For the intended purpose, there is very little fundamentally wrong with the old Lyco/Conti engines, non turbocharged. The turbo ones get thrashed a bit too hard IMHO…
172Driver, the story was heating oil. Damaged his new BMW top-of-the-range SUV engine very quickly. Reliable source.
“For the intended purpose, there is very little fundamentally wrong with the old Lyco/Conti engines, non turbocharged”
I disagree with you there Peter. When you have e an engine that runs 600 hours every year. It does annoy you. Sticking valves, a replacement cylinder head, failed spark plugs, magneteo overhaul, difficult to start when cold or warm.
Where as in the same time the Rotax 912 has never failed to start once and never used a drop of oil between 100 hour oil changes etc, etc
Bathman wrote:
the Rotax 912 has never failed to start once and never used a drop of oil between 100 hour oil changes etc, etc
It’s interesting to consider what would be required to apply the cylinder technology of the Rotax 912/914 to create a technically successful 250-300 HP geared engine. Eight cylinders would keep the cylinders small, allowing them to be partially air cooled as in the 912/914 while maintaining the 5000 rpm capability. Turbocharging would increase the power if required, as with the 914.
I personally think the existing large displacement, low rpm six cylinder 250-300 HP designs are better than that scenario, and also better (for instance, as another option) than a small cylinder, 5000 rpm, water cooled, geared V6. I’d agree with Peter however that for high altitude turbocharged service the air cooled high power designs are being pushed to their practical limit.
My favorite engine BTW is the carburated Lycoming O-320. It minimizes the number of cylinders and complexity while making 50% more power than a 912, burns low octane unleaded fuel, starts easily and runs well. Mine has currently been in service 47 years without overhaul.
Bathman wrote:
I disagree with you there Peter. When you have e an engine that runs 600 hours every year. It does annoy you. Sticking valves, a replacement cylinder head, failed spark plugs, magneteo overhaul, difficult to start when cold or warm.
What model engine is that? We run three Lyc (I)O360 engines about 1000 hr/year and we have essentially no issues. Well except that one of them is a bit tricky to start when cold.
Itnis pretty clear that these engines are living fossils and antiquated. the mixture control and ignition systems a lot more so than the core engine itself.
They iust haven’t seen the innovation that has happened due to lack of volume and investment.
What is less clear is that car engines woukd be more suitable. They have been optimised for a different duty cycle, different tolerance for weight, different output RPM, different pressure regime, different available cooling airflow etc.
So as usual, both sides are right, those who say they are fit for purpose and car engines would struggle to do what the aviation engines do, and those who point out that we are flying around with the aviation equivalent of the Volkswagen Beetle engine.
It’s very difficult to compare. There are many reasons why the Lycos and Contis are still the way they are, and also why modern automobile engines are so efficient. The automobile market is gigantic since decades, with huge R&D budgets, cost degradation, short product life cycles and lately increased regulatory pressure.
I just think we cannot compare them, they serve different needs. We should have a look at what would an aviation piston engine look, had the R&D budgets been as large as those in the automobile sector.
Let’s go through this thought experiement and assume for a moment, that the past decades had made possible constant innovation possible, that cost of certification had been relatively low, that big R&D budgets had been present, and that there was a constant competition of new products, as well as quick write off of old planes and engines. So, instead of a plane flying 40 years with constant overhaul, we would have had planes flying 5 years and then replaced by new ones.
Let’s just assume that for a moment, realistic or not. If we would have had an evolution of technlogy comparable to that of the automobile, what would have been the most likely latest outcome as an aviation piston engine ?
EuroFlyer wrote:
Let’s just assume that for a moment, realistic or not. If we would have had an evolution of technlogy comparable to that of the automobile, what would have been the most likely latest outcome as an aviation piston engine ?
Answering your question directly, I think it might be something like this.
If you asked whether I’d prefer to own and operate that engine or my Lycoming, I’d likely choose the O-320 depending on whether aftermarket PMA parts and field service would be available!
Silvaire wrote:
I think it might be something like this.
This article is from 2003 :)
If we would have had an evolution of technlogy comparable to that of the automobile, what would have been the most likely latest outcome as an aviation piston engine ?
A ruggedised car engine, probably.
It would not do any more MPG in cruise than the old ones however.
But it depends on the volume. I am told by one owner who runs a number of cruise boats that the Volvo Penta boat engines are rubbish for reliability. And their volumes are much bigger than GA – though much smaller than cars.
