NefMoto

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?

Don't run bigger than you need...     what turbos / engine specs?

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

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.

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?

id be surprised if you went past the metering range of the rs4 maf using just k04's

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. 

restriction huh?

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.

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")

My spidey senses are detecting a resurgence in the PVC pipe MAFS of yesteryear :P

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...

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.  

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?

I think you guys are misunderstanding me.

I am not looking to over-engineer the setup.  The question was simply what MAF housing do you find to be best to work with.  The idea of SD is undeniably less restrictive than any inlet setup (no I am not simply talking about JUST the MAF, I am speaking of the whole system). 

Nyet, that brings up another thing that I was curious about.  Do you find heavy non-linearity with cone filters even with MAF screens in place?

Blowthrough is an alternative compromise you might also consider..


Yes, depending on the length of the inlet before the MAF. Screens do help to some extent (see also AWE's 100mm MAF that reads like an 85mm MAF :)

But a long inlet *and* a screen can get you close... at least close enough that massaging it out in KFKHFM isn't difficult.

The way this setup is CRAMMED into the engine bay I just don't see how blow through is possible without severe modification.

Then you're stuck with SD, or a lot of time on the dyno calibrating your MAF :(

This is a ludicrous discussion to be having for k04's. You're making an issue where there isn't one. Pretty much ANY 85mm off the shelf MAF will work fine in your application. If you want a known transfer function, get an RS4 or S6 unit.

^^^ Agreed, not even sure why this is being discussed... an 85mm MAF will prove the Op with all the resolution he would need on a K04 setup w/o being a restriction.

Also SD being Speed Density?

Can I ask once and for all... can/does ME7 even really do SD?  I was always of the opinion that ME7 cannot do true SD... and that it uses tables of modeled airflow when running w/o a MAF.  That is not SD.

Or am I missing something here and there is a way to use the MAP sensor as a load input to replace the MAF?

Nope...without MAF input it basically switches to Alpha-N.

I would recommend looking at it and seeing how it actually works...
It does use the charge pressure sensor signal to scale load, but this can only be done at WOT realistically.

The problem is that ME7 with a HFM has a charge pressure sensor, not a MAP sensor.
A MAP sensor refers to Manifold Absolute Pressure. But the sensor is a charge pressure sensor before the throttle plate.

To run speed density, a second sensor, an actual MAP sensor must be installed and fed from the manifold, routed into the MAF signal on the ECU and then the ECU needs to have it's code re-written.

Right, that makes perfect sense about the pressure sensor situation.

So in the end, removing ME's primary load input (MAF) is just silly regardless if it can be "made to work" and if you look around more and more "tuners" do not offer MAF-less anymore because it's just a PITA and will never run 100%.  The Alpha-N maps in the ECU are there as a fail safe/limp home situation, not to get around tuning/driving without a MAF completely.

Correct, that's why I am working on a real MAFless solution, not limp mode.
I already have this on an older Bosch ECU and it works perfectly, but it's a different architecture and works very differently from ME7, so while I know exactly how to write the algorithms, it's a different story with putting them in the right spot for ME7 :)

No doubt, I'll be looking forward to your progress... hopefully you will share with us your project experiences (not asking you to share your code) to see how you get on with it.