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i was reading thru a few books here at the house trying to better edumacate myself and refresh my understanding of efi as i will be attempting the megasquirt system on my project vehicle, and i stumbled across an article in one of my books that i find interesting and think i should share w/ the rest of the readers on MAF sensor modifying. the 3.0 as we all know has a wonderful post that is a flow restriction on its MAF and many of the owners opted to modify the sensor, doing so had great results, but it appears i read up on a drawback according to the author that has run many vehicles on a dyno and seen the end results of doing such modifications on other engines in the past. the book is from autozoo (the only place i can find such resources in paperback w/o guessing at what im ordering is what i need). its called engine management, advanced tuning by greg banish if you wish to look this up yourself. on page 26 in chapter 4 the excerpt reads:
"a common mistake made by many perfomance enthusiasts is to cut out a portion of the MAF to improve total flow. while total flow is increased by doing this, the side effect is a change in the ratio of air across the metering element to total flow, reducing the output of the MAF at any given actual flow rate. the net effect of this is a leaner engine-operation condiion resulting from fuel calculations based on a lower airflow input to the computer. for example, cutting the center divider out a a GM LS1 MAF typically shifts the output down by about 7%. the bigger concern is that this modification does not simply shift output down across the range, as low speed flow demonstrates a more pronounced effect. while many oem systems run a safely rich air/fuel ratio at wide open throttle, leaning out the mix by changing MAF output can lead to knock.
"the problem that many performance enthusiasts encounter is that the oems have not intended the power (and total airflow) of the vehicle to be drastically increased. most oem MAFs are scaled to have the most resolution possible w/in the anticipated range of possible flow requirements. as airflow increases w/ increased power production, we often find that this anticipated max flow can be exceeded. the result is an oem meter that reaches its max output b4 the engine peaks. this is often referred to as a "pegged MAF sensor." due to the limited measurement range and a typically small size, it is common to replace the oem MAF on performance vehicles. aftermarket MAF sensors invariably have a dif output from the original, even if only slightly. the ability to shift out this output upward significantly makes their use almost mandatory on higher output engines. once the oem meter is replaced, it is up to the calibrator to change the tables in the computer to reflect the new flow rates at each output point."
due to my findings i am going to look up a larger sensor or stock sensor for a larger engine for my turbo build. possibly a stock 5.0 sensor or an aftermarket one for a 5.0/5.7 depending on the size of the piping. i want to keep my plumbing the same size from turbo to intercooler to sensors to throttlebody to manifold to keep the flow variables of multisized plumbing to a minimum. food for thought for others that may have done the mod or thinking about doing the mod, i think this tidbit of information should be open to discussion since there are a lot of ppl that have modded their MAFs w/o consequence (that we know of...) im interested to see the responses to tell the truth.
"a common mistake made by many perfomance enthusiasts is to cut out a portion of the MAF to improve total flow. while total flow is increased by doing this, the side effect is a change in the ratio of air across the metering element to total flow, reducing the output of the MAF at any given actual flow rate. the net effect of this is a leaner engine-operation condiion resulting from fuel calculations based on a lower airflow input to the computer. for example, cutting the center divider out a a GM LS1 MAF typically shifts the output down by about 7%. the bigger concern is that this modification does not simply shift output down across the range, as low speed flow demonstrates a more pronounced effect. while many oem systems run a safely rich air/fuel ratio at wide open throttle, leaning out the mix by changing MAF output can lead to knock.
"the problem that many performance enthusiasts encounter is that the oems have not intended the power (and total airflow) of the vehicle to be drastically increased. most oem MAFs are scaled to have the most resolution possible w/in the anticipated range of possible flow requirements. as airflow increases w/ increased power production, we often find that this anticipated max flow can be exceeded. the result is an oem meter that reaches its max output b4 the engine peaks. this is often referred to as a "pegged MAF sensor." due to the limited measurement range and a typically small size, it is common to replace the oem MAF on performance vehicles. aftermarket MAF sensors invariably have a dif output from the original, even if only slightly. the ability to shift out this output upward significantly makes their use almost mandatory on higher output engines. once the oem meter is replaced, it is up to the calibrator to change the tables in the computer to reflect the new flow rates at each output point."
due to my findings i am going to look up a larger sensor or stock sensor for a larger engine for my turbo build. possibly a stock 5.0 sensor or an aftermarket one for a 5.0/5.7 depending on the size of the piping. i want to keep my plumbing the same size from turbo to intercooler to sensors to throttlebody to manifold to keep the flow variables of multisized plumbing to a minimum. food for thought for others that may have done the mod or thinking about doing the mod, i think this tidbit of information should be open to discussion since there are a lot of ppl that have modded their MAFs w/o consequence (that we know of...) im interested to see the responses to tell the truth.
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