Ask Joe Mechanic: Tips for Choosing the Right Mechanic

Do your research before selecting a new mechanic.

Change is not always easy.  Especially when it comes to selecting a new mechanic, garage or service center to work on your family’s vehicles.  So, what steps can you take to make this selection process a little easier?   Not to worry, we’ve got you covered with some quick and easy tips to lessen the stress of picking a new mechanic.

·      Ask your family, friends or loved ones where they take their vehicles.  Nothing speaks volumes to the credibility of garage’s capabilities then getting a recommendation from those folks that you trust the most.

·      If you have a particular garage in mind – search for mentions of them on social media.  In a digital era wherein many customers are taking to Twitter, Facebook and similar websites to share their experiences with businesses, you’re bound to find reviews and ratings of the garage you’re considering.

·      Test-drive a new mechanic with a smaller project.  Before your vehicle requires a major repair, take it in for an oil change; tire rotation or similar type of service to get a feel for the customer service, quality of work, etc of the new location.  If you find yourself unhappy with the garage, at least you won’t be stuck with a big bill for a big repair.

·      Visit your local chamber of commerce and ask their staff for recommendations of member garages that have a solid reputation with nearby residents and other member businesses for quality of service.

·      Check with your Better Business Bureau location.  Since auto mechanics as a category of businesses tend to receive a great deal of complaints with the BBB, you can review their records to determine which garages in your area to avoid.

·      Find a mechanic that specializes in your particular model or make of vehicle.  A specialized mechanic is bound to know the ins and outs of your vehicle better than a generalist would.

There are a number of other tactics you can employ to narrow down your search for a qualified service center.  A few examples, check out certifications, look for a convenient location and stop by and ask questions about their service record.  Keeping all these things in mind should make your shopping around process a good deal less stressful.

Ask Joe Mechanic: Supercharging verus Turbocharging

For the last several weeks, we have examined turbochargers and superchargers regarding the history, methods of operation, design, innovation and performance characteristics of each. Today we will compare the two systems as far as advantages and disadvantages.  Both supercharging and turbocharging have significant disadvantages in their inherent designs, but the gain in horsepower outweighs those disadvantages. When you can achieve the same horsepower from a four cylinder as a V-6, or the same power from a V-6 as a V-8, it is possible to overlook some other factors.

            The first major disadvantage of supercharging is the amount of power that it takes from the engine to operate it. On some large engines such as the single stage supercharged Rolls Royce Merlin; the supercharger requires about 150 horsepower (HP) at maximum operating pressure.  However, the benefit outweighs the power demand because the supercharger generates an extra 400HP, so there is a net gain of 250HP. The other problem that is created is that the engine must be built to withstand the stress of the extra 400HP, not the resulting gained 250HP. While centrifugal superchargers such as those the Rolls Royce Merlin use operate at about a 65-80 percent efficiency, a Roots blower by comparison often only results in an efficiency of about 40-50 percent at maximum boost.

            The second major disadvantage is the amount of heat generated. In technical terms, it is referred to as lower adiabatic efficiency. Adiabatic efficiency is the measure of a compressor’s ability to compress air without adding excess heat to the charge air. A compressor will always generate heat as a byproduct of the compression process however; more efficient compressors generate less heat. Turbochargers generate the least amount of heat, next best are the centrifugal superchargers, and while the Roots type superchargers have the poorest efficiency, thereby generating the highest temperature spike. For a given volume of air, the turbocharged air is cooler, more dense and containing a greater concentration of oxygen. This means that it will generate more potential power, all other things being equal, than a supercharged engine. In practical application, that power difference can be as much as 15-30 percent depending on the designs and types of units being tested.

            This is the main reason why most manufacturers using supercharging or turbocharging install an intercooler (an air to air radiator) in the system. An intercooler can often restore between 20-30 percent of the power lost through turbocharging and supercharging. But, even with the cooling, the turbocharger will retain its higher efficiency rating, which usually means a gain in fuel economy and more power.

            The greatest drawback to turbocharging is throttle response. Termed “lag,” there is a time that lapses between when the throttle is depressed and when the turbo “spools up” to the point where it is generating boost. This is because at idle or low engine speed, there is little exhaust pressure to spin the turbocharger. There is a brief delay until there is enough pressure in the exhaust to spin the turbo fast enough to generate the desired amount of boost. This lag is reduced by the use of smaller, lighter weight turbochargers and by using variable pitch or twin turbochargers, but it cannot be eliminated. This is the one distinct advantage of supercharging. With supercharging, the response to throttle demand is almost instantaneous due to the fact that it is directly driven off the engine.

            In places where instant power is demanded, such as drag racing or tractor pulling, supercharging is the method of choice. Increasingly, for vehicle use, turbocharging has become the choice for most applications. Even Mercedes Benz, whose “Kompressor” models are well known and have been around since the early days of supercharging, has started using turbocharging on some of its gasoline-powered vehicles as well as its diesel models over the last few years.  No matter which method you choose, you can derive more power from a smaller engine, which equates to less fuel used.  In today’s world, that is an important factor to consider.

Material for this post was sourced from www.wikipedia.org.

Ask Joe Mechanic: Check Your Vehicle Before You Hit the Road!

It’s that time of year when many of us are thinking about or already have planned a road trip with our family to a favorite summer vacation destination.  Along with the packing list for necessary items for the trip, should be a pre-road trip checklist for your vehicle as well.  We all know that one of the worst ways to interrupt a relaxing vacation is with a broken-down vehicle.  By verifying the operational condition of a few key items on your vehicle before you depart, you can greatly decrease the likelihood of an inconvenient, and possibly expensive roadside assistance call to AAA. 

Here are a few items to check on before you hit the road:

·       Read your owner’s manual for the “how to’s” – how to properly tow a trailer, change your tires or a light bulb, jumpstarting a dead battery and more.

·       Lift the hood and verify that all fluids and belts look to be in good shape.  Top off the fluids that are low (paying extra special attention to coolant, transmission fluid and engine oil), and while you’re at it, check for fluid leaks.

·       Give your battery a once over.  Does it have clean terminals and appear to be in good working order?  If not, consider replacing it before you depart.

·       Are the tires in good shape?  Check the tread, wear and pressure.  If any of this appears questionable, take the necessary steps to replace, rotate or fill them with the needed air.

·       What about the electrical items?  Are your lights, horn and wipers working the way they’re intended?  If you’re of the knowhow to replace and/or tinker with these items yourself, then do so, if not, take them to your mechanic for replacement and repair.

·       Check the trunk.  Make sure your emergency car care kit is well stocked, your spare tire and accompanying tools are in shipshape and you readily know where your wheel key lock is, if you have a wheel lock on your vehicle.

·       What’s the deal with the GPS?  If you have an in-vehicle navigation system, be sure its mapping software has been recently updated.  If you rely on a window or dash-mounted unit, be sure you have its power cable close-at-hand.  If you use a smartphone-based GPS, consider getting a mount for the device so you can keep your hands free for driving.

·       One final note, if you’re considering a particularly long-haul trip, it might be a good idea to have your mechanic or garage give the underside of your vehicle a once over.  It’s better to be safe then sorry when it comes to axels, brakes, shocks, drive train and the other major operational items of your vehicle when your planning to put hundreds or thousands of miles on your automobile during a vacation.

Road tripping doesn’t need to be a hassle.  Taking care of your vehicle before you depart for summer vacation with these simple checklist items can definitely help reduce pre-trip jitters!  We hope you and your family have a great time traveling the highways of America as you vacation this summer!

Information for this article was sourced from AAA.com and Wikipedia.org.

Ask Joe Mechanic: Supercharging

Before I start this week’s article, I want to publicly thank Stephanie, who collaborated with me on the Meet Joe Mechanic article, for stepping in at a late time last week when for medical reasons I could not put my column together and found a suitable and timely replacement for me. I am now on the mend and am resuming my duties on a slightly limited basis.

            Supercharging in theory is very similar in what it does to turbocharging. In fact, turbocharging was originally called turbo-supercharging. The main difference between the two is where the power is created that forces the intake charge into the engine. In turbocharging, we already saw that that force was the use of the exhaust escaping the engine, which forced the intake charge into the engine. In supercharging, it is by external mechanical means, usually a belt, a chain or direct drive from the crankshaft of the engine.

            Ironically, the first effective use of supercharging had nothing at all to do with an engine. In 1860, Brothers Francis and Philander Roots of Connersville, Indiana, were exploring the means to get more air into blast furnaces for making steel and other industrial applications. Their company, Roots Blower Company, developed the first operating supercharger, which forced air into those blast furnaces.  It was that design which became the most commonly used supercharger design for many years.

           

The first use of a supercharger on a functioning engine was by Dugald Clerk in 1878 on a two-stroke engine. Gottlieb Daimler, a name well known in early automotive history, received a German patent for a supercharger on an internal combustion engine in 1885. Louis Renault, another well-known name of the Renault automotive family, received a French patent for a centrifugal supercharger in 1902.

            Ironically, the first known application of a supercharger took place in Pottstown, Pennsylvania by Lee Chadwick in 1908 and his car achieved an almost unheard of speed for that time of 100 miles per hour. The Chadwick factory still stands in Pottstown, in recent years in was home to the Bill Pollack, of Pollack Steel Company, automobile collection. That collection included a couple very rare Chadwick automobiles. The Chadwick will be a subject of a future Automotive History article, as I knew the late Bill Pollack personally and have been to his museum a number of times.

            The first production road cars with superchargers were built in 1921 by whom else, but Mercedes. The models were the 6/25/40HP and the 10/40/65HP and had Roots superchargers. They were designated “Kompressor,”, a designation that Mercedes uses to this day on all supercharged cars they build.

            Another design for a supercharger received a patent in 1878 by Heimrick Krigar of Germany. This was for a screw type supercharger, which is actually a much more efficient design, but its parts are very difficult to machine. The design utilizes two opposing screws with a 180 degree twist along their length which combines to create a full 360 degree turn. The design was so advanced for its time that it took until 1935 to be able to create the first working model by Alf Lysholm of Sweden working for Ljungstroms Angturbin AB, which became the Svenska Aeroplaten Company, which eventually became Saab. Who ironically became the first mass-produced successful turbocharged automobile and at the time the only company which produced an all turbocharged model line.

            There are two main types of superchargers, which are designated by the method of air transfer. The two types are positive displacement and dynamic compressors. Positive displacement blowers deliver an almost constant pressure increase at all engine speeds. Dynamic compressors do not build pressure at idle or low speeds; above a certain threshold speed pressure increases with engine speed. Positive displacement pumps deliver a nearly fixed volume of air per engine revolution at all speeds, minus leakage, which means its importance decreases at higher speeds.

            Positive displacement pumps are further subdivided into two groups, internal and external compression. Roots superchargers are of the external type, although the high-helix roots blowers try to have the same effectiveness as the Lysholm screw. All other superchargers have some degree of internal compression. Internal compression means that the compression of the air charge takes place inside the body of the supercharger. This is more effective and efficient than the backflow compression of the Roots type and means a smoother transition to boost than the other type. Internal compression superchargers usually have a fixed boost pressure which equals the compression pressure of the supercharger, thus back flow is zero. If the boost pressure is higher, back flow will occur, but if properly matched, they achieve a very high factor of efficiency.

Some information for this article was sourced from www.wikipedia.org.

Ask Joe Mechanic: Mecum Auction

This week, I am putting my turbocharging and supercharging series on hold again due to the significant importance of an automotive event that took place in Harrisburg this past weekend. The first Mecum Harrisburg collector car auction took place at the Harrisburg Farm Show Arena and I had the privilege of full access media credentials for the event. I attended a pre-auction event on Wednesday afternoon and evening. During this time I had a chance to talk with some of the Mecum personnel and view the vehicles that had arrived without fighting the crowd. This also gave me an opportunity took take a lot of photographs without difficulty. I will say that over the course of my time there, I took over 575 photographs.

            This was the first national and world-recognized auction company to come to the northeastern United States to hold a collector car auction. Yes, we have all attended events and auctions at Carlisle, Hershey, Atlantic City, Wildwood and others, but none of them compare to the size and quality of the vehicles that I witnessed at this event. I spent three days in Harrisburg, and I’ll tell you that if I had the money, I would have bought quite a number of vehicles. In fact, I need to retract a statement that I recently made in the Meet Joe Mechanic article. I stated that it is impossible for a car person to pick just one vehicle that he would like to have, but I could narrow it down to three or four. That is no longer true. Upon returning home and sitting down to work on this article, I wanted to pick twelve cars that I would have bought had I a seven or eight figure bank account (no decimal places), but I found that I had difficulty getting the list down to twenty.

            Those twenty vehicles I picked are featured in a special section of this week’s center glossy pages called Joe’s Picks with a short description and why I chose them. Some of these vehicles were sold, some were not, and that was only because I didn’t have money! Seriously, look through the photos and compare them with what your choices would be. I have featured about thirty or forty cars from each day, along with the price that they sold for.

Have fun and enjoy!  There is also a short article called Reflections on the First Mecum Harrisburg Auction in which I give some of my own observations.  Also featured is some information that I received in a post auction interview with a gentleman from Mecum Auctions Inc.

Ask Joe Mechanic: Turbocharging Part 1

Over the next several weeks, we are going to discuss turbocharging and supercharging.

Compressor Section of an Automobile

We’ll start with the history of turbocharging, followed by how it works and its main parts. We will then do the same for supercharging. After completing these, we will discuss the advantages and disadvantages of each in a comparison.

            Alfred Buchi of Switzerland who developed a compressor driven by exhaust gas to force air into the intake of a diesel engine to create more power patented the first turbocharger in 1905. It still took another twenty years though before an actual operating turbocharger was built for vehicular use. There were several attempts by the French to turbocharge some types of airplane engines in World War I with limited success. Turbocharging of aircraft engines was perfected by the early 1920s and a short time later the same thing took place on diesel engines on ships. 

The two biggest problems to developing a turbocharger for automotive use were the ability to scale down the size and manufacturing a seal that could be small enough but withstand the pressure and heat inherent to turbocharging. There were some applications to racecars during the 1940s and 1950s, but many of these were adapted aircraft turbochargers. The first manufacturer to produce a production built vehicle with turbocharging was Saab in 1977. Other manufacturers followed, unfortunately, many of the early turbochargers failed due to heat and seal problems. Saab started using a turbocharger which was cooled by antifreeze in 1986, and this proved much more reliable. Since that time, and especially in the last few years, turbocharging has become very popular because of the ability to derive the same or more power from a much smaller displacement engine, thereby achieving a much higher gas mileage without sacrificing performance, and in many cases bettering it.

The theory behind turbocharging is actually quite simple. In most internal combustion engines, the intake mixture of gas and air is actually drawn into the engine by the downward movement of the piston. In a turbocharged engine, that intake charge is forced into the engine by the turbocharger, resulting in a much larger volume of intake charge, which when ignited by the spark plug, creates much more power. The pressure to force that charge into the intake comes from the other half of the turbocharger, which is spun by the exhaust gases that are escaping from the engine. Also, the use of pressurizing the charge causes it to burn more fully, which increases the fuel efficiency of the vehicle.

The control of turbocharging has evolved dramatically in the last few years and is now quite complex. Many manufacturers now use knock sensors, all use waste-gates and blow off valves. And many use variable geometry and intercooling. 

            Boost is the term applied to the amount of pressure created by the turbocharger above normal atmospheric pressure. The level of boost is normally indicated on a pressure gauge in bar, psi or kPa. Boost pressure must be controlled so that the design of the engine is not exceeded which would cause it to fail prematurely. Over-boosting can damage the engine by overheating, over-stressing of parts or by detonation. Detonation or preignition means that due to the amount of heat and pressure, the intake charge ignites before the piston is near the top of its cycle. This exerts undue stress and heat on the internal parts. This is controlled with a knock sensor, which if it detects detonation, signals the computer to open to blow-off valve, which will release the boost pressure. The same thing can be achieved by the waste-gate which is vacuum controlled.

            The main components of the turbocharger are the turbine, which is a radial flow design to build pressure on the intake side. The compressor section is where the exhaust gas passes through to build the pressure. The center housing is where the seals, lubrication and cooling are contained. The size and design of the compressor components dictate how much boost it will create and how quickly it will build to maximum boost. In some turbochargers, it is possible for the impellor to spin at speeds of up to 250,000 rpm. This is the reason that seal design, heat dissipation and lubrication are so important.

Next week we will discuss the types of turbochargers and the other related technologies. Some information for this article was sourced from www.wikipedia.org.