrin recommends that the intake be stock, since an aftermarket intake could potentially replace the MAF housing with one 10% larger, 20% larger, etc. This is a variable and unknown to them, obviously. BUT - if the MAF housing stays the same, then running a cone filter on the stock MAF housing (or any other intake which doesn't modify the MAF housing) should be ok, correct?
2.) If they can say that any drop-in panel filter works with the tune, and drop-in panel filters can flow much differently (some not very well, like stock, and others very well, like Works), wouldn't this reinforce the idea that putting a cone on the MAF housing or putting an intake that doesn't change the MAF housing and only modifies things on the "cold" side of the MAF housing be acceptable? How would adding a cone to the cold side of the MAF be any different than adding a high flow panel (like the Works panel), which is acceptable?
I'm really looking for a technical explanation here, more than anything to kill my curiosity on the subject.
Anyone got any ideas? Does this make sense or am I totally off the reservation on this one?
in reality no. Panel filters change airflow and power
i have seen a 10 whp gain from a panel filter and i have seen it affect fuel trims 5-8%
Jul 15, 2010, 12:38 PM
#3
Evolving Member
Thread Starter
That's what I wanted to hear.
So if swapping panel filters (for example, going to the Perrin one, which is a foam element panel filter) makes a large difference like that with the same size MAF housing, would a cone on the MAF be THAT much different than the difference between a OEM panel vs. a foam element panel? I would imagine that it would be closer to the foam element in terms of flow, but wouldn't be outside of that "acceptable" range.
I have the AP w/ cable and Access Tuner Race. Is there anything I can log with that setup with the stock filter in place vs a different panel filter or a cone in order to check and see what's "safe" or not? Or would I absolutely have to buy a dedicated wideband sensor and wideband gauge.
So if swapping panel filters (for example, going to the Perrin one, which is a foam element panel filter) makes a large difference like that with the same size MAF housing, would a cone on the MAF be THAT much different than the difference between a OEM panel vs. a foam element panel? I would imagine that it would be closer to the foam element in terms of flow, but wouldn't be outside of that "acceptable" range.
I have the AP w/ cable and Access Tuner Race. Is there anything I can log with that setup with the stock filter in place vs a different panel filter or a cone in order to check and see what's "safe" or not? Or would I absolutely have to buy a dedicated wideband sensor and wideband gauge.
Last edited by i64X; Jul 15, 2010 at 12:42 PM.
Jul 15, 2010, 01:21 PM
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one word that sums up why a cone filter could through things off with the stock MAF housing: turbulence. any variation in turbulence from what the stock sensor is used to could cause different readings in both directions.
as far as the filter thing... a wideband is the only thing that will tell you for sure. although it may be possible to experience a dangerous lean condition with a new filter and nothing else unchanged, I would place my money on you being "ok". all depends on your tune... for instance, do you still have fuel trims affecting WOT enabled? etc...
as far as the filter thing... a wideband is the only thing that will tell you for sure. although it may be possible to experience a dangerous lean condition with a new filter and nothing else unchanged, I would place my money on you being "ok". all depends on your tune... for instance, do you still have fuel trims affecting WOT enabled? etc...
Jul 15, 2010, 08:52 PM
#6
Evolved Member
I am not sure if Perrin changed their "stage 3" tune or not, but a local gsr owner had that set up on his car, and the Cobb stage 2 shelf map ended up being more power, and it wasn't locked. Just pick the map that matches best what your intake is.
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