LeSving wrote:
But who knows how it is on modern car engines with direct fuel injection in the cylinders. I would imagine a positive displacement pump necessary for that, like diesel engines.
Yes, given the roughly 150 atmosphere pressure necessary for direct injection. That technology is not dominant across gasoline engines in general, seems to be going out of vogue, and more to the EuroGA point is not used in e.g. Rotax port injected aircraft engines. One good reason is to avoid high pressure gasoline leaks.
There is an interesting approach being taken on some cars in which both port injection and direct injection is used, with two different parallel fuel systems, but like a lot of car technology it’s heavy, impractical and not beneficial for aircraft.
Re Exhaust oxygen sensors, given reasonably good fuel pressure control etc, their purpose is long term: to protect sensitive exhaust catalysts and thereby ensure car emissions compliance over the years of operation required by regulation. They also allow wider variation of initial hardware calibration. None of that is relevant for aircraft engines. High performance engines without catalysts don’t need them either and the first thing you do on a modern motorcycle to make it run better is remove the catalyst and turn off the oxygen sensor in software. It will run better open loop and once individually tuned to that setup won’t go out of tune quickly.
That technology is not dominant across gasoline engines in general,
Since 2010 direct injection is dominant across the GM engine line under the Ecotec moniker.
A similar case can be made for Ford’s Ecoboost engine line.
All engines delivered on VW / Audi group North American market models models since ca 2008 are direct injection.
BMW introduced DI on the N35 engine in 2007 and all North American market gasoline engines are now DI.
I believe that adresses (factually – right, Peter?) the “not dominant” and “out of vogue” adjectives.
With regards to car technology being “heavy” an Audi TFSI (DI) engine puts out the same HP out of a lighter 1.4l engine block, versus the previous (MPFI) engine block.
As to “impracticality” – and perhaps quite on point for EuroGA – Austro and CD engines seem helluvalot more “practical” both for aviation in general and Europe in particular now that the birth defects have been ironed out…
Here’s an article that describes the automotive trend to use both port and direct injection to overcome the weaknesses of direct injection that have become apparent in its current use on half of the automotive fleet, including the issues with super high pressure gasoline delivery. Here’s another from four years ago that describes some of the issues that DI caused, and why it didn’t really work out for gasoline engines unless you want them to make particulates like a Diesel.
I’m supporting development of an engine that will replace the Thielert on a major platform, currently in test, and I’m aware of its attributes.
