Hacker News Reader

Comment by s17n | Hacker News Reader

In case you’re wondering:

“Now, here's the thing: this motor isn't a one-stroke engine. It has a compression stroke and exhaust stroke, making it a two-stroke cycle. INNengine acknowledges this and has said that it brands the motor as such because people would assume that a two-stroke engine would need to have oil mixed in along with fuel. Most two-strokes do. The company says that the one-stroke name was suggested by an ‘external ICE institution’ and they found it to be ‘catchy,’ so INNengine stuck with it.”

(From close to he bottom of the article)

View on HN

because people would assume that a two-stroke engine would need to have oil mixed in along with fuel

That suggests most people don't know about 2-stroke diesels, although I suspect much of the older population (at least in North America) have probably heard or been on a vehicle that uses one.

Also plenty of (gasoline) two-stroke engines use oil injection so you don't have to use premix, namely any machine where you'd typically get your fuel straight from the pump like a snowmobile or a dual sport motorcycle, back when those were still two-stroke.

I had a 1983 Yamaha DT-80 (little enduro dirt bike) that had an oil reservoir so you could use pump gas.

Those are pretty nasty for bystanders though.

And there are 4-stroke engines, such as the Stihl 4-mix[0] that use fuel mixed with 2-stroke oil for fuel and lubrication.

0 - https://www.stihl.com/4-mix-engine-lightweight-and-with-good...

> That suggests most people don’t know about 2-stroke diesels

For anyone curious, the Detroit Diesel, aka the Screamin’ Jimmy, is the canonical example of a 2-stroke diesel.

Fun fact: these engines all have a supercharger — which is required to start the engines - but are considered naturally aspirated. GM also made turbo-charged variants (which still had the roots blower for starting) that are properly forced-induction.

A few videos:

Short video demonstrating the distinctive 2-stroke diesel sound: https://youtube.com/shorts/kp5aHCRAORs

These things were kind of prone to running away, with a lots of myth and folklore about catastrophic explosions and death and destruction, so there are a fair number of Youtube videos where people rig these things to run away. This is, without a doubt, on many levels, the best example of the genre: https://youtu.be/bLRF-LRgvJk

In the UK, Foden also made 2-stroke diesels, but they were nowhere near as popular or long-lived as in the US:

https://www.youtube.com/watch?v=5pwhm_xoDiY

What they all have in common is the sound that makes people think it's not a diesel, because the 2-stroke cycle causes them to sound like they're turning twice as fast as a 4-stroke. A 2-stroke at 2000RPM sounds like a 4-stroke at 4000RPM.

My favorite thing about Detroit engines is they designed them to have the supercharger act as almost one of the cycles. Their intake isn't a valve it's actually a port the cylinder opens at the bottom forcing air in and exhaust out.

So, how do they lubricate it?

Like any other engine with a separate oil system.

The same as any other engine that doesn't mix oil into its fuel.

Lubrication in fuel vs lubrication using a separate system and 2-stroke vs 4-stroke are two entirely separate engineering decisions, that are in no way tied to each other. It's just that the most common types of 2-stroke engine use lubricant oil mixed in fuel, and the most common types of 4-stroke engines don't, and so they concepts are thought to be related to each other by most people who don't know much about engines.

2-stroke engines often go into handheld tools or dirt bikes that can't explode when you turn it upside down (at least, immediately), and since it eliminates the oiling system, premix is often chosen for these.

2-stroke engines also have great power densities (at the cost of fuel efficiency), which means those two often go hand-in-hand.

2-stroke engines also have great power densities (at the cost of fuel efficiency), which means those two often go hand-in-hand.

Large, or perhaps huge would be a better adjective, 2-stroke diesels are extremely efficient, better than 2-stroke gasoline, 4-stroke gasoline, and 4-stroke diesels:

https://en.wikipedia.org/wiki/Brake-specific_fuel_consumptio...

Reply on news.ycombinator.com