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7 Sept 2016

Video: How an internal combustion engine work



For centuries, internal combustion engine (henceforth will be called ICE) has been the staple source of motive power in mainstream transport, ranging from cars, motorcycles, aircraft and several more. Several different types of ICE in existence include piston engine, jet engine and rotary engine. 

I was at the recent BMW Innovation Day at Desa Park City and stumbled upon this working cutaway model. It was a sight to behold watching how the moving hardware interact with one another, that I could not help it but brandish my camera and record this video. 

The video above depicts how a 4-stroke motorcycle piston engine works. It is still the same principal as a 4-stroke piston engine found in cars (Suck, Squeeze, Bang, Blow). You can see from the video how the piston and valves interact with each other. 

I had a short chat with presumably a mechanic manning the booth. According to him, this is a new water-cooled engine with wet clutch system (old engine was an air-cooled system with dry clutch system). In case you are wondering what is that big round disc spinning in the crankcase, that is the wet clutch the mechanic was referring to. It is bathed in oil, hence 'wet' clutch. Before I bore you with more technical details, do enjoy the video!  
                                                       

11 Aug 2016

Mazda G Vectoring Control

                               File:2017-03-07 Geneva Motor Show 0856.JPG
                                             Source: Norbert Aepli via Wikimedia Commons CC BY 4.0

Jinba Ittai. Literally horses and riders. In Mazda's parlance, that is Mazda's philosophy in delivering their adoring customers with an unadulterated synergy between the driver and the car. Mazda has decided to take the Jinba Ittai to the next level: by adding SKYACTIV-VEHICLE DYNAMICS to the firm's suite of SKYACTIV technologies. The first technology to appear under the SKYACTIV-VEHICLE DYNAMICS family is the G Vectoring Control (GVC), which had been recently added to the facelifted Mazda 3 and Mazda 6.

GVC is basically a software that actively communicates with the engine in response to steering input to optimise vertical loading on each tyres. It does this by either reducing or reinstating torque based on steering angle. 

The idea is that by reducing torque, deceleration is induced. This initiates forward load transfer which helps in improving turn-in response when the driver begins turning the steering. This should, in theory, neutralise understeer (the car wants to go straight even after the steering has been turned).

Once the driver maintains steering mid-corner, the system reinstate torque, inducing acceleration. This transfers load to the rear which stabilises the car. Theoretically, this will make the car less prone to oversteer (the front end turns more, giving the sensation you are spinning out).  

According to Mazda, neither drivers nor passengers will notice GVC at work. Mazda assures that GVC offers significant comfort to the vehicle occupants, as GVC reduces the amount of buffeting experienced by vehicle occupants. This could be due to drivers not having to make corrections directly with the pedals and steering which (I am sure you have experienced this as a passenger) will almost always spill your coffee!

Also, with GVC, Mazda assures that it will enhance straight line stability. In other words, it reduces steering correction on straight road. Most of us barely notice it, but we do constantly make slight steering adjustment to compensate for road undulation and surface imperfection. Thanks to GVC, the lack of steering correction, according to Mazda, should reduce fatigue.

As it is just a software, Mazda assures this will not add weight and complexity as this does not require the addition of extra hardware.

All in all, the newest addition to the SKYACTIV-VEHICLE DYNAMICS family may transform your Mazda into a tiny handling monster capable of making the supercars look silly around curves, or when you are barreling down the freeway. Hopefully, Mazda's tireless pursuit for enhanced Jinba Ittai will show itself in their products.      

28 Jul 2016

BMW M52TU engine





Pictured above is a lovely, creamy inline 6 cylinder that powers my father's E46 320i M Sport. By far one of my favourite engine configuration to date thanks to its impeccable smoothness. Give the throttle a light prod, all 6 cylinders work together to provide a chauffeur smooth, yet satisfying acceleration. Well, I digress. That engine in the above photo is the M52TU. So, what is M52TU then?

M52TU is basically a variation of BMW M52 engine family, meaning it is still an inline 6 DOHC 24v with aluminium block (with the exception for North American models that used iron block instead thanks to their high-sulphur fuel). What sets apart the M52TU from the regular M52 is the former is a much enhanced version of the latter (TU stands for Technical Update). This entails the addition of features such as Dual VANOS and DISA valve.



VANOS refers to BMW's proprietary variable valve timing system. The system exists in two iterations: (1) Single VANOS (varies intake valve timing only) and (2) Dual VANOS (varies both intake and exhaust valve timing). Single VANOS is used in the regular M52 engine; the more advanced Dual VANOS is used in the enhanced M52TU engine, as found in my father's E46 320i M Sport. The advantage of Dual VANOS over Single VANOS is continuous adjustment of valve timing. In other words, it is not an on/off switch where variation in valve timing takes place over discrete steps (i.e., retard intake low rpm, advanced intake high rpm and back to retard as rpm lowers). From my understanding, Dual VANOS offers greater flexibility in choosing the most appropriate valve timing rather than sticking with Single VANOS restrictive stepped-setting. Theoretically, this further improves performance and efficiency over the M52.



Another addition to the M52TU is the DISA valve, BMW's lingo for variable length intake manifold. It adds a butterfly valve inside the intake manifold that opens and closes to create a dynamic effect of long and short manifold for better cylinder filling over wider rev and load range. In conjunction with Dual VANOS, it should theoretically aid the engine in delivering the potent performance and efficiency that improves on what the M52 is capable of.

Sounds like the M52TU trumps the M52, but does the M52TU really offer significant improvement over the M52? Lets take a look at the performance curve below:

Source: http://www.bmwtech.ru/pdf/e46/ST034/9%20Engines.pdf 



It turns out it doesn't make much difference peak torque-wise. Both M52 and M52TU output the same peak torque, but the latter peaks earlier than the former (3500 vs 3950 on the M52). Also, power peaks at the same 5500 rpm but with slightly more power for the M52TU (170 vs 168 on the M52).

The addition of Dual VANOS and DISA valve does not really do much to increase peak torque value. As suggested by the above curve, what they do instead is increase low-end torque. From the above curve, the M52TU exhibits much higher torque at low rpm and increases all the way until it reaches peak torque rpm. In contrast, the M52 has a slight bump roughly between 2000-2500 rpm and more obviously, significantly less low-end torque than the M52TU. Eventhough the M52's torque peaks at higher rpm compared to the M52TU, the curve shows that the area under the curve at the M52TU's torque peak is much larger compared to the area under the curve at the M52's torque peak. Essentially, the M52TU still has the edge as torque dips at almost the same rate for both the M52 and the M52TU.  

On the power front, the superior low-end torque garners higher low-end power for the M52TU, albeit the area under the curve is smaller. Power peaks at the same rpm for both engines, but slightly higher for the M52TU.

Overall, the addition of Dual VANOS and DISA valve do improve performance if you are looking for fatter torque curve. If peak value is what you are looking for, then it is a moot point as there is not much difference in peak torque and peak power.

That's about the detail I am able to cover in this post. If you want more details about the M52TU engine, click on this link: http://www.bmwtech.ru/pdf/e46/ST034/9%20Engines.pdf




26 Jul 2016

Autonomous cars


tesla s
Source: http://abc7chicago.com/automotive/ntsb-driver-killed-in-self-driving-car-was-going-9-mph-over-speed-limit/1444006/
Unless you have been living under the rock, you have probably heard of autonomous cars getting into an accident. One accident involving the semi-autonomous Tesla Model S unfortunately led to the fatal death of Joshua Brown, the owner of the ill-fated Model S, when his Model S drove underneath a tractor trailer making a left turn. Apparently, Brown's Model S failed to detect the trailer, as observed by Tesla, "Neither autopilot nor the driver noticed the white side of the tractor-trailer against a brightly lit sky". As a result, the Model S failed to apply the brake and hit the trailer's underside, ripping off the Model S roof, consequently killing Brown.

Source: https://www.google.com/selfdrivingcar/where/
Another accident involving an autonomous car is a Google car which struck a bus trying to switch lane. As highlighted in an article by ExtremeTech, the vehicle being tested, the 2012 Lexus RX450h, thought the bus would give way. In contrast, the bus driver also thought the Lexus will give way. Result? Neither of them budge and they came into contact, damaging the Lexus front left fender, wheel, and driver side sensor.  

What do the two incidences entailed then? Does this mean the claim autonomous cars are safer than human drivers are dubious? Before we go in with guns blazing thinking cars that drive itself around are 4-wheel deathtrap, we should take a deep breath and look at the bigger picture.

Autonomous cars are still at its infancy. More R&D is still on the card. Meaning, it will take years before the software improves. As a comparison, even automatic transmission technology took several years until it becomes impeccably refine in the present day. What used to be a sluggish and fuel guzzling 'slush box', the technology has improved so much that it is not just more fuel efficient than the manual transmission, but also enhances a car's performance level above what the manual transmission used to offer.

If automatic transmission technology can improve, surely autonomous cars can do the same. With some software tweaks, autonomous cars will be able to do what it fails to do today.

In the present state, there may be some negative perception about the credibility of autonomous cars, but with time, autonomous cars will improve so much that it can recognise wide range of road obstacles at every angle.

25 Jul 2016

BMW F10 5 series bowing out with a bang, with the M5 Competition Edition

Source: www.press.bmwgroup.com
Like everything in life, there is the beginning and the end. The same rule applies to cars. Once it reaches the end of its generation, it ceases existence, and a new generation model takes over its place. In the case of the BMW F10 generation 5 series, its end is drawing to a close, with the next generation G30 and its high-performance F90 M5 alter ego slated to take over. But, it would not be a muted farewell as Munich wants to give a special valediction to the F10 series, in a form of BMW M5 Competition Edition.

What better way to close the F10 chapter, other than giving it an extra boost of power to its wonderful 4.4 litre TwinPower Turbo V8. Thanks to recalibration of boost pressure, 600 hp and 700 Nm overall output is yours to play, up from 560 hp and 680 Nm. Result? 3.9 second 0-100 kph time, a good 0.5 second quicker than the non-Competition Edition M5. Before being consigned to the history book, it is a good idea to leave unforgettable performance figure that makes the car meaningful.

Source: www.press.bmwgroup.com
It wouldn't be a perfect send off if you end up in the ditch somewhere. So, BMW outfitted an uprated spring, an electronically controlled damper and a thicker stabilizer bar courtesy of the M Competition Package. Also, carbon ceramic brakes housed within the 20-inch 7 double-spoke alloy wheels ensure the farewell party doesn't end with mangled metal for our F10 friend.

Only 200 units are available. Colour wise, there are 2 available colour schemes: Carbon Black and Mineral White, with 100 units each getting either colour schemes.

With the F10 on its way out, hopefully the upcoming G30 and F90 M5 will be even better.

Source: www.press.bmwgroup.com 

14 Jun 2016

Fiat 124 Spider, an ND MX 5-bodied Italian sports car



Fiat 124 Spider - LA Auto Show 2015 (23121899872) (cropped).jpg
Source: https://en.wikipedia.org/wiki/Fiat_124_Spider_(2016)

Ah, the revival of a classic moniker, that captivates car enthusiasts from 1966-85. The Fiat 124 Sport Spider was a roadster that appealed to the enthusiasts looking for a basic top-down sports car during that juncture. Fast forward to 2016, Fiat Chrysler Automobile (FCA) has brought back the 124 nameplate, christened as the 124 Spider. 

Unlike the Pininfarina-designed 124 Sport Spider, the modern 124 Spider is not a result of Fiat and Pininfarina's collaboration, but rather a joint venture with a Hiroshima-based manufacturer who subscribes to the Jinba Ittai philosophy in sports car design. If you can guess what I am alluding to, kudos to you. But in case if you don't, the manufacturer in reference is Mazda. 

The 124 Spider is underpinned by the fourth generation ND Mazda MX-5 (MX-5 Miata in the US). Thanks to findings by Top Gear, the chassis is built in Mazda's Hiroshima factory. The engine, however, is not built by Mazda, but by Fiat instead. In a nutshell, lurking under the 124's bonnet is Fiat's proprietary 1.4 liter turbocharged MultiAir four banger rather than Mazda's 2.0 litre Skyactiv-G naturally aspirated four banger. Result? The 124 Spider makes more power than the MX-5, 160 for the 124 Spider vs 155 for the MX-5. Does not sound much, but every ponies count. Upon completion, the engine is then shipped to Hiroshima where Mazda's engineers marry the engine to the chassis. 

Fiat engineers then applied their own Jinba Ittai to the suspension tuning, with retuned dampers, stiffer springs and anti-roll bar to embarrass the donor car in the twisty bit. 

Taking advantage of the extra low-end torque, Fiat lengthen the gear ratio. The extra grunt at low rev is more than enough to compensate for the longer gearing. 

All these retuning sounds like a recipe for a more unadulterated driving experience. With more power and an uprated suspension, this little pocket rocket may have what it takes to make MX-5 owners clamouring for the 124 Spider.   

Source: Top Gear

Brake Override System



Nissan brakes activating a brake override system
Source: http://www.nissanusa.com/blog/brake-override-system
You have just bought yourself a brand spanking new car. You flip through its specification and inevitably come across the term Brake Override System. Wondering what it means? Wonder no more.

Brake Override System is a safety feature that allows the ability to stop a car even with the accelerator pedal depressed at the same time with the brake application.

Why such feature is introduced on modern cars? One notable example that became fodder to the system's introduction is the fatal crash involving Mark Saylor, a California Highway Patrol officer, and his family, when the accelerator pedal of their Lexus sedan became stuck, leading to a deadly runaway car. Investigators blamed the accident on ill-designed floor mat that obstruct the accelerator's movement, meaning the risk of the accelerator not fully releasing is hazardously high. In light of the accident, National Highway Traffic Safety Administration (NHTSA), an executive branch of the US government under the Department of Transportation, has mandated the system to be implemented by every manufacturers in a bid to protect vehicle occupants in an event of stuck accelerator pedal.


Source: http://brainonboard.ca/safety_features/active_safety_features_brake_override.php

How does it work? When the system detects that both pedals are depressed at the same time, it gives the brake more precedence. In a nutshell,even with the accelerator depressed, the system will make it feel like the accelerator is fully released, enabling your brake to slow the car down effectively. This should in theory prevents you from roaring down the highway with a death note sticking on your forehead.

Should this system be featured on every new cars? Like every safety features, one must know how to use it and remain responsible on the road. It is not a great idea to fall into a false sense of security thinking you can drive around like you are in Too Fast Too Furious movie scene. Nevertheless, any features with life-saving potential make great sense as an extra protection to keep you out from a wreck.