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Speed Density vs Mass Air Flow

Discussion in 'The Garage' started by sled_dog, May 18, 2005.

  1. sled_dog

    sled_dog 1 ton status

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    TPI of course. Is there an advantage to either? I am going Speed Density(cause it was a cheap computer I got), just wondering what the advantages of either would be. In class we were discussing both setups and my teachers were insisting that Speed Density is the worst setup for testing air flow/load.
     
  2. BobK

    BobK 1/2 ton status

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    Well MAF system meters the fuel delivery by ACTUALEy measureing the amount of the air coming in.
    The MAP system calculates the fuel delivery via the readings taken from the various sensors,mainly the MAP sensor and useing Fuel tables the right amount of fuel is delivered.

    MAF is a little more forgiving with "modified" engines.

    MAP or speed density is a great and easy retro into a basic or unmolested SBC350 or 305.No issues trying to route the MAF sensor.
     
  3. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    The bad part of MAF sensors is they're killed by vibration and foreign particles like sand or dirt... probably not a great choice for a 4x4.

    Like bobk said,
    Both setups use throttle position and rpm for their tables, but..
    MAF measures the incoming air into the engine... Speed Density calculates how much of a load the engine is under by the Manifold Absolute Pressure.
    Yah the Speed density is bad at measuring airflow/load because it's calculating based on a table (your chip) and the reading from the map sensor.. Its trying to calculate how much air is entering the engine based on the pressure in the manifold.
    Keep the tpi motor all stock and you're probably doing great, but add a cam and this is where you need someone who can tune your setup to make it ideal... otherwise you get a chip to get it in the ballpark.
     
  4. sled_dog

    sled_dog 1 ton status

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    eh I need a chip no matter which way I go so screw it.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Then go MAP.

    MAP sensor is about $40, MAF is somewhere in the $150+ range. Easy choice for me, especially since chip burning is in your future regardless. My MAF needs a chip burned, so just because it's MAF doesn't mean it is going to adapt to everything. Engine changes from stock are going to affect either setup and require a chip to get the most out of it. There are quite a few things that need changed in my PROM, even though the truck runs and drives. (well, when I'm not breaking other parts)

    Everythings pretty much been covered. MAF DEFINITELY makes cold air induction a bigger hassle.

    Probably back to back, similar vintage, you won't get much argument that MAP is better...more refined, more capable. When my MAF dies (again) I'm going MAP, it's fairly simple to rewire the MAF harness for MAP.
     
  6. Thunder

    Thunder 3/4 ton status

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    IMO for a 4x4, a SD (MAP) system is the best. ( MAF systems do not like water, dust,and dirt.)
    Map systems only drawback is you are limited in your camshaft choices without chip work. Also they are hard to run with high PSI boost. They Dont work to well over 6PSI.

    For a street car or turck I like MAF systems. You can run more cam and other mods with a MAF system without needing a new chip or reprograming. The stoch chip with an adjustable FPR will usually handle most cams and mods untill you get to the point where you need bigger injectors. Then a recalabrated MAF and chip work ar in order. MAF systems also handle supercharger/turbos a lot better than MAP/SD systems.
     

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