MAF

well you do need to go into the computer and change a couple things when you change injector size. But any half decent tuner can do that.

Shakerhood said:

From my understanding the Computer is what is matched to Injector Size, not the MAF!

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The MAF is what tells the computer via voltage how much air the engine is getting, so the computer knows how much fuel to deliver.

Aftermarket MAF's alter voltages (there are two different ways which you can read about here: http://www.mustangworks.com/articles/electronics/InductionBlues.html)

You want to match the MAF Physical size (73mm, 76mm, etc) to the intake/throttle body. You want to match the MAF calibration with the size of injectors you have (24lb, 30lb, etc). As mentioned in the link, Pro M recalibrates sensors; C & L uses the stock sensor and recalibrates via different sized sample tubes.

make your TB the choke point for the air as it enters the engine. there is no sense in having a 76mm MAF sucking air and pushing it thru say a 90mm TB, the TB is only working at like 70% as much as it could.

your engine only flows as good as its least-flowing part. unless you have boost but thats a different deal.

slow5.0gt said:

It is best to match the MAF with the injector size correct? However I have had a mech tell me that it would be best to match it to the intake size type? I have a c&l 76 mm intake with a 70 mm tb does he mean get one that would match the MAF to the 76 mm instead of the 24# injec?

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All you need to worry about now is that the MAF is correct for the 24lb injectors.
C&L uses a sample tube that will alter the output of the FACTORY sensor. (be sure to use your stock sensor with the C&L meter).
Check the C&L site for which tube you need. If you don't have the right one, they are about $25 and available from C&L.

With this setup, you shouldn't need to do anything with the computer.
Keep in mind though that you are using hardware that does not match exactly with the settings in your factory computer. For example you computer will still think that it is running 19lb injectors with a 55mm MAF.
Obviously there is some margin of error involved.
In most applications, the computer is able to adapt quite well. But once in a while the only way to get the car to run right is with a custom tune.

Hope that helps clear things up,
jason

onefstsnake said:

venturi effect FTW.
quote]
WTF?

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Pro-M (GMS / Granatelli Motor Sports offers the MAF meter and recalibrated sensor as a package. http://www.granatellimotorsports.com/

C&L Performance uses your stock sensor with their meter. Calibration for different size injectors is done by changing the sample tube.
http://www.cnlperformance.com/calibration.html

Venturi Effect- This term refers to the increase in velocity of a stream of gas or liquid as it passes from one area through another area of smaller size or diameter. Conversely, if the area through which the stream is passing becomes larger, the velocity of the stream will decrease.

onefstsnake said:

Venturi Effect- This term refers to the increase in velocity of a stream of gas or liquid as it passes from one area through another area of smaller size or diameter. Conversely, if the area through which the stream is passing becomes larger, the velocity of the stream will decrease.

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I wasn't looking for a definition

It's just the this is of little importance when discussing EFI.
Carb's ? - then it's appropriate.

I'm just confused how it relates to EFI.