Advantages/disadvantages of SD?
06-26-2006, 11:58 AM
#121
Originally Posted by 98Z28CobraKiller
But I am stuck on the size. The biggest MAF that I am aware off is the 85mm. I just spent a ton of cash on a FAST 90/ NW 90 TB. Am I wrong in thinking that putting an 85mm tube in front of my 90mm stuff is a restriction?
seriously though, this style of MAF needs air flowing over it evenly.. you can only make it so big before accuracy becomes a problem.. its already huge and on the edge of being too big, so unless you switch to a diffrent style MAF (something i expect GM to do soon anyway) then i doubt anyone will ever make one bigger...
in anycase, its just 5mm... and while i havent measured it, id bet that the true measured surface area of the MAF is larger then the true measured surface area of the throttlebody, once you account for the butterfly and shaft..
06-26-2006, 01:37 PM
#122
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This may be of the topic a little but I have a question for you guys. If you are looking at a log and your MAP sensor is reporting values that are less than 100Kpa ie. 95-97Kpa at WOT, does this mean that your intake system is restrictive? If it does could the stock MAF be causing this or would it be somthing else. Lets assume that the car has a lid and a clean filter, what would these MAP values tell you?
06-26-2006, 02:56 PM
#123
Originally Posted by 98Z28CobraKiller
But I am stuck on the size. The biggest MAF that I am aware off is the 85mm. I just spent a ton of cash on a FAST 90/ NW 90 TB. Am I wrong in thinking that putting an 85mm tube in front of my 90mm stuff is a restriction?
06-26-2006, 04:00 PM
#124
Originally Posted by Craigz28ss
This may be of the topic a little but I have a question for you guys. If you are looking at a log and your MAP sensor is reporting values that are less than 100Kpa ie. 95-97Kpa at WOT, does this mean that your intake system is restrictive? If it does could the stock MAF be causing this or would it be somthing else. Lets assume that the car has a lid and a clean filter, what would these MAP values tell you?
remember, pressure changes with the weather too... 100 isnt always the current atmospheric pressure.
before startup, look at the MAP.. you can see what its currently reading as atmospheric pressure... im slightly below sea level, and i see anywhere from 97 to 105 depending on the day... but its usually around 100 to 102
now if you knew it was supposed to be at 100today.. and as the engine reved higher, vac was increasing.. that would be a good indicator.
11-18-2007, 10:54 PM
#126
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01-15-2008, 04:31 PM
#127
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07-25-2016, 07:01 PM
#129
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I have a stroked LS1 that was built by Baker engineering out of MI. The tuner there has tuned car with speed density tune to eliminate things to check while he was trying to figure out why the car is loosing HP an sounds like popcorn while letting out of it.
To further the story, before the car started doing this, it was running Maf and O2's and a coil died. The car backfired and blew the exhaust apart at Y pipe and hasn't run right since.
Speed tune
new Map and Tps
countless hours
Compression is spot on
check valves
Does this sound like an issue with tuning????
Could something have been taken out from massive backfire?
Have been fighting problem for two years
To further the story, before the car started doing this, it was running Maf and O2's and a coil died. The car backfired and blew the exhaust apart at Y pipe and hasn't run right since.
Speed tune
new Map and Tps
countless hours
Compression is spot on
check valves
Does this sound like an issue with tuning????
Could something have been taken out from massive backfire?
Have been fighting problem for two years
07-25-2016, 09:23 PM
#130
I have a stroked LS1 that was built by Baker engineering out of MI. The tuner there has tuned car with speed density tune to eliminate things to check while he was trying to figure out why the car is loosing HP an sounds like popcorn while letting out of it.
To further the story, before the car started doing this, it was running Maf and O2's and a coil died. The car backfired and blew the exhaust apart at Y pipe and hasn't run right since.
Speed tune
new Map and Tps
countless hours
Compression is spot on
check valves
Does this sound like an issue with tuning????
Could something have been taken out from massive backfire?
Have been fighting problem for two years
To further the story, before the car started doing this, it was running Maf and O2's and a coil died. The car backfired and blew the exhaust apart at Y pipe and hasn't run right since.
Speed tune
new Map and Tps
countless hours
Compression is spot on
check valves
Does this sound like an issue with tuning????
Could something have been taken out from massive backfire?
Have been fighting problem for two years
07-25-2016, 11:21 PM
#131
A maf is much faster to tune. It is desirable on street cars where a variety of conditions is encountered and minimal tuning is necessary. Consistent air fuel ratios is achievable easily as it basically 'tunes itself' to whatever A/F you input as desired and then tweak global fueling constants to dial in.
The cons to a MAF sensor are, it must be installed correctly, airflow must be smooth through it wherever it is, and there can be no leaks. It also presents a slight restriction to the incoming air, depending on the sensor in question, it is often cleaner appearance to getting rid of it.
with a MAP sensor, there is much work to be done matching the VE of the engine to the pressure unit the engine runs at. So each cell needs its own special number, and a LOT of driving should be done to ensure varying conditions are met with whatever sensors are available. The fastest way to tune a MAP car is to data-log the air fuel values for every cell and multiplier in the correcting factors by comparison to a desired a/f chart (using excel usually this is accomplished easily).
I tune most MAF cars within 30 minutes easily. By comparison, a MAP car can take 3-5 hours, or more. In fact, some MAP tunes I am never happy with (my own cars) I keep tweaking for weeks... months... years... and never satisfied. there is always 0.337 of this or that to adjust for 0.04mpg here and there (it becomes a hobby). As conditions change from one dry hot day to the next wet rainy monsoon and back to concrete traffic city streets, then long hot highway drives, there is a bit of wandering in both systems as the unit in question becomes older and older (older and more simple ECU with fewer sensors available for trim features, tend to wander more regardless of MAF or MAP) If the vehicle in question is a mostly 'race/competition' vehicle then the MAP is preferable for reliability and max output reasons.
The cons to a MAF sensor are, it must be installed correctly, airflow must be smooth through it wherever it is, and there can be no leaks. It also presents a slight restriction to the incoming air, depending on the sensor in question, it is often cleaner appearance to getting rid of it.
with a MAP sensor, there is much work to be done matching the VE of the engine to the pressure unit the engine runs at. So each cell needs its own special number, and a LOT of driving should be done to ensure varying conditions are met with whatever sensors are available. The fastest way to tune a MAP car is to data-log the air fuel values for every cell and multiplier in the correcting factors by comparison to a desired a/f chart (using excel usually this is accomplished easily).
I tune most MAF cars within 30 minutes easily. By comparison, a MAP car can take 3-5 hours, or more. In fact, some MAP tunes I am never happy with (my own cars) I keep tweaking for weeks... months... years... and never satisfied. there is always 0.337 of this or that to adjust for 0.04mpg here and there (it becomes a hobby). As conditions change from one dry hot day to the next wet rainy monsoon and back to concrete traffic city streets, then long hot highway drives, there is a bit of wandering in both systems as the unit in question becomes older and older (older and more simple ECU with fewer sensors available for trim features, tend to wander more regardless of MAF or MAP) If the vehicle in question is a mostly 'race/competition' vehicle then the MAP is preferable for reliability and max output reasons.
Last edited by kingtal0n; 07-25-2016 at 11:27 PM.
