Posts filed under ‘Automotive’

Air Conditioning Affects Gas Mileage

By Chad Upton | Editor

In most cars, the air conditioner’s compressor is powered by a drive belt on the engine. When the air conditioner is activated, the compressor adds resistance to your engine. That extra resistance means your engine requires more fuel to turn at the same speed.

In other words, using your air conditioner burns more gas than not using it. Modern cars have very efficient air conditioners, but this truth still stands.

On a hot summer day, you have to keep cool. Does that mean it’s more fuel efficient to drive with your windows down?

Yes and no.

The Society of Automotive Engineers performed a study that examined this question in detail. They performed wind tunnel and track experiments comparing a car and an SUV. With the windows down, the car was half as efficient at 50 mph (80 km/h) than the SUV’s at 30 mph (50 km/h). It’s clear that driving the car with windows down has a dramatic effect on fuel economy, but it affected the SUV even more, especially when a 10 mph (16 km/h) crosswind was added in the wind tunnel.

Consumer Reports found that below 40 mph (65 km/h), drivers are better off with their windows down and air conditioner off.

Jason Toews from GasBuddy.com found at speeds above 45 mph (70 km/h), “wind drag becomes an issue.” He says, “Drive at speeds over 55 mph with windows down and you’ll decrease fuel economy by up to 20 percent or greater.”

Myth Busters has also looked at this issue on a couple occasions. The first time around, their methodology was flawed, so they tried it a second time. The second time, they came to the same conclusion as Consumer Reports and GasBuddy, that windows down are more efficient than running the air conditioner at speeds less than 45-55 mph (70-90 km/h) and the drag at higher speeds makes the air conditioner the more efficient option.

Of course, results vary by vehicle.

There are many factors other than windows and air conditioning that affect fuel economy: drive train, power-train, body aerodynamics and tire rolling resistance. If you want to know exactly how it affects your car, you might try experimenting for yourself. Some cars have a driver information center that displays fuel economy, otherwise you could order an after market product, such as CarChip Pro ($75-$85), which may help you get that data. If you’re interested, some of these are explored in more detail in another post, The Ideal Vehicle Speed for Best Fuel Economy.

If it’s hot outside, you should probably start with your windows down anyway. This gives your air conditioner a bit of a break by clearing the extremely hot air out of the car first.

Do prefer windows down or the air conditioner on?

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Sources: SAE (PDF), MythBusters (Ep 22, Ep 38), Edmunds, Bankrate, Consumer Reports, Missouri Gov

Photo: Tomás Fano (cc)

August 10, 2010 at 5:00 am 12 comments

Warning Gauges are Usually Center Normal

By Chad Upton | Editor

Even if you don’t know anything about cars, this can help you spot a problem, even if you don’t know what it is.

Virtually every car has a speedometer and a fuel gauge and you can obviously read those gauges. Many cars also have a tachometer; it measures the engine speed in revolutions per minute (rpm). This can help you understand when to shift gears and when you’re burning the least/most fuel.

Some cars have other gauges too. Generally speaking, the needle on most of these other gauges should be near the middle of the gauge when the vehicle is operating normally. Depending on the gauge, it will usually have a red mark on one or both sides of the gauge, indicating trouble if the needle reaches that mark.

Some of these gauges take a few minutes to settle near the center, particularly the various temperature and pressure gauges that may appear in some vehicles.

These are called center normalized gauges and have been a popular gauge design standard for a long time. With so many in-car distractions, simplifying gauge design makes it easy to identify a problem.

In racing some drivers even tape over the sides of the gauges, leaving on the center visible — then they can only see the needle when it is in the center position, making it even easier to identify a problem.

One of the most popular additional gauges is the engine coolant temperature gauge. It is identified by a symbol that looks like a thermometer partially submerged in liquid. This gauge indicates when your engine is overheating.

The following gauges are not exactly warning gauges, so they’re exempt from the center normal rule: speedometer (mph or km/h), tachometer (rpm), fuel, and turbo (boost).

Of course, not all cars use center normal gauges, but you’ll be able to tell a few minutes after your car has been running normally.

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Sources: Answers.com, umich.edu

Photos: Photo courtesy of Aaron Gold at _cars.about.com_, rastrus (cc)

August 2, 2010 at 5:00 am 2 comments

Drinking and Driving is Legal in Mississippi

By Chad Upton

Ever since I can remember, “Don’t Drink and Drive” has been drilled into my head.

But, the range of acceptable blood alcohol content varies from 0.01% in Albania, Guyana and a few other countries, to 0.08% in Canada, Ireland, Italy, United Kingdom, United States and many others.

It’s obviously dangerous to be drunk while driving. But, it’s arguable when alcohol consumption becomes dangerous.

Some countries have lower limits for drivers who are new or have other special circumstances and more strict penalties for blood alcohol readings at other levels above the legal limit. In some cases: state and provincial laws are more strict than federal laws or county and city laws are more strict than state and provincial laws.

Countries, such as Brazil and the Czech Republic, have a zero tolerance policy for blood alcohol content. In those countries, and a few others, you cannot have alcohol in your bloodstream when you drive.  Other countries, permit up to 0.08% blood alcohol content.

I couldn’t find a country with more internal disagreement than the United States. In most states, it is illegal to have a blood alcohol level higher than 0.08%. The rules are even more strict for drivers under the age of 21. In most states, you can’t have open containers in the passenger compartment of a vehicle — that is a container where the seal has been broken.

Conversely, there are a number of states where passengers are allowed to consume alcohol while the vehicle is moving. These states are Arkansas, Connecticut, Delaware, Mississippi, Missouri, Virginia, and West Virginia. Actually, Mississippi allows drivers to consume alcohol as long as they do not exceed the blood alcohol limit of 0.08%.

States that do not conform to federal open container laws are financially penalized. But, that doesn’t stop them, in fact, drive thru restaurants in some states serve alcoholic beverages too.

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Sources: Wikipedia (US Open Container Laws, Drunk Driving by Country), Open Container Laws, The Monitor, State Line

Relevant:

An alcohol abuse program makes use of various methods, all designed to help an alcohol abuser get the all that drinking off his system.

July 28, 2010 at 5:00 am 2 comments

Sarcastic Secret: Signal Lights

By Chad Upton

Tickers, blinkers, indicators and flashers. They have many names, but only one purpose: to let people know your car is about to change course.

In most vehicles, a lever on the steering column moves up or down to activate flashing lights on either side of the car.

I suspect a lot of people don’t even know their car has such lights, but they’ve been standard on cars since cars.

Maybe it’s a confusing concept, so I’ll try to explain it in a straight forward manner: if you’re about to turn your steering wheel, put these lights on first.

I find that some people use signal lights like the horn. They know they’re there, but they only use them when they need you to move.

Most vehicles also have a way to put all four blinkers on at the same time. The vehicle manual may refer to these as “four way flashers” or “hazard lights” but a lot of people know these as “park anywhere lights.” Their understanding of this feature is, when you want to double park, park in a fire lane or any other no parking zone, these flashing lights give you temporary immunity from parking regulations.

In all seriousness, signal lights first appeared on cars in 1907, but weren’t patented until 1938. Some cars from the 1920s to 1950s used solid (non-blinking) retractable lights on the sides of the car, called a trafficators.

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Source: Wikipeda (Signal Lights)

Photo: Wikimedia (gnu free)

July 23, 2010 at 5:00 am 10 comments

Tires Do Not Protect You During a Vehicle Lightning Strike

By Chad Upton

I’ve always heard that a car is one of the safest places to be during a lightning strike and that is true.

The tires usually get all the credit. As the story goes, tires are rubber and rubber is an insulator, so you don’t get electrocuted in the car because you’re isolated from the ground like a bird on a wire.

It’s a pretty believable story, but it’s not the truth.

If you think about it, the lightning travels thousands of feet through thin air to reach the car — it could easily continue to travel through thin air to get around a few inches of rubber tires. Compared to the power of lightning, tires don’t really provide any protection.

Trains are struck by lightning and the people inside are fine, even though trains have metal wheels, which are great conductors.

Airplanes are regularly struck by lightning in the air. In fact, the FAA estimates that each plane gets struck about once per year.

So why are people safe in these cases?

It’s all because of a principle discovered by Michael Faraday in 1836.

Faraday demonstrated that an electrical charge exists only on the exterior of a hollow conductor and not the interior. He built a wire cage, that is now know as a Faraday cage, to demonstrate that an electrical current flowing through the cage did not produce an electrical current inside the cage.  When you’re in a vehicle, with a conductive exterior shell, you’re inside a Faraday cage and the electrical charge is carried around you.

Faraday cages can also be used to shield against electromagnetic radiation. Coaxial cables are common in most households for carrying TV signals. These cables are design with what amounts to be a built in Faraday cage to protect the inner copper wire from electrical noise.

Microwave ovens are also a good example of a Faraday cage. This principle protects you from exposure to microwaves by turning the inside of the oven into a Faraday cage. The mesh you see on the inside of the door is part of that cage and explains why the glass isn’t perfectly transparent.

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Sources: Wikipedia (Ground, Faraday Cage), Weather Imagery (Cars, Airplanes), Faraday Cage

Photo: jonathan mcintosh (cc)

July 21, 2010 at 5:00 am 18 comments

Lock Your Car Better With Your Chin

By Chad Upton

I think everybody has done it. You’re walking away after parking your car and you can’t remember if you locked it. You turn around to lock it and you’re too far away – or – maybe your car has remote start and you want to warm it before you leave work in the winter. You can see it in the parking lot, but you’re too far away.

There is something that may help.

If you push the car remote against your skin, and then press the button, your body will act like a giant antenna to extend the signal. I don’t know how safe this is, but it works.

I first heard about this a few years ago and I was in disbelief, until I tried it. Not only does it work, according to New Scientist, it can almost double the range of your key fob.

When I first heard about it, I was told to push it against my chin. It turns out you can push it again your arms or other body parts too. It relies on a principle called capacitive coupling, the same principle that the capacitors on electronic circuit boards rely on.

This doesn’t work for all types of radio frequency remotes, it works best with relatively low frequency signals with rapidly changing currents, which is what many car remotes use.

You may have heard that the iPhone 4 is having signal issues when the exterior antenna is touched in a certain way and you may be wondering why it has the opposite affect on the iPhone. The difference between the iPhone problem and capacitive coupling is that there is no insulator between the transmitter and your body with the iPhone, but with your car remote, the plastic case acts like an insulator. Again, this is precisely how capacitors on circuit boards work — two conductors are separated by an insulator.

It should be noted that some car remotes may use a different frequencies and types of signals, so you’ll have to test yours to see if it works for you.

Big thanks to Max Surguy for reminding me about this one, such a great tip!

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Sources: New Scientist

Photo: nailkennedy (cc)

July 9, 2010 at 5:00 am 5 comments

Trap Doors on Car Bumpers

From satellite navigation to chilled cup holders, modern cars are full of high-tech developments that get you from point A to point B without getting lost and with colder refreshments. Overall, car technology has improved the handling, efficiency, style, safety, comfort and entertainment of our cars.

There are even high-tech bumpers out there. If you see bumpers with three or four dimples aligned across the back bumper, those are likely sensors for the backup warning system.

If you see small rectangular patches, that’s what this secret is about. They’re actually pretty low-tech, but still cool.

Even if your car doesn’t have them, maybe you’ve noticed them on other cars while you’re sitting at a red light (they may be found on front and/or rear bumpers).

They look like trap doors that cartoon characters fall through long after the audience spots them and screams at their television to warn the carbon impaired being of the obvious hazard and their impending doom. In reality, they cover anchor points where you can insert a towing eye (aka “tow hook”).

Check your car out during the summer and if you need them in the winter, you’ll know if they’re there. The towing eye is usually stored with the spare tire and/or jack and it screws in behind these covers.

bumper patch open tow hook eye door

Like all of the secrets on this site, there will be somebody reading who already knows this one — that’s cool, you can brag (or complain) about it in the comments, or retweet it and say you knew this, “like 10 years ago.”

Broken Secrets | By: Chad Upton

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July 6, 2010 at 5:00 am 3 comments

What are Truck Weigh Stations for?

There are truck weigh stations scattered along most major highways in the US, Canada, Taiwan and other countries. Obviously they’re there to weigh trucks, but why do trucks need to be constantly weighed?

Vehicles that weigh more than 26,000 pounds or have 3 or more axles have to pay fuel taxes. Motor homes and other private (non-commercial) vehicles are generally exempt. For example, if you see a race-car team drive by, you’ll often see “not for hire” on the side of the cab. That suggests the vehicle is exempt from the fuel tax charges and keeps other trucking companies from soliciting their services.

Truck weigh stations were originally developed for states to collect the fuel taxes they were owed by the commercial trucks using their roadways. It is similar to the licensing concept that I talked about in a previous post, Why U-Hauls Have Arizona License Plates.

In North America, weight stations aren’t directly used for that purpose anymore. There is now an International Fuel Tax Agreement which allows truckers to file a quarterly tax report. Weigh stations are still used to enforce the tracking and submission of the logs and the payment of the fuel tax.

The scales are still used to enforce weight restrictions. The federal weight restriction is 80,000 pounds. Trucks need a trip permit to transport a load exceeding that weight.

Some weigh stations are pretty high-tech, supporting “weigh-in-motion” technology. This technology can allow truckers to bypass weigh stations entirely. This involves the truck driving over a scale that is built into the right lane of the road, usually about a mile before the weigh station. Depending on the weight of the vehicle, its history and the history of the trucking company, the weigh station operator or an automated system will decide if the truck needs to pull into the weigh station.

Truckers who use these systems have a transponder in their truck, similar to those used for electronic toll collection. If they can skip the weigh station, they will usually get a green light on the transponder. If they need to pull in, they will get a red light.

Weigh stations are also used for safety inspections of vehicles. Truckers often refer to weigh stations as “chicken coops.” Check out my post on trucker signals for more trucker slang.

Broken Secrets | By: Chad Upton

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Sources: Wikipedia (weigh station, IFTA, weigh in motion)

Photo: OregonDOT (cc)

June 18, 2010 at 12:17 am 13 comments

License Plates and Headlights Increase Visibility to Traffic Radar

I did a previous post about how speed enforcement radar works.

There are two primary types, laser and tradition (Doppler) radar. Even if you have a radar detector, laser is the most difficult type of radar to avoid getting caught by. Laser radar gives officers a near instant reading on your speed, so you don’t have time to slow down before they get a reading on you.

Your best defense is reducing or even preventing the laser beam from bouncing back to the radar gun. The front license plate and your headlights are the most reflective thing on the front of most vehicles. If you’re not required to have a front plate in your area, get rid of it.

The next best thing is laser jamming, although it’s not legal in all places. But, if it is allowed in your area then you can buy laser jamming or scrambling units which prevent the radar gun from receiving a usable laser reading.

If laser jammers are not allowed, you have some other options. You can get plate covers and headlight treatments to help reduce the amount of laser light that is reflected back to the radar gun.

Reflectors on the back of your car are also an ideal reflector for Laser radar guns. For safety and legal requirements in some areas, you should probably keep these reflectors on your car.

I hope that some these tips will help you avoid some speeding tickets.

Broken Secrets | By: Chad Upton

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Source: Wikipedia Laser Lidar

June 15, 2010 at 1:37 am 7 comments

WD-40 Ingredients and Uses

By Chad Upton | Editor

WD-40 was created in 1953 by Norm Larsen. It was originally designed to prevent corrosion caused by water — the WD stands for “water displacement.” Norm’s 40th formula was successful and that’s where the “40” comes from.

The formula is so secretive, they decided not to patent it. This may sound counter intuitive, but filing for a patent would require disclosing the ingredients.

That strategy was good for a while, but many years later, the Hazardous Communication regulation required that ingredients of potentially hazardous products be made available to emergency responders.

I did some digging and found the material safety data sheet for WD-40 (PDF).

The main ingredient is Stoddard solvent, which is also known by its own brand name, Varsol. CO2 is used as a propellant and mineral oil is another main ingredient.

It was first used to protect the Atlas missile from corrosion and it became available to consumers in 1958. Since then, consumers have found over 2000 uses that the WD-40 Company endorses (and many more it doesn’t).

There is a popular email circulating that you may have seen. It states WD-40 is primarily fish oil, but that’s not true. The email also lists a number of uses, although the WD-40 company only recommends about half of those. Some of the 2000 recommended uses include:

  • Stop squeaks (doors, bike chains)
  • Remove and prevent rust (lawn mower blades during off season, cookie tins/sheets)
  • Remove gum, glue, ink and lipstick from fabrics and other items
  • Lubricate metal parts (zippers, tools, machines)
  • Loosen nuts and screws
  • Cleaning (shower doors, tools, lime stains in toilet bowls)

Check out the full list of 2000 uses (PDF).

PS – The WD-40 company has an affinity for product names with numbers. They also make 2000 flushes, X-14, 3-in-one-oil and a few other products.

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Sources: Official WD-40 Uses (PDF), MSDS (PDF), Snopes

June 11, 2010 at 12:24 am 10 comments

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