Take an engine from a 1970s Ford, Toyota or Chevy and put it next to one built today, and the differences are easy to spot. Dig down into the performance and economy figures, and there’s no comparison between the 30-plus-year-old technology and today’s — the newer engines are better in almost every way imaginable, with tuneups now required once every 100,000 miles, oil change intervals of 15,000 miles and fuel economy for many new small sedans of 40 mpg or better. Yet if you lift the cowl on a 1970s airplane and compare what you see with a brand-new piston engine, the two will appear remarkably similar. Which leads to an inevitable question: Why has piston engine technology in airplanes seemingly lagged so far behind the advances being made in the automotive world?
Before answering that question, let’s ask a couple more: Did you know that the common-rail port fuel injection systems on the latest Lycoming aircraft engines are actually far ahead of automotive fuel injection technology, and only slightly less sophisticated than what’s found in Formula One cars? Or that just about every conceivable parameter on the newest engines from Continental Motors are monitored and controlled by full-authority digital engine controls that in some respects are more advanced than the fadec systems on turbofan engines?
The fact is that reciprocating engine technology in aviation has advanced tremendously in the last dozen or so years, even if by outward appearances these latest aircraft engines seem little changed. There is a misconception among many that, because the engines being built by Continental, Lycoming, Rotax and others look similar to those that have been flying in GA airplanes for years — and indeed are based on the same basic certifications — they haven’t advanced very far in the last 30 or 40 years. That’s flat-out wrong.
One of the biggest improvements has come in overall build quality. Aircraft engine makers have spent many millions of dollars to improve and automate their manufacturing processes for much tighter build tolerances, and that has translated to improved durability. They’ve also perfected their fuel delivery systems, introduced advanced coatings to many components and, probably the biggest breakthrough, connected the engines to advanced aviation-grade computers that are capable of monitoring just about every conceivable engine-related parameter — a million times over in the span of a few minutes. Advances have also been made in turbocharger technology, and several manufacturers are now working on alternative fuel technologies, not to mention highly fuel-efficient diesel engines that are designed to burn jet-A.
How Far We’ve Come
Before we dive into a technical discussion of the current state of the art in reciprocating aircraft engine technology, here’s a quick trivia question to get us started: Who built the first successful piston aircraft engine? Obviously the answer is the guy who built the engine that powered the first airplane, the Wright Flyer. We don’t celebrate it, but Thursday, Feb. 12, 1903, ranks as one of the most important days in aviation history. To the Wright brothers, it was everything. On this date, the bicycle builders from Dayton, Ohio, finally had confirmation that their fanciful dreams of being the first to achieve manned, powered flight were close to coming true — they finally had an engine.