Even though we’re over 100 years into internal combustion engine development, we’re still optimizing this device with new technologies. One of the more recent innovations is direct injection. Direct fuel injection engines offer some benefits compared to the usual port injected engines, and today we’ll explain what these benefits are. We’ll talk about different types of fuel delivery, what it brings, and how all of this affects you as a driver.
The Basics of Fuel Delivery and Management
Fuel delivery has always been one of the key areas of any internal combustion engine design. How you manage fuel determines not only how powerful your engine will be, but also its efficiency. This part of automotive design has defined performance ever since we ironed out the basic internal combustion engine layout.
The Carburetor
One of the earliest forms of fuel management and delivery was the carburetor. The core idea behind carburetors was to use a combination of mechanical controls and a venturi effect to balance the air/fuel mixture.
Although rather effective, an average carburetor was a crude device. There were many iterations of carburetors, some featuring a second venturi installed to control the fuel better.
However, it soon became apparent that using carbs was simply not capable of meeting the requirements of ever-evolving automotive needs.
Fuel Injection
As the ’80s rolled around, the entire world slowly realized the impact exhaust emissions had on the environment. The newly imposed emission regulations were a noose around the neck of your average carburetor. You see, building a simple carb was cheap and efficient. Back in those days, fuel was cheap, and fuel efficiency wasn’t something people worried about.
However, building a carb that would meet all the emission standards proved to be too expensive and too complex.
Right around the same time, we’ve seen the rising trend of electronics being used in cars. Computer chips were getting smaller, making them suitable for use in the automotive industry. That, paired with the emissions standards, made it possible and feasible to use fuel injection instead of carburetors.
Port Injection Explained
We’ll jump ahead and skip the entire development path of port injection engines since there’s too much to cover. However, the idea of port injection remained more or less the same. Your standard port injection system consists of a fuel pump pumping the fuel through the lines up to the engine.
There it is being distributed across the fuel rail into intake mounted injectors. In a way, what you got is a much more modern carburetor that’s ECU controlled and managed.
It’s important to note that each injector is shooting gasoline into the back of intake valves. The gasoline is essentially hitting the intake valve right as it’s opening, thus mixing with air and creating the air/fuel mixture as it enters the cylinder.
Overall, the port injection has worked flawlessly so far. It’s still working great for us as we speak. That being said, the world is moving on.
We’re seeing more and more restrictive emissions standards being passed, forcing car manufacturers to develop more efficient engines. And since fuel delivery and management was always one of the areas with room for growth, port injection had to be reinvented.
What the industry came up with as a replacement was the direct injection.
Direct Injection Technology
Direct injection is the next step in bringing gasoline to the cylinder. In fact, it doesn’t get much up close and personal than this. Instead of spraying the fuel in the rear of intake valves, with direct injection, you’re getting gasoline delivered straight into the cylinder. The injection port is right next to the spark plug.
As was the case, every time fuel delivery had evolved in the past. Direct injection is much more complicated than port injection. Plus, it has some pretty serious flaws that have only recently been recognized.
The Anatomy of Direct Injection Systems
The direct injection system uses the same principles as the port injection system up until you reach the engine itself. In other words, the fuel pump picks up the fuel from the tank, sends it via fuel lines, and hoses up to the engine.
There, instead of being sent into a low-pressure fuel rail like on port injected engines, the fuel is sent into a high-pressure pump that charges the individual fuel injectors, allowing them to shoot a fine mist of fuel into the cylinder.
The high-pressure pump is often driven by the camshaft and is essential. The fact that you’re delivering fuel directly into the combustion chamber means that it has to be fine enough to mix with air and create an efficient air/fuel mixture.
Benefits of Direct Injection
Fuel management has reached a point where computers can tweak everything instantly. Modern ECUs can make fine adjustments on the fly, even in an engine that goes through all four cycles thousands of times in a minute.
The use of direct injection is essentially using modern engine control units’ full potential, thus reaching new levels of fuel efficiency and power delivery. DI systems allow you to tweak every combustion parameter and adapt the engine to work under various conditions in real-time.
However, that isn’t without a cost.
Dealing with Blow By
All modern engines have to deal with blow-by. Blow-by is nothing more than oil particles going past piston rings, mixing with unburned fuel, and being shot back into the crankcase. This is why we have PCV valves.
A PCV valve is there to suck up all of these unwanted particles, diverting them back into the engine’s intake to recycle and ultimately burn them during the next combustion cycle.
What engineers who worked on modern DI systems didn’t anticipate is handling of recycled blow-by. The PCV valve would do its thing, sending the blow-by particulates back into the intake ports. However, there was nothing there to force the recycled oil/fuel gunk into the combustion chamber.
See, with port injection, one of the beautiful things about shooting fuel onto the rear of intake valves is the fact that it cleaned up all of this buildup. Every time the injector was fired, the valve would be cleaned over and over again. With DI that effect was missing.
Although the gunk doesn’t build up overnight, you could see obstructed intake valve trains after as 20,000 miles or even sooner on some engines. Worst of all, there were no simple ways of cleaning the intake ports.
DI + Port Injected Hybrids
After this issue was recognized, engineers came up with the simplest solution possible. They’ve decided to use both port injection and direct injection systems in tandem. The fact that you have both systems present and working simultaneously leaves plenty of options to dial in the timing and combustion within cylinders.
Engines that use both DI and PI systems don’t use them 100% at all times. Instead, many brands utilize the port injectors down in the lower RPM range, only transitioning to DI as the RPMs increase.
The reasoning behind this is simple – PI offers a better air/fuel mixture in terms of stability. However, as the load increases, the DI takes the lead offering more refined power distribution and efficiency.
How to Keep DI Engines Operational?
Dealing with carbon buildup in the intake can be tricky, especially if you’re running a straight DI engine. However, there are several things you can do to keep the buildup at a minimum or to eliminate it.
Use Good Quality Oil
One way to deal with carbon buildup is to prevent the oil from blowing by your piston rings. Naturally, we’re talking about healthy engines and not ones where pistons rings are shot. The idea is to use oil that doesn’t produce large amounts of vapor.
We strongly suggest that you stick to Motul or other high-quality brands as they are often the only ones who deliver reliable specs for their lubricants.
Catch Cans?
Another method that’s been proven to be efficient is the use of oil catch cans. The idea here is quite simple. Instead of letting the PCV system take to recycle the oil vapor and unburned fuel, it gets trapped by the catch can. For this to happen, the can needs to be installed after the PCV valve and before the air intake, intercepting the debris.
Where to find a Quality Oil Catch Can?
If you’re looking for quality engine oils and oil catch cans, you’re in the right place. Here at eEuroparts.com, we carry a wide range of cans and lubricants that will help you keep your DI engine running clean and smooth. To find out which products match your specific car, simply input your vehicle’s make and model into our search bar, and you’ll get a list of results.
