Once upon a time, back in the 80s, hardcore car enthusiasts argued whether fuel injection is better or not in much the same way some argue today whether electric cars are better. But today, thirty years later, it’s clear that fuel injection was the winner compared to carburetion, and for good reasons.
The fuel injection vs. carburetion differences are pretty simple. Fuel injection is computer-controlled, which equals much more control over fuel delivery. That results in more power and better fuel consumption, among other things. Carburetors are entirely mechanical with fixed fuel delivery parameters, and their only advantage is a lower cost of manufacturing.
Fuel Injection
Before we dive into fuel injection vs. carburetion, a brief history lesson. Although fuel injection has been around in various forms since the 1900s and through the 1940s, pretty much all fuel-injected vehicles during that period had diesel engines. The only exception to that is the Swedish Hesselman gasoline engine made for buses and trucks, but then again, that engine could run on several types of fuels, including diesel, so it hardly qualifies.
The first gasoline-powered fuel-injected passenger car was the 1954 Mercedes-Benz 300SL, which, like all the fuel-injected cars in the following decades, had mechanical fuel injection. Those mechanical fuel injection systems were extremely expensive to produce and were far from reliable. That’s why a lot of classic car owners convert mechanical injection to carburetors, and needless to say, that type of injection was never going to be a substitute for carburetors.
Then, enter the 1980s, the rise of computer software, microchips, and high-end electronics. That’s when fuel injection evolved into the system we all know today. And that’s a computer (ECU) controlled fuel injection with one fuel injector for each cylinder, also called port injection or MPI.
The reason computers are so important for fuel injection is that they can take into account the air pressure, air temperature, airflow, and the amount of oxygen in the exhaust to precisely determine how much fuel an engine needs at any given moment. That allows for an optimized fuel delivery regardless of outside conditions or engine load.
Also, in a fuel injection system, the fuel is under constant pressure as it enters the combustion chamber through almost microscopic holes in the fuel injectors. That atomizes the fuel immeasurably better than carburetors, which, again, results in more efficient combustion. Also, the whole system, apart from computer programming, is pretty straightforward.
There is a fuel pump in the tank that moves fuel to the engine, where it enters a fuel rail. The rail has a pressure regulator that sends excess fuel back to the tank, but before that, all injectors are plugged into the rail. Those injectors are electronically controlled, and the ECU can open them for any duration of time it deems best, giving it all the control it needs.
There are also the more modern direct fuel injection systems where the fuel injectors don’t spray fuel into the intake manifold but directly into the combustion chamber. The whole system is very similar to port injection, with the only exception being a secondary, high-pressure fuel pump.
The high-pressure fuel pump sits on the fuel rail and pressurizes the fuel before they go into the injectors to as much as 2,000 psi. That complicates the system somewhat and increases maintenance costs and the initial production cost, but it further optimizes fuel efficiency, which gives you more of all the advantages a conventional fuel injection system provides. That means even in those highly complicated systems, the disadvantages of fuel injection over carburetor are almost invisible.
