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Author Topic: Larger MAF options  (Read 18130 times)
16g-95gsc
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« on: April 02, 2013, 11:43:33 AM »

I would like to finish up picking up the parts needed to properly setup a tune.  I am curious if there is any fundamental reason to stay with an 83-85mm MAF housing instead of just going 95mm or so?  Typically I just went speed density on previous cars, so I'm curious if going significantly larger like this poses any issues that I'm not aware of.  Thoughts?
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s5fourdoor
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« Reply #1 on: April 02, 2013, 11:52:43 AM »

Don't run bigger than you need...     what turbos / engine specs?
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nyet
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« Reply #2 on: April 02, 2013, 01:32:44 PM »

Very large MAF housings may not provide stable readings at idle.

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16g-95gsc
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« Reply #3 on: April 02, 2013, 01:58:52 PM »

That's what I assumed was the case.  I'm running K04's, 3" downpipes, SSAC catback, and will have an 044 pump/52lb injectors going in at the same time as the tune. 

I've done a number of custom mil-spec wired standalones in the past.  Is there any fundamental issues with running one on this car other than the obvious DBW throttle setup?  I'm assuming ESP may require feedback from the ECU for example.
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ddillenger
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« Reply #4 on: April 02, 2013, 02:09:36 PM »

That's what I assumed was the case.  I'm running K04's, 3" downpipes, SSAC catback, and will have an 044 pump/52lb injectors going in at the same time as the tune. 

I've done a number of custom mil-spec wired standalones in the past.  Is there any fundamental issues with running one on this car other than the obvious DBW throttle setup?  I'm assuming ESP may require feedback from the ECU for example.

Your setup is well within the comfort zone for me7. I'd consider keeping it, especially if you want to keep your ABS and ESP.
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16g-95gsc
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« Reply #5 on: April 02, 2013, 02:14:09 PM »

Yea, understood.  The complications of tuning an ecu like this vs moving to a dedicated standalone are hard to swallow.  I'm willing to tune the ECU but it always seems like a bandaid compared to being able to ditch a lot of the hurdles that we force ourselves to face.

85mm maf or 95mm?  Any good reason to stick with a RS4 83mm maf vs running a 034 billet adapted B5 S4 unit?
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s5fourdoor
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« Reply #6 on: April 02, 2013, 02:35:47 PM »

id be surprised if you went past the metering range of the rs4 maf using just k04's
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16g-95gsc
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« Reply #7 on: April 02, 2013, 03:02:03 PM »

I doubt I would as well.  However restriction is still restriction.  Why stay 83mm if there are larger options available? Ideally Id rather run SD and ditch the complicated flow paths and open up a ton of options. 
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aysix
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« Reply #8 on: April 02, 2013, 03:06:21 PM »

restriction huh?
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ddillenger
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« Reply #9 on: April 02, 2013, 03:16:42 PM »

I doubt I would as well.  However restriction is still restriction.  Why stay 83mm if there are larger options available? Ideally Id rather run SD and ditch the complicated flow paths and open up a ton of options. 

Larger housing=less resolution at lower volumes. Like everything, it's a compromise necessary to optimize your configuration. You can get a 55 gallon drum, cut the ends off and stick a sensor in it if all you care about is reducing restriction.
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nyet
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« Reply #10 on: April 02, 2013, 03:21:38 PM »

I doubt I would as well.  However restriction is still restriction.  Why stay 83mm if there are larger options available?

This is not a N/A motor. the size of the housing is not a restriction.

Quote
Ideally Id rather run SD and ditch the complicated flow paths and open up a ton of options. 

Contrary to popular belief, running ME in SD does not open up a ton of options. It causes more problems than it "solves" (if by "solves" you mean "I don't have to understand how to tune ME")
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« Reply #11 on: April 02, 2013, 03:28:47 PM »

This is not a N/A motor. the size of the housing is not a restriction.

My spidey senses are detecting a resurgence in the PVC pipe MAFS of yesteryear Tongue
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s5fourdoor
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« Reply #12 on: April 02, 2013, 03:38:34 PM »

what i'm trying to say is that get your car together, get your fueling calibrated, then your boost under control, and then worry about pushing 22+ psi with the rs4 maf.  the s4 maf can handle 300 wheel no problem.  get there first and don't over-engineer.  save your money dude - get the rs4 maf and airbox, or some other type of airbox, and you can run those k04's to their absolute breaking point if you want...  you'll have no resolution issues if you stick to the rs4 maf...
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16g-95gsc
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« Reply #13 on: April 02, 2013, 03:39:39 PM »

This is not a N/A motor. the size of the housing is not a restriction.

Contrary to popular belief, running ME in SD does not open up a ton of options. It causes more problems than it "solves" (if by "solves" you mean "I don't have to understand how to tune ME")

Not sure why you think NA or turbo engines are that different.  Reduce restriction prior to the turbo and you reduce the ultimate pressure ratio across the compressor and are able to maintain higher boost levels without running into the overrun/inefficient regions of the map.  The turbo will reach desired boost regardless (if it can) with a slight inlet restriction.  However, it will operate more efficiently, produce less heat (something certainly more desirable with most of our stockish intercoolers), and not require the shaft speed to increase to dangerous levels (prime example is K03's and their failure rates at high boost).

I am not saying SD with ME, I am saying the idea of running simple single inlets to each turbo.  
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nyet
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« Reply #14 on: April 02, 2013, 03:44:55 PM »

I've tuned cars with just about every MAF there is, and the MAF diameter is not a significant source of restriction, compared to the rest of the way the intake is plumbed. And if you go open element right in front of the MAF housing, you'll be wasting time fighting non-linear MAF readings rather than tuning for power.

OH, and while you are at it, you are going to fab completely different inlet pipes, right?

Oh, and, what is the diameter of the inlets of this mythical K04 that is restricted by MAF diameter? You know, the ones with inlets >72mm?
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Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
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