robin
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« Reply #15 on: February 18, 2011, 03:17:10 PM »
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How about you don't do that. I'm sure you'd have no problem coming up with it on your own, right?
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Tony@NefMoto
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2001.5 Audi S4 Stage 3
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« Reply #16 on: February 18, 2011, 03:23:09 PM »
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EPL. Since EPL has successfully incorporated the 360deg maf linked above, it sounds like this would be way to go. According to these people, it can reliably measure air up to a vicinity of 800HP which is more than anybody sane would need on 2.7t engine. All we would need is the maf map for it  . Can we hijack EPL tune to get it? You can buy the MAF map from the company that makes the MAF. Or, you can just figure out the MAF map yourself with some testing. |
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blundar
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« Reply #17 on: February 18, 2011, 04:26:38 PM »
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Probably a ProM MAF ...
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NOTORIOUS VR
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« Reply #19 on: February 19, 2011, 12:54:51 PM »
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Other tuners are using the stock Hitachi sensor with 85 or 90mm housings and making 600+whp... Are they just underscaling the MAF then?
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julex
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« Reply #20 on: February 20, 2011, 02:39:54 PM »
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Other tuners are using the stock Hitachi sensor with 85 or 90mm housings and making 600+whp... Are they just underscaling the MAF then?
The real problem is that you're running out of values an ECU can read when you approach such WHP figures with 90mm MAF. What happens is that there is so much air going through the MAF that its readings go over 5v....which is the ceiling for ECU. Anything higher than that registers as 5v...regardless if it is 5.5v or 6.0v. The wider tha gap, the more unaccounted for air is in the system causing you to go lean. To date a way to go around it was to make some dyno runs at WOT and massage correction table for MAF and call it a day. EPL (finally) approached if from the right end and implemented that POM maf that can read much higher air velocities without losing low end resolution. It still reads 0-5v but when it indicates 5v, the actual flow is much higher than what 90mm with Hitachi elements measures at that voltage... |
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nyet
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« Reply #21 on: February 20, 2011, 11:29:22 PM »
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EPL (finally) approached if from the right end and implemented that POM maf that can read much higher air velocities without losing low end resolution. It still reads 0-5v but when it indicates 5v, the actual flow is much higher than what 90mm with Hitachi elements measures at that voltage...
Does the POM MAF have a non-linear transfer function? |
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julex
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« Reply #22 on: February 21, 2011, 09:24:38 AM »
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EPL (finally) approached if from the right end and implemented that POM maf that can read much higher air velocities without losing low end resolution. It still reads 0-5v but when it indicates 5v, the actual flow is much higher than what 90mm with Hitachi elements measures at that voltage...
Does the POM MAF have a non-linear transfer function? No idea... but almost all mafs are non-linear and in their description/order page they talk about non-linear transfer function so I guess it is a "yes". |
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nyet
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« Reply #23 on: February 21, 2011, 01:29:39 PM »
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No idea... but almost all mafs are non-linear and in their description/order page they talk about non-linear transfer function so I guess it is a "yes".
Err, i should say, even MORE non linear than stock? |
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julex
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« Reply #24 on: February 22, 2011, 08:40:31 AM »
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No idea... but almost all mafs are non-linear and in their description/order page they talk about non-linear transfer function so I guess it is a "yes".
Err, i should say, even MORE non linear than stock? Definitely. I mean it supposedly can measure far more air mass than any other MAF currently available for S4 so in order to accomplish this and still not lose low-end resolution, it needs to compress high end reading into fairly narrow voltage range resulting in much steeper curve. I am currently in talks with LOBA (european tuner out of germany) who has 100mm MAF in their offerings. It is not the cheapest option by any shot (almost 200 pounds), but seeing that there really is no other option while still preserving Hitachi maf, I might go that route... |
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julex
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« Reply #25 on: March 09, 2011, 09:12:23 AM »
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I changed directions a bit. PMAS HPX slot style MAF sensor is de-facto one of the best on market and used all over the scene on high powered cars. It can support up to 750whp on a simple 3" maf and ramping up from there. I think this will be my new setup: 3" or 3.5" MAF housing with honeycomb screen option: http://www.treadstoneperformance.com/product.phtml?p=1289&cat_key=467&prodname=MAF+Mass+Air+Flow+Adapter+Pipe%2C+Nissan%2C+FORD+and+GM%2C+Hitachi+StyleSensor: http://www.vmptuning.com/store/index.php?p=product&id=193&parent=30Sensor come with application that will generate necessary maf curve. I am not sure if the curve will be suitable for ME map as it needs 512 values for 0.01-5.12 volt range, but even if it isn't here is the software that will do this for you pretty accurately (the more points you have the better): http://www.curveexpert.net/Download evaluation version, import or type in your X,Y points. Hit "Apply Fit", "nth order polynomial", choose between 4th - 6th order (best results) and once you get the graph, right click it and choose generate table. Enter 0.01 for minimu, 5.12 for maximum, 0.01 for increment and output to table... voila. You might have to massage the table near 0.01 voltage but otherwise it is pretty nicely interpolated. I will report back once I get it all up and running. |
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judeisnotobscure
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« Reply #26 on: March 09, 2011, 09:36:30 AM »
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This sounds nice, I'm in for results.
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I have a b5 s4
but i just want to dance.
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Rick
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« Reply #28 on: March 09, 2011, 05:27:04 PM »
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Why not use just use the MAF on one of the turbos and double the transfer function values?
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julex
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« Reply #29 on: March 09, 2011, 08:20:45 PM »
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Why not use just use the MAF on one of the turbos and double the transfer function values?
That's a bad idea, b/c no one turbo works with the same efficiency, that's for one - so one would pull more air than he other as it is almost impossible to set wastegates exactly the same. But the real problem is with plumbing in our cars. you'd have to redo the PCV system to not return blow-by gases to accordion/Y-pipe anymore as you'd be metering this air now if you had the MAF on one of the turbos. This assumes it was still on "sucking" side of plumbing. Re-doin the current set up with a MAF th can actually meter more air is the way to go as proven over and over. |
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