Thursday, March 25, 2010

THE END FOR THE KOMPRESSOR?



Driven by engine rather than exhaust gases, the supercharger has to burn extra fuel to provide similar power to a turbo, and in era where saving energy is next to godliness, the supercharger can no longer compete. It is no surprise that the new W212 E-class range currently comes with turbocharger eg: E200 CGI,E250 CGI,E350 V6 turbocharged...etc

Turbo have always been in the a ascendancy for diesel engines, partly because they work within a relatively narrow range which reduces problems with turbo lag and Kompressor stall, and partly because diesel s are not prone to detonation as they run at much higher pressures. But the turbo’s expansion in mainstream petrol engine design has been much more recent.

Until very recently we could enjoy supercharged 180K, 200K, and 230K engines across the C,E,SLK, and CLK-class ranges. As well as the legendary 55AMG V8 in E,S,SL,CL,CLS-classes . but the only new Kompressor models now in the Mercedes range are C-class and CLC-class, while the SLK only has 200k unit. and these may soon be no more.

Advantages :
-Immediate pick up during acceleration.
-They produce additional power from much lower engine speeds and do not suffer from the inherent lag of turbo.

Disadvantages:
-There will be extra noise and decrease in fuel economy as high amounts of boost are produced from the supercharger
-There is a very slight power/efficiency loss because it is driven by the crankshaft, reducing the efficiency only until the compressed air travels from the supercharger into the intake manifold.

Sunday, March 21, 2010

SBC-Sensotronic Brake Control -Mercedes to drop SBC brake system





It's being reported today that Mercedes is dropping their Sensotronic Brake Control (SBC) from some of their models, starting with the E-Class.

The SBC system has been a chronic thorn in Mercedes' side. Manufactured by the Robert Bosch Group, the SBC system has led to the recall of over 2 million Mercedes models (namely the E-Class), and has played an integral part in the widespread "Mercedes quality problems" you hear about so often.

So what exactly is the SBC Braking system?The SBC braking system uses a microcomputer to monitor the car and driver actions. In the event it's needed, such as emergency braking, the system monitors brake pressure, and applies the appropriate stopping power necessary, even if the driver doesn't exert enough power.

SBC features a host of other features as well, including distributing brake force to different wheels during cornering, to ensure greater stability in the vehicle as well as maximum stopping power; the SBC system even dries the brake discs if a film of water forms on them.

In other words, the system sounds like a milestone achievement in braking technology, and it would be, assuming it worked properly. Unfortunately, although the intent was good, the execution was not.

As you can probably tell, the entire system relied on electronics, and as I'm sure everyone can attest to, nothing is more prone to malfunctioning than electronics. And that is exactly what happened. Before long, wiring in the SBC braking system deteriorated, and suddenly the SBC system no longer functioned.

Of course, Mercedes had a backup hydraulic-only braking system in place, but the feeling of suddenly not having the same stopping power was enough to send Mercedes' owners everywhere heading for the hills - and we haven't stopped hearing about Mercedes' quality problems since.
http://www.youtube.com/watch?v=PpvCoaRoQa4

Advantages of SBC:

-Emergency braking: stopping distance reduced by up to three per cent
-Driving stability: precise braking impulses for perfect ESP® performance
-Braking in corners: greater safety thanks to variable brake force distribution
-Comfort: no pedal vibrations during ABS opereration

Disadvantages of SBC:

-Maintenance is high, electronics parts are costly to replace,eg: SBC hydraulic unit has operating hour, when the service threshold is reached the unit has to be replaced.
-Some people don’t like the noise from SBC hydraulic unit(motor build in)

Apparently, Mercedes is finally getting tired of trying to convince consumers of the benefits of the SBC system. Although the system is, in my opinion, a definite advancement in braking technology, poor implementation and poor design are ultimately leading to its downfall.

That's not to say Mercedes will entirely scrap the SBC system. I'm sure Mercedes will continue to develop and improve the braking system in the future; I just have a feeling the next generation of SBC will be slightly less prone to malfunctioning.

In the end they decided to drop SBC and substitute it with ABR(adaptive brake) new brake system. ABR available on W211 facelift models. from the pictures above the top one is facelifted model and the first model at below.

Saturday, March 20, 2010

Plastic Headlamps Restoration




Plastic headlamp lenses reduce
weight and reduce lens breakage,
which can improve nighttime
visibility and safety

Advantages
The use of plastic in headlamp applications enables automakers to reduce weight without
sacrificing optical performance while increasing resistance to breakage.

-Glass headlamp lenses began to be replaced with polycarbonate ones in the 1980s.3 Today,
virtually all glass lenses have been replaced by transparent polycarbonate plastics.4

-Plastic offers the advantage of being an inherently light material that can be easily made in thin sections and stepped shapes, reducing weight and the possibility of breakage “without sacrificing optical performance.”


Disadvantages
Having your headlights on or being exposed to the heat of the day causes the pores to open allowing debris from the road to get in. Debris, together with a combination of environmental factors such as the sun (UV rays), smog, acid rain, car exhaust, and harsh chemicals used to wash your car can cause the plastic headlight lenses to become oxidized.

-Plastic oxidation leads to lens discoloration, which transforms new, clear, bright, shiny plastic to a dull yellow tint that appears to be foggy, hazy, or cloudy.

- This process (oxidation), as described above, not only becomes an eyesore but also is unsafe. Because of the degradation of the plastic lens, less light passed through resulting in diminished visibility during night driving.

-The car owner either had to deal with these cloudy yellow, oxidized headlight lenses posing serious safety issues or purchase expensive replacement headlights costing hundreds or thousands of dollars.

Here are budget tools i used for this excercise :
-A few pieces of cloth for polishing
-1000 and 800 grit sandpapers
-1 tube Autosol Metal cleaner( it cost MYR 8.50)
-Soft99 meta clean(MYR 20.00)






Direction
-Cover up other body parts with masking-tape,to prevent unwanted scratch.

-Carry out wet sanding on the lense surface with 1000 grit sandpaper,follow up with finer 800 garit sandpaper.about 3to 4 sheets of sandpaper will be used.Wet sanding is very important if you want to see a good result.

before:


After wet sanding it will become like this:


(make sure all micro-cracks have been eliminated before polishing job)

-After wet sanding,bring the gloss back with Autosol Metal Cleaner on the first stage polish,final stage with soft99 Meta Clean,and you will notice the different.

Check out the result!