Fueling box summary
03-04 HPCR Dodge Cummins Turbo
Diesel
© Doug (DTR), Dleno (TDR). Please do not re-use or publish in any form
without my permission
This is a work in progress
Explanation of HP
comparisons: Interpretations of what torque and
HP mean are in abundance, and the purpose of this narrative is not to comment
on anyone else’s, but to describe mine. J
Torque is the best parameter to describe the pulling strength of the engine in
any given (fixed) gear and over the associated RPM range. It is literally the force pushing on the back
of your seat; the torque curve is what describes drivability and “seat-o-pants”
feel when the transmission is not between gears. Peak torque is simply a number at the
highest point on the torque curve, and is not very descriptive as the pulling
ability of a vehicle with gears or driveability.
Horsepower is the best parameter to describe
the ability to achieve speed. It is
literally the rate at which work is being done, or (equivalently) energy is
being released (one HP is equal to 746 Joules of energy per second). Peak
horsepower is a good measure of an engine’s total output capability. It correlates with, for example, how fast you
can pull a trailer up the hill, if the gearing is optimum, the engine can run
at WOT at the right RPM and you don’t’ care about fuel economy. It is also a number reported on dyno
day.
Isaac Newton informs us that the ability to accelerate an
object (change it’s velocity or speed) is completely described by the force
pushing on it. Suppose you are in a
small compact that has stalled on the road, and you put someone in the driver’s
seat while you go push on the back bumper.
You are applying a force to the vehicle (just like engine torque does),
and this pushing force causes the vehicle to move. If you push hard enough to overcome rolling
resistance, you will accelerate the vehicle (change its speed), and at the end
of some time period, the vehicle will be rolling at some speed. Push harder (more engine torque), and it accelerates
more quickly. Keep pushing longer and it
(and your legs) go faster (higher engine rpm). Now think about your own physical output when
you are pushing: You push with a certain
force, but the faster you go, the more difficulty you have in pushing with the
same force. This is because at higher
speeds (higher engine rpms) you are working harder (expending energy at a
higher rate). In fact, the rate at which
you expend energy is called horsepower.
Thus, while
force (or torque) describes what
pushes on the back of your seat, it is horsepower (rate of doing work) that
moves the truck from point A to point B (i.e. performs work) in a small amount
of time (performs that work fast). In evaluating an engine’s ability to pull, it
is always best to think of the problem in terms of horsepower – in particular, horsepower at the rpm of interest. This will avoid discussions of what shape is
“better” than another and concentrates on the real issue, which is the ability
of the engine to perform work quickly. Of
course, the mathematically astute will notice that once we specify horsepower
AND rpm, we are now talking about torque.
This is simply due to the mathematical relationship, which is: horsepower = (torque x rpm)/5252. Thus,
the horsepower curve and the torque curve reveal the same information and are
related to each other by the formula. Its
just that the horsepower curve is more descriptive of what is most
important. In
this context, consider the following objectives and how a fueling box might
fulfill them by providing torque and horsepower curves that best fulfill your
own goals:
1) The ability to post big numbers on
dyno day: There are generally two things of interest on
dyno day -- peak torque and peak horsepower.
Peak torque is simply the highest point on the torque curve, without
regard to the RPM at which it occurs, or the shape of the curve itself. Peak
horsepower also looks at one point on the torque curve – where the product of
torque times RPM is the greatest. Again,
shape is not important on dyno day -- all we want is the greatest total engine
output, and this usually occurs when BOTH torque and RPM are high. As a practical matter, high peak HP numbers often
mean that the torque curve itself extends broadly into the high rpm range, but this
is no guarantee, and the HP measurement itself doesn’t care what the shape of
the torque curve is.
2) The ability to accelerate, whether
empty or towing. From a theoretical standpoint, an engine is
optimized to achieve speed (accelerate) when it has a large area under the torque curve. This, of
course, assumes that the rest of the drive train, including the tires, are able
to deliver all of this torque to the ground.
As a practical matter, the Cummins Turbo Diesel has more to give at low
rpms than at high rpms -- the characteristically flat torque cure is achieved
via electronics and does not represent the maximum mechanical capability of the
engine. Indeed, a diesel that is
optimized for its mechanical ability to burn fuel will have very high torque
output at low rpm, tapering off somewhat to a lower figure at the high rpm
(referred to as “high torque rise”).
Ultimately, such a shape results in a very large “area under the curve”.
3) Towing performance is usually characterized by rock
solid cruise speed and, of course, “pulling power”. There are two aspects of a diesel that
apply: (1) make no mistake, engine horsepower (rate of doing work) is what
pulls the load up the hill. However,
that does not mean that the peak
horsepower rating necessarily benefits the tow, unless of course you tow at
the rpm where peak horsepower is made. (2) It
turns out that the natural (mechanical) characteristic torque curve of a diesel
is well suited for towing because it is possible to achieve very high “torque
rise”. This benefits the cruise because
as road speed drops, torque rises, ultimately resulting in a flatter horsepower
curve. Ultimately, it all boils down to horsepower at the rpm of interest.
As a practical matter, many fuelling boxes change the shape
of the stock torque curve, some raising torque in the lower RPM region to
higher levels than the upper RPM region (usually done to avoid high EGTs). This gives rise to very responsive
acceleration at low RPMs, followed by some reduction in pulling power as RPM
increases.
It is important
to understand the contribution of a fueling box, both for its peak HP gain (total engine output, sometimes called “peak
to peak” gain), and for its contributions to drivability and pulling behavior (total
power delivery) via the torque curve. I
have tried to reflect this meaning into the comparative
matrix . The first column is the
gain in total engine HP – literally the highest RWHP output possible with the
box minus the highest stock RWHP (this is “peak-to-peak” HP gain and of
importance to dyno day bragging rights).
For the stock truck, the highest HP output occurs at or near 2900 rpm
which is where the 305 HP engine generates 547 ft. lbs of torque at the
flywheel (per mfg specs) and makes 305 HP.
For the enhanced truck (with a
fueling box installed), peak HP may or may not occur at the same RPM.
The second
column attempts to describe the torque curve below the (stock) peak HP point. Where possible I’ve added a [“xx % harder”]
figure in square brackets to help answer the question, “how much harder does it
pull?” This figure expresses the improvement
in acceleration provided by the box as an average increase in area under the
torque curve (“total power delivery” as mentioned previously).
To factor
out variability between dynamometers, I deliberately avoided using any absolute
measurement numbers. I used torque gain
(delta) from the dyno run, and applied the broad assumption that torque to the
rear wheels over the same rpm range in a stock 305 HP truck is approximately
480 ft. lbs and approximately 510 ft. lbs for the 600 (15% loss through the
power train). For example, according to
the dynamometer run for the Volumizer (on a 305), this box adds approximately 180
ft lbs of torque +/- 8% from about 2000 to 2600 rpm, and the stock truck
delivers 480 ft. lbs over this same range.
So I say that the volumizer provides 180/480 or “38% more” torque over
this range. In other words it pulls with 38% more lbs of force
or 38% harder than stock.
Owner responsibilities
Any
discussion of fueling box enhancements needs to also describe the
responsibilities you take on. For
example:
Emerging or un-released boxes are beyond the scope of this
document. My intent is to include only
boxes that are released to production, available now and currently
shipping. As new boxes become
available, re-introduced, or if one exists that is not included, please notify
me via email at doug.leno@hp.com
Misc. details:
The purpose of this document is to provide distinguishing comparative
data, and every attempt has been made to present data as accurately as
possible. However, much of the data is
not directly comparable and requires interpretation. Consider the following:
“Pressure” boxes work by introducing analog error
into the pressure feedback loop to the ECM (pressure fooling). This is
accomplished by intercepting the fuel pressure signal itself, either via the
pressure port connector or the ECM input connector. By introducing negative error into this
signal, the box causes the ECM to think that fuel pressure is low, and in
response to this, the ECM sends higher and higher pressure commands to the CP3
pump until it (the ECM) is satisfied.
The ECM also changes injector pulse width and injector timing in very small
amounts in response to the “low” pressure signal provided by the box. In order for the box to produce a HP gain,
there will be a difference between the pressure commanded by the ECM and the
pressure measurement it reads. The ECM
in the 600 engine is able to detect this condition, and will set an engine code
if the difference between commanded and measured fuel pressure is large. Apparently, this condition does not matter to
the 305’s ECM.
Fuel
pressure is one of the ways the ECM controls fuel delivery and drivability,
varying rail pressure from approximately 3,200 to 23,300 psi (on the 305). Introducing
error into the fuel pressure feedback loop means that the fueling box manufacturer
has control over drivability, “smoothness” and to some extent when (at what
rpm) the power “comes in”. Such control
is typically based on associating Manifold Absolute Pressure (MAP) readings (or
other parameters such as RPM and throttle position) with the error inserted
into the fuel pressure feedback loop – the box basically dials in fuel pressure
error based on these inputs. These associations are often called “fueling maps”
having “dimensions” (one dimension for each parameter).
Boost
fooling is another task that pressure port boxes perform. In its simplest form, boost fooling simply
passes through Manifold Absolute Pressure (MAP) signals to the ECM (as normal)
but caps (limits) the signal at some maximum level before the ECM tries to
de-fuel and/or set an over-boost code. In its advanced forms, more complex
manipulation of the manifold absolute pressure signal itself also affects
drivability, responsiveness, and available power, especially at the low end.
Available
pressure boxes include Edge EZ, TS Ramifier, Quadzilla towing module, Van Aaken
Smart Box L1, and the Bullydog Adjustable Torque Dog. What differentiates boxes in this category is
the fueling map -- how the algorithms relate fuel pressure error to whatever
they measure as input (MAP, rpm, TPS, etc.) Some boxes make power come in earlier than
others; some have wider power bands than others, some do a better job than
others creating a smooth application of power, some are more throttle
responsive than others, etc. Some are
in-cab adjustable; some are re-programmable by the mfg. With three notable
exceptions (Banks, Ramifier, and Van Aaken), none of the pressure box manufacturers
will state a max fuel pressure achieved by their box, preferring instead
to make vague references to operating
“within factory pressure specs” without defining what that is or what it means
to exceed those specs. I hope to have
more complete information on pressure versus HP after I perform more testing.
The
advantages of pressure boxes include the fact that there are easy to install
and remove. The electronics itself is
not complex, so the cost of most pressure boxes is low compared to others. The main disadvantage to the pressure box is
that it raises fuel pressure above what the factory ECM would normally do. Pressure box proponents believe that there is
plenty of design margin built into the high pressure common rail system and
that raising rail pressure is both effective and safe. Those against the use of pressure suggest
that only about 70 HP gain (over stock peak) can be taken via pressure before putting
long term HPCR reliability at risk. The chief concerns over elevated rail
pressure are (1) erosion of manufacturing tolerances of the CP3 pump and the
rail itself (including connection points and
seals), and (2) the higher fuel pressure is raised, the closer the HPCR
is to its factory pop-off safety point mentioned above. Once
the factory safety valve has opened, dealer service is required to bring the
rail up to “factory new” condition once again.
Within the
pressure box category, the Ramifier and Volumizer boxes are noteworthy in that they
are able to not only read and use the factory MAP signal to influence fuel
pressure fooling, but can re-map the MAP signal itself to new values. Since the ECM adjusts fuel pressure, timing,
and duration in response to boost, these boxes are able to coax the ECM into
adjusting these parameters simply by giving it higher than normal boost
signals. This of course works at boost
levels below that which would normally cause the ECM to de-fuel, and allows the
boxes to fuel more aggressively than other simple pressure boxes especially at
the low end. At WOT, however, these
boxes are on equal footing with other pressure boxes as regards peak output.
"Pressure/Timing” boxes raise fuel
pressure and perform boost fooling like pressure boxes do, but also provide
injection timing advance via direct connection to the crank and cam sensor. By introducing artificial delay into these analog
timing signals, the ECM is essentially “time fooled” into advancing the
injector opening event. Approximately 30-40HP is available via timing
alone without additional fuel, depending upon how radical the advance. In
order for the ECM to be happy, a very precise phase relationship between the
crank and cam signals must be maintained, and for this reason, manufacturers
have been struggling to achieve successful timing advance on the 3rd
generation trucks without setting an engine code.
With the
exit of the Bullydog and Quadzilla pressure/timing boxes from the market (due
to engine code problems), there are two boxes that I know of in this category: One is the Banks six gun, and the other is the
PDQ Volumizer. My personal experience
with these boxes show that the Volumizer behaves very nearly like a pure
pressure box in terms of total output and smoke, suggesting that timing advance
is very small. My own results with the
Banks six gun suggests that this one advances timing enough to make a
measurable difference in both power output and smoke control.
Within the
pressure/timing box category, the PDQ Volumizer is unique because it, like the
Ramifier, is able to re-map the MAP signal itself to new values. This allows greater low-boost fueling, a
stronger low end, and more smoke.
“Analog Timing/duration" boxes advance
timing by connecting directly to cam and/or crank sensors. Like the pressure/timing boxes, they
time-fool the ECM to obtain timing advance, but they do not connect to the fuel
pressure port and do not raise fuel pressure above the stock maximum value of
23,300 psi. They connect directly to the
high voltage injector control harness and keep the injector open longer than
the ECM has directed and without its knowledge.
Currently, TST is the only box in this category, achieving 150 peak HP (over
the stock maximum), and well over 500 ft. lbs of torque gain at a very low rpm. The biggest advantage of timing/duration
boxes is (1) fuel economy due to timing, and (2) no fuel pressure increase
whatsoever.
“Digital Duration” boxes control injector pulse width
only without adjusting pressure or timing, and without connecting to the high
voltage injector control harness. At
this writing, Van Aaken is the only mfg in this category, connecting to just
the ECM connector and adjusting pulse width by manipulating/changing the ECM
instructions digitally. The advantage of this method is that (1) the
complexity of direct injector control via the high voltage harness is avoided,
(2) the connection point is simple, and (3) like the timing/duration boxes, there
is no increase in rail pressure. The
disadvantage to this method is that lengthening pulse width without a timing
advance results in effectively retarding fuel delivery timing. Experiments have shown that this (duration
without timing) is a decided EGT disadvantage.
One of the
most common questions arising on the forums relates to the ability of the ECM
to detect the presence of a fueling box. Remember, “You are your own warranty
station”. However, I can offer the
following comments based on the best of my knowledge:
It is
beyond the scope of this article to discuss “Cummins 600” injection technology
in any detail, except to highlight the major points believed to affect the
application of fueling boxes. The
fueling technology used on the 04.5 600 engine is significantly different from
that on the 305, largely motivated of
course by a reduction in NOx to meet January, 2004 Federal EPA emissions
regulations. In particular, there are
three instead of two injection events per charge cycle, but the main injection
event on the 600 is characterized by a larger, more concentrated fuel charge
delivered later and with less swirl.
This is accomplished by an injector with fewer, larger holes, a
different head design, and by retarded timing.
Some relevant observations and comments are:
One of the
most common questions asked about fueling boxes is whether or not there will be
an increase in fuel economy. The
potential for fuel economy improvements are in many cases highly individual and
dependant on driving conditions.
However, the following can be said:
The
practice of “stacking” two fueling boxes together means essentially hooking them
both up and using both at the same time.
The success or failure of this effort requires a general understanding
of how the boxes work so that the choice of boxes to stack can be made
intelligently. For the most part,
fueling boxes are not made to be stacked, but there are some that have more
promise than others and some have been tried successfully. In general, stacking to obtain greater
horsepower is usually disappointing because of limitations in the fuel system
itself. Stacking to mix pressure with
duration, however, has been successful, not to increase HP but to reduce EGTs
of pure duration. Some general guidelines to follow when
stacking are:
1) Only boxes that are “dissimilar” can
be stacked. Dissimilar in this context
means that they connect to, interface with, and manipulate different fueling
signals. If two boxes attempt to
manipulate the same signals, they will fight each other and the result will be unpredictable.
2) The effect of stacking two boxes is
to combine (or add) their fueling curves together. Look closely at the individual torque curves
to understand whether or not a particular combination is a good thing – the two
boxes may or may not compliment each other well.
3) Stacking to add power may be
counter-productive, as the fuel rail itself will probably run out of
capacity. In fact, stacking to achieve
additional power is usually a bad idea, at least without upgrading the fuel
system. Adding fuel via electronics
doesn’t mean that the mechanical system is capable of delivering it.
4) Any time you add fuel (regardless of
the method, i.e. pressure or duration) and then use the additional power, there
will be an EGT consequence that the stock truck will not be able to handle,
even with intake and exhaust modifications. For example, stacking the least powerful
duration box (VA) with the least powerful pressure box (VA) will likely require
a turbocharger upgrade.
5) The only two stacks I am aware of
that achieve a useful goal (utilizing the stock fuel system), have nothing to
do with additional power – they have to do with attaining the desired fueling
curve and/or a reduction in EGTs. Both
the TST and the VA duration boxes have been stacked with simple pressure boxes
with good results in this regard. Note, however, that the opportunity here is
to achieve a reduction in EGTs by using
more pressure and less duration to achieve similar power levels. This means turning the duration box down when
adding a pressure box. For example, the
VA duration box on its lowest setting, combined with a pressure box on a ~50 HP
setting, will achieve about the same power level as the VA by itself, but will
do so at lower EGTs.
For
purposes of stacking, the fueling box market can be quickly broken down into
two general categories that are compatible with each other: In general, a pressure box can be stacked with
a duration box. In particular, the
simpler pressure boxes represent the best opportunity to stack with either the
TST or the Van Aaken “level 2”
(duration) box. Beyond that, the most
important consideration is boost fooling – all boxes perform boost fooling in
some form so the main consideration is how to utilize both boxes when each is trying
to do the same thing and (potentially) one might be fooling the other. The order in which the boxes are connected
could be very important in that regard. Some box-specific comments follow:
Ramifer:
This is an aggressive pressure box characterized by a unique method of
manipulating the boost signal. This makes the Ramifier a difficult stack
without modification. For example, it
has been shown that success in stacking the Ramifier with the TST Powermax requires
that the Ramifier be modified into behaving like a more simple pressure
box. The main points of modification are
(1) it normally fuels very aggressively at the low end which needs calming, and
(2) its MAP signal manipulation requires special attention to insure
compatibility with the stacked box. The
best chance for success is to hook up the Ramifier directly to the engine
block, modify its boost fooling behavior so that none is performed (let the TST
box perform boost fooling), and tame its low end fueling. The Ramifier is not a box that will work well
off the shelf with anything else, but it is fully programmable and as long as
TS remains in business, the box can be modified to behave any way you want, and
that is an advantage. As for stacking the Ramifier with the VA
duration box, there are no electronics incompatibilities, but the VA will be
forced into reading the Ramifier’s boost signal. Again, modification of the Ramifier as above
will probably yield the best success.
Edge EZ, Bullydog Adjustable Torque Dog:
These boxes are simple pressure boxes in that boost fooling isn’t fancy
and they are not known for aggressive fueling at the low end. This makes them good candidates for
off-the-shelf stacking with a digital duration (VA) or an analog duration/timing
(TST) box. Since both the TST and the VA
fuel aggressively at the low end, the pressure box fueling curve is a natural
complement. For the TST, the most obvious
opportunity is to hook its MAP connection to the engine block, and to hook up
the pressure box MAP connector to the TST.
This allows the TST fuel map and boost gauge to work correctly. No modifications should be necessary, but
manipulation of the TST torque and HP settings will allow you to tune for best
performance. As for the VA, the
connections are very straight forward – the VA always connects directly to the
ECM, and the pressure box always connects to the MAP and fuel ports on the
engine block. The VA always reads the
boost-fooled MAP signal from the pressure box because the VA connects to the
boost signal “downstream” (at the ECM connector).
TST
Powermax: This is a very aggressive box capable of 81
(9x9) different settings. It has been
successfully stacked with the EZ, but any of the simple pressure boxes should
work well. Care must be taken to allow
the TST to see full, unadulterated boost signal from the MAP sensor. This allows it to control its own fueling,
and for its boost gauge to work correctly.
One potential problem with stacking another box with the TST is that the
EGT-based de-fueling may not work correctly.
The TST may de-fuel, but the other box won’t.
Quadzilla
towing module: This box behaves like the EZ and Torque Dog
Plus, but I broke this one out separately because it is targeted at a slightly
less touchy throttle and a very strong upper end. To the extent this is true, it would be an excellent
choice as a stacking partner to either the TST or the VA. Stacking the Quadzilla with the VA duration
box works well on the 305 HP engine, especially with both boxes adjusted to
their mid-level settings.
Van
Aaken Smartbox level 1 (pressure): This is mild
pressure box that uses RPM and boost information to build its fuel map. It fuels moderately strong at the low end,
and then tapers off towards the high end to control EGTs. On its mild setting, its torque curve is very
flat, which makes it a good candidate for stacking. Stacking with the VA duration
box on the 600 has not yet been validated (early reports suggest stumbling and
rough idle). Stacking the VA pressure
box with the VA duration box works well on the 305 HP engine, especially with
both boxes adjusted to their mid-level settings.
Banks
six gun: Conceivably, this could be stacked with the
VA duration box to yield an interesting combination of drive train slip
detection, pressure, timing, and duration.
However, at the time of this writing, this combination had not been
attempted and results are not known. One potential problem is that the EGT-based
de-fueling feature may not work correctly – the Banks will de-fuel and the VA
will tend to keep on going.
Volumizer:
As a pressure/timing box, this could also be stacked with the VA
duration box (theoretically) but, as with the Banks, this has not been done so
the results are unknown. Also, the
Volumizer re-maps the boost signal like the Ramifier does to obtain a stronger
low end, and this, in my opinion, makes it a poor choice to stack with the
VA. Don’t even think about stacking the
Volumizer with the TST.
Van Aaken
smartbox level 2 (duration): This box
has a very strong low end, tapering off towards the higher RPMs to control
EGTs. When adjusted to its mid-level
setting, the torque curve is flatter. A natural compliment to this curve is probably
the Quadzilla, EZ, and Bullydog (simple pressure boxes) mentioned above. The VA level 2 box has been known to stack
well with the Edge EZ. Since the main
objective here is to improve upon the EGT disadvantages of duration without
timing, the objective is to add either pressure or both pressure and
timing. I expect that the VA C3.2 might
stack well with the Banks six gun, which is a timing/pressure box.
Stacking
the VA duration box with the TST duration/timing box:.
While this should theoretically work (there is no signal conflict), I
don’t think it’s a good idea. Note that
the TST is already a very aggressive duration box, already maximizing what the
HPCR has to give, and the VA also has an aggressive low end. The VA would work in the digital domain,
coaxing the ECM to give wider pulse width to the high voltage injector control
harness. The TST, then, would take these
already widened injector pulses and stretch them out even further. I don’t think this is a good match – it would
be much better to stack either the TST or the VA with a simple pressure box
such as the Bullydog, Quadzilla, or Edge EZ.
Stacking
similar boxes (that
is, those manipulating the same parameters via the same connection points) should
never be attempted. For example,
Ramifier, EZ, Bullydog Adjustable Torque Dog, Van Aaken Smartbox level 1, Banks
six gun, Volumizer, and Quadzilla Towing Module are all incompatible with each
other. They each manipulate the same
parameters by connecting to the same engine signals. The only viable stacking opportunities are a
duration box with a pressure box.
A
comparative matrix of all known fueling boxes currently in production can
viewed by clicking here .