Prechamber Mod "Flame" Front

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01-28-2011, 07:02 AM #85

(01-27-2011, 07:16 PM)DeliveryValve How can 135 bar injected fuel can create this so called turbulence.

It doesn't, thats what the ball inside the prechamber is for. The ball disturbs airflow coming into the prechamber and aids in atomizing the fuel (like spraying a pressure washer at a wall). If you've ever looked at the spray pattern from our injectors its pretty much a straight point, unlike the fine mist of most injectors, and its what sets our IDI system apart from others such as VW as anjay pointed out...

Quote:In passanger cars pre cup engines are used do to it more quite operation.

(01-27-2011, 07:45 PM)OM616 Given that #1 is getting the most votes

There is nothing to "vote" on, people's opinions won't change the physical operation of the engines.

Quote:It has been suggested that a very small portion of the fuel that is injected ignites in the prechamber, creating heat that will preheat the remaining injected fuel, that is not ignited, and pressurize the prechamber causing the heated fuel fog to be expelled from the burn holes.

Correct, that is how precombustion chamber diesels operate.

Quote:For example, if only a very small portion of air is allowed to enter the prechamber, then the prechamber pressure will be lower than the cylinder pressure, and the less air that can get into the prechamber, the grater the pressure differential.

You're missing combustion. Compression is only one of the cycles.

Quote:wouldn’t all the fuel need to be injected into the prechamber before a small portion of it is ignited?

http://hubpages.com/hub/Combustion-in-Diesel-Engines
Ignition delay period is the time span between commencement of injection and the start of ignition.

* The fuel emerges into the cylinder as small liquid particles, which are surrounded by hot compressed air.
* They receive heat from the air and more volatile constituents of the fuel vaporise.
* During the ignition delay period a large part of the fuel charge is prepared for combustion.
* During the ignition delay, the injector continued to inject the fuel and, if this has built up a sufficient quantity, the rapid combustion and pressure rise will be quite violent, causing detonation and shock loading creating a noise termed diesel knock.

Quote:First, what ignites the fuel, or more correctly stated, what prevents the fuel from igniting in the prechamber, until after all the fuel is injected into the prechamber?

First; the ball in the prechamber aids in ignition. In operation the ball is glowing hot from the combustion, thats why glowplugs are required to start these engines cold when most DI engines don't even have glowplugs (they can ignite from compression heat alone). To the second part, see ignition delay above.

Quote:Also, what keeps all the fuel from burning in the prechamber?

At idle and low power, nothing. The injected quantity is plenty small to burn completely even in the limited air volume.
At higher loads its the restricted volume of air prevents complete combustion and is what pretreats/vaporizes the fuel to allow high-speed power. Thats why we can make power 3000-5500+rpm when most DI diesels fall on their face above 3000rpm.

Quote:And another thing, if the combustion chamber is in the cylinder, and not the prechamber, how does the prechamber have any affect the ability of the engine to rev faster than a DI engine?

See above. Modern common rail engines are catching up because the common rail design allows multiple injections per cycle, which allows the computer to superheat the compression air (pre-injection) so the main injection burns smoother and faster.

Quote:Statement (A) of fact #1

Quote:Additionally, there seems to be a consensus that the prechambers ability to maintain a high pressure longer than the cylinder, allows the IDI engine to rev higher than a DI engine. If that is the case, and the majority of the fuel is burned in the cylinder and not the prechamber, then how does the pressure in the prechamber, ... have anything to do with the combustion environment in the cylinder?

It doesn't. The prechamber is still pressurized by the initial combustion, and being restricted by the orifice, the pressure inside will be higher than the cylinder pressure for most of the power stroke.

Quote:Once the fuel is in the cylinder, the combustion environment in the cylinder is the same as in a DI engine isn’t it?

For old DI engines, no. The fuel in an idi engine is much better atomized and heated.
For modern CR DI engines, they're pretty close, but not quite there yet.

(01-27-2011, 09:03 PM)ronnie Perhaps to get the pressure higher in the pre chamber?

Half. It must make up for the restriction in the prechamber, but the conditioning of the fuel allows the higher compression because it burns smoother.

Quote:What would happen to the Cummins if the compression where raised to the same as the Mercedes?

Higher efficiency. There are a few competition pullers running high compression, there was recently one in Diesel Power Mag running 21:1.

Quote:Do we know if an IDI engine is capable of higher speed because of the pre chamber or the higher compression?

Neither directly. There are plenty of competition DI engines revving past 5000rpm.

Quote:In closed system (space) in any location pressure is the same. Dalton's Law of partial pressures.

Thats not what Dalton's Law is, and it only works for ideal gases.

Quote:I'm trying to drum up support

Denial doesn't alter fact.

Quote:Maybe he still believes in soviet russia thats why he is always so angry?

Mother Russia never died.

This post was last modified: 01-28-2011, 07:17 AM by ForcedInduction.