GeeBee Posted December 1, 2020 Author Report Share Posted December 1, 2020 A lot more than easier starting. It would bring LESS maintenance, greater reliability, better LOP operations to name but a few. Quote Link to comment Share on other sites More sharing options...
RLCarter Posted December 1, 2020 Report Share Posted December 1, 2020 3.5 L (214 ci) 375 horsepower @ 5,000 rpm and 470 lb-ft @ 2,500 rpm. I run 80+mph pretty much all the time. Auto engines are designed to give the best all around performance in a wide RPM range, you could easily grind a cam for good performance at 2500~3000. Don’t get me wrong I run both a Lycoming and a Continental and have no problem with either other than they could be made to be great engines if the certification process wasn’t so painful 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted December 2, 2020 Report Share Posted December 2, 2020 If my Chevy V8 LT1 engine turns 6k rpm.... to develop 300hp.... 3 or 400 ft-LBs of torque... moving a 3k# vehicle.... To get the same amount of fuel converted to produce the same torque at 3krpm... would require it to grow displacement... The LT1 is a 5.7 liter engine... 2X = 11.4 liters... The IO550 is a 9 liter engine... Saving the cost of development... My LT1 version 2... would need 16 cylinders! Compare that to Doc’s IO720 where two identical engine blocks are placed end to end... (sort of...) the gearbox on a V8 isn’t a bad idea... compared to a sixteen cylinder engine... fuzzy memories of torque, HP, and rpm.... PP thoughts only, not an engine designer... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Skydancer2992 Posted December 2, 2020 Report Share Posted December 2, 2020 12 hours ago, carusoam said: If my Chevy V8 LT1 engine turns 6k rpm.... to develop 300hp.... 3 or 400 ft-LBs of torque... moving a 3k# vehicle.... To get the same amount of fuel converted to produce the same torque at 3krpm... would require it to grow displacement... The LT1 is a 5.7 liter engine... 2X = 11.4 liters... The IO550 is a 9 liter engine... Saving the cost of development... My LT1 version 2... would need 16 cylinders! Compare that to Doc’s IO720 where two identical engine blocks are placed end to end... (sort of...) the gearbox on a V8 isn’t a bad idea... compared to a sixteen cylinder engine... fuzzy memories of torque, HP, and rpm.... PP thoughts only, not an engine designer... Best regards, -a- Variable valve timing allows auto engines to become smaller while developing more power and gas efficiency. Fuel injection and computerized timing, same. Now, auto engines are Atkinson cycle (Prius and Honda hybrids), with an extended power time but shorter exhaust or intake. Toyota has introduced truck engines that are Otto cycle during acceleration and revert to Atkinson during cruise. NOx environmental controls have the opposite effect, forcing the engine to run at a cooler and less efficient/less power mode. This is where VW cheated, by tuning for power/efficiency when the engine was not in a test mode. The mod market for 4X4 and street rods also over-ride this "feature". 1 Quote Link to comment Share on other sites More sharing options...
Awful_Charlie Posted December 3, 2020 Report Share Posted December 3, 2020 7 hours ago, Skydancer2992 said: Variable valve timing allows auto engines to become smaller while developing more power and gas efficiency. Fuel injection and computerized timing, same. Now, auto engines are Atkinson cycle (Prius and Honda hybrids), with an extended power time but shorter exhaust or intake. Toyota has introduced truck engines that are Otto cycle during acceleration and revert to Atkinson during cruise. <snip> These mostly affect the low power regimes of an IC engine where they are predominantly quite (or very!) bad already, so there are substantial and worthwhile gains to be made when the unit spends a significant time at lower power. This contrasts so much with our GA environment where the power units are run at relatively high power for the majority of their time, to the point that in GA we are regularly seeing BSFC in the 0.35 arena for spark ignition, which is something an automotive engine can only dream of obtaining for the majority of its operating cycle. With a quick search for "BSFC map" it becomes clear we need another technology to make the next leap. Those running a NA engine up high (and thus consequently at a low power) would potentially see some advantage from long existing technology such as variable ignition timing/VVT etc., but where we are now (or where we have been for circa 80 odd years) is looking quite conclusively pretty close to as good as it gets for sustained & continuous high power output reciprocating metal based technology. My feeling is that the Atkinson will take considerably longer to determine if even the effort is worth it - if the consumption can be made to look attractive, the increased weight will have a negative impact, and the complexity and potential to induce a failure are too significant to ignore (would you carry a 50+lb device that reduces your fuel consumption for taxi and descent only, but which if it fails even when not making that saving would likely cause a catastrophic power unit failure?) https://en.wikipedia.org/wiki/Brake-specific_fuel_consumption has some figure that may be interesting (eg for gasoline engine output efficiency, Ford Ecoboot 33.5%, IO720 34.2%, Prius 36.4%) Maybe new(er) materials could resolve some of the current design constraints on reciprocating engines and gain a percentage point or two, but we really want something that gives us a massive leap, not just a minor enhancement - eg in IC engine that is twice as efficient (so 70-80%) My personal feeling is that those efforts are probably best directed to looking at alternatives to a fuel based on long dead trees and dinosaurs - and possibly even re-visiting old ideas and updating them (windmill/solar for twisting up a a rubber band?!) 1 2 Quote Link to comment Share on other sites More sharing options...
Skydancer2992 Posted December 3, 2020 Report Share Posted December 3, 2020 https://www.liquidpiston.com/ Quote Link to comment Share on other sites More sharing options...
steingar Posted December 3, 2020 Report Share Posted December 3, 2020 For not being a Wankel engine it sure looks like a Wankel engine. Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted December 3, 2020 Report Share Posted December 3, 2020 24 minutes ago, steingar said: For not being a Wankel engine it sure looks like a Wankel engine. They say it isn't a Wankel, but if it looks like a Wankel and runs like a Wankel, I think it is a Wankel. FWIW, I have a turbo Wankel in my garage waiting to go into a sand car. Whenever I have time where there is no airplane work to do. Which so far is never! 1 Quote Link to comment Share on other sites More sharing options...
PT20J Posted December 6, 2020 Report Share Posted December 6, 2020 I wish these guys luck. They’re not the first to try it, and I haven’t seen any great success stories over the years. Engineers generally optimize a design for its mission, and the missions for auto engines and airplane engines are very different. Auto engines seldom put out rated power, are designed for low end torque and optimized to generate low emissions when cruising at 10% power. Really, our engines are pretty good for their mission. They are efficient and reliable. That’s not to say they couldn’t be improved. But I think the biggest improvements would come from electronic engine controls. Skip 1 Quote Link to comment Share on other sites More sharing options...
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