Minimum Compression Pressure for Naturally Aspirated Diesel Engine Operation

I am looking for information on what is the minimum pressure for diesel engine operation. Ordinary naturally aspirated.

How much did you get?

At least to get it to fire? About 26 bars.

At 26 it fires normally, I fired vw 1.6 which had 9, 16, 18, and 19, not in that order of course. There was no frost, the candles were heated for 2 minutes because even the self-starter did not want to start on zinmo, then the self-starter with air from the heat gun and a minute on the starter with symptoms of catching and gas in the floor and as soon as he managed to pull himself, he arrived to replace the engine ☺

Hello. From what I remember, most naturally aspirated diesel engines are installed in agricultural machines and tractors, but not only. Not all engines, even naturally aspirated ones, have the same compression pressure. I will give you only the example of our well-known engines from the URSUS C-360 and C-330 tractors. The pressure in the compression chamber for one engine and the other is 2.8-3.2 Mpa (nominal pressure, new engine). The difference between the reference values and the results of compression pressure measurements exceeding 35% of the reference value indicates the need for engine repair.

Specifically, I meant how much I would have to boost the gasoline engine to be able to power it with diesel fuel.

forget it. By adding petrol, you will overload the piston-crank system, i.e. connecting rod bearings, main bearings and piston pins. The durability of such an engine will be very short.

dharma123 wrote:

Specifically, I meant how much I would have to boost the gasoline engine to be able to power it with diesel fuel.

Well, in this case, you should probably talk about the compression ratio. Roughly speaking, for the engine to work (at least in theory) on ON, you would have to increase the compression ratio almost twice. And this, as the colleague above said, will greatly burden the structural elements of the engine. Diesel engines have a much more massive construction than petrol engines because they have to withstand much higher operating pressures.
Besides - to make such a modification in a simple engine, you would have to replace all the accessories of that engine (because the power supply of a petrol and diesel engine is radically different). To sum up, such a modification will encounter so many technical problems that in my opinion it is unprofitable.

The first Golf MK I engine from '74 1500 petrol and diesel were structurally identical, block, shaft, cranks, only the pistons and heads were different

Nevertheless, forget about converting any gasoline engine to diesel

So far, most engines have been made on the same block and crankshaft - old Opel, Renault, etc. I have never looked at the connecting rods themselves in terms of petrol / diesel differences. Pistons, of course, are different - much heavier, with thicker bottoms, walls and more massive pin seating, often with embedded steel inserts. The head is a whole different story. Especially in the middleman. In any case, it's easier to build a diesel engine than to convert a gasoline one. Unless it's supposed to be something similar to fairy tales about WSK motorcycles riding on ON?

Added after 2 [minutes]:

dharma123 wrote:

Specifically, I meant how much I would have to boost the gasoline engine to be able to power it with diesel fuel.

A gasoline engine is usually around 13-15 atm, below 10 atm the wear limit is assumed. Diesels - 26-28 atm, limit consumption below 20 atm. So as you can see, you would have to double the compression. Added to this is the shaping of the chambers in the pistons to achieve swirling - not such a simple matter.

I assume a minimum pressure of 20 bar. I consider the subject exhausted.