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Discussion Starter #1
So once its available, I'm going to get the SCT Pro Racer package to hopefully tune my car.


I've searched, and read, and searched and read but have not come to a conclusion yet. I'm running an Recharger Stage II, with a manual boost controller adjustable from 5 up to about 8. Only other mods are a FC ORP, 2.5" Borla, and a panel filter.

First of all, injector sizing. For my long term goal of a maximum of 200Whp (once intercooled), what size injectors should I be looking at? Is there an easy way to calculate injector sizing for an application? Any links would be greatly appreciated.


Second, MAF sensor. 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 effectively measure flow above a certain flow rate. Or is the stock computer not programmed to read values above a certain point. Or both? I'd like to maintain my stock air box or try to get my Volant to work, so I'm nervous about trying a MAF from something like a Lightning or a GT. So my first choice would be the 70mm Pro-M from Pro-flow. But any recommendation would be welcome.

One of the reasons I'm asking about the MAF is that the SCT guy over on www.modulardepot.com has told me that I can "change the injectors and all will be well" I posted a follow up question to clarify if I can keep the stock MAF sensor. They're out of town until Wed so I don't imagine I'll hear anything from them for a few days.

Edit: I just had to add this quote. As much trouble as we have with our fuel pumps:
One cool thing about he Focus is that it has a great fuel pump. So great that there are, as I'm sure you know, a lot of Mustang guys running that pump with blowers. So, the pump can put out a lot of volume at high pressure.
Nothing wrong with the pumps themselves...Just the tank and pick-up design.
 

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I think I know the answer to your second question. Someone can correct me if I'm wrong.

The MAF sensor works by sending a signal between 0 volts and 5 volts, based on how much air is coming in. Once so much air is being read by the MAF sensor, it will be only be able to send back a signal of 5 volts to the ECU, even though there may be more air coming in. I hope this makes sense, it's getting kind of late.
 

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just to add to this..if you have a bigger maf.. the reading will drop.. so for example.. if you have a 5v reading on stock maf.. the same amount of air in a 70mm might send a 3v reading ? but with the SCT, you won't have to worry about all that.. unless the maf is just physicly too small.. that's another issue..
 

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I would recommend 42lb injectors to you. They are the biggest high impedance injectors you can get "off the shelf". They idle fine, and will give you room to grow, and they're not really any more expensive than 30lb injectors. It just makes sense to get that, and never worry about them again.

As for the MAF, I recommend a used 99+ GT MAF. It just strikes me as being the right size. 260hp from the factory, probably scaled for 300-350hp. A little big, but not too bad. And cheap.

But, if you want stock size/shape, go with a PRO-M I guess. But you're gonna need the flow calibration numbers.

I don't think you can use the stock meter. I would guess that if the SCT guys said you could, it was because they didn't realize that the meter maxes out at 5V at about 180ish hp. It's not that the meter can't handle more air, but you end up going off the 5V airflow calibration map.

So, unless they can actually extend that map beyond 5V, which I doubt, then you'll need to rescale your meter downward.
 

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Discussion Starter #5
It's not that the meter can't handle more air, but you end up going off the 5V airflow calibration map.
Ahhhh, Now it makes sense. Thanks.

Where do you find a 99+ GT MAF sensors cheap? Definately not from Ford @ ~$175. Are you talking used (fleabay) or a slavage yard? I had never thought of picking one up at a salvage yard. Might have to price it out. Anyway, the 70mm Pro-M is $185 calibrated from McNews so thats another option. Edit: Forgot to mention that the Pro-M supposedly comes with flow curves that SCT can use.

As far as injectors go, anything wrong with the Ford Racing injectors? I assume that they are just a re-badjged (proper term: brand labeled) injector from another company? And 42's not too big? Can you explain why.
 
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