Measuring LT1 MAF? 3" or 3.5"?

[YGETV8]

Silly question: do you just measure the outer diameter of the housing, or is there more to it? I bought one some time ago, and the O.D. is 3.5", but it sure "necks down" in the I.D.? Just ordered a T+ and want to make sure I'm off to a good start when it arrives! Thanks,

 

[bruce]

What size tubing does it take to mount it?,
is the sensor size.


The inner areas around the actual sensors are the same.

 

[YGETV8]

<<What size tubing does it take to mount it?,
is the sensor size.>>

It is 3.5" on the outer diameter, so I guess that is what it is!

<<The inner areas around the actual sensors are the same.>>

So, why did I bother getting a 3.5"?!?!

 

[99Formula]

The LT1 MAF is supposed to be 3, and the LS1 3.5. I have the LT1 on my car, and I can fit a 3" tube INSIDE of it with room to spare. I thought the stock maf was 3" and assumed the LT1 would be the same size and a direct bolton. I ended up having to run out and get a couple of Fernco 3.5" couplers to mount it.

Peter

 

[bruce]

Originally posted by YGETV8
So, why did I bother getting a 3.5"?!?!

The calibration between the two is different.
That's why I said just the area is the same.

Use the wrong sensor with the wrong housing and you can have dodo.

 

[TurboDave]

Hmmm. My 3" LT1 (not the F body LT1), and my 3.5" LS1 sensors ARE NOT the same inside! Not even close. the difference inside is the same as the difference outside.

Hence the extra flow. These MAF's have already been flow tested extensively. Although I can't remember who did it
The differences were substantial.

 

[UNGN]

1320 tested them a few years ago. The 3.5" flowed around 200 CFM more than the 3". Removing the screen gave around 100 CFM to each. Using ported, airfoiless ends gave the 3.5" less than a 100 CFM improvement (not the 400 CFM that vendors claim AND it will screw up the calibration to the lean side)

With slight mods a 3" can be made to flow over 800 CFM: Remove the screen, Blend the screen ridge and put a 3.5" to 3" bellmouth on the opening (and use a 3.5" opening filter). This won't screw up the calibration. Doing similar mods to a 3.5" but using a 4" to 3.5" bellmouth should result in over 1000 CFM flow.

Jay, you could probably whip something up in a couple minutes

 

[YGETV8]

<<Jay, you could probably whip something up in a couple minutes >>

Already removed the screen and ported the MAF as you described, and am going to machine a bellmouth for my air filter (one of the ones with the "reverse cone" on the end).

Thanks for the info! Jay

 

[salvageV6]

Stupid question but I'm good at it.

How much airflow do you need for a 500 HP. motor?

TIA

 

[RobR]

All V8 F-Body MAFs, LT1 and LS1, are 3.5". The B-Body MAF were 3".

All '94-'02 F-Body MAFs are 3.5". The calibration is different between the LT1 and LS1 MAF.

 

[Dan Thompson]

The GM part number for the 3" is 25180303.