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2byte airflow limit?

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Old Dec 16, 2008, 09:26 PM
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2byte airflow limit?

Sorry I searched and couldn't find specifics, or I didn't search well.

Either way...

Anyone know the Hz limit on the stock MAF? Hit 3200hz on a car today and I would like to know how little/much headroom it still has.
Old Dec 16, 2008, 10:04 PM
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yikes... big turbo huh?

no idea on the limit - jcsbanks or mrfred is undoubtedly know
Old Dec 16, 2008, 10:08 PM
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Originally Posted by tephra
yikes... big turbo huh?
indeedy:

https://www.evolutionm.net/forums/ev...-e85-army.html
Old Dec 16, 2008, 10:14 PM
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well if you hit a ECU limit you should see it plateau to a fixed number (or perhaps suddenly roll over to a tiny number)

if its not flatlining then its not limited.
Old Dec 16, 2008, 10:19 PM
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Originally Posted by tephra
well if you hit a ECU limit you should see it plateau to a fixed number (or perhaps suddenly roll over to a tiny number)

if its not flatlining then its not limited.
yea it's not flatlining, just want to know how much more room there is.
Old Dec 17, 2008, 06:19 AM
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I think you will get to a functional limit before you ever get to an ecu limit. Let me search through the DSMLink forums to see what numbers those guys are getting on the Evo MAF. When I used to frequent that board years ago, there were plenty of people maxing out the stock 2g MAF and had datalogs to show it.

From what I remember, the signal would just become very unstable and choppy and start causing erratic airflow readings. That's why DSMLink implemented a 'fake maf' code which basically was a speed density system after a certain maf hz value, which was then controlled via a VE table.
Old Dec 17, 2008, 06:50 AM
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Wow that is a gorgeous dyno chart.

I am with l1r99gst. you will most likely hit the physical limit of the MAF. You may want to talk to Mellon, i know he is has a lot of experience in this area.
Old Dec 17, 2008, 06:58 AM
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Bryan,

I couldn't find too much info on the DSMLink board anymore. Most guys that are still using Mitsu Mafs use the maf clamp feature within DSMLink.

What I gathered was that the 2G Maf start missing/dropping counts somewhere around the 3000Hz mark. The Evo Maf, I would assume, should be in the same neighborhood, maybe somewhat higher.

From what I read, the way to tell is just to look at your datalog and notice any places where the MAF reading seems to drop a bit, then come back up. It will start to do this more and more, until it drops a lot, then comes back.

Either way, I would think you are close to the max stable readings, but that's just a guess. Just keep an eye on the Hz readings and AFR readings.
Old Dec 17, 2008, 07:07 AM
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That jives with this page from the DSMLink nee ECMLink wiki...they estimate 20-30% additional metering capacity.
Old Dec 17, 2008, 08:36 AM
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I haven't been logging airflow...sorry, maybe I can do that when I get the tranny back in.
Old Dec 17, 2008, 12:00 PM
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I don't know how to do the fancy Excel graphs like Bryan but here's a screenshot of the log.

Attached Thumbnails 2byte airflow limit?-load_airflow.gif  
Old Dec 18, 2008, 07:25 AM
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how much whp is it making while it made that log?
Old Dec 18, 2008, 11:05 AM
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3rd gear pull
https://www.evolutionm.net/forums/ev...-e85-army.html
Old Dec 18, 2008, 12:13 PM
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Originally Posted by MR Turco
Wow that is a gorgeous dyno chart.

I am with l1r99gst. you will most likely hit the physical limit of the MAF. You may want to talk to Mellon, i know he is has a lot of experience in this area.
+1
Old Dec 18, 2008, 04:28 PM
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It should be "At what Hz does the aluminum honeycomb collaps on itself?"

It would be nice to see the full log of the 500+ car to view rpm vs time


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