400 psi static compression ratio will ignite Diesel fuel in a 617 prechamber without glowing. Common rail systems handle Diesel fuel at tens of thousands of psi. Why doesn't Diesel fuel ignite in a CDI fuel delivery system?

Sixto
87 300D

No oxygen in the fuel delivery system -- only fuel. No oxygen, no combustion.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Man, I'm glad someone here is thinking

Thanks,
Sixto
87 300D

The 617's 400psi is compressed air, the CDI is compressing fuel.

ehh sometimes i think air bubbles can get into the system... but CDI injection systems don't get hot enough to ignite the fuel.

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-Trevor

OBK #12
1980 300SD 333,XXX miles - Totaled
1986 Mazda RX-7 212,XXX miles - impounded and auctioned off
2005 Jeep Liberty CRD Limited 33,000- SEGR, Provent, Fumoto

Correct, the combustion is caused by the high temperature (resulting from the compression of the air), not from the pressure itself. You will not get combustion by pressurizing liquid fuel, which actually does not require very much energy and does not add much energy (heat) to the liquid fuel.

Yes, what he said...that's why bicycle pumps and air compressors get so darn hot, it is the energy of compressing the air which makes it hot enough to burn the fuel, not the act of compression per-se. Technically liquids are considered incompressible too (though they do compress ever so slightly) which is why it takes so little energy to spike the pressure in a liquid filled space (like your brake system) but so much more to compress a gas like air.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz