In my gearhead days I had a dead-tree copy of Yunick's Power Secrets, and read about his adiabatic modified car engine.

My understanding at the time was that the main barrier to market was emissions related. Oxides of nitrogen in particular were far too high from the high temperatures. If you look at an emissions test summary NOx is one of the few things they actually measure.

> NOx gases are usually produced from the reaction between nitrogen and oxygen during combustion of fuels, such as hydrocarbons, in air; especially at high temperatures, such as in car engines. [0]

So I'm pretty sure the opening line "meets all emission standards without electronic equipment" from TFA is incorrect.

[0] https://en.wikipedia.org/wiki/NOx

I read the PopSci article on this way back when and always wondered what became if it, thanks!

NOx can be reduced using non-electronic equipment. Well, you could do it in 1983, anyway.

Honda had a famously complicated mechanical contraption IIRC.

I'd recently learned of emissions-reduction kits fitted to diesel systems which use ammonia to reduce NOx emissions.

I believe that's Selective catalytic reduction:

<https://en.wikipedia.org/wiki/Selective_catalytic_reduction>

The process uses "diesel exhaust fluid" (not to be confused with blinker fluid), sold as "AdBlue" in Europe, possibly elsewhere:

<https://en.wikipedia.org/wiki/Diesel_exhaust_fluid>

This is all very fascinating, but also very over my head!

I found a post detailing some reasons why this technology never made it to production; apparently such an engine is always running rather close to its limits and could more or less self destruct if there was a small problem with air/fuel ratio and timing.

https://www.yellowbullet.com/threads/smokey-yunicks-hot-vapo...

Great link, thanks.

Sidenote, I don't know why the forum software makes you hit "See More" to see the whole post. Here are filters for uBlock Origin:

  www.yellowbullet.com##.MessageCard__content-inner:style(max-height:none!important;overflow:visible!important;overflow-wrap:break-word!important;position:static!important)
  www.yellowbullet.com##.MessageCard__collapse-link

He's a very interesting character: https://en.wikipedia.org/wiki/Smokey_Yunick

Was. And the linked Wikipedia article doesn’t capture nearly enough. I recommend picking up a copy of his “best damned garage in town” autobiography.

RIP Smokey

So is this basically HCCI?

And there's this: https://en.wikipedia.org/wiki/Transonic_Combustion

There are a bewildering array of 'revolutionary' ICE engines, that have yet to revolute.

What happened to these? - https://en.wikipedia.org/wiki/Wave_disk_engine - https://studymafia.org/wp-content/uploads/2015/10/MECH-Ball-... - https://www.dukeengines.com/technology/overview/ - https://cyclonepower.com/ - https://www.starrotor.com/technology/engines/ - https://en.wikipedia.org/wiki/EcoMotors - https://en.wikipedia.org/wiki/Stelzer_engine - https://en.wikipedia.org/wiki/Scuderi_engine

And I'm sure many others.

> There are no electronic devices. Smokey prefers to avoid them. So, his engines run with simple carburetor and breaker points. Yet, the system fully meets all emission standards. Consequently, manufacturers could eliminate all those expensive, ridiculous converters and air pumps.

Oh please let's get back to this!