Your Car on Steroids
I used to not respect enthusiasts that chose nitrous as their
means for achieving horsepower. I felt it wasn't a "real"
power adder; that it was chemical enhancement like steroids
are to the athlete. I held the position that if the power
isn't obtained mechanically, through cubic inches or belts
and pullies, then it isn't "real". Needless to say
I got into many arguments with those in the nitrous camp.
But I am here to admit that I've since changed my position
- I have come to really like nitrous. Let me explain why,
and justify where some of that early negativity came from.
I had experimented with nitrous on several cars over the
last ten years. All of my early attempts at nitrous shared
a couple things in common - first, the kits were an installation
nightmare. Most systems, carbureted or EFI, required extensive
wiring and mounting of solenoids, relays, a throttle position
switch, a master arming switch, among other ancillary components.
The installation took the better part of a day to accomplish,
and left a mess of wires strewn across the engine bay. I may
sound like I'm whining but there are many novice horsepower
junkies out there who haven't purchased a nitrous kit for
this very reason. The second issue had to do with tuning.
Early "plate" based nitrous systems were not consistently
effective at mixing the nitrous and fuel charge. If bottle
pressure was slightly low you immediately had a rich condition.
On EFI systems such nitrous systems were prone to fuel puddling
in the intake manifold due to poor atomization. I recall many
strip passes where my car ran inconsistent ET's because the
bottle pressure was slightly different than the previous run.
Reinventing the Nitrous System
So what changed my mind? Evolution. A company has finally
figured out how to make nitrous systems better. A few years
ago Comp's master cam designer Billy Godbold and engineer
Matt Patrick were testing some of Comp's new Nitrous HP camshafts.
Matt noticed that engine performance would vary significantly
due to very minor changes in nitrous bottle pressure. As he
looked into the root cause he discovered the poor ability
of fuel to stay properly atomized in the nitrous plume. The
existing spray bars and nozzles simply shot a stream of fuel
towards the nitrous spray and hoped for atomization. These
kits deliberately over-compensated on the fuel jetting to
"play it safe" and avoid a potential lean situation.
Yet ask any EFI guy who has had a nitrous back fire and they'll
tell you that it wasn't due to a lack of gasoline. The problem
with adding excess fuel as a safety buffer in a nitrous system
is that it can have the exact opposite effect. The additional
volume becomes even more difficult to atomize and tends to
drop out of the gaseous mixture, forming puddles in the intake.
The nitrous gas effectively moves forward into the cylinders
without the fuel and a lean condition is created.
A new nitrous division, ZEX, was formed within the Comp Performance
Group and they began researching and testing new nozzle designs.
They knew they had struck gold when, as Matt told us, "the
air-fuel ratio on our dyno engine stayed constant even as
the nitrous bottle pressure dropped." What Matt had developed
was a nozzle design that delivered unprecedented levels of
fuel atomization - consistently and accurately. Their patented
nozzle features a stainless steel fuel transfer tube in the
center of a cup. As high pressure nitrous gas passes out of
the cup and over the tube it draws the fuel out into the highest
pressure area of the gas plume. The fuel is actually sheared
in ultra thin layers resulting in a super fine mist. This
design is so sensitive that fuel enrichment is adjusted in
correspondence to the vacuum created over the transfer tube
by the nitrous gas. The amount of vacuum created is in direct
proportion to the nitrous bottle pressure. According to Matt,
the Active Fuel Control Technology can adjust fuel 3% in either
direction. "It's not going to solve a situation where
bottle pressure is at 500psi," comments Matt, "however
it will easily adjust to the normal pressure drop in the bottle
after a drag strip pass." As bracket racers well know,
this type of pass to pass consistency is crucial the difference
between between going on or going home.
With the fuel atomization issues resolved, ZEX turned their
attention to addressing the wiring and installation shortcomings.
The outcome of their efforts was the Nitrous Management Unit.
This purple box, about the size of a kids carton of milk,
houses both nitrous and fuel solenoids, relay, and associated
logic processor for the activation switch. By putting everything
inside the box and adding digital processing, all that is
required for installation is a ground and switched hot lead
plus tapping into the throttle position sensor (TPS). On Ford
EFI systems, for instance, a signal from 0 to 1V indicates
a closed throttle, while 4.5 to 5V indicates wide-open throttle.
By tapping into this signal the ZEX nitrous management unit
knows exactly when to activate the solenoids. There are no
mechanical micro-throttle switches to deal with.
Installing ZEX on Project '67
It's learning about this technology that got me excited about
installing nitrous on our Project 67. Yes it is a little detour
from the blower that are planning, but rest assured the nitrous
will work well the the future blower as it helps cool the
hot blower air. As you'll see and read, the installation is
very simple (compare it to the Nitrous Works install we did
a couple years back on our 2001 Mustang GT) and the power
output is consistent and spot on the advertised rating for
our jet combinations.
|I. Mounting the Bottle and
Nitrous Management Unit
We like to begin any nitrous system install by first mounting
the nitrous bottle. Use the supplied bottle brackets so
that the bottom of the cylinder is angled downward and
facing the back of the car. This way gravity and acceleration
will force the nitrous liquid to the bottom of the cylinder
where the pickup tube is positioned.
The nitrous cylinder must be securely mounted. We drilled
through the trunk floor and secured the brackets with
the supplied nuts and bolts. It goes without saying that
you must take caution not drill into the fuel tank.