FUTURE | CONNECTING RODS | COMBUSTION CONTROLLING ADDITIVES
I found an article
a while back, and could not resist responding to it.
Hello
Article: “Don’t
expect your mechanic to know everything about your car” is well written. I
can tell you the difficulty experienced by dealerships, regular garages. I am
an automotive computer system specialist. I diagnose computer systems or the
devices controlled/monitored by them and install computer systems, or modify an
existing system. Often, you can find me at a garage, chain repair or a dealer
diagnosing problem vehicles. I agree with your opinion plus outline more
reasons why a garage or dealership’s have problems.
1. Regardless of
the diagnostic tools a shop or dealership may have it is the technician’s
capability/skill most needed to understand the information provided by these
special tools and finally test the suspect component to determine
serviceability. It is common for shops to have invested a tremendous amount of
money in equipment but have difficulty using them properly.
Example: Edge Diagnostic produced a
fantastic tool called “Personal Automotive Computer” (PAC) with all in one
capability. This tool was/is still the most advance tool available but has been
discontinued and here is why. This tool has all in capability and is equipped
with touch screen menus, a scan feature, scope, grounding test, signal
generator. During development it was beta tested by technicians such as
my-self. All problems with the
software/hardware were sorted out and made ready for the average shop. The tool
had been sold too many shops, it was expensive but very capable in the hands of
someone who new how to use it. It was not long before some of the tools were
returned to the repair center for repair, and tested, functioning as designed.
The company was so overwhelmed with the influx they discontinued production.
Only then did they figure out they designed a tool for advanced users. I was
fortunate to have purchased this tool before the remaining unsold tools were
destroyed by Snap On for tax reasons.
2. Tremendous reliance is placed on codes to
help the technician quickly isolate a problem with a computer system. Codes are
a reference to look up information; they do not isolate the cause but will
identify the suspect circuit.
3. Very often a
problem will occur within the computer system and a code will not be set. That
type of complaint will cause some technicians to run from the vehicle. Often
cars have a number of parts replaced before the problem disappears. When you
include cost of labor parts and diagnostic time, it adds up. To make this
scenario worse, you cannot return parts that were not the cause of the problem;
plug in that computer, and the problem is still there, you just bought a spare.
Lastly
intermittent problems are a terror to fix. 15% of problem vehicles are very
hard to diagnose. Right now, I am driving clients Eagle Premier. This car will
run fine for about 3 to 4 weeks, and then one day it will not start. So far
this car has not shown any sign of this problem. Yet, when I arrive at the
location to inspect the problem, each time in the middle of the diagnosis the
car has started. This is very frustrating but I will find the cause.
Tools don’t make a
technician it is skill, and is the technician’s most valuable possession that
will determine the capability of a repair center not the tools.
Years ago, even today it is believed that inertia of a
column of air would cause combustion chambers to fill and empty, this
understanding is defined as Kadanacy Method. It described air movement through
a passage that would generate a low pressure in its wake.
In the early 1900's, F. Ernshaw had postulated the existence of wave forms that
were similar to sound waves. The wave forms are defined as finite amplitude
wave forms. If viewed on an oscilloscope, the waves are compressed have
many cycles with in a measured time period but most notably the amplitude of
the wave forms was the most striking characteristic. Another feature is the way
the wave form changes even after it has left its point of origin. It will
continue to change never having the same amplitude or shape. Finite wave forms
have a unique and distinct quality making them useful in an internal combustion
engine. The strength of the wave form has a tremendous influence on air flow
within a chamber, moving a large quantity of gasses causing a differential in
pressure.
Calculations to simulate and predict the effect a 'finite wave form' will have
on airflow are time consuming and require an understanding of hyperbolic,
partial-differential equations. Chamber shape, air density, temperature and
direction are all considerations for predicting what will happen. Recently, Roland S Benson observed the effects of
thermodynamics and gas dynamics within the combustion engine. He detailed the
effects, and phenomena that occur within the gas engine, developing a
method/formula to calculate wave forms, called the 'Mesh Method', it simplified
the effort and time required to predict the effects.
Passage design has a greatest impact on the engines ability to produce high
torque levels with the RPM curve of an engine. Torque will be reduced due to
pumping losses or gained because of a design that encouraged wave forms to
occur. Header tubes have wave forms traveling up and down the tube during
exhaust cycles, the most important event is during the return of the wave form
to the exhaust port. This will create a negative pressure at the exhaust port,
scavenging the remaining combustion gas from the cylinder. At the same time the
intake valve is open, intake gasses are drawn in to the cylinder, the same wave
forms occur within the intake tract assisting this process.
Computers are an
incredible asset to the auto industry. Each year car lines have improved in
quality, go faster, handle better, burn less fuel, produce fewer emissions and
last longer. It makes me wonder what the future of performance will be like in
the coming years. I have a few theories and hopes.
I have some ideas of what the future could
hold for the automobile, first let’s take a look back. The Model T Ford is the
most notorious of automobiles that created the dependence for transportation.
The vehicle is very simple in its design and was touted as reliable, the engine
is a piston engine and consumed gasoline; this basic design has remained the
same for almost 100 years, the only difference is the engineering and research
to improve the automobile. The engine has remained pretty well the same in its
function over the years and could benefit from a few changes. I feel that
burning a fossil fuel will remain the norm for quite a while and other fuels
will become more abundant, hydrogen, natural gas, etc. I also believe the gasoline
engine has not reached its limit in power and fuel efficiency, there are more
improvements to be made.
As a kid, I had an idea for an engine that
did not use a camshaft, the valve rate of opening and duration were controlled
by a computer and the valves were opened and closed by actuators, oil used in
this system was viscous stable for use in all environments. I have also thought
about a way to modify the incoming air stream to the cylinders, changing peak
cylinder efficiency because the intake runner is tuned. How about an intake
that could change its shape to give an incredibly wide torque curve through the
RPM range. An electric motor is capable of this, example 100% torque at zero
RPM and a 100% at its Max RPM. The intake would have to be constructed with a
material that would have a way to change the shape (a fluid) This material
would move to a position that it remembers, (polarity sensitive) and be
controlled by a computer with the capability to make constant modifications to
the algorithm making the engine even more efficient and powerful. Plastics are
becoming a major player in the content of auto construction, what about the
engine, plastic has remarkable fatigue resistance and transfers heat poorly.
This is an advantage, how about high temperature resistant plastics or
composites that could replace the piston, become a cylinder wall or an engine
block or cylinder head. Skinning of heat from the combustion process robs
cylinder pressure, plastics poor transfer of heat would be an advantage. Imagine
an engine with short connecting rods but having a better brake mean effective
pressure - considering piston dwell time @ TDC- than a long rod equipped
engine.
Surely there is a better method to improve
the beginning of the combustion process, how about a plasma type ignition or
even a surface discharge type of ignition, and what about increasing the
amperage to provide a fatter arc. If the kernel size could be increased the
time for total mixture consumption versus cylinder dimension and piston speed
would be reduced. Overall this engine would be incredible. Now let’s combine
all this into a car with a computer with a CPU that can process info from a
drive and be modified by a change in the program via a CD/DVD Player. With the
addition of this new instruction the computer would modify the engine,
transmission, suspension for a type of driving. I like it all ready.
Check next time
for more Driving Topics.
First off the
connecting rod has the task of transferring the forces from both the crankshaft
and the piston, also the rod has to withstand tensile stress and the forces of
combustion which are tremendous. Certain rod lengths are suitable for a type of
performance and correct rod length must be carefully picked when boosting cylinder
pressure (turbo)
1.) Long Rods.
-Pros-
Provide a longer piston dwell time which maintains a longer state of
compression and maintain peak cylinder pressure for longer periods. This has
obvious benefits better combustion, higher cylinder pressure after the first
few degrees of rotation passed TDC, and reduced hydrocarbons due to the higher
temperatures within the combustion chamber and burn duration remains the same
but within a smaller volume. This type of rod will produce very good mid to
upper RPM torque where as the shorter rod will begin to produce less, also a
longer rod will reduce friction within the engine. This is due to the reduced
angle associated with a longer rod which will place less stress at the thrust
surface of the piston during combustion. These rods work well with numerically
high gear ratios and light body cars.
a.) Long Rods.
-Cons-
They do not promote good cylinder filling due to the reduced velocity of air
flow. After the first few degrees beyond TDC piston speed will increase in
proportion to crank rotation but will be biased by the connecting rod length.
In other words the piston will descend at a reduced rate and gain its maximum
speed at the center of its stroke (5 inch stroke, piston speed fastest at 2.5
inch), it is important to select a passage dimension that will promote a high
velocity within both the intake and exhaust passages. Long runners and reduced
inside diameter air passages work well with long rods, and camshaft selection
must be carefully considered. Long duration cams will reduce the cylinder
pressure dramatically during the beginning moments of the intake cycle.
b.) Boost: Caution must be used when
long rods are used in a Nitrous, Turbo or Supercharged engine. Care must be
taken due to the high cylinder pressures caused by these methods to increase
power. With piston speed reduced and cylinder pressure increasing at a greater
rate as compared to a non boosted engine during combustion, the pressure can
become great enough to cause damage to engine components (increased frequency
of severe detonation)
b.) Short Rods.
-Pros-
Provide very good intake and exhaust velocities causing the engine to produce
good low end torque, mostly due to the higher cylinder pressures at the
beginning of the intake cycle. High intake velocities also create a more
homogenous (uniform) air/fuel mixture within the combustion chamber. This will
produce greater power output also low emissions due to this effect. There have
been great strides in the technology related to combustion engines. Combustion
has become more efficient and provides a compromise between emissions and power
in the short rod engine. Due to the increase in piston speeds associated with
the use of shorter rods the engine will respond well to boost also nitrous and
will not as sensitive to over camming as is the long rod engine.
c.) Short Rods.
-Cons-
Cause an increase in piston speed which at very high rpm will out run the flame
front causing a decrease in total cylinder pressure 'Brake Mean Effective Pressure'.
Due to the reduced dwell time of the piston at TDC the piston will descend at a
faster rate with a reduction in cylinder pressure and temperature as compared
to the long rod equipped engine. This will encourage reduced total combustion
and an increase in hydrocarbon emissions.
Rod length will
modify an engines torque curve considering the displacement and configuration;
the rod angle must not encourage excessive friction at cylinder wall and piston
skirts. Connecting rod angle is a product of stroke and rod length, greater
angles can occur by installing a shorter rod or by increasing the stroke.
Reductions in angle will occur with a longer rod or a reduced stroke and stroke
is not affected by a change in length of the connecting rod.
1.) Rod Angles. Developed as a result of
stroke and rod length and has a directing influence on the stress at the major
thrust surface. The rod angle will determine the friction that occurs during
the compression and combustion phase.
2.) Angle
Limitation.
It is important to measure the angle of the rod at 90 degrees of crank rotation
from TDC. Angles beyond 17 degrees promote excessive wear at the piston major
thrust surface and piston breakage could be the result. Before you purchase
connecting rods that are shorter than previous or you increase the stroke of
the crank, calculate the new rod angle. High rod angles will require quality
rods that have been checked for cracks and have quality fasteners, and piston
selection must be carefully considered.
4.75 (Stroke/2)
6.535 (Rod Length)
= .3634276
Sin 1 = will equal rod angle in degrees
DEGREES 21.31085248
This engine must use quality components
Popular
connecting rod calculations.
Big Block Chevrolet 454 CID.
1st) example: 6.135/4.250= 1.44
2nd) example: 6.353/4.250= 1.49
The first example would be suitable for an engine to produce
good low to medium torque.
The second example would be suitable for an engine that will produce its power
at a higher RPM.
You will notice the stroke remained the same but the
connecting rod length was changed.
1st Example.)
-Pros-
This engine will produce good low end torque, won’t be as sensitive to long
duration cams and will produce higher port velocities.
-Cons- This engine will have greater friction at the cylinder walls and
piston skirt, and piston speed at high rpm will out run a flame front causing a
drop in cylinder pressure.
2nd Example.)
-Pros-
This engine will generate very good torque values at a high RPM, piston speed
will be reduced, maintaining higher cylinder pressure dwell time, and friction
is reduced.
-Cons- This engine will produce
an overall reduction in port velocities and will be very sensitive to long
duration cams. This engine could not tolerate a sudden increase in boost or
Nitrous without damage.
Rod function is a science all its own. I recommend you always spend time to
consider the use for the engine you are building and choose the parts that will
work best.
COMBUSTION
CONTROLLING ADDITIVES
High Performance
Engines usually burn the same gas available at the gas pump. Unfortunately
combustion will be erratic if straight 87 regular fuels are used. Below are
additives that will improve the combustion process.
Aniline
A
highly effective octane booster, aniline was once used as the main ingredient
in several after-market retail-level canned additive products; but because of
its many undesirable characteristics, has today been mostly phased out. You
could expect about a one octane increase for every % aniline added to the
gasoline base stock, up to a 5% concentration. Aniline removes combustion
chamber deposits, so it also raises the "apparent octane". On the
other hand, aniline is extremely toxic; it can be absorbed through the skin,
enter the bloodstream and starve the body of oxygen. Also it is not compatible
with paint and will damage rubber seals.
MMT
Otherwise
known as methyl cyclopentadienyl manganese tricarbonyl,(whew!) MMT was once
hailed as the replacement for tetra-ethyl lead, since it both prevents exhaust
valve seat recession and raises octane. But the EPA claims it fouls catalytic
converters and increases hydrocarbon emissions; they have mandated its use only
in leaded gas for pre-1975 cars in concentrations that do not exceed .1 g/gal.
High Octane Gas
Tetra-ethyl
lead cannot be beat in its octane-boosting and exhaust valve seat
recession-preventing ability. Race gas and aviation gas are chock-full of the
good stuff. As shown in the chart, significant octane increases are obtainable
by blending either race gas or 100/130 Av-Gas with pump premium unleaded.
Unlike most other additives, there are no serious, adverse drive-ability or
maintainability consequences incurred by using high-octane gasoline. Compared
to automotive gas, cold weather drive-ability will be slightly impaired due to
the anti-vapor-lock (low Reed Vapor Pressure) characteristics of these fuels.
Due to Av.-Gas' lower specific gravity, you will have to re-jet the carburetor
when running it in high percentages. Av-Gas is available at airports, you can
buy it by the 55 gallon drum for off-highway use. Stay away from inferior 80/87
Av-Gas. "Low Lead" 100 Av-Gas has plenty of lead for any street car,
but in blend has less octane-boosting ability than 115/130.
Moving beyond
pre-mixed gasoline blends, in some cases you can purchase the specific
high-octane hydrocarbon components in pure unblended form from a chemical
supply house. These include various aromatics and alkylates such as Benzene,
ISO-octane, Triptane, Isodecane, Cyclopentane, Toluene, and Zylene. Triptane
has tremendous potential knock resistance but with present technology is
impossible to reliably and economically refine, and any presence in blended gas
is mainly by accident. Benzene is not available to the general public because
it is a component used in the production of some drugs. Racers are most
familiar with toluene, which has been used with varying degrees of success to
make home-brewed race gas. It and xylene are available in bulk at the local
chemical supply house. West Star Enterprise's "Power Plus" contains
xylene among its active ingredients. All these hydrocarbons have a relatively
heavy SG - so you'd have to lean out the carb. RVP is extremely low, resulting
in daily drive-ability problems. Exact octane-boosting properties are hard to predict,
since these heavy hydrocarbons are already a part of existing gasoline blends
in varying degrees.
Tetra-Ethyl Lead
In pure, undiluted
form lead is so dangerous that it is not recommended for the average person to purchase
it. (You can't). Several after-market manufacturers offer TEL in, .1
gram/gallon form. Adding a 32 oz can to 22 gallons of leaded pump gas will
double the blend's TEL concentration. That won't raise the octane much, but
will provide iron-clad exhaust valve protection. MMT and lead; boost octane,
but they don't participate in the combustion process (they do help the exhaust
valves). The various hydrocarbons individually and in blend raise octane, and
participate in combustion, but don't help valve life. We now come to
oxygenates, which while not helping the exhaust valve situation, not only
participate in the combustion process while (in most cases) boosting octane,
but also carry some of their own oxygen with them. They offer the potential for
increased power - either in pure form or in blend - beyond that offered by any
hydrocarbon, MMT, or lead blend.
Common oxygenates
often added to base gasoline include various alcohol compounds, (MTBE) methyl
tertiary butyl ether, nitrous oxide, and nitroparaffins. Oxygenate specific
gravity levels are generally higher than gas, but this is misleading because
part of the added weight is supplied by the oxygen molecules; the net effect of
adding an oxygenate is to greatly lean-out the overall air-fuel mixture. Major
carburetor mods or even supplementary fuel metering systems are sometimes
required when running high concentrations of oxygenates. The down-side to MTBE
is the ability to contaminate water, testing for MTBE has shown most of the
drinking water in the U.S having levels above EPA standards.
Alcohol's
Types of alcohol's include:
Ethanol, Methanol
Isopropyl Alcohol (rubbing alcohol) and
Tertiary Butyl Alcohol.
Relatively
inexpensive, they provide a great bang for the octane buck and in pure form can
boost horsepower, but its use will have side effects. Methanol is the most
common alcohol octane booster, but also has the greatest adverse results.
Ethanol is as effective as methanol, but its side effects are not as severe.
While all the alcohol's are to some extent corrosive and cause water to
separate out of gas, these problems are much more severe with methanol, which
has an unlimited ability to absorb water and will eat rubber, plastic,
aluminum, and gas tank linings.
Instrumentation 1986 Nissan 300ZX
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I really do miss the digital dash fad of the
1980’s and early 90’s, it was a period of time when driving a high tech car
really meant what it was, a real time electronic display telling you everything
going on under the hood, high tech. I have noticed more cars now have analog
(needle) type displays and it appeared the electronic fad has past and we are
back to the cable driven style tach and speedometer. Well, I have news for ya,
there is no gear driven cable, in fact the speedometer for example is nothing
more than a toned down frequency meter. Now it is time for a change up. I have a few hopes for the car interior
information. How about an LCD display with configurable displays. You select
the type of display you want as well position the information anywhere on the
panel. Short, tall person it doesn’t matter. How about putting more info on the
displays, like road construction, weather, global tracking. When important info
occurs the speedo display is removed for the short duration of the alert.
As a technician my job could be made a bit
easier not having the lug around scanners hoping for the correct protocols to
communicate with the vehicles computers; besides scanners are enormously
expensive and require updating. The protocols are already installed in the car,
only accessing diagnostics and going through the usual procedures is all I need
to do. In a few years I expect there will be an even greater amount of
electronics installed. After typing out this short blurb and thinking back I
hope we don’t go back to the cable type speedometers, really I welcome the
advances engineered into vehicles I diagnose, which makes my job far more
interesting.
RPM Research,