I thought the video was pretty convincing, this engine seems pretty badass.
Honestly, this engine could be a pretty big deal for a few industries, small aircraft especially. Switching to these two stroke engines could improve the power/weight ratio of your engine by nearly 2x and not lose any fuel efficiency in the process, for small aircraft that’s a really big deal.
For a specific example, a Cessna 172 carries about 300 lb of fuel, and we know that the plane’s performance improves significantly when it’s tank is nearly empty, the top speed for example is about 15% higher on a nearly empty tank. Its standard 4 stroke engine weighs about 250 lb, so a 125 lb weight reduction would mean a proportional improvement, but not just to top speed, but also shorter takeoff distance, faster climb, higher max takeoff weight, etc.
jorm1s@sopuli.xyz 6 days ago
It sounds it’s just that: a cleaner two stroke. It fixes the issue of requiring oil mixed in the charge with some reasonable extra complexity compared to a regular (turbo-)supercharged two stroke. But on the other hand it’s hard to believe it could match a four stroke when it comes to emissions and durability.
The design as presented here has a longer compression stroke compared to exhaust stroke which means there will be extra pumping losses compared to a regular four stroke, and is the exact opposite of what high efficiency 4 stroke cycles tend to do (eg. miller cycle). As mentioned in the YouTube comments, ensuring sufficient lubrication for the upper piston rings will probably present a design challenge. Especially given that piston rings and honing patterns are difficult enough to get right even in current engines.
So I guess it may be a better design when compared to a high revving supercharged two stroke (like for example some snowmobiles have) assuming that emission regulations keep getting even stricter. But it’s not that much simpler than a four stroke, and most likely has much higher development costs given the relative novelty of the design. So I’m not really sure If there’s a business case for this, given that four strokes are slowly replacing the current two strokes in pretty much every application, and smaller recreational vehicles will probably go all electric anyway. But as far as novel ICE designs go, this one at least seems like it’s simple enough to be cost effective if ever produced.