I'll try to keep this simple: (and yes as such I'll be omitting a fair amount of info and possibly leaving assumed relations/comparisons which aren't 100% accurate)
osiderida06 said:
What excatly is a GM MAF or speed density.
A MAF is a Mass Air Flow sensor. It's used in measuring the MASS of the air entering the engine. The differences between one of these and the N/A's AFM (Air Flow Meter, a generic term) are numerous. There is no physical valve which the incoming air has to move for measurement. The GM MAF (a "hot-wire" type meter) is a very common sensor and as such it's CHEAP. It's less sensitive to disruptions in the airflow and foreign materials then the GTE's Karmen Vortex AFM (which is used to calculate mass). They're available in numerous diameters including 3.5". The large diameter and less restrictive inlet buffer make it a very popular choice. This is what I'm running in my N/A at the moment.
The 7M-GTE employs a Karmen Vortex AFM. This system is rather complex and can fail if improperly handled or subjected to certain conditions. The Karmen Vortex system uses an inlet screen designed to create a vortex from the incoming air. This vortex is monitored optically and the mass of incoming air is calculated from the data provided. If the optics should become clouded (due to oil or similar contaminates in the air) or if the inlet screen should become damaged the entire meter can fail to relay enough usable data to even limp the car home.
Technically, the N/A has a VAF (Vane Air Flow meter). The meter works by employing a spring loaded trap door (aka flapper or valve) to calculate the volume of air entering the system. Another way of measuring air flow, different physics and math.
Speed/Density (aka MAP) is a system which measures the pressure and temperature of the air within the intake manifold. These datum are used to calculate the quantity of air within the intake. This system is popular as it places extremely little material in the path of the incoming air and as such creates the least resistance of the four options mentioned here.
In order of restriction (lowest at the top) we have:
1) S/D or MAP
2) GM MAF
3) KV AFM
4) VAF AFM
You can find out more specific data on air flow meters here:
http://www.autoshop101.com/forms/h34.pdf
osiderida06 said:
So if i get maft pro i can run an intake right into the turbo and not have to have a afm? Is there any tutorials or anything on the way of tuning the car in this way?
Yes, that's speed/density. There are some walk throughs, but unfortunately speed/density can be a tricky system to get just right and the settings can vary heavily even when installed in two of the same cars.
Setting up the MAFT Pro for MAF Translation (get it? MAF-T
) is easier but it does impose some restriction. Plenty of turbo guys use this system without issue and there's no reason you can't.
By the way, you can place a GM MAF either before or after the turbo. The latter is referred to as a blow-through configuration. The benefit to this is greater accuracy and if you blow an IC pipe/hose the car will still run well, you just won't have any boost. The same goes for S/D when you want to be sure if something goes wrong you can still get home.
osiderida06 said:
And what kind of boost controller do you guys suggest for this first set up im going to do? And how does boost control work? Just turn it up or down depending on the setup you have? Just think of this as adding to the wealth of information this thread will have for the newbs! Like me! LOL
Boost control uses a mechanical valve to control the amount of pressure seen at the wastegate. The waste gate is a valve which allows exhaust gases to bypass the turbo's exhaust impeller and stop/slow the turbine's movement. When you add a boost controller (manual or electronic) it's important to remember that it won't be able to cut your boost to any level below the wastegate's actuation level. In other words, if you have a wastegate with a 7psi actuator the boost controller won't allow you to lower that amount... it only allows you to up the boost.
Manual boost controllers (MBCs) are rather simple valves, they hold back the pressure which would normally actuate the wastegate until their pressure requirement is met. So, your 7psi actuator won't budge until the manifold is at 14psi which is when the MBC opens up and allows the wastegate to open up.
Electronic boost controllers (EBCs) come with a variety of features. Some systems let you set different boost level depending on certain criteria (such as throttle position and engine speed). Some have inputs for a second tier as well... this is nice for a daily driver. You can set a lower level for day to day driving and add a switch to the dash which activates a secondary more aggressive tune and boost routine. How these function and how they are adjusted depends on the device.
lifted said:
for one you cant use afm when your ge has a maf, you will have to have the gte electronics to use the lexus afm.
What? I don't think I understand what you're saying.... actually I'm pretty sure of it.
AFM is an acronym for Air Flow Meter, a generic term nonspecific to the type of sensor. MAF indicates HOW the air is metered (which is to say it's measured by its MASS). Technically, the GE uses a VAF (Vanee Air Flow Meter) and the GTE uses a KV type sensor to calculate mass.
Also, it should be possible for an N/A running a MAFT Pro to use either the 7M-GTE or the Lexus AFM... but why?
Sl1dewaysSupra said:
I was referring to the timing map that CRE stated. But I totally understand what you are saying.
Yes, the turbo effectively increases both displacement and compression. BUT, keep in mind that the GTE also uses less aggressive timing advance maps. I don't know about the MKIII but I do know that on some turbo vehicles the timing map is scaled back further depending on boost levels.
Sure, you can pull 5º of timing or more, but why take it off the low end as well if you don't have to? It's not a big issue, just something that I would like to be able to tune in the event I decide to go with an aggressive tune.
I do agree though, a turbo on stock N/A electronics isn't for me either... but mine aren't quite stock. The MAFT Pro has given us an option which really bridges all the gaps quite well. Don't get me wrong, some parts of it have one hell of a learning curve (I'm trying to work through some of this right now). It's not the easiest or prettiest system. However, given everything it's capable of I really don't see the reason to go through the hassle of swapping in $500 worth of used parts and still probably needing to add a fuel controller (and depending on your needs a boost controller and a timing controller).
This is one of those things where everyone has to make up their own mind. There are ups and downs to each solution available.
