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Well, I'll be ....

I haven't seen that web site, but it is associated with Quality Roadsters.

Quality Roadsters builds repro Cobras, selling the EFI system began as something they did as a service to their Cobra customers. Apparently the Cobra clan is big on fuel injection. I knew the EFI business was catchng on, but ...I guess its safe to say that EFI has become a BIG business for Quality Roadsters.

Plug & play fuel injection using a Ford computer & Ford parts, with all the hot rod capabilities that Mustang guys have enjoyed for over a decade. It bolts on in place of the carburetor & except for the fuel rails, doesn't change the appearance of your engine.

The price of the kit has doubled, but they are providing all the necessary parts now, before you had to scrounge the wrecking yard for wiring harnesses and things.

There's a reason this business is expanding. Check it out.

I have this in my 73. Ran right out of the box and included everything, love it when the pre-run before shipping. 500+ hp out of a stroked 351, it is a sweet package. The ECU is based on the holley box which is perhaps the weak link. Only problem I had was the loss of the MSD box, I was a fool and went with their new digital series 6, I think that product needs a bit more time to de-bug. I suggest popping for the main girdle to stiffen up the lower end. Idles great and pulls like hell above 4500 rpm. With a two year warranty one can do a lot of damage before it expires.
I'm building a new engine (9.2" deck Fontana aluminum block, 3.85" stroke
crank, 6" rods, custom pistons, C302B high port cylinder heads, custom
hydraulic roller cam) and will be running a carb on a single plane intake
initially. Over the Winter, I'll be installing an independent runner EFI
system using one of Kelly Coffield's IR EFI intakes (Weber style lowers
with cast-in injector bosses).

There are lots of things to consider when putting together an injection
system - type of intake manifolding, type of controller, fuel system layout
and sizing (injectors, pump, lines, regulator, throttle bodies), gauges,
injector placement size, datalogging and programming, air cleaners, stacks,

> based on Ford EEC IV electronics ('89 - '95 Mustang).

That's a mass air-based system which will have certain limitations. There
are three popular EFI control schemes:

1. mass air flow
2. speed density
3. alpha-n

They differ primarily in the way they sense engine load. Speed density
systems use manifold vacuum via a MAP (manifold absolute pressure) sensor
to sense load. Fuel is metered using the MAP input, engine RPM, and
volumetric efficiency tables. Mass air systems use a MAF (Mass Air Flow)
sensor to directly measure the amount of incoming air. Those sensors
typically use wires that air exposed to the air flow. As the air flows
over the wire, it changes the voltage drop across the wire. Tables in the
computer convert the voltage drop to air mass. Alpha-N systems are the
simplest, using only RPM and throttle position to determine load. Note
that a MAP sensor can be used with Alpha-N, but it's used as a barometric
pressure sensor to detect altitude changes.

Each of these approaches have pros and cons...

Mass air systems don't handle large overlap cams well. Reversion pulses
produce an unsteady flow over the mass air meter which can lead to surging
at idle and lower RPM. A friend runs an EEC-IV mass-air based system in
his drag race Mustang and the engine has a strong surge below 3000 RPM due
to the large overlap of his cam. Wide lobe centers helps some (most 5.0L
"EFI" cams are ground on 112 degree lobe centers for this reason) and some-
times you can tune out the surge by repositioning the mass air meter relative
to the intake valve but the amount of overlap a mass air system can tolerate
is finite. Since the airflow is directly measured, mass air systems can
tolerate larger variations (in cam specs, cylinder head flow, etc.) before
tables in the EEC need to be reprogrammed. Mass air is particularly good
for idle and emissions.

Speed density systems can be cheaper and more reliable than mass air systems
because they don't require mass air flow sensors. They can also make a bit
more power than mass air systems since a mass air flow sensor is a restriction
in the intake flow path. Speed density is somewhat less sensitive to cam
overlap than mass air but still has limitations as overlap can cause unsteady
vacuum readings. The GM guys have used speed density with fairly hot cams,
though. A vacuum chamber to smooth out the signal helps. Speed density
systems are less tolerant to changes than mass-air systems in the engine
before requiring re-programming of the volumetric efficiency tables. The
commonly available EEC tuning tools (twEECer, PMS, etc.) don't typically
support speed density systems since the majority of Ford performance
applications are mass airflow. However, Ford's Cosworth F1 V8's ran speed
density EEC-IV's for many years. The situation is reversed on the GM side
and many GM guys will change from mass air to speed density.

Alpha-N is best for big lumpy cams. Most of the aftermarket EFI systems
like ACCEL/DFI, Electromotive, Haltech, BigStuff3, etc. are either speed
density or Alpha-N (or blend between the two).

The type of manifolding can influence your selection of control scheme.
With independent runner throttle bodies, throttle position is a better
indication of load than a MAP sensor once off idle. This is because a
small opening in the throttle body will cause manifold vacuum to go to
atmospheric. Beyond say 10-15% throttle opening, there is little
response to a MAP. Alpha-N is the way to go with naturally-aspirated
independent runner. Supercharged applications tend to have cams with
less overlap so speed density or mass air may be better. Supercharged
applications using Alpha-N require a MAP upstream of the throttle to
act as a barometric compensator.

Independent runner manifolding will tame down a big cam. Since the runners
are isolated from each other, reversion from adjacent cylinders does not
foul the intake stroke, allowing a longer cam duration with a streetable
idle. Kirby Schraeder runs a PPC-sourced IR EFI system on a 377 cubic inch
Cleveland stroker (iron 4V heads with Weber lower and 48mm TWM throttle
bodies). He runs a fairly large overlap 288FDP Crower solid flat tappet
oval track cam. Specs on his cam are 254/258 degrees at 0.050" (288/294
degrees advertised), 0.569"/0.580" lift (0.022"/0.024" clearance hot) with
105 lobe centers. That's a lot of duration and tight lobe centers for a
street car (Kirby drives it to and from work but also competes in a lot of
open track events). According to Kirby, with a 700DP Holley on a Ford
aluminum dual plane intake manifold, it had a wild idle and wouldn't start
pulling well until 3000 RPM (Crower rates the cam range as 3500 to 7000 RPM).
When he installed the independent runner EFI, the first thing he said was
"Where'd my idle go?". He noted it now pulls 5th gear from 1500 RPM. Kirby
also noted it's tough staying off the 7200 RPM rev-limiter in lower gears.

Independent runner also allows tuning of the inlet tract length generally not
possibly with single 4 barrel plenum type intakes. On my engine, the short
stacks that fit under the stock Pantera engine cover and decklid is close to

A big benefit of EFI is being able to adjust the spark curve easily in ways
a mechanical system won't permit. If you want to lean out the mixture at
cruise for best fuel economy, you'll also need to adjust timing. Combustion
gets much slower under lean conditions and if you don't adjust spark timing,
the combustion occurs much later and exhaust temperature climbs. That's bad
for the seats and valves. However, if you adjust for MBT spark at each A/F
ratio, exhaust temperature will actually decrease relative to stoichimetric.

Normal narrow band O2 sensors basically just toggle back and forth between
rich and lean, trying to stay at stoichimetric. That's why they are generally
only closed loop during cruise. At wide open throttle, the control schemes
usally revert to tables. Some of the latest aftermarket controllers (e.g.
BigStuff3) are using wide-band O2 sensors for data logging and also in "learn"
modes. They also have a simple model built in to get you in the ballpark for
start-up operation. You simply enter your bore, stroke, compression ratio,
etc and the computer defines a start-up map.

I'm leaning towards the BigStuff3 ( controller for my
application. BTW, most of the controllers are designed around serial
data interfaces but most of the laptops have gone to USB ports. There
are supposedly USB-to-serial adpaters but you may need driver software

Dan Jones
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