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Wow... the choices...
Let me start by reminding you (the reader) that I am building a 300+ HP
Ranger with a supercharger. PLEASE do not send me any hate
mail/questions like "Do I really need to do this?" as the answer is
no. I need to do this.
Now, there is nothing WRONG with the Ranger Fuel System, it was just never
designed with serious HP in mind.
The following is theory that I used, and can help YOU decide what YOU need to
do to YOUR fuel system to support YOUR needs.
Our Pathetic Pump
No, you are not seeing things. The pump I pulled out of my 1994 Ranger
3.0L is a 60 LPH pump.
Warning: Math!
Using the formula HP=FR/BSFC (Where HP= Horsepower, FR= fuel pump flow rate
in pounds of gasoline per hour and BSFC= Brake Specific Fuel Consumption), we
can see just how far we can go with the stock fuel pump.
Assumptions:
Fuel weighs 5.8 to 6.5 lbs per gallon. We will assume 6.1 lbs per
gallon.
BSFC is .45 for NA, .65 Turbo/supercharged (If you know
your ACTUAL BSFC from a recent dyno run, use that number!).
We can see the factory pump is good for 60 LPH (as marked plainly on the
case), so:
60 LPH divided by 3.785 (to convert liters to gallons) is 15.85 GPH.
15.85 GPH x 6.1 lbs (to get lbs per hr) is 96.68 lbs/hr.
So, FR=96.68 lbs/hr, BSFC is assumed .45 and our 60 LPH pump can support a
maximum of 193.37 HP.
That is for a Normally Aspirated Engine. For my supercharged 3.0L, we
get:
FR=96.68 lbs/hr, BSFC is assumed .65 and our 60 LPH pump can support a
maximum of 148.92 Supercharged/Turbocharged/N2O Injected HP.
I put that at the rear wheels without the charger!
Now, we know that the factory pump from a Mustang is 88 LPH. Using the
same formula, we come up with:
88 LPH, 23 GPH, 141 lb/hr, and 315 HP, so that is a much more realistic pump
for a Normally Aspirated 3.0L. As luck would have it, it is also a
direct swap. So, if you are running a normally aspirated 3.0L, use the
old pump your 'Stang buddy just removed! ...heck, check eBay
, they must be a dime a dozen!
But, for the supercharged engine, the numbers look like this:
FR=141 lbs/hr, BSFC is assumed .65 and our 88 LPH pump can support a maximum
of 216.92 Supercharged/Turbocharged/N2O Injected HP. Still,
not enough.
Then I found a chart on the Holley
website that covered some other pumps, and decided to try a 155 LPH pump from
BBK Performance.
155 LPH, 40.95 GPH, FR=249 lbs/hr, BSFC is assumed .65 and the 155 LPH pump
can support a maximum of 384.31 Supercharged/Turbocharged/N2O
Injected HP. Ahhh, plenty! (Actually the 110 was fine, but what
the heck!)
These pumps come from Walbro, so send
them your money instead. They also come in 110 LPH, 190 LPH and finally
255 LPH (pure overkill!).
If you REALLY don't want to change the in-tank pump, you can add an
additional inline fuel pump, but beware, they have been know to cause
problems. At high demand levels, the in-line (more efficient) pump
sucks the line from the in-tank pump dry and then your new, high dollar pump
cavitates (fancy word for "overheats and dies").
Look for any brand (Holley,
Walbro,
BBK
{made by Walbro}, Granatelli
{also a Walbro Pump, see picture!}) pump for the 1986-1997 4.6L/5.0L Mustang.
88LPH (Stock), 110LPH (Cobra, Saleen, etc), 155LPH, 170LPH (Ford Motor Sport
Only), 190LPH, 255LPH. Check Summit
or Jegs.
Fuel Pressure Regulator:
Any time you change fuel pumps/line size, recheck your pressure. The
'99 and later Ford's are all a returnless fuel system, with no fuel regulator
(so stop looking!). The EEC pulses the fuel pump like the injectors
based on TPS, rpm, vehicle speed (VSS), even what gear its in (auto trans).
It has no bypass loop, So, your only option for a fuel system upgrade
is a new pump (go big!) or a refit of a '98 or earlier rail system to run a
dry N2O system (I would stick with a quality wet system and big
pump myself).
Adjustable regulators are 2 and 3 bolt. They vary by year:
2 bolt: xxxx
3 Bolt: xxxx
Options: External regulator, must handle 40-60lbs pressure (EFI) and
have a vacuum/pressure connection. The fuel rail will have to be
modified to attach the regulator and (if not already equipped) a return line
installed to the tank.
Injectors:
Ford uses a Top fed, internally filtered, solenoid operated needle valve with
pintle (BOSCH) style injectors to control the air-fuel ratio. These are
standard items available from MSD, Accel, Bosch, GM, etc. The injectors
are "hot" any time the fuel pump relay is energized and will fire
when grounded at the ECU.
Our injectors are a pitiful 14 lb/hr model, the smallest installed by Ford.
There are 3 ways to correct this, but first you must determine what you
will need:
Fuel injector size = (HP X BSFC)/(# of Cylinders x duty cycle)
Assumptions:
HP= Desired Horsepower level
BSFC= Same as above
# of Cylinders= 6
Duty Cycle= percentage of "On" time for each injector expressed in
tenths. Ford normally uses .85 for a safety margin.
So: (150 hp x 0.45 [NA engine]) / (6 x 0.80) = 14.05 lbs/hr
Meaning: The 3.0L Vulcan Engine is "Injector-Challenged" [To quote
JoeB of RPS]. Notice there is no "slop" built in to accommodate
for clogged injectors, dirty screens or bad spray patterns. 14.05
lbs/hr is assuming you have a clean set of Matched Injectors.
Now for a 200HP 3.0L without a turbo, nitrous or a supercharger:
(200 hp x 0.45 [NA engine]) / (6 x 0.80) = 18.75 lbs/hr, meaning 19lb
injectors are fine on a NA engine producing ~200HP. Ford installs the
19 lbs/hr injectors in almost every other engine made, so happy hunting!
There is a limit to this though. If the injectors are too big (i.e.;
30lbs in an otherwise stock vehicle), your throttle response will suffer.
This is due to the fact that the injector "On" time is too
short, and proper metering does not occur. You must use realistic
numbers here, otherwise performance and driveability will suffer. Now
you know why they are always on eBay, you have to change them out with each
level of performance.
What about me? I am expecting 230 HP at the flywheel:
(230 hp x 0.65[for a supercharged engine]) / (6 x 0.80) = 31.34 lbs/hr
(230 hp x 0.65[for a supercharged engine]) / (6 x 0.85) = 29.31 lbs/hr
(230 hp x 0.65[for a supercharged engine]) / (6 x 0.90) = 27.68 lbs/hr
So, 30 lbs/hr injectors will carry me up to 230 HP at an 85% duty cycle
(Fords NORMAL safety margin).
How do we get the computer to accept the new injectors (since injector size
and fuel pressure are part of the lookup tables)?
First, the correct way.
Have you local Ford Service Center re-flash your ECU with the new injector
size/fuel pressure, or pay for a custom burned chip (I can only recommend SCT), check with Doug at Bama-Chips for pre-’96 vehicles, and see
my tuning page for ’96 and later
Ford Gas Trucks and all Ford Focus.
Second, a cheat:
Aftermarket MAF's (Granatelli, Pro-M, etc) can be calibrated to a new
injector size, but we don't want to FOOL the ECU, we want it to know exactly
what it is suppose to be doing. This makes life easier on you, your ECU
and troubleshooting is easier on injector problems.
Third, another Cheat: The adjustable fuel pressure regulator. You can
increase your fuel pressure to act like a higher output fuel injector, but
this is limited. As pressure rises, it is more difficult for the
injector to unseat and can cause problems.
Again, you are fooling the ECU by providing more fuel during each injector
"On" time. Great tuning tool, but not the way to do business.
Notes for REAL power Adders:
Wet system: No problem, extra fuel is added to the mix, so you could get by
with just installing a larger fuel pump to meet the demand. Wet system
adds the needed fuel to support the additional 50 hp, so:
(150 hp x 0.45 [NA engine]) / (6 x 0.80) = 14.05 lbs/hr
Dry system: NO WAY. Without 19lb (50 hp shot), you will run lean and
eventually (if not instantly) fry your engine from running lean. No
additional fuel, so injectors bare the burden:
(200 hp x 0.45 [NA engine]) / (6 x 0.80) = 18.75lbs/hr
Again, 19 lbs/hr injectors are needed.
I HIGHLY recommend the following mods for Huffer's and N2O use:
Chip or Flash Tuner to slightly retard timing (EEC-V) and remove the rev-limiter
completely. The problem being, Ford cuts fuel injector "On"
time in half as a way to limit RPM's. Not only is this the least effective
way to control RPM's, with Supercharged/Turbocharged/N2O Injected
vehicles, bouncing off the rev-limiter causes a 50% lean condition (even with
a wet system!) and you can damage your engine. To control engine RPM's,
I highly recommend an MSD Soft Touch Rev-Control or MSD-6AL.
Another new possibility is the MSD Fuel Pump Booster. As boost pressure
(indicated via a vacuum line or signal from a dry nitrous system controller)
rises, your factory fuel pump is fed greater voltage (up to 22 volts at 30 psi
boost) to feed the greater demand for fuel. Perfect for any real power
adder if you don't want to swap a bunch of parts.
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