Hey Guys

After reviewing the EU manual cover to cover, both of them, I'm really taken by the dual MAF (ala RB26DETT) option. I'd be great to use it on our TT setups; dual pre-turbo MAFs, the way tthey were always meant to be used. This may very well be worth it, and in principle is definitely the way to go.

However, the manual was very scant on the details. In fact, when you look at the wiring diagram, it shows the wiring of this setup to interrupt the two MAF signals coming from the sensor, but only a SINGLE MAF lead going back to the ECU from EU. How is this supposed to work, assuming even that we are in fact using this on an R34 GT-R? The ECU is still expecting dual MAF inputs, correct? On teh other hand, that wiring diagram does work very well for us, where we are trying to adapt dual MAFs in a single MAF ECU car like the Z/G.



Any thoughts?

I am already working on what is probably a very accurate map, an 'Airflow Output Map' that can output a simulated MAF voltage for the stock ECU, i.e. to simulate a 'normal' MAF output (for which this map is intended) from our custom dual or even single pre-turbo MAP.

Also, there are no details on what this dual MAF option does. Does it simply use one of the inputs and do all the mapping using one input (and just use the fact that we have two MAFs as a fail-safe, sending the car into limp mode in case one fails), or does it somehow combine the two inputs into one(far less likely, since I am not seeing any available maps in the EU windows program).

Does this option even work? ANy contacts at Greddy/TRUST that we can talk to about this?

 

i think it might take both signals and send the avarage to the ecu.

 

what size/type of MAF would you think of using on our cars if you went dual?

 

dual stock MAFs of course. thats what i got

 

exactly. Dual stock MAF...should be plenty...in fact if you think that the turbos will have on average 75% efficiency at 0 boost and above, you should theoretically have range of AT LEAST 20psi. In reality, the efficiency is not that high, so your range is likely to be a little higher than that.

 

It's not this simple, i do not think. I guess I will find out long enough.

 

Hmmm...

Maybe it takes both signals and then reports both signals... out of phase.

 

Not sure.. it's an analog 0-5v output, so the phasing doesn't apply, correct? I am not an EE, but with a simple analog 0-5v output, i belive that's the case. We won't really know until we strap that second MAF, with the stock MAF still in it's own place. That's when well have to do some exhaustive logging...thanks to LogWorks, such an undertaking is as easy as it gets.

I cna already forsee the experiement.

 

How about an EU for each MAF/side?

OK. I'll be quiet now.

 

Lol ^^^^

 

wiring schematic of the r34 should tell alot. i could only imagine the eu to take one signal for reference, then have a diagnostic code or "blinking light " if the other does not match.
just shootin ideas hear.

 

Could you shed some more light on the subject? and why would you want twin MAF if you have a stand alone using MAP?

Thanks,
Az

 

I like the idea of consistency that is offered with MAF over MAP. MAP tuning is strictly an assumption of VE at various load points and revs. MAF is a true measurement of the incoming mass of air, allowing for a precise prescription of fueling.

I have removed my air conditioning and we have started to make the power steering mount that will relocate my power steering pump to where the AC was. This will allow the space required for me to run 3" intakes to both turbos, and then I can install these MAFs and I will be sure and let you guys know how its working out for me. Up to this point in time, my car has run MAP. But I have everything required here to run dual MAF and the FCON software 100% supports it.

 

Exactly, MAF offers far better consistency than MAP. Just look at how MAP is supposed to work. Remember that the whole point is to deduce the number of air molecules (of which 20.8% is O2, regardless of elevation). A MAF sensor gives you that directly...period. If you are using MAP, which is absolute pressure, you are required to know the temperature as well. This can be grossly simplified by looking at the ideal gas equation, PV=nRT, this is at any given instance in time in the intake manifold. V (volume) and R are constant, n is number of moles of gas (what you are trying to find), T is temperature, which is an unknown and to be measured. SO, to find n, you need to have pressure P (MAP) and T (IAT), hence the need for what we call a VE map, where n would change with temperature. Another thing is that for accuracy, you NEED to measure the intake temp INSIDE the intake manifold, even passed the plenum neck, since air will undergo adiabatic expansion as it goes from a narrow intake run/plenum neck and dumps into a much larger cavity -- the plenum space; this drops it's temperature. So, to get a good speed density-based map, you need MAP AND IAT to be taken deep inside the manifold. In my opinion, this makes the use of the "intake temerature correction map" in the EU mandatory if you are doing speed density-based tuning, this basically becomes your VE correction map.

CJ--- is that what's done with the HKS vPro? Are there any specific tables that calculate IAT-based VE maps, etc?

 

charles is my hero

 

Ok, I agree with both of your statements (Charles & Gurgen). But let’s look at it, as complicity of installation versus gains? is it worth it?

The reason that I ask is, Charles already knows, I want to run a stand alone on my car, either an HKS or a Motec and one of the thing that I’m still thinking off is the MAP versus MAF issue. As you guys have mentioned a dual MAF would be great but then again with a Motec you can compensate for IAT plus other factors, as far as the HKS I have no idea.

So we go back to the same question, is it worth the gains?

Thanks,
Az

 

YES... a resounding one. But it's not about gains in terms of HP..but relibility. The only difficulty is that noone has done this yet. In fact, the same reliability can be done using a single MAF pre-turbo, as it's next to impossible that a catastrophicturbo failure will occur. If it occurs on the same side as the maf..no problem..engine shuts down. On the other side, well it will just run rich. However the consistency gained through MAF tuning is VERY much worth it, my $.02. You will not have to worry about thigs like going to different elevations, where VE will be grossly affected, or different temperatures... there is a reason why OE's almost exclusively migrated to MAF (with the notable exception of Honda...last time I checked).

 

so you think the gains would be worth it ...



I think with my turbo kit I can do it, without having to relocate anything.

Az <----- still thinking about MAF vs. MAP ...

 

Dual 300ZX?

 

Well might as well get some good range and go with the full 350z ones. Actualy I think the ranges of the two would be pretty close.