How to Decide On Your Very First Race Car (Part 6)
Probably the most important factor that one must consider when purchasing an automobile for auto racing is the engine. The engine is the heart of the machine, and is what powers everything in your car, from brakes to traction control to air conditioning.
But most importantly, the engine is what gets top fuel drag racers to do a quarter-mile in less than 5 seconds and at speeds of up to 536 km/h (333 mph).
There are many different types of engines, but we will take a look at the most popular. First up we have DOHC engines. DOHC stands for Dual OverHead Camshafts. Now what in the world does that mean? Well, a normal camshaft, also known as SOHC meaning Single
OverHead Camshaft, has two valves for each cylinder. One valve is to let air into the engine, and the other one is to let the waste, or exhaust, out. A DOHC engine simply has four valves instead. Two of the valves are for putting air into the cylinder, while
the two remaining ones are for letting exhaust fumes out.
Although a DOHC system is more complex and expensive than a SOHC, manufactures accept the tradeoff to attain better design flexibility and greater engine performance. Although a DOHC engine is arguable one of the best available for racing, there are many
other types as well. One feature common in most engines is using variable valve and lift technology.
Honda calls it VTEC. Mitsubishi calls it MIVEC. Toyota has christened it VVTL-i. Porsche calls it VarioCam Plus. What do all these fancy terms mean? Well, Variable Vavle Timing and Lift Electronic Control, or VTEC, was invented by Honda’s Ikuo Kajitani,
so we will refer to Honda engines, although Porsche, Toyota, and Mitsubishi use the same concept.
VTEC is basically a valvetrain system that improves the efficiency of a four stroke engine. For those who haven’t got the slightest inkling about valvetrains, it is a term used to refer to the entire system of controlling the valves in an engine.
Now, back to the point. VTEC improves engine performance by simply controlling when the valves will open and close. Although this is simple to say, it is an extremely complicated process. To understand this better, let’s use an example.
Although a normal engine idles at around 1,000 RPM, let’s imagine for a second that we are running the engine even slower, at about 20 to 30 RPM. Although this is impossible, imagine it for the purpose of an explanation. Now, one would grind the camshaft
to that it opens the intake valve as soon as the piston starts moving downwards in the intake stroke. When the piston gets to the bottom of the intake stroke, the intake valve will close immediately. The next step, the combustion stroke, will occur with both
valves closed. The exhaust valve will open as soon as the piston begins the exhaust stroke and close when the exhaust stroke is complete.
Engines that do not have VTEC have their valves open at slightly different times, thus decreasing performance and increasing gas consumption. Another feature of VTEC can make your race car a daily driver as well. If you have a car that has a DOHC VTEC, then
the VTEC controls only two of the valves to work when the engine is not worked so hard. But when you floor the gas, all four of the valves start working and the car shoots off like a rocket.
VVL from Nissan, MIVEC, AVCS from Subaru, VVTL-I, and VarioCam Plus are essentially the same as VTEC. They just use different names because the VTEC name is owned by Honda.
In the next article we will be taking a look at the Mazda RX-8’s legendary rotary engine, also known as the Wankel engine. Besides that, HEMI’s are also powerful engines and will be discussed. In the following articles, other features will be discussed that
should be taken into consideration when purchasing your very first race car.
Take a look!
Tags: