ok i wa stold that i wont be able to run more then 7psi on my car cause the maf will max.But if i switched over to sd system i could run 15 psi without any modifications to it.true false?

is there a diffent maf sensor i could use on the 2.8

if the maf does max at 7psi can i use a fmu to run higher boost levels ?
and if i run a to atmosphere bov will the engine load up on fuel

 

Not true. It depends on what your N/A setup flows for CFM. If you are already maxing out the MAF then you can run 0 PSI of boost.

If you switched to SD Syclone ECM/code with the stock 2BAR then you can run up to 15 PSI.

You can run a different MAF but will probably need a signal translator for it.
You can use an FMU. Either way, if you max the MAF then the only way to tune is with an O2 sensor and the MAF fuel tables.
When you let off the throttle the ECM will go into decel. fuel cutoff mode.

 

well im gonna try and use the maf setup for now i figure starting at 5 psi and see if the motor goes lean under boost and make boost adjustments from there to find the max amount of boost the maf system can handle.then tune with fmu from there ?


what i dont understand with the maf is.is it the maf itself that cant measure the incomming air over a certian point,or is it due to the ecm/prom?


if i use a bypass valve instead fo to atmosphere bov does it dump back inot the intake before or after the maf sensor?

 

Keeping the MAF and using an FMU is a good way to start. Get an adjustable FMU so that you can tune the fuel easier. Using the FMU is a replacement for tuning the PROM. You can't fine tune an FMU like a PROM but it will be fine. Search for 89JYTurbo's setup. He uses this method and it works well.

The MAF itself has the problem. The MAF sees a certain amount of air flow and reports a voltage to the ECM. When the MAF is at maximum flow then the voltage is at a MAX to the ECM. You could play with the MAF signal are recalibrate the ECM fuel tables. You need test equipment to do that and it isn't worth it.

Not sure about the BOV. I use a CBV that returns the air to the air cleaner pipe. All of the factory MAF boosted cars I have read about use the CBV and return the air to the air cleaner pipe. Maybe someone else can give more info about the BOV and MAF setups.

 

thanx man very helpful.but one last question what ratio fmu is good to start with ive seen them ranging from 2-1 to 12-1

 

The fmu "rate of gain" number you're talking about, at least with the TPI setup I have, depends upon the size of the injectors you're using. Vortech's old literature, in a nutshell, states that their kits for vehicles (primarily the 5.0 Mustangs) with 19 lb/hr injectors use 12:1 or 10:1 ratios. They state bluntly that the Bosch style injectors on Fords can tolerate bursts of high fuel pressure (100+ psi), so the high rates of gain are possible. They also state that Rochester injectors are far "less tolerant" of these high FP bursts, an will effectively "shut off" at around 72 psi. As the Vortech kit was basically designed for the 350, if you do the math, that puts total FP on a 350 TPI with 6 psi of boost at about 70 psi. For the 305, the numbers (due to the greater amount of boost from the same sized pulley) are higher and demand more attention from you (translation: bigger injectors and probably a recalibrated PROM). It ultimately is about making sure you don't lean out under boost. 24 lb/hr injectors use about an 8:1, down the line from there. I scraped up the cash for Vortech's super FMU but I'm nowhere near being ready to start tearing into the fuel system yet. No time right now. I hope my .02 helps at least a little bit. Good luck.

 

gflow a member on this board was running over 10 psi through his stock maf without an fmu.

 

That configuration must be spot on. I couldn't imagine doing that. I'd like to know, just for the sake of the knowledge, how it's being done.

 

I'm using a MAF on my Twin Garrett 87 Firebird, I have a secondary computer controlling addional injectors in boost. Works great, the Air-to-water intercooler keeps the air-mass cool enough not to change tuning...

 

That's amazing. The general consensus on these boards is that it's nearly impossible to do it that way, without upgrading to the SD setup. I know that there are a few people who have used the versa-fueler type devices, but I'm really not familiar with them.

 

You know whats kind of funny. On fox body mustangs if you run boost everyone switches from speed density to a maf.

 

It always really burned me that Vortech offered so much in the way of upgrades for 5.0 owners, while never really offering nearly as much to the GM crowd. The Ford MAF (or at least the Vortech high-flow units) were good until a much higher horsepower level was reached. And, there were what Vortech called "sampling tubes" that could be swapped in and out depending on injector size, basically negating the need to mess with reprogramming (I believe this, but I'm not 100% certain about it). If you look at the pictures that were in Vortech's old catalogues and literature, the MAF's for the Ford crowd had no screens, and were obviously far less restrictive than the Bosch ones that the TPI owners were used to. The thing that I've been trying to find info on, to little avail, is "translator" units. I think Granatelli offered some kind of setup that allowed us to use the 5.0 units at one time, but again, I'm digging deep into my memory for this information. I remember CarCraft doing an article on this that mentioned it briefly, but I don't remember the details. I know Vortech's decision was strictly based on the rabid demand that existed, and probably still does to some degree, for these products. But, you have to figure that they could still make money if they decided to offer something to us.

 

It is simple actually. In this case, you run large injectors and tune the MAF tables and the WOT AFR to get the fuel right using a WBO2. It is a hybrid MAF/ Alpha-N setup. It is the WORST way to run a boosted engine. Yeah, it works but the problems with wanting more boost and tuning is an endless nightmare.

Ford guys are lucky? Actually, the opposite is true. The reason Ford guys use MAFs is because the computer code for SD isn't as good as GMs SD code. There wasn't as much info about the Ford ECM code like there was about GMs SD code early on.

As for the case where Ford guys switch to MAF from SD. Well, Ford speed parts are more expensive than GM stuff overall. They are used to paying top dollar for big MAFs. GM guys can use a stock Sunbird/Syclone/GN ECM with a $50 MAP sensor. GM guys are accustomed to going just as fast for less money and still "doing it right".

Start with the GM MAF and FMU at first if you don't want to learn about PROM stuff. It is better than nothing. Eventually, you may want more and can go to a big MAF and big injectors. Or could go to SD and big injectors. Either way requires learning on your part. Overall, it comes down to one thing. You can "fix" a problem by throwing money at it (Fords do it this way) or you can "out smart" the problem (GM does it this way). The GM way requires time (the equiv. of money).

So which is better is the end, MAF or SD? Imagine that, the blow-thru carb guys don't use either. Which is best, MAF, SD or nothing?

 

Very true. Ford speed density set up is terible. I do agree that gm speed density is the way to go. Although I have seen fords with over 600 wheel hp. With the aftermarket mafs and stock ecus. All I am going to say is that I have speed density now and I will never look back.

 

thnx for the help guys

im gonna stick with the maf setup for now,i should have my setup complete in 2 weeks or less,so ill see how it runs

 

At the time I was reading all of those catalogues from Vortech, I was unaware that anyone was doing custom prom burning, or converting to the SD configuration. Looking at it from that relatively ignorant perspective, all I saw were these components offered for Ford, that GM fans didn't have at their disposal. The hybrid setup makes sense, as I was just going to eventually use a WBO2 to do the fine tuning anyway. For now, like many, I'm sticking with my super FMU, though. SD will probably come later. Thanks for the info....

 

FMU's are junk I would stay away from one of those.

 

No offense, but when something works well for a long period of time, and someone comes along and makes a generalization like that (especially someone who admittedly went the extra mile and did everything in the ECM), my first tendency is to say, "Here we go again, a naysayer." Everything has its proponents and opponents. That's life. I'll probably eventually do everything in the computer anyway, but for now, it's the FMU. Horror stories or not.

 

Stick with the FMU and you will be fine. Just run it rich at first so you don't blow it up. That applies to either FMU tuning or the PROM tuning method. Naysayers typically post with no back up info so don't listen to it.

Keep it rich at first. Even to the point of fouling plugs. Changing spark plugs are easier to change than an engine.

 

Honestly, I wasn't trying to be a confrontational PITA. I got totally blindsided by someone on these message boards a couple of months ago. His choice of words would've earned him a trip to the hospital had he uttered those words in front of me. I don't want any part of that kind exchange. I respect people's right to have opinions different from my own, I just wanted to state my own personal choice to use an FMU until at some point down the road I choose to change things... And that they do work, seeing as I have used one for some time, albeit under far less than ideal conditions.

Thanks to you Junkcltr, for your words of encouragement. I was planning to err on the rich side. As an individual far wiser than I once said, "Better black smoke than white smoke!!" My particular car is getting two new Walbro's, the super FMU, and -6 AN plumbing under the hood. It has recently gotten 24 lb/hr Ford injectors and a custom chip, so the first part is already done. Hopefully, with some wrench time and seat time, it'll come together... Thanks again.