Good rule of thumb but also dependant on what is upstream of the maf.

If there are maf problems I'd suggest trying to lengthen the scace between the filter and maf, using a straightening screen, and or incorporating an airhorn or one of the filters on the market that includes air straighteners (i think apexi has something like that off the top of my head)

 

Maybe, but there is no way I'm putting an air horn on my setup. I plan on using a screen at the mouth of the MAF tube if necessary but I was hoping that by choosing the proper length and size for the MAF tube that I would not need it.

 

Length from the inlet to the outlet with the MAF centered and perpendicular to the flor.
As r0tor notes, what happens before and after can affect what the MAF sees.
Necking it down before the MAF with a smooth transition will have a less adverse effect than dropping the diameter afterwards.

 

I was thinking more along the lines of the General Lee.

 

I think the revi pipe/filter/horn can be made to fit. and run one screen .I think I am headed that way.
WHo all have widebands(MM I know you have). I am installing one VERY soon--recommendations? Innovate? Summit wideband, AEM? What values are Pettit people seeing?
Anyone heard of Rick Engman?
oscd

 

From my fluid dynamics days a good rule of thumb for fully developed laminar flow in a pipe is a Length to Diameter ratio of ~8:1. Based on that to get smooth flow across the MAF sensor (I assume this would be the most accurate) in a 3" pipe you would want 24" ahead of the MAF. That's probably why the screen is there, to artificially smooth out the flow ahead of the MAF since 24" is a bit impractical.

 

thats good info shaun keep it coming--with the flash we need to pay attention to the maf
oscd

 

im using an autometer cobalt digital wideband..nuthin fancy...but its easy to read.

 

shaun - r u saying that using an AEM CAI (or something similar) would help with increasing the distance to the MAF?

 

I've got an Innovate LC-1. I will be mounting mine in the catback to hopefully keep it from burning up.

 

aem uego here. mounted in the midpipe. No issues with 14k miles turbo, original sensor is OK.

 

I wonder if all major brand widebands are sorta created equal? AEM, Innovate, Auto Meter, Summit ,NGK etc.
Summit (about 45Miles from my home) has a digital readout wideband (bosch sensor) for $249--software etc-- all are included. looks like the Innovate one.
What a/f's are yall seeing?
oscd

 

All of the above WBO2S use the Bosch LSU4.2, 5-wire sensor.
So, it just comes down to features and accuracy of the driver "box".
FordMuscle compared the Innovate LM-1 (which is what I use), AEM, Dynojet, FAST, FJO, NGK, PLX & Zeitronix units against each other. The LM-1 came out on top.

The Autometer is pretty much just for show - its calibration routine sucks and they've been shown to be as much as a full point off in either direction from day to day in different ambient conditions.

I've got more than a couple of posts with details on what your target A/Fs should be.

 

249 isnt bad for a wideband...mine ran me about 369

ive got my sensor on the mid pipe up front..

are all autometers create equal?

 

Yeah, unfortunately, they are to some extent.
I used to love their stuff - I had the Phantom series in my last car - but they are junk.
Especially the "high-end" WBO2S and EGT gauges.

 

*** Crawls under table.....***

I'll have to run some testing on my Autometer stuff and see if it really is that bad.

 

Why are you guys installing the wideband after the cat? (where you have one)

The cat changes things, that is why the factory WBO2 is before it. Anyway - you got a perfectly good WB02 sensor already!!

Cheers,
Hymee.

 

Who put it after the CAT? I missed that.

The OE wide-band is a bit non-linear at the rich end. It tends to read progressively less rich than reality below 11.5:1 or so.
Plus, you can't datalog it without dealing with the CAN bus stuff.
A nice voltage output is an excellent thing to throw at your engine management.
If and when your flash programmer becomes viable, then it will be a whole different can of worms.
Until then, the OE sensor is just a curiosity.

 

No one has done this past the cat! Where did that come from?
I think i will go with the Summit version--it appears to be the same thing Innovate has--same o2 sensor, same gauge front, even comes with the innovate software!
oscd

 

WHoa back up--just read MM post on the comparison study. Looks like Innovate is the way to go--so ordered one at $289.
oscd

 

how would we do that??

 

I got your back Shinks!!!!

I'll get an Innovative one and cross compare; and let you know.

 

i just cant imagine that there would be that big of a difference...

 

I would LIKE to think not - but Jeff can be annoyingly; maddeningly; emptying-my-wallet-y accurate! HAHA

I will log them both as inputs off the same Bosch sensor and run it through my software to see if

1 - They are close
2 - They are off; but a consistent amount
3 - The behavior is so random as to not be predictable

If it is either 1 or 2; they you can decide whether to live with it or not - if it is three; then I will for sure be taking mine out.

 

Turbulant flow has a more uniform velocity profile then laminar flow and it a more efficient way of transporting stuff through a pipe. Fully develped turbulant flow is fine for measureing - easier to measure accurately actually. Its transitional flow full of votexs and uneven distributions that will kill a measurement. So usually you can get away with 3-5 diameters upstream/downstream or less when using straightening devices.