Vroooooommmm

[ripstik]

When I have more time, I will respond the other post. Every MAF sensor I have seen has a temperature sensor integrate into them to compensate for different intake temperatures. (it seem like the sensor use a thermal-couple to me)

 

yea it uses 2 thermocouples one for intake temp to scale the mass flow tables and one to measure the temp of the wire so it knows the voltage it needs to maintain the desired temp, which is then used to figure out the mass flow.

[dgoodhue]

not if you block off the opening. since it is sealed, there is no air flow through it so you're not changing the dynamics of how air is moving through the box, only how pressure waves move around the box.

 

It's possible but i highly doubt it, i did the mod, and then resealed the box and saw no changes in the things i monitor with my tune. i believe our MAFs (and most) are hot wire. so all it does is measure how much electricity it needs to keep the wire at it desired temp, and figure out the speed of flow past it. pressure does affect heat transfer but do to the fact that pressure waves are "high" pressure zones followed by "low" pressure zones i think any difference would in transfer in the high pressure zones would be negated by the following low pressure zone. also the fact the the waves are originating from the side of the sensor that has been unchanged (the engine side) would likely make any change that might be present have less of an effect on the sensor.

 

correct, the filter buffets airflow, but pressure waves are not air flow and will be relatively unaffected by the filter

 

correct, tho they have little to no effect on the MAF

 

well i did study fluid mechanics, compressible and in-compressible flow. so i wouldn't say i have NO technical expertise, but if you have a reason as to why/how these minor fluctuations in pressure effect the cooling of a wire than i would love to hear it.

 

I am an EE and I not going to pretend I am an expert on Air Flow. In reading your above posts you acknowledge the pressure changes, but I think you diminish the sensitivity of MAF sensor and its calibration and how resonance can affect it.

 

In a MAF the calibration of the sensor is critical. The intake system is part of the calibration of the sensor. The MAF sensor play critical role in the ECM calculations of fuel the engine, when one remove the close loop feedback of the O2 sensor, it does not take much of fueling change to affect the AFR and how the engine runs. IMO you really need an accurate calibration of the MAF to tune an engine. I tune by trying to isolating the tuning parameters I was trying to change, so I am playing with (or at least attempting to play with) one variable. If I was tuning for intake change, I would tune 1st with the stock intake once I had that down, I would tune the intake afterwards.

 

I removed the metal screen (It wasn't that tight of mesh screen, a mosquito might be able to slip through) from my Corvette's MAF sensor and it changed the sensor calibration. I really didn't notice a difference when I remove the intake metal mesh screens but that just because I didn't initially notice it doesn't mean the calibration wasn't affected. (As a side note it actually seemed to help make more power but in reality it was tricking the ECM to lean out the fuel mixture.) One of the tuners did some extensive testing to prove the calibration change with and with the screen. I changed back and the engine seem easier to tune and get running smoothly (at the time I didn't have a wide band O2 as those where expensive @ $2500) I am sure you can find some tuners who will disagree with me on this subject as it was a controversial subject on the mailing lists and later forums, but the people were the where smartest people in the room were advocating for accurate MAF calibrations. The newbie tuners were usually arguing against.

 

I was trying to find a datalog of a factory intake with the resonator removed and found this. This here is an example of a WOT run SRI is short Ram intake and combination SRI connected to the factory air box with the factory resonator. This is on a NA Subaru. The author of the subject mention that pre MAF changes affected the reading, but post MAF. Unfortunately he did not do a resonator removed testing. I found it interesting nevertheless.

 

http://farm4.static.flickr.com/3131/2335732841_5c1781e4c7_o.png

 

 

https://www.brighthubengineering.com/machine-design/84316-how-intake-resonators-improve-volumetric-efficiency/

 

I found this article which I thought is very interesting about the Helmholtz intake and how it works as benefit to VE in NA vehicles. (ie removing it is a performance decrease) I don't know accuracy of this article, as I have not really research this subject. It would not surprise me as I have seen other performance mods that owners insist on doing that are actually downgrades and they insist it helps or has no negative affect. If this true, that person with the 3.6R who I initially responded, probably should keep the intake resonator.

 

I would imagine in theory with a Turbo & Intercooler in between acting as filters, the effect isn't as large, but I would have to see for myself.

 

I can see that you changes to your intake and you didn't notice any differences with how the engine ran. Just because you didn't notice changes doesn't mean the sensor calibration wasn't affected. I imagine you heard an audible change which would lead to my intuition is that some of the calibration of the sensor has changed. If it didn't change, it probably was more luck than anything else.

Edited May 2, 2019 by dgoodhue

[ripstik]

I can see that you changes to your intake and you didn't notice any differences with how the engine ran. Just because you didn't notice changes doesn't mean the sensor calibration wasn't affected. I imagine you heard an audible change which would lead to my intuition is that some of the calibration of the sensor has changed. If it didn't change, it probably was more luck than anything else.

 

thanks for posting up all this knowledge! it has certainly given me some food for thought. i always knew this mod wasn't for performance, and strictly a sound improvement, but it's interesting to see the how just how out of wack the sensor was down low with no resonator. in the middle of the range it seems they are all have a fair amount of fluctuation but clearly at the top of the range the stock set up is the smoothest. than you compare the SRI to the Hybrid with the resonator an don't see that same smoothing, possibly because they weren't running a filter between the 2? do you know if the hybrid set up was basically a whole ram air setup w/ filter tacked onto the stock box? in that case i'd assume they wouldn't run the panel filter. this stuff is so interesting to me i really need to start diving further into it.