Since the prior thread is closed, I'm posting this in a new thread referencing the original thread.  I previously posted that when new technical information became publicly available, I would link it here.

On October 25, 2010, Transonic Combustion presented an SAE technical paper detailing it's novel new injection ignition combustion process at the Society of Automotive Engineers 2010 Powertrain Fuels and Lubricants Meeting in San Diego CA.

So it's a diesel:

"Spark ignition gasoline engine efficiency is limited by a number of factors; these include the pumping losses that result from throttling for load control, spark ignition and the slow burn rates that result in poor combustion phasing and a compression ratio limited by detonation of fuel. A new combustion process has been developed based on the patented concept of injection-ignition known as Transonic Combustion or TSCi?; this combustion process is based on the direct injection of fuel into the cylinder as a supercritical fluid. Supercritical fuel achieves rapid mixing with the contents of the cylinder and after a short delay period spontaneous ignition occurs at multiple locations. Multiple ignition sites and rapid combustion combine to result in high rates of heat release and high cycle efficiency. The injection-ignition process is independent from the overall air/fuel ratio contained in the cylinder and thus allows the engine to operate un-throttled. Additionally, the stratified nature of the charge under part load conditions reduces heat loss to the surrounding surfaces, resulting in further efficiency improvements. The short combustion delay angles allow for the injection timing to be such that the ignition and combustion events take place after TDC. This late injection timing results in a fundamental advantage in that all work resulting from heat release produces positive work on the piston. Other advantages are the elimination of droplet burning and increased combustion stability that results from multiple ignition sources."

How long does it take from when I stick the key in until there is sufficient supercritical fluid available to start the engine?-balance vavle

Here's an approach from Mahle that achieves essentially the same results as TSC, but with less costly and more durable hardware.  This Mahle pilot ignition system gets very close to CV combustion conditions, with very little NOx and good SFC.

btrueblood hit the nail on the head.  This supercritical fuel injection system proposed by Transonic will have long-term issues with deposits in the high-pressure pump and injector nozzle components.  Current 4-stroke, high pressure CR diesel injectors require careful liquid-cooling of the nozzle and pintle to prevent accumulation of fuel deposits and loss of operating clearances in these very close tolerance parts.

The basic principles behind the TSC injector are sound.  Reduced ignition delay and close to constant volume combustion conditions are beneficial for NOx, SFC and BTE.  And I'm sure it works quite well under laboratory conditions, with fixed speeds and loads.  But in the real world of engines, I'd doubt that it would survive.

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