LSx MAF questions

[Shiwnath]

Just 3 questions...

1.) Since I have a 65mm TB and a Ported UIM, would I benefit from getting tuned for and upgrading to an LS1 MAF? I did see Redog's MAF upgrade thread and it kind of sparked a little bit of curiosity for me.

2.) Considering the LS6 MAF has a built in IAT sensor, would this be a better solution than having a separate MAF and IAT. I Found a harness adapter from casper that looks like it would work:
http://www.casperselectronics.com/st...oducts_id=1072

The only issue I see with this MAF is that it's 85mm in Diameter as opposed to the 75mm LS1 MAFs. 85mm seems much too big for a 3400. I just thought that the IAT being a separate unit would cause a very mild restriction in airflow and would cause some sort of turbulence.

Edit: I've read that the LS1 MAF is also 85mm so now I'm VERY confused.

3.) If I was to switch to an LS1 MAF, what intake piping diameter should I be using?

Any thoughts?

[sleepyalero]

i put a stock LS1 maf from my buddies ws6 on my car. cold air barely fit over it but it worked. car ran like shit though. so i put the stock one back in.

[Shiwnath]

I'm going to assume you didn't tune for it lol. You can't run stock MAF tables on an LSx MAF.

[MMGT1]

not needed, unless you cap your stock one I would leave it as is bud. Our MAF caps at 11,500Hz and I hit 11,375Hz with the charger on my built engine!

Really, it takes a helluva naturally aspirated build to max out a stock MAF.
If using forced induction, that's another story.

[WhiteV6]

I have the LS1 on my 3.4 DOHC, but I also have a 75mm TB. More cross section gives less restriction to flow. You have a screen that restricts flow, so you don't have as much power as a car without the MAF. Has nothing to do with running out of flow as much as it does relieving restriction. What it gives performance wise, I couldn't tell you.

[Redog]

I tuned for it, I only bought it because my old one broke

[MMGT1]

The screen is a necessary evil though guys. It actually smooths flow over the sensor making the accuracy of it's readings much more reliable. Guys have tested this by using a plexi glass tube with different MAF set ups in it. Then use smoke to visually see what effect the honeycomb has on it and its' reported Hz. They found that the amount of flow that was reduced was next to nothing, but the results in accuracy of fuel delivery and stability of the engine at idle, far out weighs the flow change between the two. There is also a company now that makes the honeycomb that you can "tune" your MAF with. Different cell counts and length allows you to perfectly match minimum flow restriction against the smoothed air flow. Ive seen the results myself, and I would say that any of you that are using a MAF, and have removed the honeycomb, that you replace it.

[WhiteV6]

I didn't say to remove the screen, jus that it there, and a restriction. Its hard to say if the 5hp gain from removing the MAF screen on a 95 3.4 DOHC was from a fueling change or the restriction being gone. When it comes to comparing flow, you should use a flowbench. Until someone cares enough to do that, ill stick with going larger = less restriction. If you want to remove it, tune for MAP and disable/remove MAF. That is what OBD1 is anyway

[MMGT1]

Yup, bench flow has been done by Greg Banish I believe it was. I'll find a couple of links for you guys to check out. This came up in great detail on HP about two years ago. Some really cool stuff if your into this type of thing! SD tunes are ok if you are a manual as well, but in the auto's its a nasty result. Removing MAF results in SD mode and trans will tear its' self apart. Program puts shits to full line pressure and the bang in gears is insane! I have had a few convo's about the SD vs MAF tune and the end result seems to always be that a MAP sensor cannot adjust for change as quickly as a MAF. Using a combo of the two sensors is the way to go for best driveability and performance.

[AleroB888]

Originally Posted by WhiteV6

I have the LS1 on my 3.4 DOHC, but I also have a 75mm TB. More cross section gives less restriction to flow. You have a screen that restricts flow, so you don't have as much power as a car without the MAF. Has nothing to do with running out of flow as much as it does relieving restriction. What it gives performance wise, I couldn't tell you.

I had that same combo on my track car, and it definitely flowed more air, but the tranny broke at the track the first time I ran it. I did have to position the MAF straight into the TB to get the full benefit. I miss that setup!

[Shiwnath]

I understand what you guys are saying and I know that I'm not anywhere near maxing out the MAF itself, but with only a 65mm TB and a ported UIM, obviously the LIM and cylinder heads being un ported will cause a bottleneck effect right? Would there even be a point to going with an LS1 MAF in order to prevent the MAF from being flow restrictive when you consider that there's already a pre-existing bottleneck?

Also how do you guys feel about having a separate IAT and MAF as apposed to 1 unit? Would having it all in one be better for air flow considering the IAT being a separate unit might cause more turbulence as apposed to all-in-one? Obviously I have no proof to back up my claim, just an assumption. From what I see, having it as an all-in-one unit makes the intake less restrictive, but I'm no expert on the subject. Thoughts?

[WhiteV6]

You can disable the codes so the trans shifts fine without the MAF.

The G6 guys run a separate IAT because the stock one heatsoaks like crazy. Of course, thats a G6, so who knows if its going to do so on an N body. Their intake tube goes all the way around the front of the engine bay to the passenger side. A MAF is only useful for cams that provide no vacuum at idle or low speed. Practically useless for ITB where alpha-n takes over. MAP is more accurate for depression changes at the intake valve. Each has its advantages, but I wouldn't say MAF is important for performance.

You can always say "this is stock, so why mod that". No one has dyno results or flow comparisons. It stands to reason that the more modded you are, the more a larger MAF will help. 65mm TB will notice more than a 56mm, if there is a gain to be had from TB size alone. If the MAF is smaller than the TB or the exact same size, then I would say its important to go larger.

Id like to see what Greg found out on the bench. We can do the same thing once our vac source is complete. New bench will do over 700 CFM accurately.

[sleepyalero]

yeah i did not tune for it.

[MMGT1]

Looking for the picks I know were posted on HP, but here is a starter for you guys to read...

http://navier.stanford.edu/bradshaw/...nelconfig.html

[MMGT1]

And some testing:

OK, I installed a couple of the samples that Jason sent (thanks Jason!). First I did a baseline (honeycomb-0), then I installed the 4:1 ratio sample (honeycomb-4), then I removed that and installed the 5:1 sample (honeycomb-5). I didn't use the plastic 6:1 sample because my intake tube has a dent in it from ECS to clear the radiator and it deformed the metal samples somewhat (pics tomorrow) so I didn't think the plastic 6:1 sample would like being deformed like that. I only scanned RPM and MAF Hz to get a good sample rate, I commanded 1200 RPM's with VCM controls (as high as I could command in the latest beta) and let it run for a minute. I set up the test config's histo #12 to display the MAF Hz right around 1200 RPM's and I looked at the average frequency, lowest and highest frequencies recorded. the high-low is what I'm looking at.

No honeycomb:
RPM Avg Low High High-low
1190 2539 2024 2949 925
1200 2526 2031 2920 889
1210 2544 2105 2930 825
Average frequency=2536
Average high-low=880

4:1 honeycomb:
RPM Avg Low High High-low
1190 2606 2147 2987 840
1200 2659 2379 2891 512
1210 2655 2407 2969 500
Average frequency=2640
Average high-low=617

5:1 honeycomb:
RPM Avg Low High High-low
1190 2591 2152 2883 731
1200 2596 2280 2898 618
1210 2593 2318 2860 542
Average frequency=2593
Average high-low=630


There may be a better way to do this but this is what I whipped up. The average high-low went down significantly with the honeycombs installed so the it definitely made a difference and the difference between the 4:1 and 5:1 ratio didn't seem very notable.

The average frequency actually went up with the honeycombs installed which would indicate an increase in airflow but I believe this is erroneous. Maybe if I was logging VE airflow that would have been a better representation of whether the honeycombs reduced airflow.

[MMGT1]

Crude mock up but it will clearly show what I'm getting at

Without Honeycomb: http://i823.photobucket.com/albums/z...ohoneycomb.jpg
With Honeycomb: http://i823.photobucket.com/albums/z...hhoneycomb.jpg

[AleroB888]

Originally Posted by MMGT1

And some testing:

OK, I installed a couple of the samples that Jason sent (thanks Jason!). First I did a baseline (honeycomb-0), then I installed the 4:1 ratio sample (honeycomb-4), then I removed that and installed the 5:1 sample (honeycomb-5). I didn't use the plastic 6:1 sample because my intake tube has a dent in it from ECS to clear the radiator and it deformed the metal samples somewhat (pics tomorrow) so I didn't think the plastic 6:1 sample would like being deformed like that. I only scanned RPM and MAF Hz to get a good sample rate, I commanded 1200 RPM's with VCM controls (as high as I could command in the latest beta) and let it run for a minute. I set up the test config's histo #12 to display the MAF Hz right around 1200 RPM's and I looked at the average frequency, lowest and highest frequencies recorded. the high-low is what I'm looking at.

No honeycomb:
RPM Avg Low High High-low
1190 2539 2024 2949 925
1200 2526 2031 2920 889
1210 2544 2105 2930 825
Average frequency=2536
Average high-low=880

4:1 honeycomb:
RPM Avg Low High High-low
1190 2606 2147 2987 840
1200 2659 2379 2891 512
1210 2655 2407 2969 500
Average frequency=2640
Average high-low=617

5:1 honeycomb:
RPM Avg Low High High-low
1190 2591 2152 2883 731
1200 2596 2280 2898 618
1210 2593 2318 2860 542
Average frequency=2593
Average high-low=630


There may be a better way to do this but this is what I whipped up. The average high-low went down significantly with the honeycombs installed so the it definitely made a difference and the difference between the 4:1 and 5:1 ratio didn't seem very notable.

The average frequency actually went up with the honeycombs installed which would indicate an increase in airflow but I believe this is erroneous. Maybe if I was logging VE airflow that would have been a better representation of whether the honeycombs reduced airflow.

Good info!

My limitation was not being able to run optimum MAF and filter tubing sizes in the available space. I always use "honeycombed" units. The transition from MAF to TB seems pretty critical, at least in my boosted setup.

What I found on testing was that before, I measured 3 - 4.5 in hg vacuum at the SC inlet, but after mounting the MAF straight into the TB, 0.5 - 1 hg, almost no vacuum. The MAF frequency Hz on the scans was a couple hundred Hz higher, and fuel demand increased. But also after doing that, I ran out of room in the engine compartment to route unrestrictive intake tubing to the filter, so it was not practical on the street.

[MMGT1]

I am installing the "Card Style" MAF in mine now, so I will make use of that connector listed. It's a nice find for those that do need it!

[WhiteV6]

If no honeycomb = inaccurate, how can you use the MAF frequency to compare airflow? Mind you, I am only interested in MAF vs MAP flow comparison at this point, to keep it simple.