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Friday, October 5, 2007
A flywheel is a rotating disk used as a storage device for kinetic energy. Flywheels resist changes in
their rotational speed, which helps steady the rotation of the shaft when a fluctuating
torque is exerted on it by its power source such as a piston-based (reciprocating) engine,
or when the load placed on it is intermittent (such as a piston pump).
However, it is bad when a driver need a fast engine response. Flywheel need to take a lot of effort to make the wheel rotating and stops the engines revs increasing or slowly
down quickly. Lighted flywheel will cause the engine momentum reduced which mostly
noticeably on driving up the hill. Different weight of flywheel allow to get the free
revving capabilities and best torque.
But WHY? It means faster acceleration for both
positive and negative.
By shortening the time a rider waits as the engine speed matches the speed of the selected gear so they can
mesh without clashing.
Besides that, lighter flywheel is less likely to shear off the crank during hard
acceleration or deceleration. Few kilos of metal rotating at several thousand rpms is a
pretty fair gyroscope. When the scooter leans to turn, that little flywheel can exert
strong gyroscopic vectors which may affect the handling of the scooter, and may contribute
to the aforementioned crankshaft failure.
The disadvantages include an increased risk of over-revving when miss shift a gear. Besides that, in order
to get the scooter rolling from dead stop will need to rev the engine a bit more. This is
because it has less rotational inertia to trade off. Plus, the spark will only last as
long as your battery, so this won't be practical for an endurance race. The newly-
lightened flywheel should be rebalanced to prevent vibration or failure.
Please click on the link for full article
Many racers and engine tuners (I get caught myself sometimes) have opted for state-of-the
-art diagnostic equipment but have forgotten one of the simplest, as well as most accurate
tuning tools ... the vacuum gauge.
Of course if your engine is barely able to sustain 2"Hg vacuum at idle, it will be hard to
tune using this method, but it is still useful. In most cases if you use a quality large
faced Vacuum gauge, with some experience you can effectively tune your race car's fuel and
timing systems. This is a starting point, we all know that dozens of passes and laps will
more than likely be required to verify tuning adjustments and compensate for variations.
First, A Few Basics:
Connection of the gauge is to a simple "manifold" vacuum source. "This must NOT be "ported" vacuum that rises as RPM increases". In
most cases this will be a direct manifold source or in many cases the PCV port (larger
port on the carb) on a typical carb.
NOTE: Connection to EFI cars is best done "Tee'd"
into the source line. If you are not careful, disconnecting a particular line can affect
the idle speed as well as information that the ECM needs to see. For this reason it is
best to tee into your vacuum source for the gauge.
You must have the timing "Pre-Set", or at least do all ignition settings "Before"
any carb adjustments.
After each adjustment is made, you MUST RESET your idle speed setting. You do this to have
a standard or baseline to compare against.
Small adjustments are best, and in fact "optimum" carb settings on the vacuum gauge
(highest reading) is usually richer than it needs to be. In other words, after the highest
reading is reached, the best setting (depending on engine) is to set mixture screws back
"lean" approximately 1/16 to 1/4 turn.
Proper Carb Adjusting
Procedure:
With the above items taken into consideration, the first thing you do with the gauge
connected is to lean one of the mixture screws until the gauge as well as the engine
begins to shudder.
Note: With a properly jetted carburetor, turning
either of the mixture screws all the way lean, should kill the engine. If not, you're too
rich! This may require re-jetting, or drilling the primary butterflies to add more idle
air. Many of the newer "race" carbs allow you to change Idle air bleeds to fix this.
You now bring the screw back towards rich, watching the gauge. (I'm not being specific as to "in or out" movement of the mixture
adjustment for there are a few carbs that are actually "In" for rich instead of the
standard "Race style" Holley that is "Out" for richening the mixture). As the gauge climbs, you will stop adjustment when
the gauge reaches it's highest reading.
Now do the same process for the other mixture screw. You may have to repeat this process a
few times to get optimum results, plus it's worth the time an effort.
For carbs with the 4-corner mixture screws, you have to take a bit more time setting
these. You can also run the engine at a "steady-state" RPM of say, 2500 RPM to double-
check your secondary mixture screw settings. Do this with temperament! It takes time to
get used to what you are seeing as well as if it is actually helping. each engine will
behave differently.
Vacuum gauge needle
readings explaination
Normal reading (usually 17-22" Hg. in stock engines) Race engines vary "a lot" and in most
cases will be considerably less.
Ignition miss, sticking valves, lifter bleeding off (hydraulic), or just a BIG camshaft
Late timing, low compression, sticking throttle valve, carb or manifold vacuum leak
(remember most race engines with a big cam and a tight centerline and high overlap will be
naturally low ... you must decide your baseline vacuum reading)
Improper carb setting or minor vacuum leak
Ignition miss, blown head gasket, leaking valve or weak or broken valve spring
Burnt valve or incorrect valve setting (too tight), "needle will fall when bad valve
operates"
Clogged exhaust, excessive backpressure (extreme cases engine will die at idle)
Worn valve guides
Kia
unveil of its Kee coupe concept at the IAA in Frankfurt.
The Kee seats four, and is distinctive for its long greenhouse. Power comes from a 2.0-liter version of Kia’s next
generation V-6 engine, rated at 200 horsepower.The car measures 4.3 meters (169.3 inches) long. This powerful engine
which is mated to a six-speed automatic transmission.
“The new Kia Kee is a clear and emphatic statement that the future of the Kia brand is set
to be one that will excite and surprise an entirely new audience of consumers,” said Peter
Schreyer, Kia’s design chief, in a statement. “Our sports coupe concept is not simply a
flight of fancy but represents an affordable dream for sports car lovers.”
Please click on the link for full article
Why cars break down?
Nothing lasts forever; any car eventually will start having problems. However, while some
cars may provide you with few hundred thousands miles of trouble-free driving, others
start having problems from the beginning. Why there is such a huge difference?
Sometimes cars start having problems after accidents. Sometimes it may be a factory defect
or design flaw. Heavy conditions like, for example, driving only short trips without
letting the engine to warm up fully also make the engine life shorter.
Corrosion is another factor - for example, park the car for a few months in place with
high humidity and later it will probably have more problems than the vehicle driven all
this time on daily basis.
Yet, lack of maintenance is one of the most often reason for a car to break down.
Here is a visual example:
Compare the two images below: the left Mazda's engine hasn't been maintained well. Looks
like it the engine oil hasn't been changed for long time. This engine has relatively low
mileage and already needs serious and costly repair. On the right, the Mercedes-Benz
engine that has been maintained well. After 310,000 km (192,000 miles) it's still in a
very good condition, and needs no repair at all.
So, what's most important to keep your engine in a good shape?
- I guess, I won't say something new stating that regular oil changes is most important
factor to keep the engine running. If you do it more often than suggested by
manufacturer's schedule, that's even better.
- Avoid overheating the engine
- Changing spark plugs, air filter, timing belt and other items from maintenance schedule
may save you from costly repairs.
- Fix any small problem right away before it causes a serious damage.
Engine oil change
regular oil changes are so important? What will happen if I miss my oil change? Engine oil
has limited life - after a certain point it starts losing lubricating qualities and
carbonizes. Once it happens, the engine gets contaminated with carbon deposits or sludge
(see the pic.) that significantly shorten engine's life. When you change oil at or before
manufacturer suggested interval, you change the oil before this "carbonizing" point,
engine remains clean and once refilled with new oil ready to work hard again. If the
engine oil has not been changed for long, carbon deposits start clogging the oil pick-up
screen decreasing oil supply and increasing friction. Through the engine ventilation
system the same carbon deposits build up inside the throttle body and EGR system causing
rough idle and possible check engine light. Compression decreases and engine start wearing
much faster.
If you don't remember when you changed the oil in your car last time - just check the oil
on the dipstick. And every time you change the oil, the oil filter should be replaced as
well.
Checking the engine oil
the engine oil regularly, I'd recommend at least once a month or even more often if the
car has high mileage.
Driving with extremely low oil level (less than min.)
or with low oil pressure warning lamp on may cause serious engine damage.
If you note, that oil pressure gauge indicates extremely low oil pressure - have your
engine inspected as soon as possible.
- While checking the oil level, look at its condition. Check the image at the left. If the
oil is black like on the right image, I'd suggest to change it.
- Always use only appropriate engine oil type (usually you can find it on oil cap or in
the owners manual).
- Check your parking space for leaks. If you find any, fix it before it results in more
serious vehicle problem
Synthetic oil vs.
conventional mineral oil
The advantage of synthetic oil is that it can withstand higher temperature and can work
longer without losing its lubricating qualities. It doesn't get thicker at below-zero
temperatures providing good engine lubrication at a cold start. However, since it's more
"thinner" a high-mileage engine filled with synthetic oil will more likely to develop
leaks and you will more likely to hear lifters tapping noise at a start. Therefore, If you
have low mileage or turbo engine and driving under heavy conditions such as high
temperature, excessive load, long intervals without an oil change, etc., or simply want to
provide extra protection for your engine, synthetic oil may be a good solution. But I
don't think it's worth to use synthetic oil in high-mileage engines - thicker mineral oil
will provide better protection as long as you change it regularly.
Engine cooling
system
overheating causes serious engine damage. In order to avoid the engine overheating:
Check the coolant level periodically. It should be at least at the "min" mark in the
coolant reservoir. If it's lower, add the coolant bringing the level to the "max" mark.
Caution: Never open the radiator or the coolant
overflow reservoir when engine is hot!
If you discover a coolant leak, have it fixed as soon as possible - it may cause engine
overheating.
If you note that the engine temperature starts rising higher than normal, have your engine
inspected before it will cause serious problems.
Check the front of the radiator - sometimes it may be obstructed with leaves or dust. It's
one of the possible reasons for the overheating. Look at the image on the left. This
Buick' radiator is clogged. Try to avoid using front end covers - they cause restrictions
to the air flow through the radiator
Tune-up, timing belt, fuel
injector flush
There are certain vehicle components that need periodical replacement (check your owner's
manual for details) such as, for example:
Fuel filter -
dirty fuel filter may cause engine stalling and loss of engine power.
Air filter -
dirty air filter causes loss of engine power, increased fuel consumption, air flow sensor
failure, etc.
Engine coolant -
old engine coolant loses its anti-corrosive and other characteristics and may cause water
pump to fail.
Spark plugs -
simply spark plugs replacement can significantly improve the engine performance.
Timing belt -
timing belt failure may cause serious engine damage, especially if it's diesel engine.
Having a problem with fuel consumption or rough idle on a high mileage car? - Try fuel
injectors service. You will note the difference right away.
Battery
can produce explosive gases. Handling a battery be careful and always use protective
glasses and gloves. Don't use open fire, smoke, or create a spark near
battery.
Most of batteries nowadays are maintenance free. All you check is battery terminals that
shouldn't be loose or corroded. Corroded battery terminals will cause all kind of problem:
blinking instrument lights, low charge, no-start, dim headlights, check engine and ABS
malfunction light etc.
Also, if you see any acid leaks, cracks or any other damage - replace the battery. Acid
leaking from the battery destroys everything underneath. For example on VW Golf it will be
the fan control module located right under the battery.
Tiny Germany independent manufacturer Loremo plans to launch an electric version of its
lightweight car.
Starting in 2010, Loremo says it plans to sell an electrically powered version of ia small
car currently sold with a diesel engine.
A spokeswoman said Loremo plans to sell 10,000 vehicles in the first year of production.
“We hope then to increase that number,” the spokeswoman said.
The sub-compact 2+2 Loremo will weigh less than 600kg. Loremo intends to keep fuel
consumption of the version powered by a two-cylinder diesel enegine below 2 liters per
100km.
Loremo’s retail price target for the diesel version is below 15,000 euros.
