MAF or speed density
good info ^^^ 
TECH Apprentice
Joined: Sep 2005
Posts: 360
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From: Bay Area, CA
I say run a MAf and a 2 or 3 bar set up.... Run the MAF for the crusing and then for the Wide open runs go off of the SD. Because i like to take my car anywhere. Go from Sea level to 8,000 ft up
Teching In
Joined: Nov 2009
Posts: 47
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i just like the idea of the sd cause it would allow me to use an atmospheric bov on my supercharger 
where do i get the 2 or 3 bar map sensor that I would need, or would I even need it with only 9psi? also, what would be the best way to control meth with boost?
where do i get the 2 or 3 bar map sensor that I would need, or would I even need it with only 9psi? also, what would be the best way to control meth with boost? i know speed inc can set you up with a SD configuration im just not sure of the price. so i guess SD is the way to go
You just change out your stock LS1 MAP sensor with a 2 or 3 bar MAP sensor depending on the amount of boost your running. I went with a GM 2 bar Cobalt sensor which is more percise then a 3 bar from what ive heard and read on here and is good to 15 PSI and takes the same plug as our F bodys .After the tune ,you just tuck your mass air flow plug up out of the way as you wont plug it back in to your mass air flow sensor after the tune is complete
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^^^it is a computer problem not a maf problem. the computer is not able to read the maf after a certain level (usually 500whp)
yea if you are making under 500whp i would defiantly keep the maf, but most FI cars max out the maf
yea if you are making under 500whp i would defiantly keep the maf, but most FI cars max out the maf
Great post, Ive been looking for an answer to this question myself....just wondering where is the stock MAP sensor located on a 2001 f body ls1?....friend of mine has a FAST intake on a ls1 GTO and they put the MAP sensor right on top of the manifold behind the TB.
I have used SD and MAF. Each has 'advantages'. The MAF is limited in the amount of AFGS (Air Flow Grams/second) to ~500 which is said to represent ~500 RWHP.
So if you are using MAF at the point the MAF maxes out you lose the ability to use the MAF to determine that the Air flow changed from say 500 to 600.
Ok I said it poorly I meant to say I have used both Speed Density and MAF.
There is not a mode that I am aware of to be in SD and use the MAF. HOWEVER, what do we call a setup that is in MAF mode, but is locked in open loop?
You can lock open loop by setting the temperature for entering closed loop to say 130 degrees C.
There is not a mode that I am aware of to be in SD and use the MAF. HOWEVER, what do we call a setup that is in MAF mode, but is locked in open loop?
You can lock open loop by setting the temperature for entering closed loop to say 130 degrees C.
Teching In
Joined: May 2009
Posts: 22
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I like sd for a fi tune but its nice to have a decent maf tune for when emissions come around if you gotta deal with it.
This thread is full of bad info...
Speed Density is beneficial when...
1) you max out the MAF
2) you want an atmospheric BOV
3) you want to tune yourself and go boosted
If you have a proper SD tune, you wont go lean when it gets colder or you go down in elevation. The computer has an IAT (intake air temp) multiplier to compensate. Also, your MAP sensor takes altitude out of the equation as its compensating for air pressure
Speed Density takes the air temp, air pressure, and RPM and feeds it into an algorithm with the volumetric efficiency to determine the same value that the MAF is providing. Once the MAF no longer can provide the readings you need, you need to let SD do it for it.
Speed Density is beneficial when...
1) you max out the MAF
2) you want an atmospheric BOV
3) you want to tune yourself and go boosted
If you have a proper SD tune, you wont go lean when it gets colder or you go down in elevation. The computer has an IAT (intake air temp) multiplier to compensate. Also, your MAP sensor takes altitude out of the equation as its compensating for air pressure
Speed Density takes the air temp, air pressure, and RPM and feeds it into an algorithm with the volumetric efficiency to determine the same value that the MAF is providing. Once the MAF no longer can provide the readings you need, you need to let SD do it for it.