Does anyone run an aftermarket MAF on their forced induction car.
What are the pro's and con's to this mod on supercharged motors.

 

i've had both the stock (descreened) and GMS MAFs on my car -- both on the pressurized side. I really didn't notice a difference between the two in either SOTP or data logging.

I assume you're talking about a mild build-up since the MAF maxes out at about 475 rwhp anyway, right?

At that level, the added "flow" of the aftermarket one (on the pressurized side)won't really help out much. The couple horsepower you gain probably aren't worth the cost.

On the non-pressurized size, the added flow may help out quite a bit more, but I don't have any data or experience there...

 

Are you talking about 3rd gen MAF or 4th gen? If your not talking about 3rd gen, what kind of hp can you get out of a 3rd gen MAF.


A while back I posted I was going to go with a turbo setup, and I was told to go Speed Density. It was my fault b.c I did not tell them what kind of hp I was looking to put out, but I am only looking to put out 350-400hp, not even rwhp. Also, with a turbo do you blow through the mass air or suck through?

I dont mean to but in on someone elses post, but any info you could give me I would really app.

 

I was talking about the 4th gen one's max capability.

_IF_ you go with MAF on a turbo setup, you have to do blow-through because you need a blow-off valve after the turbo. If you just bypassed unused boost back through the turbo like the supercharger kits, you would just be re-heating and re-heating the air.

The reason I emphasized "if" is because a MAF determines mass air flow. With boost, mass air flow isn't a good measuring tool for determining how much fuel to dump in because any amount of air above 0 boost will not be measured accurately due to it being pressurized.

For a turbo setup, I would recommend FAST or DFI if you can afford it. If not, a custom programmed speed density ECM with a 2 or 3 bar map sensor (to understand boost). Another viable alternative is standalone fuel and spark, such as MSD 6BTM + carrol superfueller (or similar setup).

 

Just wondering what the companys do that make superchargers for third gens that have MAF. They say direct bolt on?

I work on Talons all the time. They have a mass air on the intake side of the turbo. ...I no they also have map sensors....so Im not exactly sure how it works, but if you dont blow through the maf, the maf will sence how much air is being sucked.

Im not sure what you mean about the blow off valve and reheating the air over and over. The unused boost would just go through the exhaust side of the turbo and right out the exhaust pipe, I think Im missing something.

 

The MAF is calibrated to work at 1 atmosphere. If you put it on the pressurized side, say at 1.5 atmospheres (a little over 7 psi boost), it'll won't be calibrated to read the air correctly.

1 cubic foot of air at 1 atmosphere has a LOT less molecules of oxygen in it than 1 cubic foot of air at 1.5 atmospheres.

How do companies compensate for this? Easy -- FMU. They increase fuel pressure based on pressure in the intake manifold. The higher the fuel pressure, the more fuel that is dumped in per millisecond of injector pulsewidth.


As far as reheating the air, I was talking about if you have the MAF on the suck-side of a supercharger. Once you meter air, it cannot be dumped back into atmosphere. All metered air will have fuel dumped in accordingly. Instead, you have to use a bypass valve to re-route the unused pressurized air back to the intake side of the supercharger (after the MAF). Since that air is accounted for, it has to stay in this loop until it is used. compressor inefficiency keeps re-heating it.

That's a big advantage of having the MAF on the pressurized side and being able to dump unmetered excess air to atmosphere.

 

Nice man, Im suprised that someone else out there remembered chemistry, everytime I try to explain boost its over everyones head, I just wasnt sure how the maf read it.

I have the fmu for my 79tt that carburated. Thats easy as hell to set up .....but an a fuel injected motor, should i get the tuneable one that only adds fuel after a certain rpm? I will have to do some more research on that. well I have to run....I will post again later to explain more what i mean. THanks for all the good advise!!!

 

Wow. we hijacked this thread. Sorry NiteRyda. (at least there were free TTT's for ya )

Anyway, Using an FMU is really based on what kind of boost you plan on running. On fuel injection, you typically use 4-6:1 FMUs, which means it's raising fuel pressure 4-6 psi per psi of boost. The higher fuel pressure you use, the higher the chance of injector lockup.

Starting at 40psi fuel pressure and 10psi of boost, you're running 80-100psi of fuel pressure, which is way too high. You can use bigger injectors and a smaller FMU ratio...

With a turbo, you cannot rely on RPM since you can reach full boost anywhere based on load. With any real amount of boost, FMUs become useless because of max fuel pressure. The only "real" alternatives are boost-aware EFI computers (accel DFI and FAST).

 

Sorry, but that's just wrong.

Mass flow has nothing to do with it being boosted or not. I have personally done quite a few blow through setups, both LS1 and LT1, and the MAF is just fine with boost. Up until the point it is maxed out.

 

I second that!

And I have run a BOV (vented to atmosphere) with the MAF on the suction side of the turbo, No problems....

 

The reason I thought that I should put it on the intake side of the turbo is bc many factory cars use this method. Mass air just senses how much air is being sucked in, so if you put it on the intake side of the turbo.....regaurdless of it being compressed and dense after it goes through the turbo, it still requires a certain amount of air to be sucked in thats not dense. So the mass air should have no problem reading it.

I have had many mass air problems in the past with just ram air, I dont no if I really wanna blow through it.


How much hp can a third gen mass air handle?

Has anyone actually had a turbo thirdgen, and what is your experiences with it? Anything to look out for? Its getting warm here, so the bike is going back on the road so I can work on the car.

 

So are you trying to say that the MAF is only calibrated to read correctly at 1 ATM? If this is the case the MAF would only meter air correctly at 1 ATM (sea level standard day), the atmosphere is rarly ever constantly one ATM. What about cars that are driven in Denver, one mile high about 85% that of sea level pressure. Besides the changes in altitude, what about changes like high and low pressure areas, they can vary almost as much, and in a very short distance or period of time.

There is no reason why the Mass Air Flow sensor could read the Mass Flow put forth by a forced induction setup, up to the point that it physically, and electronically is maxed out.

P

edit: forgot to add that my understanding of the MAF was that it meassured a flow rate, ATM, bar, psi, "HG are all weight messurements, which is what I thought the MAP was for hence the reason for going to a 2-3 bar map to comensate for the extra air being put into the intake.

 

nope. i was retarded... well kinda...

I had a huge loss of AFGS when i put my MAF to the pressurized side and attributed it to that. Later, I found out why... I had somehow broken the MAF in the process

I didn't feel a noticeable power loss. extra fuel is fed under boost through a superfueller, so I didn't run lean, but i did notice my fuel trims way up. no spark retard because i run a really safe tune (105k miles on stock shortblock).

Anyway, my MAF readings looked really low, even out of boost, so I replaced it and boom. back up to normal. That'll teach me to stop analyzing things and jumping to conclusions too early.