MAF and Injector sizing for boosted Focus.

[Penguini66]

Thought I'd give everyone a chance to chime in and let me know what they think I should be running.

I'm currently using a 5th injector setup for fuel management and zero spark management. So, I've decided to go with the SCT Pro Racer package. It will give me the opportunity to add an appropriate MAF sensor and some large injectors. As well as pull some timing while I'm under boost. My plan is to get the 4 bank chip version so I can program four different tunes, then go to a dyno and test them out and see which works best.

Just for anyone who is not at all familiar with the Focus, we run into a problem very quickly when trying to add additional air flow. The MAF sensor runs into a 5V cut-off very easily. It is in to way designed to run that much air. Even at 5 or 6 psi. The stock 19# (I believe) injectors max out pretty early as well. In addition, the stock Zetec 2.0 usually dyno's at around 105-112hp at the wheels. The turbo I'm running is only capable of flowing up to about 200-220 hp at the wheels. (with an intercooler of course)

My handy dandy 5th injector setup right now includes a small piggy-back system that clamps the MAF voltate at 4.95V to keep the four stock injectors firing. As well as spraying in some extra fuel. The problem is that is is in no way tuneable. I run lean on the bottom end and 'pig' rich on the top end. I could mess around with different injector sizes for the 5th injector but I'm still going to be lean on the bottom end and I don't have the opportunity to pull any timing on the top end. So thanks to SCT, I think I've found a solution.

My dilemma now is to find an appropriate MAF sensor and appropriately sized injectors for my application(200whp max). Although I won't be near 200whp until I add an intercooler. My current goal is to get somewhere around 150-160whp with my non-intercooled setup. I don't want the injectors to be to large but I also don't want to have to buy new injectors when I add an intercooler and increase the boost next spring or summer. Just looking at my choices from FordRacing, I have 24, 30 & 42 lbs/hr injectors available. My first thought was to go with the 42# injectors since that is what one of the Focus tuners offers as part of his MIC (MAF Injectors Chip) kit. But I think that kit is capable of way more hp than I will ever be at. So now I'm leaning toward either the 24# or 30# injectors.

As far as the MAF goes, so far the only option I've found is the 70mm Pro-M from Pro-Flow. The nice thing about it is that I believe I will still be able to retain my stock air-box with panel filter. Or use the Volant box and cone filter that I have sitting in my basement.

I'm still learning so please point me in the right direction.

[BlackBeauty02]

This is where mixing and matching parts is going to do you some good. Especially using the SCT. When I was running the aerocharger on my focus back in the day I would hit maf voltage at 6.5 1/2 lbs of boost and usually only in 3rd gear. Here's what I would suggest. From what I understand you are probabl still running on the stock bottom end. 200whp should be fine, but realize that the aerocharger may be able to go past that mark. Although the aerocharger reps claimed different. For an aerocharger equiped focus without an intercooler this is the setup I would be looking at.

1. 99+ GT maf (should be able to load this in the SCT values)
2. 24lb injectors (again able to load this value in SCT; ditch the 5th injector)
3. Esslinger UDP
4. FS race header
5. 2.5" pipes after the turbo.

Honestly you will be able to make 200whp without the intercooler, but it's going to require a bit more in depth tuning. Do you have the boost switch from aerocharger that the stage 3 and 4 kits have? If not GET IT. I used it on my setup without the intercooler and the difference between 5 and 6 psi was huge. With the boost switch you can crank the boost. One cold nights I would take the fitting out and run it full open which I saw a max boost on occasion of 11 psi.

That's basically all I can recall from my focus days, hope that helps you a bit.

-Jason

[Penguini66]

Thanks Jason...Wow, somebody on here has actually heard of Aerocharger!

Yea, the 5th injector goes out the door the day I get SCT stuff.

Thanks for the tip on the 99+ GT maf. I'll look into it. I guess there'd be no way I could 'max out' a GT maf with my little 2.0. Any ideas what it looks like (size wise) compared to the Focus maf? I'd like to use it with my Volant box which is still in my basement. It will take some tinkering to get it work with the Aerocharger turbo inlet pipe. But I think its possible and know of one person on Focaljet who got it to work.

So you think 24# injectors will be enough? I've gotta do some more looking into this on focaljet. Honestly, I was going to leave it all alone until the SCT stuff came out. I hadn't been thinking about upgrading until recently. I'm a little behind on my research.

Also, what size injectors is the 99+ GT maf calibrated for? I guess it doesn't really matter with the SCT software, but I'd be curious anyway.

As far as boost controll, I'm running a "Do It Yourself" bleed valve. It works very similar to the Aerocharger switch except I turn a dial instead of flipping a switch. Cost me about $20 to make and gives nice incremental boost controll from around 5 to almost up to 8. I may have to do some more work on it to get it up to 10+.

Edit...I forgot to mention that I'm running the FC off road pipe with the stock manifold. It should make a pretty easy swap when emissions time comes around. If they're even that picky. I've yet to find out since they are just starting emissions inspections here this fall. Not going to get into that now since it opens a whole nother can of worms.:mad:

[BlackBeauty02]

If I'm not mistaken the stock injector size for the 99+ mustang is 24# but don't quote me on that I'm not 100% sure. Either way this won't be an issue with the SCT. If you want the 42 lbers (a little big for the amount of power you are looking at) then I would do a lightning maf which is already calibrated for the 42 #ers. As far as the MAF goes i think unless you go with a pro-m you might have to ditch the stock airbox and do something a little on the custom side, which can be a pain especially with that turbo inlet tube (crappy design if you ask me). Depending on what year GT you get it will be different sizes. the 99-00 GT's have 70 or 75mm throttle bodies, and the 01+ GT's have 80mm MAFs. then the lightning MAF is a 90mm. I'm not really all that knowledgable on what low intake velocities do on boosted applications but the larger the maf you go with you are deffinately going to be reducing velocity up to the turbo due to the wider diameter. After the turbo things get sped up a LOT so it may or may not effect performance in a negative way like it would on an NA application. I would really suggest going with the 99-00 GT MAF, I think that might be your best bet. Do you have a focus central throttle body? If not get it, with boost it's gonna help you. Trust me we can get your ride to 200whp WITHOUT the intercooler....saving you some coin.

-Jason

[KenB]

The 99GT has 19# injectors. No stock MAF is calibrated for any injector size. Calibration of the MAF is something that aftermarket companies do to fool the computer. With the new software you will be able to tell the computer what injector you are running and what MAF, so this is not an issue anymore.

Ken

[BlackBeauty02]

Thanks Ken. Wasn't sure on the 24# or not.

Wow I havn't talked tech on foci for so long...almost nastalgic :dontknow:

-Jason

[Penguini66]

Hey thanks for the tips guys. Yea, I think I've come to the conclusion that the 42's are too big. I may go with 24's or 30's. What do you think?

Its funny you mentioned the TB. I was just thinking about that today. You must have read my mind. It got me thinking though. If the turbo charge tubes are smaller than the TB in the first place, how is that actually going to increase flow? But will the bigger throttle body opening make a bigger 'hole' for the air to go? I guess so. Right?

I'm just starting to catch on to how things work with the MAF, Injectors, and the SCT software. And that takes me to my original question that got me looking for a new MAF in the first place. We've always been told that the Focus MAF "maxes" out. What does that actually mean? Does the MAF sensor physically max out such that it can no longer measure flow above a certain flow rate. Or is the stock computer not programmed to read values above a certain point. Or both?

And if the stock MAF is physically "maxed" out, how do you know what MAF to get such that it won't max out as well? Is this documented anywhere?

Sorry for all the questions but I do really appreciate the help. Its nice to get a different perspective.

[BlackBeauty02]

The stock MAF is "maxed out" but it's also a computer thing. The unit will only send out 4.95v which is reallyonly good for about 6.5psi. From my understanding usually bigger MAF's gain process more flow. You will be fine with a GT MAF, they can handle 10+ lbs of boost as there are plenty of SC guys running that psi through vortech's, and prochargers.

One thing Aerocharger did right with their setup is to keep thier intake piping from the turbo outlet to the TB small diamter. This gives you quicker oof boot to positive boost times. It also keeps the speed of the air up so you don't loose velocity (remember my previous post about low velocity hurting performance). Because the TB is close to the point at which the air enters cylinder you aren't loosing much if any velocity and the larger diamter will let more air through thus actually having more air in the cylinder per which increases power.

-Jason

[1turbofocus]

BlackBeauty02 I dont agree with a few things stated here

24LB injectors are not big enough for 200HP it takes 42`s just to make a safe 200 and even at that you are at close to 100% duty cycle

The AC3 over spooled WILL lock up i have seen it many times ,,Dont get me wrong i for one do not like the AC3 at all and it is well none

KenB QUOTE,No stock MAF is calibrated for any injector size
*maybe im not understanding what you are saying but i dont agree all stock mass airs are calibrated for the range of the stock injector ,

On the focus if some one was to install a turbo kit and a set of 42lb injectors NOT change the mass air are you saying that with the SCT all i have to do is change this in the scailer and it wont hit 5 volts

From what i understand once the mass air hits 5 volts thats it your through till you get the mass air Recal.

And is it realy to fool the computer or does it just move the range of the mass air to match the range the injectors are good for

Tom

[KenB]

Originally posted by 1turbofocus

KenB QUOTE,No stock MAF is calibrated for any injector size
*maybe im not understanding what you are saying but i dont agree all stock mass airs are calibrated for the range of the stock injector ,

On the focus if some one was to install a turbo kit and a set of 42lb injectors NOT change the mass air are you saying that with the SCT all i have to do is change this in the scailer and it wont hit 5 volts

From what i understand once the mass air hits 5 volts thats it your through till you get the mass air Recal.

And is it realy to fool the computer or does it just move the range of the mass air to match the range the injectors are good for

Tom

When I refer to calibration, i'm talking about what Pro-M does for example. Let's say you are moving from 19# injectors to 24# injectors. The output voltage of the MAF is scaled by the ratio of .791 (19/24). This is what I meant by fooling the EEC. It works for WOT but there can be some part throttle drivability issues. It gets much more complicated than this but that is the basic idea.

What you are talking about is maxing out the MAF. By calibrating the MAF as mentioned above, you improve the headroom.

Soooo, if the MAF is maxing out you can do one of 2 things. Get it recalibrated (not the best way) or get a new MAF that is capable of handling the airflow you require. That does not mean it needs to match the injectors.

[Penguini66]

Originally posted by KenB
When I refer to calibration, i'm talking about what Pro-M does for example. Let's say you are moving from 19# injectors to 24# injectors. The output voltage of the MAF is scaled by the ratio of .791 (19/24). This is what I meant by fooling the EEC. It works for WOT but there can be some part throttle drivability issues. It gets much more complicated than this but that is the basic idea.

What you are talking about is maxing out the MAF. By calibrating the MAF as mentioned above, you improve the headroom.

Soooo, if the MAF is maxing out you can do one of 2 things. Get it recalibrated (not the best way) or get a new MAF that is capable of handling the airflow you require. That does not mean it needs to match the injectors.

So, with what you're saying about the way they calibrate the Pro-M, sounds like my best option would be to look for a 99+GT MAF and try to get it to fit. Since I have no idea what the GT MAF looks like, I'll have to wait and see how practical that is.

And Tom, thanks for clearing up the injector size question. I knew you went with 42's for a reason. I just couldn't dig up why.

[KenB]

Originally posted by Penguini66
So, with what you're saying about the way they calibrate the Pro-M, sounds like my best option would be to look for a 99+GT MAF and try to get it to fit. Since I have no idea what the GT MAF looks like, I'll have to wait and see how practical that is.

And Tom, thanks for clearing up the injector size question. I knew you went with 42's for a reason. I just couldn't dig up why.

I'm not saying Pro-M is bad...I run a Pro-M. I'm just saying that the calibration is not necessarily needed with the SCT software. Mine is for a stock GT (19#) and I run 24# injectors.

Ken

[Penguini66]

Originally posted by KenB
I'm not saying Pro-M is bad...I run a Pro-M. I'm just saying that the calibration is not necessarily needed with the SCT software. Mine is for a stock GT (19#) and I run 24# injectors.

Ken

I'm getting more confused here...I guess it shows my inexperience.

From your earlier post about the Pro-M reclaibration:
This is what I meant by fooling the EEC. It works for WOT but there can be some part throttle drivability issues. It gets much more complicated than this but that is the basic idea.
I got the impression that I would not want a Pro-M that has been re-calibrated if I didn't have to. My question now is, can you get a Pro-M that is not re-calibrated. In other words, set up for the stock injectors as a drop in replacement. And, would this 'stock setting' Pro-M be able to measure flow over double what the stock MAF can measure? I guess that may be a questin for Pro-Flow.

[KenB]

Originally posted by Penguini66
I guess that may be a questin for Pro-Flow.

Yes, it is:)

My MAF is for the stock injectors, so there is no correction or "fooling" going on. At least in theory, the Pro-M will flow better and read better.

Ken

[Penguini66]

Based on SCT guy's recommendation, I picked up a 96-97 4.6 T-Bird MAF. At my first glance, I think it might fit rather nice. But of course, I'll have to take things apart to find out for sure.

So, here's where I'm stuck. The stock MAf is of the 6 wire type with the outside two wires being for the integrated IAT sensor. The T-Bird sensor is of the 4 wire type. I did not know this until I opened up the box and looked at it.

I plan to re-locate the IAT sensor to a post turbo location anyway so that is not a big deal. I'm wondering about what I should do about wiring it up. And what makes it even more complicated is that I will have to swap the stock MAF and injectors back on for emissions once a year.

Can I get a 4 wire MAF connector with "pigtail" and solder the leads in-line with the existing 6 wire connector. In other words, I would be able to unplug the 4 wire connector, swap back to the original MAF, then plug the 6 wire connector in. Or is there any way to get an adapter that would go from my 6 wire harness connector to the T-bird 4 wire MAF connector. It would be optimum if the adapter included the two leads that could go to the re-located IAT sensor. It would be even better if they had the connector on them for the IAT sensor. I'll try and draw up a sketch of what I want and post it later.

Does anybody know of a place to buy these style of automotive connectors so I could make my own adapter harness.

Any suggestions welcome.

Edit: I forgot the main reason I posted this. Will all these extra electrical connections distort the signals from the MAF and IAT sensor? Should I just try and get a 6 wire Sensor that will fit?

And here's the adaptor I would like to build.
http://www.imagestation.com/picture/sraid85/pacbcdfaae0e209e65781ffbfabd865f7/fac3f1b6.jpg

[1turbofocus]

Yes if your question is can you use a stock MAF with larger injectors the answer is yes ,But it will hit the 5 volt cut in the same place as the stock one did

The reason for the recal on the MAF is to give it the range of the injectors you are using ,,You want the MAF to hit the 5 volt at about the same time as the injectors hit 100% duty cycle

Even the SCT software cannot over come the 5volt cut

Tom

[Penguini66]

I just did some more re-reading and lots of thinking. Let me see if I've got this straight. I'm trying to put a bunch of things together here. And I am by no means a technical writer so be easy on me.

A Mass Air Flow Sensor does just that. It measures the ammount of air passing by and communicates it to the computer via a voltage reading. And based on the minimum and maximum ammounts of air that is to be measured, a factory MAF is designed to measure a certain range of flow. On the Focus for example, the factory MAF is designed to measure up to a specific flow rate. This maximum flow rate (whatever flow value it happens to be) is denoted by the maximum 5V that the meter can output. On a side note: it would also make sense that the meter may not be as accurate near the maximum flow rate as it is in the middle of the range. And the same may go for the lower end of the range.

A MAF sensor has nothing to do with injector sizing. The idea that a MAF is calibrated for a certain injector size is not correct. The terminology of "MAF calibrated for 42# injectors" is from the concept of MAF voltage scaling. This is where the MAF voltage is scaled down in order to be able to measure more flow than the stock sensor. And in turn, larger injectors are used to compensate for the extra flow.

A stock MAF is not calibrated for an injector size. It is calibrated as mentioned above: To measure min and max flow rates based on engine design. To switch MAF sensors, all you have to do is tell the computer what the MAF voltage values mean. From what I understand, it was not possible to tell the computer what those values meant until the SCT software.

So, back to my situation. I now completley understand why a 70mm Pro-M with stock Focus calibration will still max out for my setup. Simply put, the Pro-M in stock trim will only measure the same maximum flow as the stock meter. (sorry I was a little slow on getting this one...its so obvious to me now)

What would happen if I were to get a Pro-M "calibrated for 42# injectors". (Well, actually I mean scaled don't I?) Now, above I just said that a meter is designed to measure a certain range of flow. So we have a meter that was designed to measure a certain range of flow, let's say 100whp worth of flow. How is that same meter physically capable of measuring 200whp worth of flow? I guess all I can assume is that its in the design of the meter? There was a mention of partial throttle problems with re-calibrated Pro-M units. Can anybody explain in any more detail.

(If I was not using the SCT software--->) I understand that the voltage values would be scaled down so that, to the computer, it looks like less flow.

But if I am using the SCT software, the software will be able to interpret the MAF voltage readings as actuall flow values. Right?

So, in the end, I'm trying to justify purchasing a Pro-M ("calibrated for 42# injectors") since it is a drop in replacement for my setup. Any thoughts, comments?

[1turbofocus]

I dont agree with everything you said above but you have the idea and i can make it easy for you

Get a set of 42LB injectors these are good for 200 to 220 HP and a COB30 Calibration 70MM mass air from Pro-M and the SCT can take care of the rest

Tom

[SCT Guy]

I think you win the prize. I don't know if I could have set it better myself. You are correct on everything. (Well, the autologic software I think allows you to change air meter transfer function, but how to do any of this is not understood very well in those circles and hence isn't done very often).

Let me add some numbers in for you. You injectors, based on the EEC info, flow 17.8#/min at 39.5 PSI pressure drop. At 5 volts, your stock MAF is sensing 20.4#/min of air flow across the MAF. If you get a MAF setup for 42's, your new MAF should have a max flow of 42/17.8 times 20.4 or 48#/min. Total over kill. The Vortech Focus that I did flowed about 24#/min of air, and in reality, for your setup, you want a MAF that will handle no more than about 35-40 #/min incase you get stupid later and turn up the boost, and to protect for a good air density day, etc, etc.

So, working backwards, you need a MAF setup for 40/20.4 times 17.8 injectors, or about 35# injectors, Maybe slightly less. So, I'd order a Pro-M set up for 36's, maybe 30's if you plan on staying convervative for ever.

There is nothing wrong in getting a MAF setup for 42's, you just won't use all of it, and hence, as you pointed out, the control won't be quite as good (in reality, probably not even noticeable) due to the unsed range.

[Penguini66]

Well, I got my Pro-m MAF today and there is no way that it will work with the stock box. Actually, after looking at the casting marks on it, its the exact same casting as the T-Bird MAF I picked up a week ago. I guess I'm going to have to hack things up afterall.:mad:

I guess its not that big of a deal though. I had just really hoped that it would fit so it made for an easier swap come emissions time. And I was told that it would work with the stock box by the place I ordered it from.

Now the decision I have to make is do I return the Pro-M (if I even can) and try and use the T-Bird MAF? Since they are the same casting, the only extra work will be to splice in a 4 wire MAF connector to hook up to the T-Bird MAF connector.

One more question...If I decide to stick with the Pro-M: To simplify things, I'm going to use a cone filter on the MAF. When I had the meter calibrated, I told them I was NOT using a cone filter. Does anyone know how much this will effect the flow measurement if I switch to a cone filter? Do I need to have it recalibrated?

[Penguini66]

One more thing, what are the concequences (if any) of hacking up the wiring harness? Does it affect the signals when you add connections and/or splices in the wiring?

[jsnorman]

Yeah, I had the same problem. I ended up spending about 2 hours modifying the stock airbox to fit the Pro-M that supposedly was made for the Focus.

The MAF transfer function should not be affected by whether or not you use a cone or airbox style intake (someone correct me if I am wrong on this, but I think it is just a mapping from airflow to voltage). However, if you ever want or need to run the stock computer without the SCT chip, you may have some problems because the calibration that Pro-M applied will be off a little... that, plus the fact the Pro-M has stated that they get the best numbers off a stock airbox with the Iceman ducts, is why I went through the trouble of modding the airbox.

In case you are interested, here is how I did it:

1. Remove top of airbox, and use high speed cutting tool (Dremmel) remove the bottom ridge, and cut out the bottom of the circular opening bit by bit until the Pro-M mounting flange will fit. Note that you will be creatting several large gaps around the base no matter how careful you are -- there is no other way to do it. Also, wear a mask and eye protection - -the plastic is nasty stuff with it is ground and filed with e Dremmel .. it actually melts and gets all over.

2. Put a fine sanding tool on the Dremmel and remove as much stuff around the edges as possible, smoothing out roughness.

3. Place the airbox top in a large clamp or vice or workbench with the opening facing up. Place the Pro-M mounting flange in the opening, and that the electrical connector will be on top when installed.

4. Mix up some bondo or epoxy cement. I used bondo with fiberglass reinforcement but anything should work ok. put the Bondo/epoxy all the way around the interface of the Pro-M mounting flange with the airbox, and fill in the gaps/holes that were created by the dremmelling procedure. Let dry, turn it over, and do the inside seam.

5. Mount the Pro-M MAF to the flange. You will need to drill a couple of holes, to go straight through the airbox. You will need longer bolts too, and nuts. After mounting, seal the holes around the bolts with RTV sealant. I only used 3 out of the four bolts by the way, and only 2 go through the body of the airbox. (I used one of the bolts/nuts that came with the Pro-M just to secure the MAF to the flange, then 2 from Home Depot to go through the airbox and secure the whole assembly).

6. You will need flexible tubing for the intake with a 65mm openining on one end (assuming you have a FC tb), and a 70mm opening on the other end for the MAF. Stock tube will not work and likely any custom tube you have for you a/c will not unless it can be stretched. Luckily, my JRSC came with a flexible tube I was able to stretch to fit.

[bartlomiej]

Im a bit confused with all this info.... I plan on going FI soon. I have stock injectors for the moment but plan on getting 42#.

I plan on getting a 99+ mustang gt MAF (apparently "scaled" for 19# injectors). When I get my turbo setup I can just change the maf transfer function for bigger injectors, right?
How about before I get the FI setup, since they are off a 99+ stang gt with 19# injectors, will work for my zetec and produce a higher flow rate (for the 5v cutoff) than the stock MAF?
I am a little unclear with all this info, all help is appreciated!

thanks,
bartek

[jsnorman]

bartlomiej -- yes and no. Yes, you can change the MAF transfer function for larger injectors. HOWEVER, to do this correctly, you need to have a flow table (basically a correspondence of volts to airflow) -- that is why a lot of us buy the Pro-M because it comes with a flow table.

Without the flow table, you are going to have to just scale based on an assumed calibration (@19lbs x 8 injectors vs. 42 x 4 injectors). This method is not as accurate.