The Difference Between 4WD And AWD

March 31, 2021 by Lewin Day 102 Comments

Car manufacturers will often tout a vehicle’s features to appeal to the market, and this often leads to advertisements featuring a cacophony of acronyms and buzzwords to dazzle and confuse the prospective buyer. This can be particularly obvious when looking at drivelines. The terms four-wheel drive, all-wheel drive, and full-time and part-time are bandied about, but what do they actually mean? Are they all the same, meaning all wheels are driven or is there more to it? Let’s dive into the technology and find out.

Part-Time 4WD

Part-time four-wheel drive is the simplest system, most commonly found on older off-road vehicles like Jeeps, Land Cruisers and Land Rovers up to the early 1990s, as well as pickup trucks and other heavy duty applications. In these vehicles, the engine sends its power to a transfer case, which sends an equal amount of torque to the front and rear differentials, and essentially ties their input shafts together. This is good for slippery off-road situations, as some torque is provided to both axles at all times. However, this system has the drawback that it can’t be driven in four-wheel drive mode at all times. With the front and rear differentials rotating together, any difference in rotational speed between the front and rear wheels — such as from turning a corner or uneven tyre wear — would cause a problem. The drive shaft going to one differential would want to turn further than the other, a problem known as wind-up.

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The Rise And Fall Of The Fan Car

March 5, 2021 by Lewin Day 51 Comments

The advent of aerodynamic wings in motorsport was one of the most dramatic changes in the mid-20th century. Suddenly, it was possible to generate more grip at speed outside of altering suspension setups and fitting grippier tyres. However, it was just the beginning, and engineers began to look at more advanced ways of generating downforce without the drag penalty incurred by fitting wings to a racecar.

Perhaps the ultimate expression of this was the fan car. Mechanically complex and arguably dangerous, the technology offered huge downforce with minimal drag. However, the fan car’s time in the spotlight was vanishingly brief, despite the promise inherent in the idea. Let’s take a look at the basic theory behind the fan car, how they worked in practice, and why we don’t see them on racetracks today. Continue reading “The Rise And Fall Of The Fan Car” →

Custom Ignition For A Citroën Mehari

February 5, 2021 by Lewin Day 42 Comments

The 20th century saw a great many cheap, utilitarian vehicles enter the marketplace. Cars like the Mini and the original Jeep offered low-cost, no-frills motoring. However, they were also decidedly low-tech, and not as reliable as modern cars by a long shot. The Citroën Mehari fits into this category neatly, and when [FVFILIPPETTI] grew tired of the unreliable points ignition system, he decided to build a more modern replacement.

The system is based around at ATmega328, the venerable chip many are familiar with from its starring role in the Arduino Uno. The chip tracks engine position with a magnet mounted on the flywheel combined with a hall-effect sensor, passed through an optocoupler to avoid nasty high-voltage spikes from the spark system interfering with the microcontroller. The chip then charges the ignition coil and fires it at the necessary time to ignite the air fuel mixture.

Old-school mechanical ignition systems were, if we’re honest, terrible compared to more modern solutions. This build has rewarded [FVFILIPPETTI] with a far more reliable ride, which we’re sure is very satisfying. If all this hacking has you thirsty for an automotive project of your own, dive into our primer on how to get into cars!

Sony’s Electric Car Now Road Testing In Austria

January 27, 2021 by Lewin Day 73 Comments

The Consumer Electronics Show was not typically a place for concept cars, and Sony aren’t known as a major automaker. However, times change, and the electric transport revolution has changed much. At the famous trade show, Sony shocked many by revealing its Vision-S concept — a running, driving, prototype electric car.

Far from a simple mockup to show off in-car entertainment or new fancy cameras, Sony’s entry into the automotive world is surprisingly complete. Recently, the Japanese tech giant has been spotted testing the vehicle on the road in Austria, raising questions about the future of the project. Let’s dive in to what Sony has shown off, and what it means for the potential of the Vision-S.

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How To Get Into Cars: Drifting Mods

January 4, 2021 by Lewin Day 31 Comments

Drifting is a hugely popular motorsport unlike any other, focusing on style and getting sideways rather than the pursuit of the fastest time between two points. It’s a challenge that places great demands on car and driver, and proper attention to setup to truly succeed. Here’s a guide to get your first drift build coming together.

Getting Sideways (And Back Again)

Drift cars are specialised beasts, and like any motorsport discipline, the demands of the sport shape the vehicle to suit. If you’re looking to drift, you’ll want to choose a project car with a front-engined, rear-wheel drive layout. While it’s somewhat possible to drift with other layouts, the act of kicking out the tail and holding a slide at speed is best achieved with the handling characteristics of such a vehicle. It all comes down to weight transfer and breaking traction at will. Of course, over the years, certain cars have become expensive on the second-hand market due to their drift prowess, so you may have to get creative if your first choice isn’t available at your budget. It pays to talk to the drifters down at your local track to get an idea of which cars in your area are the best bet for a drift build. Once you’ve got yourself a car, you can get down to installing mods!

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Road Pollution Doesn’t Just Come From Exhaust

September 25, 2020 by Brian McEvoy 48 Comments

Alumni from Innovation Design Engineering at Imperial College London and the Royal College of Art want to raise awareness of a road pollution source we rarely consider: tire wear. If you think about it, it is obvious. Our tires wear out, and that has to go somewhere, but what surprises us is how fast it happens. Single-use plastic is the most significant source of oceanic pollution, but tire microplastics are next on the naughty list. The team calls themselves The Tyre Collective, and they’re working on a device to collect tire particles at the source.

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Improving More Leaf Design Flaws

September 16, 2020 by Bryan Cockfield 19 Comments

[Daniel] was recently featured here for his work in improving the default charging mode for the Nissan Leaf electric vehicle when using the emergency/trickle charger included with the car. His work made it possible to reduce the amount of incoming power from the car, if the charging plug looked like it might not be able to handle the full 1.2 kW -3 kW that these cars draw when charging. Thanks to that work, he was able to create another upgrade for these entry-level EVs, this time addressing a major Leaf design flaw that is known as Rapidgate.

The problem that these cars have is that they still have passive thermal management for their batteries, unlike most of their competitors now. This was fine in the early ’10s when this car was one of the first all-electric cars to market, but now its design age is catching up with it. On long trips at highway speed with many rapid charges in a row the batteries can overheat easily. When this happens, the car’s charging controller will not allow the car to rapid charge any more and severely limits the charge rate even at the rapid charging stations. [Daniel] was able to tweak the charging software in order to limit the rapid charging by default, reducing it from 45 kW to 35 kW and saving a significant amount of heat during charging than is otherwise possible.

While we’d like to see Nissan actually address the design issues with their car designs while making these straighforward software changes (or at least giving Leaf owners the options that improve charging experiences) we are at least happy that there are now other electric vehicles in the market that have at least addressed the battery thermal management issues that are common with all EVs. If you do own a Leaf though, be sure to check out [Daniel]’s original project related to charging these cars.

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