By Razvan Balanescu
Copyright ©2016 Razvan Balanescu
All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the publisher, except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permitted by copyright law. All pictures are held by commercial license and may not be duplicated by anyone without express permission.
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First, I personally would like to thank you for downloading this book. This proves that you’re interested in cars and you love them as much as I do.
I would like to mention that all my CarTalks will be free of charge for the eBook editions. If it doesn’t appear free to you, it’s because you’re not living in the United States (or it hasn’t been updated yet). You can get it from here as well – (Shakespir). If you enjoyed it and you want to support my efforts, you can purchase the paperback edition via CreateSpace.
I regularly post answers and questions on Quora, I constantly write blog posts, and I regularly upload YouTube videos (you can check out my channel ) about cars (reviews, how they work, etc.)
CarTalks basically contains my blog posts, Quora answers (my best answers or the most viral ones). I will add at least one book per month to the series (I’m doing my best to add 2).
If you’re wondering why I’m doing this, here’s why – I want to share my knowledge with as many people as possible and I also want to help as many people as possible.
Offering a free eBook is one of the best ways to reach new people just like you.
Enough talking, and let’s get to cars!
When the internal combustion engine was invented, the Otto (gasoline) engine was the first one to use fuel derived from crude oil – gasoline.
1. Intake – Air-fuel mixture enters the cylinder through the intake valves. The piston moves from TDC (Top Dead Center) to BDC (Bottom Dead Center). The difference between TDC and BDC is called stroke.
2. Compression – Air-fuel mixture is compressed. The piston moves from BDC to TDC. Valves are completely closed.
3. Ignition – A spark plug gives a spark and ignites the mixture. The ignition (explosion) forces the piston to move from TDC to BDC. This is the only stroke that produces mechanical work.
4. Exhaust – Exhaust gases are evacuated from the cylinder. Inertia from the other cylinders move the piston from BDC to TDC, evacuating exhaust gases.
Key Features of Gasoline Engines
Exhaust gases can reach up to 900° C, which is why the engine heats up quickly even in cold sessions.
Gasoline freezes at -60° C and the engine can start up at -40 without a problem.
Gasoline engines can be turbocharged, supercharged, or naturally aspirated.
They are also environmentally friendly compared to diesel engines – no black smoke, less pollutants.
When Rudolf Diesel created the diesel engine, he initially used coal powder to power up the engine. Eventually, he started using crude oil, and then the diesel fuel we use today.
At first sight, it works pretty similar to the Otto (gasoline) engine – internal combustion, 4 strokes, fuel derived from crude oil.
However, here’s how it works and why it’s different (images from the other engine work here):
1. Intake – Fresh air enters the cylinder through the intake valves. The piston moves from TDC (Top Dead Center) to BDC (Bottom Dead Center). The difference between TDC and BDC is called stroke.
2. Compression – Air is compressed up to 700-800° C. The piston moves from BDC to TDC – valves are completely closed.
3. Ignition – An injector sprays diesel fuel into the cylinder, and fuel auto-ignites (without using a spark). The ignition (explosion) forces the piston to move from TDC to BDC. This is the only stroke that produces mechanical work.
4. Exhaust – Exhaust gases are evacuated from the cylinder. Inertia from the other cylinders move the piston from BDC to TDC, evacuating exhaust gases.
Key Features of Diesel Engines
Exhaust temperatures reach 300-400° C, which is why diesel engines have more difficulty warming up.
For the fuel to auto-ignite, it must have a high Cetane Rating, which is the opposite of Octane Rating. For cetane rating, the fuel must have the lowest possible delay to auto-ignite, whereas for gasoline engines, it shouldn’t auto-ignite at all (to prevent engine knocking).
In Europe, diesel fuels vary from 51 to 55 cetane rating. Running on low CR fuels with high auto-ignition delays will result in incomplete combustion (black smoke), and engine wear.
Compression ratios in diesel engines vary from 16 to 20 (Compression Ratio = VBDC / VTDC).
Modern diesel engines use Common Rail technology, which is efficient, silent, and reliable. If you want to buy a car with a diesel engine, make sure it’s Common Rail. Other injection technologies are Pump Duse (Pump-Injector Unit) and Injection Pump (Classic, old cars diesel engines).
Diesel engines use steel alloys for engine blocks, which is why they’re heavier than gasoline engines.
Diesel engines have an average fuel efficiency of 45% compared to 30% (or less) in gasoline engines. However, maintenance for diesel engines is higher. Parts are manufactured at much higher precision, resulting in higher costs.
There are drivers who are pro-diesel, and there are drivers who are pro-gasoline, and guess what? Neither are right.
It depends on your preference and what you use your car for. Heavy trucks won’t ever use gasoline, so does this mean that gasoline sucks? Of course not…
Sports cars don’t use diesel, because aggressive driving and diesel don’t end well. Does this mean that diesel sucks? Of course not…
If you’re driving over 20,000 miles/year and you drive outside the city, then a diesel is definitely for you.
However, if you’re driving only 7,000 miles/year and you drive inside the city, you should go for a gasoline engine.
I would like to mention that diesel engines are over 5 times more polluting than gasoline engines, which is the main reason behind banning diesel cars in most of the busy cities around Europe starting in 2020. Let me tell you something, I currently work in a car service, and I’m responsible for technical inspections (Road Worthiness Certificates), and how they measure exhaust gases isn’t right.
Gasoline engines don’t emit smoke (unless they’re broken or completely worn up), but diesel engines emit black smoke (generally from incomplete combustion). Diesel engines emit lots of pollutants and fine particles that cause cancer (that’s why manufacturers use Diesel Particulate Filters – DPF).
During technical inspections for exhaust gases, for diesel engines, we only have to check (legally speaking) the opacity of the smoke. For gasoline engines, we need to check lambda (pressure of exhaust gases), CO (carbon monoxide), CO2 (carbon dioxide), and HC (hydrocarbons). If we had to compare the data on both engines (I did that for my own knowledge), diesel engines are 5 times more polluting than gasoline engines.
Without further ado, I will make a list below with advantages and disadvantages:
Diesel Advantages over Gasoline
- Higher fuel efficiency (45% compared to 30%)
- More torque (excellent for trucks and SUVs)
- Excellent for those who drive over 20,000 miles/year and for transport companies
- Easier to drive (for manual transmissions)
- In case of an accident, diesel fuel ignition isn’t violent
Gasoline Advantages over Diesel
- The optimum operating temperature is reached 3 times faster, which makes it an excellent choice for cold areas
- Excellent for sport driving
- Maintenance is cheaper (especially for naturally aspirated engines)
- Less vibrations (more comfort)
- Higher top speeds can be achieved
- It’s great for hybrid vehicles
- Less emissions (pollutants)
What Would I Choose?
I personally love sports cars, I love this planet, so I would do anything to protect it. I also drive around 12,000 km/year in Europe, mostly inside the city (60% in the city, 40% outside). I live in an area where temperatures go as low as -20° Celsius during winter.
All of this being said, my choice is a gasoline engine.
We’ve all seen standard and premium fuels in every gas station, and most of us are wondering “What happens if I use gasoline with a higher Octane Rating?”
It all depends on what kind of engine you have.
In gasoline engines, the average compression ratio is around 11. Older cars have from 9 to 10.5 while newer ones can have 12 (especially those with direct injection).
If an engine that runs on gasoline has a high compression ratio of 12, and you’ll be using fuel with 91 Octane Rating, the gasoline will auto ignite before the spark plugs will give the spark for combustion. This is called engine knocking, and it’s dangerous for your engine.
In some cases, using a premium fuel with a superior Octane Rating can also have some unpleasant consequences (like burning up or overheating the valves). Generally, premium fuels are recommended for engines with a high compression ratio or for competition vehicles, but if you choose to use it, you’ll get some extra power out of your engine. Here’s why:
- Fuel burns completely, producing more power
- Performance additives will increase power
- It helps lubrication (yes, gasoline lubricates and cools the combustion chamber)
In addition to the benefits mentioned above, fuel consumption will decrease if you’ll drive normally, and will increase if you drive aggressively. As an example, if you’re cruising on the highway at 80 mph, fuel consumption on premium fuels will slightly decrease.
My recommendation is to use premium fuels from time to time and make a case study – do you really need it, does your engine support premium fuels?
Since the internal combustion engine was invented, there has been development of different ways to arrange the cylinders, and the number of cylinders.
The most commonly used engine is the I4, which stands for inline 4 (4 cylinders). Without a doubt, this engine is the most efficient in terms of costs, fuel consumption, and reliability. That’s why most of manufacturers used it and still use it.
Before we get into more detail, I would like to note down the other engine design layouts:
I3, I4, I5, and I6 – There are few manufacturers who don’t use Inline at all, manufacturers such as Porsche (they use V or H).
There are V6, V8, V10, V12, and V16 (Rolls Royce Phantom from Johnny English Reborn – 9.0L V16). Compared to an Inline engine, the V is more equilibrated, vibrations are significantly lower, and larger power outputs can be implemented.
H shape (Boxer)
Porsche and Subaru use this engine layout. Subaru uses this layout for all its engine – both Diesel and Gasoline engines. There are H4 and H6 engines (H6 used by Porsche in their 2.7 and 3.4L gasoline engines).
This is basically an engine which has 2Vs with different angles. The main purpose of this engine is to reduce space for huge engines (6L and above). This kind of engine can be found in the Audi A8 6.3 W12 or in the Bugatti Veyron 8.0 W16.
Originally developed by Mazda and used only in the RX8, the Wenkel engine is a rotary motor that can reach 9,500 rpm. Power output is huge, 231 hp from a 1.3L engine, but reliability and fuel consumption are not great. The engine’s lifetime is around 90,000 miles, and fuel consumption is around 20 MPG.
We all know that diesel engines are much more polluting than gasoline ones, and measures had to be taken.
Since 2006, new cars equipped with diesel engines (especially in Europe) had particulate filters.
Now, let’s get a little bit in depth.
Every car has a catalytic converter, a device that contains platinum and other rare metals that absorb (even destroy) most of the harmful pollutants. In diesel engines, besides these pollutants, there are fine particles from 2.5 to 10 microns that are extremely harmful to our health. If we inhale those particles, they remain stuck in our lungs forever, which cause fatal injuries and in some cases, even cancer.
To reduce the amount of particles that come from diesel engines, engineers have created the particulate filter, a device that absorbs particles with the diameter greater than 2.5 microns.
Also, diesel engines with particulate filters emit less smoke.
The sad part about particulate filters is they break pretty fast and they’re expensive. Whenever the particulate filter is stuck or needs regeneration, you need to drive 10-20 km constantly at 3,000 rpm and return to its standard state.
Driving such cars around the city for short distances will damage the particulate filter in less than 500 miles, and one particulate filter costs from $800 to $3,000, depending on the car and manufacturer.
That’s why I prefer gasoline…
If it was up to me, every car would have to have a manual transmission – you feel the car, you control the car, it’s cheaper, and it’s easier to maintain. It makes your life easier and it makes driving a pleasure.
I got my driver’s license at 18 years old – I can drive heavy trucks, trailers, long vehicles, ride motorcycles, both manual and automatic. I’ve driven over 100,000 km in 6 years and I’m just 24 right now. No accidents, no incidents, just a few scratches (I think this is quite normal for everyone).
I think that less than 1,000 km are driven on automatic transmissions. My personal car (an Audi A3) has a manual transmission. My dad’s car (Skoda Octavia) is also manual. We never owned automatic transmission and in Romania (and in Europe in general), there are 50% automatic and 50% manual.
Why am I wondering if they’re going extinct?
I’ve noticed that most manufacturers are eliminating the option to choose a manual (mostly in Europe).
Audi removed the manual transmissions for the S4/S6 and all the 3.0 TDi versions. BMW, too. Mercedes, too. Everyone now has an automatic option and manual transmissions are available for low cost models.
I think that, in 30 years, we’ll talk about manual transmissions as if they were fairy tales. Maybe a story to tell to our children (or grandchildren) – “When I was young, I got the chance to drive a manual transmission, what a joy!”
I don’t know what I am going to do when manual transmissions will disappear. I just hope that there will still be manuals. If they will really go extinct, it means that in 30 years, I would be driving “historical” vehicles (the vehicles made now).
Not long ago, our beloved cars had big, naturally aspirated engines that produced low power outputs, somewhere around 40 to 70 HP/Liter. Those engines could have run for over 400,000 miles without breaking. Unfortunately, those are legends now, and there are no manufacturers that stick to that rule.
Fast forward to our modern world, and we see high power outputs (100 to over 150HP/liter) from small, turbocharged engines. That’s the current tendency.
Diesel cars have 1, 2, or even 4 turbochargers (BMW 750xD), and most of the gasoline engines are also turbocharged, whether they’re high performance vehicles or just simple passenger cars.
Now here’s a short list of what you should not do if you own a turbocharged engine:
1. Don’t lug the engine – What I mean by lug is to full throttle the acceleration when the engine is at low revs. The turbo will break apart easily – you’re forcing it to give you boost when the engine doesn’t have the power and torque.
2. Don’t stop the engine if you’ve driven aggressively – Temperatures in turbocharges can reach 900° Celsius, so your oil will get burnt and thick. The next day, that thick oil will run through your engine, leaving it unprotected. Thus, you have to change the oil quicker, and problems may occur. To solve this, simply let the engine cool down (let it run idle) for 2-3 minutes and that’s it.
3. Take it slow when the engine is cold – Even though this is available for every kind of engine, turbocharged engines require even more attention. If you have a naturally aspirated gasoline engine, you can rev it at 4,500 rpm without any problems. Turbocharged engines (especially diesels) are sensible when the engine is cold, so try not to push it too hard until you reach the optimum operating temperature.
4. Rev it to the max from time to time – Constantly driving at low rpms will slowly damage the turbocharger. Oil, dust, and fine particles will be deposited inside the turbo, so what you need to do is floor the throttle several times to clean things up. Do this when you go on a longer journey, when the engine runs at optimum operating temperatures.
5. Be aware of the turbo lag – Unlike supercharged or naturally aspirated engines, a turbocharger works based on pressure of the exhaust gases. To get pressure, you need to accelerate, and the whole process takes between 0.5 and 1.5 seconds before you feel the boost. Naturally aspirated engines respond almost instantly, so be aware of this.
Manual transmissions are much more reliable compared to automatic transmissions, and the reason is quite obvious – less tech, less sensors, less everything. It’s simple and efficient.
There’s nothing more reliable out there than a manual transmission.
However, to protect it, there are a few things you should never do in a manual transmission.
1. Don’t put it in reverse while you’re moving – The gearbox has a gear selector for the 5 or 6 gears (forward), but not for going in reverse. If you’re trying to put it in reverse while the car is moving, it will make a specific sound when the gears growl.
2. Don’t keep your hand on the shift knob – You’ll put pressure on the gear selector, adding more wear to it. This will shorten its life and it will eventually need to be replaced.
3. Don’t shift fast when the engine is cold – This may sound awkward, but if the engine is cold, the gearbox’s oil is even colder. If the engine gets to optimum operating temperature in 10 minutes, the gearbox will need at least 30 minutes to warm up. You’ll notice that it’s much easier to shift gears after the oil reaches its optimum operating temperature.
4. Don’t downshift in 1st gear – If you’re decelerating from 40 mph to 0, don’t downshift into 1st gear. When you get below 20 mph, simply put it into neutral. 1st gear has the smallest shaft and it’s the most sensible gear. Use it just to start from standstill.
5. Don’t drive in just one gear – It’s true that you can drive in 3rd gear from 20 to 80 mph, but you have 5 or 6 gears! Use them all. Make sure to have between 2,000 and 3,000 rpm (diesel) when you’re driving at constant speeds (or 2,000 to 4,000 rpm for gasoline).
Before I purchased my own car, it had its gearbox changed at 100,000 miles and that was because of point no. 5. It was driven on the highway in 4th and 5th gear at 5,500 rpm – a lot of friction, a lot of wear, it fell apart.
Engineers know how brutally this coefficient affects your car, but most people don’t know how to treat it. I will do my best to explain everything about it below.
Air is everywhere around us. We need air to breathe, cars need air to run as well. If you wing your hand fast enough, you’ll feel the air blowing to your hand.
When you are cruising at 60 MPH, the air blows your car with 60 MPH (even more if there’s any wind outside). At speeds below 40 MPH, the friction forces with the air are pretty reduced. That’s why you’ll get the best fuel consumption at speeds below 60 MPH.
After 60 MPH, friction forces (ground + air) increase exponentially. How much power do you think you need to overcome friction forces with the air at the car’s maximum speed? 10%? 30%? 50%?
Nope. It’s 70%, or more (depending on the drag coefficient).
I’ll use my personal car, a 2004 Audi A3, as an example. It has 1200 kg, a drag coefficient of 0.34, 102 bhp, and a top speed of 110 MPH. I need 75 bhp to run at max speed just to overcome the friction forces with the air, and I need just 27 bhp to overcome the friction forces with the ground (+friction forces from the engine and transmission).
Modern vehicles have better drag coefficients, from 0.19 (Tesla Model 3 – the best drag coefficient) to 0.30.
Simply imagine that you have a drag coefficient of 0.24 – it’s better with 0.07 than my car. It sounds a little, but 0.10 out of 0.34 is 30%. If I had a drag coefficient on the same car, I would need 52.5 bhp instead of 75 to drive my car at 110 MPH. Obviously, this will result in having a lower fuel consumption at 110 MPH and in reaching a greater top speed, probably 130 mph.
When you buy a car, the drag coefficient really matters.
The perfect aerodynamic model for a car is a rain drop – it has a natural drag coefficient of 0.04 and engineers have been studying it for dozens of years to improve the cars we drive today.
Generally, sports (short) cars have bigger drag coefficients whereas limousines and long cars (luxury) have smaller drag coefficients.
A small engine (naturally aspirated) is “fighting” with the weight of the car, and fuel efficiency isn’t that great. Having a small engine (1.3L naturally aspirated with 75 bhp and 125 Nm, for example) on a heavy chassis will significantly effect fuel consumption and performance isn’t great.
By adding a turbocharger on this engine, this will happen:
• Use exhaust gases to get boost to increase power and torque
• With more power and more torque, the engine won’t be “fighting” with the weight of the car as much
• Performance levels increase
• Overall, adding a turbocharger is more efficient.
Regarding downsizing – going down from a 4.0L V8 (BMW M3 E92) to a 3.0 L Twin-Turbocharged (M4) this happened:
• Average fuel consumption (official) – 12.4 L/100 km
• Power – 420 bhp at 8250 rpm
• Torque – 400 Nm at 3900 rpm
• Weight – 1680 kg
• Average fuel consumption (official) – 8.8L/100 km
• Power – 431 bhp from 5,500 to 7,300 rpm
• Torque – 550 Nm from 1,850 to 5,500 rpm
• Weight – 1,520 kg
So, as you can see, that’s why downsizing is efficient. You increase power and torque throughout the entire rev range. Having max torque of 1,850 to 5,500 means that the engine moves the car easily. Weighing less and having fewer pistons (6 instead of 8), more power, and more torque => better efficiency.
I don’t want to bore you with too much information in one place. I will be constantly releasing CarTalks booklets wherein I will share my automotive knowledge.
If you like what you found here, I invite you to follow me on
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I absolutely love cars and I want to connect with people who share the same passion as me. I also love the environment and this planet. I’m proud that we’re finally moving towards electric vehicles (even if we won’t have any roaring V8s).
I’m telling you, I am proud to see people like Elon Musk trying to create electric cars and new technologies for us.
In the next 30 years, we should be using our cars for free by using water, solar energy, or electricity. Whether you like it or not, what I’m telling you now will eventually happen one day.
Talk to you soon,
I'm an Automotive Engineer and I absolutely love cars. I want to make others love them and the best way to do that is to share my knowledge and passion with you. Have you been wondering how cars work or you want to learn more about your current car? Then you have come to the right place. I release YouTube videos and I write answers on literally anything related to Automotive. I will constantly release small (free) eBooks on how cars work, so make sure to follow me if you want to learn more about this topic.