Preamble
Now that we have had a look at how to keep our cars trouble free. Well, here’s some more - keeping in mind that cars are somewhat like other living beings and let off distress signals when all is not well with them. So as an intelligent owner/driver, it’s worthwhile to detect them in good time before it’s too late - be it as a driver or as a passenger.

1. Fuel Odours:
Such smells can be most dangerous of them all - implying a potential fire hazard. These arise due to either a perceptible leak or ’sweating’ in the ‘plumbing’ between the fuel tank and the engine. A competent Garage or a DIY owner can spot them by inspecting the fuel lines to and from engine to fuel tank and take remedial measures.

However, in some of the present day cars, in-cabin fuel odours are often noticed even when the above plumbing shows no flaws. These have been traced to a faulty gasket on the fuel tank flange for accessing the fuel pump/level gauge under the rear seat! In the older non-Mpfi cars, in addition, these could also arise due to ‘over-filling’ the fuel tank.

2. Burning Odours:
Present day cars deploy a variety of synthetics and plastics within and outside their cabins. A ‘normal’ person can distinguish amongst these as those arising out of - a) Friction materials used on Brake Linings/Clutch Plates, b) Rubber or Plastic Parts and c) Lube Oils or other engine fluids.

The friction material odours can arise due to ’sticky’ brakes or more commonly, the Parking Brake not having been released fully. A Clutch too can give out burning smells if ‘rode on’ in heavy (b2b) traffic or uphill.

For rubber type odours, under inflated tyres are the most common culprits and plastic types prima-facie mean overheated electrical wiring either within or outside the cabin. Most common cause for such ones is the deployment of ‘unauthorised’ and crudely installed electrical accessories such as a high-powered Music System or a Remote/Central Locking System.

In addition, if the roof lamp is left on for long times, its plastic cover can over heat and emit such odours. Tampering with OE wiring harness is an absolute taboo with the present Mpfi Cars.

On the other hand, Oil/other fluids’ burning type odours invariably imply either an overheated engine or oil leaks from the engine/gear box coming into contact with exhaust line that can run as hot as 500.C+ next to the engine - tapering off to nearly 100.C towards the tail end. This too can be a fire hazard. Brake Fluid leaks within the wheel assemblies can also emit burning smells, as brake discs/drums can get very hot under hard braking.

3. In-cabin Odours:
The last of in-cabin odours can be ‘organic’ type - let off by decaying matter within. Most common ones are from the Car AC, due to rotting matter deposited on its Cooling Coil. Since such matter can gain access via the fresh air duct if kept open and in our conditions, it’s advisable to keep it shut most times. The only remedy here is to have the AC/Cooling Coil Serviced, which can be a time consuming and expensive. As in most cases, prevention is better than cure.

Other major offenders in this class are debris of eatables accumulating in the inaccessible corners. The best thing to do is to avoid any eatables inside the car especially with children and if inevitable, have the car internals first vacuumed thoroughly and only then have the various nooks and corners blasted out with compressed air - only to be vacuumed again. If ‘pre-vacuum’ were omitted, most of the dust so dislodged would settle down on the AC Cooling Coil - with its own undesirable consequences.

Having ensured all these, it’s a good idea to keep a car ‘air freshener’ inside but mind you, let it not be like spraying perfume to suppress bad body odours!

Also read:
How do I keep my car trouble-free
Noises in a car

Preamble
Besides noises, in any car some ‘vibrations’ are inevitable. These are ‘noises’ that can be ‘felt’ but not heard. It can be difficult for an average person to distinguish between normal or abnormal vibrations. So let’s try and explore them…

Causes of Vibrations
It’s elementary physics that any rotating mass will vibrate if its weight is not evenly distributed around its ‘axis of rotation’. Their ‘intensity’ is proportional to such ‘unbalance’ AND speed of rotation. If vibrations are not contained to ‘safe’ levels, ‘metal-fatigue’ sets in a machine, eventually leading to its wreckage.

Prime source of vibrations in a car is its engine – followed by wheels and road undulations transmitted to its body by its suspension. Let’s look at each of them.

Engine
The ‘reciprocating’ movement of pistons in an engine is converted to a ‘rotary’ one by its ‘Crankshaft’, which is linked to them by ‘Connecting Rods’. Therefore, unless each one of these parts is individually well balanced, it will vibrate.

Despite, some vibrations are inevitable. These are ‘damped-out’ by flexible ‘foundations’ between the engine/gearbox and the car body. Such foundations are made of rubber fused on metal anchors but in more expensive cars, ‘hydraulic’ foundations have become a norm.

However, even a well designed engine can vibrate if – i) its ‘idling speed’ is below normal, ii) it’s over loaded due to improper gear selection, iii) its foundations are damaged or misaligned, and iv) if one or more of its cylinders is not producing right amount of power compared to others.

Wheels
Until the advent of Maruti-800 in mid ‘80s, concept of ‘wheel balancing’ was unknown in India. A wheel being an ‘assembly’ of its rim, tyre/tube, is invariably unbalanced even when brand new, because of permissible manufacturing ‘tolerances’ of its constituents.

And when the wheel diameters get smaller, their ‘rpm’ for a given road speed goes up compared to larger ones. Given the overall ‘lightness’ of cars nowadays, such unbalance in wheels produces unwanted vibrations in an otherwise ‘smooth’ car. Worse still, it makes the steering ‘wobble’ at higher speeds.

It’s worthwhile remembering that a wheel once ‘balanced’ won’t stay so for long because of daily/uneven wear going on its tyres due to braking/cornering etc. Worse still, the ‘balancing weights’ can and do fall off for many reasons. So it’s advisable to get one’s wheels re-balanced, say, every 5,000 kms.

It’s a popular misconception that only front wheels need re-balancing because that immediately reflects as steering wobble. Since any unbalance in rear wheels also produces vibrations and these, even if not felt as such, do eat into the lives of rear suspension bushes, shock-absorbers AND wheel bearings.

Like wise for Stepney – for simple reason that one may need it any time upfront and if it’s unbalanced, one’ll have a wobbly steering till re-balanced. From this point of view, it makes a lot of sense to have a wheel re-balanced immediately after puncture repairs before stowing away as spare.

A finer nuance to have all the 5-wheels in good balance all the time is that if they’re not, the front ones will inevitably wobble a bit even if not perceptible. Consequently, car’s ‘rolling’ resistance and hence fuel consumption stand to go up!

Conclusion
From the foregoing, it can be visualised that a well tuned engine and all the five wheels in good balance can add significantly to the overall life of a car.

I’m often asked this question and I tell them that every Car Maker provides a ‘Preventive Maintenance Program’ in its ‘Owners Handbook’ that comes with it - which lays down a detailed recommendation on time-bound as well as distance-bound basis. Execution of these in toto at a competent and well- equipped Authorised Workshop is your best insurance towards its reliability.

Next comes ‘how to get maximum mileage out of it’. Well, the logic is simple i.e. by ensuring that all the above ‘PMPs’ are done well and in time. In addition -

1. Maintain correct Tyre Pressures by checking/resetting once a week when ‘cold’, using a reliable Gauge,
2. Ensure correct Wheel Alignment by checking once every 10,000 kms,
3. Restore ‘Dynamic Wheel Balance’ of all the 4-Road Wheels every 5,000 kms if not earlier on ‘SOS’ basis - such as after a puncture repair,
4. Avoid short runs to the extent possible, and above all
5. Drive sensibly and in correct gear all the time - without any ‘Jack-Rabbit’ starts and stops.

Quite often, overly cost conscious owners mislead further by their ignorant road-side mechanics act penny-wise-pound-foolish, by questioning the very basics of present day car designs. For example ‘what purpose does ‘Coolant’ Serve and is it necessary to use it’! I must confess that I’m at a loss at such ones, though I try and recover my composure as quickly as possible.

The logic here is that the present generation Car Engines are high performance ‘precision machines’ with complex and narrow Coolant Circulation Passages within. Use of a good quality Coolant ensures they stay ‘corrosion and scale-free’ for a long time and lubricate the Water-pump internals as well. If not, you can rest assured that your car will start overheating at the slightest provocation. For best results, only distilled water should be used to dilute the ‘coolant-Concentrate’ to the recommended level. Coolants, like Gearbox Oils, have a life too and should be regularly replaced as recommended in your car’s ‘PMP’.

hen there are some other features of present day cars that baffle not only their first time owners but their friendly road-side mechanics also - such as “my Car heats-up very fast and runs much hotter than my earlier Cars of the ’70s. My Mechanic tells me to remove the ‘thermostat valve’ from the Cooling System”.

Nothing could be farther from truth and asking for trouble. The present generation Cars are ‘designed’ to run between 85-95*C for maximum fuel-efficiency and reducing exhaust pollutants to a minimum when the engine is below its designed operating temperature. The purpose of the Thermostat Valve is to ensure that these two requirements are met silently and that too regardless of the Ambient Temperature outside.

Then there are some others, such as ‘when should I use the 5th-Gear’. The answer is that 5th gear is a ‘cruise gear’ and in most cars, depending on their ‘cc’, one can comfortably get into it at speeds ~ 50 kph. It relaxes the engine by ~ 20% and affects the fuel consumption (and pick-up) accordingly. However, there’s no point in getting into the 5th gear unless one can sustain it for atleast a km or two. Otherwise, one will be shifting 5th and 4th/3rd all the time. This will waste more fuel than saving and prematurely wear off the Clutch and the Gearbox also at the same time.

Last but not the least, in these days of driving in the ‘fast-lane’ when people have no time even for a breakfast before dashing off to work, most tend to forget some basic daily checks on a car that hardly take a minute but can save hours by the road side in case of an avoidable breakdown. Here’s what one should do as a habit -

1. look at all the 4-tyres to see they appear properly inflated,
2. if one can see the car’s undersides while approaching from a distance, see if it has dropped any significant oil or other fluids overnight. If not, then after moving it off but before taking off for good,
3. smell for any petrol or oil odours inside before starting the engine,
4. after starting, wait for atleast 10-secs for it to fully ’stabilise’ electrically as well as mechanically before vrooming off. Look out for any unusual noises/vibrations during this time and
5. ensure all lights incl cabin are switched off while parking during the day and at night for good. Otherwise, be prepared for a flat battery to greet you when you try to start it the next time!

Also read:
Smells in a car
Noises in a car

With more and more new generation cars hitting the market as a result of the on going economic liberalization, car buyers are being bombarded with a slew of automotive jargon that leaves most of them quite confused.

In this concluding Part 4, we wrap-up some of the remaining FAQs that most motorists look for answers and trust that the surfing through parts 1 to 4 would leave them somewhat wiser than before.

Q14: How does a Variable Power Assisted Steering System work?
Answer:
The main objective is to achieve as uniformly and reasonably effortless a ‘feel’ of the Steering throughout the various ‘steering angle’ conditions and Car speed. In other words, it calls for ‘max assist’ during parking maneuvers and practically zero during straight cruise conditions.

In a Hydraulic System, this is achieved by progressive transmission of higher and higher PS Pump pressure to the actuating mechanism, depending inversely on the engine rpm and directly on the degree of steering wheel turn. The unwanted pressurised fluid returns to the Hydraulic Pump via a by-pass/relief valve.

In the case of an All Electric System, the on board ECU decides the degree of Assist, based on the ‘stress induced’ on the driver side of the Steering Wheel Shaft, by altering the Voltage Supply to the ‘Assist Motor’.

Q15: What is ‘Torque Steer’ and what are its disadvantages?
Answer:
This is a phenomenon peculiar to FWD Cars – the more powerful –the worse ! What actually happens is:

Given the practical Power Train layout in FWD Cars, the Differential ends up being off-centre relative to the axis of the Car.

This in turn results in one of the drive shafts (usually the lhs) being shorter than the other – as we are all aware of.

Since the ‘Torsional Stiffness’ of the longer DS is lower than the shorter one – both being capable of transmitting the same power – under sudden Surge of High Power such as during a hard acceleration, there is a fraction of a second ‘delay’ in the 100% Torque appearing at the Wheel end of the Longer DS than the shorter one.

As can be visualized therefore, such a ‘delay’ results in the Car ‘noticeably’ pulling to the longer DS side, briefly, when accelerated very hard. In view of this, High Powered FWD Cars are now being designed with their Diff so positioned that it results in equal DS lengths on both sides.

Besides this, torque-steer can appear even in conventional/low powered cars if the ‘road holding’ of either side drive wheel is different than the other – for whatever reason.

Q16: A Tachometer consists of a red zone at high rpm markings. What happens actually after that limit?
Answer:
Upto the beginning of the ‘Red Line’, an ICE can rev safely/repeatedly without any internal damage. If revved beyond/into the Red Zone, it stands to get damaged due to inadequate Lubrication/Cooling and therefore, Mechanical/Electrical ‘Speed Governors’ are provided in the engine management system to prevent such a mishap.

Q17: What is coefficient of drag? How can it be known? What is its significance and what is its unit?
Answer:
A Car has a ‘profile’ – endeavoured to be practically as ‘aero-dynamic’ as an Arrow but at the same time it also has a square or a rectangular cross-section’ related to its W x H.

If such a ‘cross-section/flat board’ is ‘inflicted’ with a blast of air in a Wind Tunnel corresponding to the road speed of the Car, it would experience a ‘push’ of say, 100 kgs.

On the other hand, if the actual Car is put in the place of the ‘flat board’, it would experience a push much lower than as above, coz of its ‘aero-dynamics’ – say 30 kgs.

Therefore, the ‘Coefficient of Drag’ is the ‘ratio’ of the above two i.e. 0.30.

Since it’s a ‘ratio’, it has no Unit and obviously, the lower it is - the better. Present day ‘Stock Cars’ have managed to achieve a “cee-dee-alpha” (coefficient of drag) of less than 0.30 – typically 0.25.

Q18: What is Engine Life Factor (ELF)? How can it be calculated?
Answer:
It’s a ‘Factor’ given by the Formula ‘ELF’ = 100,000/Max RPM x Compression Ratio’ of an ICE. In other words, higher the operating Rpm and/or the compression ratio, lower the ‘ELF’. Since it’s a ‘number’ only, it’s devised to ‘compare’ the Life and Reliability amongst comparable ICEs.

Q19: What is Terminal Engine Meltdown?
Answer:
It’s the ‘irreparable’ damage to the internal moving parts of an ICE, caused by overheating, either due its Lube OR Cooling System failure.

Also read:
Fundamentals of Automobile Engineering Part 1
Fundamentals of Automobile Engineering Part 2
Fundamentals of Automobile Engineering Part 3

With more and more new generation cars hitting the market as a result of the on going economic liberalization, car buyers are being bombarded with a slew of automotive jargon that leaves most of them quite confused.

So here in Part-3, we continue with our attempts to bring about a greater technical awareness amongst Motorists as to exactly does the new marketing jargon mean to them.

Q10: What is the difference between an Alternator and a Dynamo as far as working, efficiency and performance is considered? Which is better and why?
Answer:
Any Rotating Electrical Machine is inherently a ‘multi-phase’ AC Device and NOT DC !

For DC applications, as necessitated in a Car due to the unavoidable existence of a Battery, which can only be DC, the Dynamos/Alternators/Starters all ‘have’ to be ‘converted’ to be ‘DC Friendly’.

In the Dynamos of yore and even in present day Starters, it’s done by using an in-built ‘Rotating Mechanical Rectifier’, commonly known as the ‘Commutator’. On the other hand in an Alternator, it’s done by using a built-in solid-state ‘Bridge-Rectifier’ system.

Talking of a Yesterday’s Dynamo, which was invented long before reliable and durable ‘solid-state/high-powered’ Rectifiers became commercially viable, the commutator part of it was the ‘black-sheep’, by way of reliability/durability AND Radio-interference.

Besides, it needed an external ‘cut-out/voltage-regulator’ too, coz of its inability to develop sufficient voltage at idling RPMs and in any case when the Engine was to be shut down, it had to be isolated from the Battery as otherwise, the Battery would be short-circuited/discharged through it.

The mass availability of solid-state power electronics by the ’60 gave way to a lot more robust and reliable ‘Alternator’ for the Car applications, as the Commutator could be replaced by an in-built three-phase ‘bridge-rectifier’ stack having 3x the power output capability compared to a Dynamo – which coincidentally also did away with the need to have an external Relay type ‘cut-out’.

Consequently, the Alternator could also be designed to have a larger frame diameter/number of field poles, resulting in it’s ability to produce not only much higher but sufficient output even at idling speeds to keep charging the battery, even with the head lamps and other loads on!

Soon, the Electro-Mechanical external Voltage Regulators too gave way, by the mid ‘80s, to in-built solid-state regulators, making the complete Alternator package far more robust, reliable and long lasting as compared to a Dynamo.

Q11: Why do Diesel Engines feel more sluggish with the AC ‘on’ than their petrol cousins?
Answer:
The ‘Size/Power requirement’ of an Car A/C System is dictated by the Cabin volume AND the initial temperature (can get as high as 70*C for a Car parked in the Sun) and the rate of initial cooling desired – amongst other factors which are common to most A/C Systems. This results in an average Car AC System to have a Rating of almost 1.5 Tons 0r 3 Bhp when on!

A diesel engine has a lower ‘specific power’ output compared to equivalent petrol – typical Example Accent-D (57 Bhp) a/a Accent-P (94 Bhp). In the mid driving range it’s ~ 50% of that. Therefore, with a more or less ‘constant’ A/C load of 3 Bhp, the ‘drag’ works out to a much higher % age of Power available in a Diesel a/a Petrol.

Q12: What is a ‘Common Rail’ Diesel Engine? How does it work?
Answer:
A ‘common rail’ diesel engine does away with the ubiquitous diesel FI Pump, as we know it. It is a diesel fuel injection system where in an Engine or Electrically driven pump keeps a Rail/Header constantly pressurised to a pressure of about 1500 bars, as against only 2-3 bars of petrol Mpfi and 400 bars of conventional diesel engines !

In Crdi’s, each cylinder’s ‘fuel-injector’ is tapped on to such a header. The injectors in turn, like an Mpfi Petrol Engine, are electrically/Solenoid Operated, based on the ECU commands, and ‘squirt’ in multiple steps the diesel fuel at high pressure into the cylinders.

Such a system results in higher fuel efficiency/BHP and a smoother power delivery, compared to the conventional Fops hitherto in use.

Q13: How many Power Steering Systems are used presently? Which is better in all aspects, such as performance, reliability, economy, etc.? How do they work? Which types corrupt the vital engine horses more and Why?
Answer:
There are three basic power steering systems in use today – i) Hydraulic, ii) Electro-Hydraulic and iii) All Electric.

As they say, there are no free lunches in this world. All the three eventually derive their power input requirements ultimately from the Engine, either being directly powered off its Crankshaft OR the Car Battery/Alternator.

Of the three, The Hydraulic one is the most time-tested and
Popular, as it can be applied from a Small Car to a Giant Earth Mover. However, by virtue of the nature of its design, it’s more maintenance prone and a little less energy-efficient.

On the other hand, an All Electric ones presently have their application limited to Passenger Cars – weighing, say, from 750 kgs to 1500 kgs or so. This is coz it primarily depends on the Car’s Battery to Power it, which in turn depends on the Engine driven Alternator to charge it back. Since it can be ‘Computer Assisted’, it can very easily be programmed to any desired ‘spectrum’ of ‘Assist’. Since there are fewer moving parts in it and can be virtually made ‘idle’ at straight cruise conditions, it’s more ‘direct’ and Energy Efficient. An Electro-Hydraulic System is a ‘cross’ between the two, by way of advantages and disadvantages and doesn’t seem to be much popular these days, presumably from initial cost considerations.

Also read:
Fundamentals of Automobile Engineering Part 1
Fundamentals of Automobile Engineering Part 2
Fundamentals of Automobile Engineering Part 4

Most of us are only too well aware that a lot has changed in the Country’s Auto Scene during the last 20+ years since the ubiquitous Maruti-800 first hit the roads – atleast by way of how present day cars are made and marketed. And with the economic liberalization on in full swing, there’s a lot more to come.

So here in Part 2, we continue with our attempts to bring about a greater technical awareness amongst Motorists as to what makes their Cars tick.

Q6: What is the ‘Compression Ratio’ of an Engine and how does a manufacturer fix it when they design an engine?
Answer:
The Power that an ICE can develop is given by the formula -
BHP = P x L x A x N, where P = the ‘Brake mean effective pressure’ in a cylinder during the ‘complete power cycle’, L = Piston Stroke, A = Bore Area and N = RPM. Further :

i) The ‘CC’ of an ICE is the max volume of Water its Cylinder(s) can hold i.e. with the Piston at the ‘bottom most of its Stroke’ (BDC), multiplied by the number of cylinders it has. Therefore, the unit cylinder volume of an M800 is 796/3 = 265 cc.

ii) The ‘Compression Ratio’ (CR) of an ICE is defined as “Swept Volume + Clearance Volume/Clearance Volume”. From (i) above, it may be inferred that CC = SV+CV.

iii) Every ICE is designed and produced to have a CR as one of its vital parameter, for max power/efficiency it can produce, GIVEN the type of fuel it’s designed to operate with. In our Country, the “regular” Gas is 87 Octane and “premium” is 91-93. An M800 is, therefore, designed for 87 Octane with a CR of 8.7:1.

iv) It may be noted here that higher the CR, the higher Octane Rating Fuel it would require to produce higher Power - for a given CC of the Engine.

Q7: What are Gear Ratios?
Answer:
Due to the inherent ‘Torque vs Rpm’ Characteristic of an ICE i.e. with its Torque rising practically from nil at idling to the max somewhere midway in the rpm range, one needs ‘suitable gearing’ to ‘match’ the road speed/acceleration related Torque/Power requirements of the Car to the Engine’s Torque vs Rpm characteristics, to enable the Torque required by the Wheels match the one the engine can develop.

Since the Wheels’ Torque requirement varies from take-off to cruising, one needs a ‘variable’ Gear Ratio to make the ‘transition’ as smooth as possible.

Hence in practice, five forward (and of course one reverse gear) of ‘appropriate’ ratios are provided – starting from, say, I/Reverse - 3.5:1, II - 2:1, III - 1.5:1, IV - 0.9:1 and V - 0.8:1.

On top of these, there is the fixed ‘Final drive/Differential’ Ratio of say 4.5:1, which stands to be ‘multiplied’ to all the five/six above, to give the ‘Overall Wheels to Engine’ Gear Ratio, in any given gear position. The ‘Ratio’ of any two mating gears is the Ratio of their respective number of teeth.

Q8: Why Automatic Transmissions are more thirsty for fuel than their Manual counterparts?
Answer:
An AT uses a ‘Fluid Coupling’ instead of the conventional mechanical clutch, to eliminate the need for its external manipulation, in order to make it fully ‘Automatic’. A Fluid Coupling basically comprises a pair of Turbine-like ‘Rotors’, one of which is coupled to the Engine and when ‘driven’ by it, develops pressure in the surrounding ‘Fluid’. This in turn ‘tends’ to ‘drive’ the other ‘Follower’ Turbine Rotor, which is coupled to the AT. As can be visualized, such a Fluid Coupling will always have some ‘slip’ even when ‘fully coupled’ and this inevitably results in constant ‘churning’ of the ATF resulting in some Power loss – leading to higher fuel consumption – typically 5-10%.

However, with the advent of ECU controlled MPFI Engines, the ‘commands’ to the AT are now given by the ECU, which make sure that the Car is always in the ‘right gear’, under all possible driving conditions.

This in turn results in overcoming the lack of Driver Skills towards timely Gear Changes and therefore, today’s ATs are almost as Fuel Efficient as their MT counerparts.

Q9: What makes a ‘Distributor-less’ Ignition System better than the conventional ones and how does it work?
Answer:
In a conventional Ignition System, the ‘Primary’ Circuit of the ‘Ignition Coil’ has to be continuously ‘interrupted’ by ‘electro-mechanical’ means, such as the Distributor ‘CB Points’ (Pre-MPFI M800’s) or the semi-electronic variants of it (Zen/Esteem).

In a DB-Less System, the on board ECU performs the ‘primary coil interruption’ function electronically in a ‘contactless’ manner. Since it does away completely with all moving parts, it’s considered to be more stable and reliable and ‘theoretically’, having an infinite life.

Also read:
Fundamentals of Automobile Engineering Part 1
Fundamentals of Automobile Engineering Part 3
Fundamentals of Automobile Engineering Part 4

Apart from answering your questions on the ‘Ask an Expert‘ section of our website, we decided to do a Q&A covering the fundamentals of automobile engineering.

A surf around our site will reveal that during the coming times, we have all the intentions and resources of giving you at the click of a mouse, what most other automotive sites/magazines seem to lack.

In other words, culled out of our years of hands down experience, Clinical analysis’ and remedies of performance.

Since we are all only too well aware that today’s Cars are a far cry from the good old Ambys and Fiats of the 1970-80s and there is a lot more to come, it’d be worthwhile for most auto-enthusiasts to first get better acquainted with the basics of Car Design and what makes a car tick the way it’s intended to.

What follows, therefore, is an attempt to bring about a greater technical awareness amongst Motorists in a simple QnA format spread over four ‘editions’ - as to what makes their Cars tick.

Q1: What is PS? What is its relation with BHP?
Answer:
‘PS’ stands for ‘Pferde Starke’ and it’s a unit of Power Measurement. It was popular in post-war Germany and still in use there. One PS is slightly less than one HP (1 HP ~ 1.07PS).

Q2: Why are four cylinder engines more stable, refined and smooth in operation compared to three-cylinder ones?
Answer:
Simply put, a Four Stroke Engine needs 2-revs to complete a 4-stroke cycle. Consequently, when one cyl is in its ‘compression/power sapping’ mode, ‘simultaneously’ there is another one undergoing its ‘power’ stroke. This results in a fair ‘power balance’ at the flywheel of the Engine.

On the other hand, in a 4-stroke/3-cyl Engine – during a period of 2-revs, only 3-cyls are firing. So there is a ‘fluctuating’ ¼ of a cycle period during which no cyls are firing (power stroke) and the other one/two are in their compression/power-sapping mode. This results in appreciable ‘Power Unbalance’ at the Flywheel, leading to unacceptable vibrations.

To overcome this inherent limitation, present day 3-cyl engines employ various techniques to smoothen out such vibrations. It may be interesting to note here that a 5-cyl engine doesn’t suffer from such an inherent limitation and was used first by Audi in the ‘60s with great success.

Q3: Why ‘Multivalve’ Engines are more fuel-efficient than ‘Two-Valves/Cyl’ ones?
Answer:
Given the basic Bore/Stroke and Compression Ratio of an ICE, its Power Output is directly proportional to the ‘weight’ of Air/Oxygen that it can draw-in to burn the matching Fuel quantity and inversely to the effort it has to make to expel the Exhaust Gases. Multi-Valve engines therefore have better ‘Volumetric’ efficiency/Specific Power Output than one-in and one-out types.

Q4: Why the four stroke engines do not require 2T oil unlike the two stroke engines?
Answer:
As far as lubrication is concerned, even four strokers do require oil. However, the oil is almost always stored in the ‘sump’ below the engine in case of four stroke engines. Consequently, it has a Crankshaft driven Oil pump, which ‘circulates’ the oil under pressure to the desired areas, along with supplementary ‘splash’ lubrications to the Cylinder walls in some designs.

Two stroke engines cannot utilise an oil sump/pressurised lubrication system as above, as the sump over here is used as a ‘compression’ chamber during part of the two stroke cycle. Therefore, to provide adequate cylinder wall lubrication, a small percentage of specially formulated/low combustion residue oil (2T) is mixed with petrol to do the needful.

Further, the inevitable use of 2T oil in 2stroke engines is not very environmentally friendly, as the oil also burns away along with Petrol. In addition, since there is no (forced) Exhaust Stroke in a 2-stroke engine, one has to resort to ‘over scavenging’ of exhaust gases, resulting in some un-burn air-fuel mixture also getting thrown out.

Q5: Which has a longer life span – a two stroke or a four-stroke engine? Why?
Answer:
Theoretically and practically, a small 2-stroke engine has a lower lifespan, since there is a bang/power stroke in the cylinder once every two strokes, as opposed to the once every four strokes in the four-stroke engine. Consequently, they can and do operate at higher RPMs, yielding practically double the Power to weight Ratio as compared to a 4-S engine – thus resulting in comparatively shorter life.

Also read:
Fundamentals of Automobile Engineering Part 2
Fundamentals of Automobile Engineering Part 3
Fundamentals of Automobile Engineering Part 4

Is Your Vehicle Tyre Designed for Speed?
When disaster struck VIP vehicles, it made headline news. While some reports did touch the tip of the iceberg, the events that lead to these accidents remained unexposed. Suddenly we have, in India, not only the roads, like Mumbai-Pune Expressway in the West, Delhi-Jaipur highway in the North and East Coast Road linking Chennai-Pondicherry in the South, ideal for speeding but also the bigger, mightier horsepower engines in current models powering higher torque. Even the diminutive small cars can touch over 150 kilometres per hour when stepped on. The question is should they?

While transport vehicles are proscribed from exceeding a particular speed that is prominently painted on its side, along with the maximum load and rear axle load, car owners and drivers are totally ignorant of the fact. As long as you use OE tyres that come with the vehicle, which are mentioned in the owner’s manual, and you observe the maximum speed, you are safe. Several manufacturers however do not mention the maximum speed; where they do, the dealers’ sales staff is unaware - leave alone the end user.

Tyres too have Max Speed and Load Factor
The most important aspect of tyre safety is its permitted load and speed limitations. Till recently the tyres manufactured in India were only good for speeds of up to 150 kms/hour. MRF however has just launched the V rated tyre capable of up to 260 kmph. As per European and American safety requirements and standards, tyres are statutorily punched with an alpha-numerical coding - first the numbers that indicate the dimensions of the tyre, followed by an alphabet that rates the maximum speed which the tyre can safely withstand. It is very essential to know your vehicle’s ‘tyre speed’, because exceeding that could cause serious damage like peeling leading to a tyre burst. The second important factor is the load index - this applies more to goods carriers and transport and utility vehicles. Overloading beyond the load index could again result in a tyre burst. It would be really tragic and a deliberate act of negligence to allow such an eventuality. Other factors like a blow out caused by glass or iron pieces or other debris alone could be accidental. But at least here you will have the time to control the vehicle since there will be a minimum time of 30 seconds, before all the air exits and the vehicle veers out of control.

According to the management of a 30-year-old tyre re-treading company, fitment of altered wheels or alloy wheels of wrong specifications, fitting wrong size tyres, and even wrong alignment can cause the tyre to overheat and cleave. At speeds above 60 and even at lower speeds, sometimes, a tyre burst will send the vehicle careening out of control. A few years back a Maruti Omni toppled to the right when the rear left tyre burst in front of a ladies’ College in Chennai. The vehicle was doing only 30 kms/hour at the time, but the person driving could not control the situation, with all his experience. While his mother and pet dog were unhurt, he was not so fortunate and the skin of his right hand suffered abrasions from wrist to shoulder. Later the fault was diagnosed as over inflation of tyre pressure due to a defective gauge.

Speed Category Symbol
The speed category symbol indicates the maximum speed at which the tyre can carry a load corresponding to its load index under service conditions specified.

How Responsible are our Manufacturers?
Who is to say? But consider this: out of some leading tyre manufacturers contacted only Goodyear responded positively, providing unhindered access to the data on speed category and load index figures. On a query regarding quality control (QC) parameters and percentage of rejects, there was an ominous silence. None of the manufacturers contacted responded. The perception of the quality and safety of vehicles, individual components, and tyres can best be discerned from the remarks first of a student of automobile engineering, and the other of a CEO of UK’s leading brake oil manufacturer, both of whom visited factories in India and raised pertinent queries about ‘what is done to the rejects?’ They were shocked to hear that there were no rejects. They in turn asked me whether production skills and quality assurance in India were so immaculate that there was not even a single defect discovered. How is this possible when even in highly developed countries, be it Germany, UK, USA or Japan all manufacturers report at least a 0.01% rejection rate? A visit to an exporter of automobile components was revealing. A permanent board fixed at a prominent location gave batch-wise, product-wise figures of rejection quantities. The MD assured me that in the absence of this he would not even be short-listed by the importing company. The readers have to draw their own conclusions.

Manufacturer’s Responsibility
A suggestion to vehicle manufacturers is to include the ’speed category’ chart in the section on tyre specifications for the model, in the owners’ manual with statutory warnings on maximum speed, and importance of correct replacement. The tyre manufacturers on their part should give wide publicity to this aspect and provide a sticker to be pasted on the vehicle, probably inside the luggage compartment near the storage place of the spare wheel and tyre. In fact the tyre manufacturers association should take a proactive approach to safety and release public interest advertisement from time to time highlighting these aspects. Mass distribution of leaflets through vehicle and tyre dealers and display of the chart as POP material, and at the petrol pumps near the free air filling point, could do wonders in enhancing public awareness. Ultimately every life thus saved will be a boon to the family and relatives and be the best CRM.

Here are some useful tips to help you plan your driving tours.

Some notes before you begin planning:

We all know that planning is boring but it is essential to help you have un-spoilt fun so that you look forward to the drive. We recommend that you gang up with people whose company you enjoy. Ensure that there are a few who share a passion for motoring. Now, get together for coffee and start preparing for the trip using our guide.

Planning your holiday:

• Choose the right time
  Check your schedule(s) for long weekends or times when everyone would be relatively free from work pressure. Planning in advance would allow everyone to apply for leave and service the vehicle(s).
• Choose the right destination
  Choose a destination that is suited for that time of the year. Also, ensure that there is enough time to soak yourselves at the chosen holiday spot. You don’t want to spend most of the time on the road.
• Choose your vehicle(s)
  You must consider the number of people traveling, the luggage to be carried, distance to be traveled before deciding on the vehicle(s) to be taken.
• Draw up a rough budget
  Consider expenditure for fuel, consumables, and accommodation over the number of days you plan to spend. It is recommended that you carry twice that amount to meet any emergency situations like a breakdown.
• Arrange for accommodation
  This is especially important f you plan to travel during peak tourist season. As interesting as it may sound, you don’t want to end up sleeping in your car or under the open sky.
• Chart out an itinerary
  Read about the roads that would take you to your holiday spot(s), the time taken to cover the distance, the places you would like to see and the time you have to stay at each place. A timetable gives you the freedom to change your plans with greater confidence.

Readying the car(s):

Check the following aspects in your car while preparing it:

• Mechanical fitness: Tune the engine; check the brakes and the clutch
• Fluid leakages
• Condition of hoses and belts
• Proper function of electrical equipment like lights, indicators and fuses
• Condition of tyres

Things to carry for your car - Brake fluid, engine oil, coolant, distilled water for the battery, spare hoses and belts, tool kit, torch, owner’s manual, car documents, road maps, music.

Packing luggage

• Pack minimum including only the most essential things you need unless you’re traveling with children. Try to restrict luggage so that it can all fit in the boot. Carrying luggage on a roof rack is not advisable as the additional air friction hampers the car’s aerodynamics and the luggage may fall off at times. All items in the cabin should be securely placed and should not move about during hard braking and cornering.
• Keep the food and camera(s) in a handbag that can be accommodated in the passenger cabin. Also, drinking water, napkins and the first aid kit should be kept within reach.
• Do not place anything on board in front of the rear windshield, as it will obstruct the drivers view.

First aid kit

A first aid kit is very important and should always be a part and parcel of your car. Also it should be kept within immediate reach.

Items in the kit should include:

• Adhesive bandages of different sizes
• A roll of sticking plaster
• Sterile gauze pads and rolls of 1 and 2 inch gauze
• Set of paper tissues
• Scissors, tweezers, safety pins
• Antiseptic spray
• Thermometer
• Basic medicines for fever, headache and stomach disorders

Keep a record of the journey

Keep a track of the distances you travel and the fuel spent so that later on it will help you calculate the costs in terms of fuel. Also make a note of the refueling stations on route so that you can share your notes with someone who wants to venture on a similar trip.

For your convenience, we have created a PDF file that can be printed and carried along to make your Tour Notes. Click here to download.

Other points to note

• Make an early start. This helps you avoid traffic so that you can hit the highway in no time.
• Switch drivers at regular intervals. You can enjoy the driver better if you are able to switch driving with someone else. This way it also gives you time to relax, take a nap or two. Also a spare driver could help in situations where one driver is not too confident driving through different terrains.
• Don’t stop too often. Minimize your breaks on the way as it will not only break a drivers rhythm, it will also reduce the speed and the traveling time. Try combining fuel and refreshment stops.
• Keep your eyes on the road and hands on the wheel. You can still have a good time doing both. Avoid eating while driving and if you need to drink water or use your mobile phone you can always pull the car aside to do so.
• Drive safely & keep your cool. Do not break rules just because you are on the highway. Also, keep your cool even if you see others driving irresponsibly. Get into the holiday mood and enjoy your drive.
• Handling breakdowns. Always keep emergency help line numbers with you in case of a breakdown. Also, ensure passenger safety in case you have to go seek help.

Handling accidents

If any individual (passenger in your car or outsider) is injured in an accident, get immediate medical attention. The first aid kit should come in handy but drive to a hospital in case of serious injuries. If the accident involves other people, try to resolve the matter amicably. Drive down to the police station and report the matter only if necessary.

Make sure you have your driver’s licence, registration book and insurance policy when you file a complaint. These will have to be handed over to the police. Also, the police may take possession of the car for inspection by the Regional Transport Office (RTO).

All motorised road vehicles are tagged with a licence number in India. The licence plate number is issued by the district-level Regional Transport Office (RTO) of respective states - the main authority on road matters.The licence plates are placed in the front and back of the vehicle.By law, all plates are based on modern Hindu-Arabic numerals with Roman alphabet, though many states violate this by writing the numerals in the local script. Other guidelines include having the plate lit up at night and the restriction of the fonts that could be used.In some states such as Sikkim, cars bearing outside plates are barred from entering restricted areas.

Plates for private car and two-wheeler owners have a white background with black lettering (e.g., KA 05 M 5399). Commercial vehicles such as taxis and trucks have a yellow background and black text (e.g., DL 2C 6011). Vehicles belonging to foreign consulates also have the same yellow and black colouring. The President of India and state governors travel in official cars without licence plates. Instead they have the Emblem of India in gold embossed on a red plate.

Since June 1, 2005, the Government of India has introduced High Security Registration (HSR) number plates which are tamper proof. All new motorised road vehicles that come into the market have to adhere to the new plates, while existing vehicles have been given two years to comply. Features incorporated include the number plate having a patented chromium hologram; a laser numbering containing the alpha-numeric identification of both the testing agency and manufacturers and a retro-reflective film bearing a verification inscription “India” at a 45-degree inclination. The numbers would be embossed on the plate, rather than being painted for better visibility. The term “India” is to be in a light shade of blue.

Format
Format of the registration is as shown below

AA 11 BB 1111
Where AA is the two letter state code; 11 is the two digit district code; 1111 is the unique licence plate number and BB are the optional alphabets if the 9999 numbers are used up. An example would be:

MH 01 CA 1002
The first two alphabets MH indicate that the vehicle is from the state Maharashtra. The next two are the district (In this case the capital Mumbai). CA 1002 is the unique licence plate number. In some states (such as Delhi) the initial 0 of the district code is omitted; thus Delhi district 2 numbers appear as DL 2 not DL 02.

The National Capital Territory of Delhi has an additional code in the registration code:
DL 11 C AA 1111
Where DL is the two letter code for Delhi (DL). The additional C (for category of vehicle) is the letter ‘S’ for two-wheelers, ‘C’ for cars and SUVs, ‘P’ for public passenger vehicles such as buses, ‘R’ for three-wheeled rickshaws, ‘T’ for tourist licensed vehicles and taxis, ‘V’ for pick-up trucks and vans and ‘Y’ for hire vehicles. Thus a Delhi-specific example is:
DL 5 S AB 9876

States
All Indian states and Union Territories have their own two-letter code. This two letter referencing came into action in the 1980s. Before that each district or Regional Transport Officer’s office had a three letter code without mentioning the state, which lead to a fair degree of confusion - for example, MMC 8259 could fit in anywhere in the country. To avoid this ambiguity the state code was included along with the district or RTO’s office. In some states such as Maharashtra, licence plates before 1960, when the state was known as Bombay Presidency, bear notations such as BMC or BDL.

In some states certain licence plates are rendered redundant after the creation of new states. After the carving out of Uttarakhand, Chhattisgarh and Jharkhand, from Uttar Pradesh, Madhya Pradesh and Bihar respectively, the entire registration numbering in the newly chalked territories had to be overhauled.

The Government of India, Ministry of Road Transport and Highways, the nodal ministry, has formulated strict specifications and enforcement rules for the new High Security Registration Plates ( new number plates). The states have recently started introducing them in phased manner. This standardisation along with strict enforcement is expected to bring about sea change in law enforcement and registration process of vehicles in the country.

The list of two-lettered state codes is as follows:

Districts
Since all states have a two or more districts, the district is given the charge of registering the vehicle. A vehicle bears the registration of the district in which it is bought rather than the district of residence of the owner. In many states, officials insist that the plates be changed to the local numbers if the owner shifts residence.

The number of districts in the state need not equal the number of permutations of the district field of the licence plate. Often, in large cities the geographical district can be split into two or more administered regions, each governed by an RTO. A case is the Mumbai Suburban district which has the plate bearings MH-02 and MH-03. Also the 01′ digit may reflect the capital district of the state, though it may not always be the case.

In some states such as West Bengal, each RTO issues two numbers, one for commercial vehicles and another for private vehicles. Eg. Kalimpong has the numbers WB-79 for private vehicles and WB-78 for commercial or public ones.

Though the district field is of two digits, in some areas such as Delhi, the 0 is omitted, usually because Delhi has less than ten districts thus removing any ambiguity. Eg. DL-6 . But also in some states like bihar and kerela 0 is omitted like Patna - BR 1AH, Ernakulam- KL 7BB

Unique numbering
The last four digits are unique to the vehicle. Usually, the lower 100 numbers are government registered numbers, but it may not always be the case. Special lucky numbers such as 3333 or 6666 fetch a premium and may touch above rupees 10,000.

Unique alphabets
If all the 9999 numbers are used up, the RTO adds the letter ‘A before the number space so that more numbers can be accommodated. In some states, the two letters also give the description of the make of the vehicle. Eg. In Mumbai, MH-01 AA would point to a two-wheeler; where as MH-01 CA is a small car. MH-01 J **** and MH-01 X **** are taxis.

The alphabets may also reflect the subdivision of the district if the district is geographically large.

In Tamil Nadu, the letter G is reserved for Government (both the Union Government of India and State Governments) and the letter N is reserved for Government Transport Buses. Eg. TN 69 G 3333 will be a government vehicle registered in Thoothukudi District TN 72 N 2222 will be a government Bus registered in Tirunelveli District.

Karnataka started number series SS DD AA NNNN from 1 January 1990. While issuing these numners they reserved the “DD” for certain categories of vehicles. Numbers issued without DD eg KA 19 1111 was for commercial vehicles, E for two wheelers and P for cars. The alphabets G was reserved for Government vehicles, and F for KSRTC busses. The alphabets I, O, and Q where never issued. In all cases when the 9999 number was exhausted the next alphabet was reserved for that vehicle category. So A to D for commercial vehicles, F, H, J to L, R to Y for two wheelers M, N, P, Z for cars. Additional alphabets are added as mentioned earlier.

Prior to 2005 Karnataka used to charge Rs 1000 for obtaining a unique last four digit number. These numbers used to be issued either from the current running series or from one or two future series. When the numbering system was computerised numbers could be issued from any future series. However the Karnataka RTO has now steeply hiked these charges to Rs 6000 if the number to be obtained is in the current series, and Rs 25,000 if it is to be issued from a future series.

Military vehicles
Military vehicles have a unique numbering system unlike any other licence numbers. The numbers are registered by the Ministry of Defence in New Delhi and appear to have a pseudo-random numbering. The first (or the third) character is always an arrow pointing upwards. The first two digits signify the year in which the Military procured the vehicle.

Diplomatic plates
Vehicle belonging to foreign missions bear the plates CD or CC, which stand for Diplomatic Corps or Consular Corps respectively. A diplomatic plate numbered 13 CC xxxx would refer to country 13, probably a country close to the letter A or B. For example, a vehicle bearing the number 77 CD xxxx in India refers to a vehicle owned by either the United States mission in India or by a person working with the mission. As per international law cars bearing these license plates enjoy diplomatic immunity.

Other numbering
Other numbering include the special numbers allotted to public transportation such as buses, taxis and auto-rickshaws. The numbers are registered by the organisations which run the services and are usually printed on the side of the vehicle.

Temporary numbers
As soon as a vehicle is purchased, the dealer of the vehicle issues a temporary licence sticker known colloquially as a TR (To Register) number. This is valid for one month, during which the owner must register the vehicle in the controlling RTO of the area in which the owner is residing to get a standard licence plate. Some states like Tamil Nadu does not allow vehicles with TR numbers on the road, the dealer will hand over the vehicle to the purchaser only after the registration process is done. To register a vehicle, it has to be presented to the RTO’s office, where a Motor Vehicle Inspector will verify the applicant’s address and other details, confirm that the engine and chassis numbers are identical to what is written in the application and issues a permanent registration certificate which is usually valid for 20 years. The permanent registration certificate is one of the four important documents a vehicle plying on the road should always have; the others being a valid insurance certificate, a pollution under control certificate (PUC) and of course, the driver’s license. For public utility vehicles like buses, trucks, taxis and pick-up vans, there are a number of additional documents like a road-worthiness certificate and a transportation permit.

Historical numbering
Until the late 1980s, the Indian license plate system followed the scheme:

SAA 1111
Where S was the state code (e.g. C for Karnataka since K was allotted to Kerala); AA were alphabets; and 1111 was the unique licence plate number. Older vehicles still exhibit this legally valid numbering scheme.

In the early 2000s, the number plate colouring scheme moved from SAA 1111 to SAA 1111 for private vehicles, and from SAA 1111 to SAA 1111 for all other vehicles. The colours of the older plates were made illegal after a notice period.