Injectors And Tune. (it's Not The Dead Horse Y'all Are Thinking If)

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Are you thinking "bigger" is better? Stock are 19# what do you want to install and why? The ECU may be able to manage 24# without a tune to get to a tuner. Larger will most like require the car to be trailer-ed to the tuner.
 
As long as you have a maf calibrated for the injectors you're using and you're not going too far from the stock size, a tune is not required, beneficial yes, but not required. Many, many people run this way and it works fine.

If you DON'T have the proper maf, and the combo is too big for the stock 19s then a tow is probably in the cards, but if 19s can get you there they can be changed out in about 30 minutes if you know what you're doing.
 
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As long as you have a maf calibrated for the injectors you're using and you're not going too far from the stock size, a tune is not required, beneficial yes, but not required. Many, many people run this way and it works fine.

If you DON'T have the proper maf, and the combo is too big for the stock 19s then a tow is probably in the cards, but if 19s can get you there they can be changed out in about 30 minutes if you know what you're doing.

This is what the large majority, including myself, have done.

Joe
 
As long as your meter matches your injectors and they are the proper size for your setup you are fine.
But if you are going to run 42's on a car that makes 250rwhp, it's not going to work right without tuning.
 
Are you thinking "bigger" is better? Stock are 19# what do you want to install and why? The ECU may be able to manage 24# without a tune to get to a tuner. Larger will most like require the car to be trailer-ed to the tuner.
I'm running 19s and fmu. Before the vortech I was making 223 rwhp. I haven't had a retune yet but will. I'm thinking 24s or maybe 30's w matching fmu diaphragm would be better since the consensus seems to be 19s are maxed at 300 horse at the motor. I'm thinking I'm at or over 300
 
Remember, the max duty cycles for injectors are less on a power added motor than for a N/A motor. I know the base kits are meant to work with stock injectors, fuel pumps and such, but who ever keeps the boost at the base level?

You are probably maxing out the stock injectors. If you are going through the trouble of swapping out the injectors, then go ahead and get at least 30's, ditch the FMU, and get a tune. If you already have an aftermarket MAF then the tune will recalibrate it to your new injectors. If running the Ford OEM MAF , then you need to get either a LMAF or a PRO M MAF.
 
Remember, the max duty cycles for injectors are less on a power added motor than for a N/A motor. I know the base kits are meant to work with stock injectors, fuel pumps and such, but who ever keeps the boost at the base level?

You are probably maxing out the stock injectors. If you are going through the trouble of swapping out the injectors, then go ahead and get at least 30's, ditch the FMU, and get a tune. If you already have an aftermarket MAF then the tune will recalibrate it to your new injectors. If running the Ford OEM MAF , then
you need to get either a LMAF or a
PRO M MAF.
I was under the impression that the stock maf could be "calibibrated" via tune and that the aftermarket "calibrated" mafs were used more so in lieu of a tune. I can get a tune cheaper than I could purchase a new maf since its been tuned before. Why couldn't one use an fmu and get a tune? If I get 30#'ers would I need a new intank fuel pump or can I use the same setup as now which is stock pump and inline T-Rex pump? Anyone here actually run an fmu and t-Rex and it didn't work? As for adding more boost my power level won't be changing anytime soon. There will head upgrade or pulley swap in the for seeable future, the $'s not there. Fmu or no fmu it's going to go to the tuner since it'll only run about $200. Only $200... I need a money tree..
 
on a blown car, I would ditch the fmu, get injectors and custom tune
This exactly^^^
One more question: How does one know if their injectors are "maxed out"? What are the symptoms.
I personally don't like to run the injectors beyond 80% duty cycle. When we tune cars in house we use a zedtronics datalogger to map out different paramaters like injector duty cycle and maf voltage on an obd1 car. I personally would recommend leaving it be or 42lb injectors and matching maf and a custom tune to eliminate the fmu with the later always being the best bet in my opinion
 
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It's EITHER the FMU or a tune. You don't do both.

Regarding the MAF, the stock one is 58MM- way too small for a blown application. You will need to step up and might as well do it right the first time with a LMAF or PRO M. I've used anywhere from 30-60lb injectors on supercharged cars with a tune and no FMU. 30's IMO will support well into 400hp, but if you don't already have them then go right to 42's, a tune, a good MAF.

For the fuel pump, I would replace the stock 88lph in tank with at least a 255lph. You have $3k of power adders and there is no reason to not spend $90 on a new pump. The one you have is 20+ years old an and barely adequate for stock levels. Remember you can run fat all day long with a supercharged application, but lean once.

For duty cycles, you can data log that when they do your dyno run. This is a good reference

http://mustangpartstech.com/FuelInjectorMath.html
 
It's EITHER the FMU or a tune. You don't do both.

Regarding the MAF, the stock one is 58MM- way too small for a blown application. You will need to step up and might as well do it right the first
So they can't check and set air/fuel ratios, play w timing etc if one has an fmu? Regarding the maf I have a '95 which has a whopping 70mm I believe. I really wasn't trying to get off on the fmu vs injectors debate. But while I have you on the line give me a quick schooling on fuel pumps. Are they something you can grow into? For example say there was this guy w a stock motor and his stock pump went out. Could he replace it with a 255lph pump or would it be feeding too much fuel?
 
It's a return fuel system, another words it dumps the unused fuel back in the tank. That's why there is 2 fuel lines. One up and one back.

You have a supercharged car, just buy a walbro gss340 in tank replacement pump.
Honestly, i feel that you should have already replaced the fuel pump. It's cheap insurance.
 
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Listen to what these guys are saying.
Here I'll break it down for you:
-Install at least a Walbro GSS#340 -255LPH pump. I chose to go with an Aeromotive #11140- 340LPH pump.
-Do not use a T-Rex. They are old school and unneeded in most cases with today's larger fuel pump and injector options. ( I think of it as less parts to fail later). "AND they do"
-Do not use an FMU. They also are old school and unneeded in most cases with today's larger fuel pump and injector options. Most reputable tuners will disable or remove these if proper injectors are used. (I unknowingly installed one with my first supercharger install 10 years ago on my Saleen. My tuner removed it while the car was strapped on the dyno before he started tuning).

Go get it tuned and be done. So simple!
Trust me!
 
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Listen to what these guys are saying.
Here I'll break it down for you:
-Install at least a Walbro GSS#340 -255LPH pump. I chose to go with an Aeromotive #11140- 340LPH pump.
-Do not use a T-Rex. They are old school and unneeded in most cases with today's larger fuel pump and injector options. ( I think of it as less parts to fail later). "AND they do"
-Do not use an FMU. They also are old school and unneeded in most cases with today's larger fuel pump and injector options. Most reputable tuners will disable or remove these if proper injectors are used. (I unknowingly installed one with my first supercharger install 10 years ago on my Saleen. My tuner removed it while the car was strapped on the dyno before he started tuning).

Go get it tuned and be done. So simple!
Trust me!
The wait list for a tune is rediculously long, we're taking months. Could I put the pump in and drive around with the fmu and 19's and then upgrade injectors just prior to the tune or will the 255 lph pump not work w out a tune either?
 
The wait list for a tune is rediculously long, we're taking months. Could I put the pump in and drive around with the fmu and 19's and then upgrade injectors just prior to the tune or will the 255 lph pump not work w out a tune either?
You cannot have to big of a fuel pump. Any extra fuel that is not used is returned back to the tank. Install the pump asap! Then when you go for the tune you can upgrade the injectors,ditch the fmu,calibrate the Maf,etcetera. You can "grow" into the fuel pump size but it won't hurt anything in the meantime