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-   -   Boring out injectors. (http://www.peachparts.com/shopforum/diesel-performance-tuning/220192-boring-out-injectors.html)

Bio240D 11-26-2008 08:45 PM

Hi everyone,
One more thing to consider on the the nozzles is that the fuel pressure acting on the face of the pintle is what pushes it back against the spring. If you are flowing more fuel, the back pressure from the orifice will increase, thus pushing the pintle further back in the injector body and pulling the pintle further out of the orifice thus opening up more area. The injector is basically self adjusting to the volume of fuel flowing through it.

By the way, according to the fender stickers I've seen on 300D turbos, the Stock injection volume on a 617 is 51.5 cubic millimeters, and on NA engines
(616, 240D and 300D non-turbo) its 41.5 cubic millimeters. Forced Induction said that 100 cubic millimeters was just approaching stock volumes for the turbo engines. I'm assuming he's talking about some of the later model engines. 100 cubic millimeters is twice the stock 617 turbo output, and its atainable with a stock pump just by removing the start/run lockout bar in the IP.
CHeers, CHris

tomnik 11-27-2008 12:14 AM

Quote:

Originally Posted by Bio240D (Post 2032552)
Hi everyone,
One more thing to consider on the the nozzles is that the fuel pressure acting on the face of the pintle is what pushes it back against the spring. If you are flowing more fuel, the back pressure from the orifice will increase, thus pushing the pintle further back in the injector body and pulling the pintle further out of the orifice thus opening up more area. The injector is basically self adjusting to the volume of fuel flowing through it.

You are correct...
until the pintle course it at the end... (something about 0.72 mm)
Then the orifice is the bottleneck.
I got some comparison flow values of the Floyd nozzles. 10% more flow at the same pressure!!! The effect is identical as for the larger elements (not this much). This also reduces the injection time at the same volume or more fuel within the same time. Plus the spray pattern is symmetrical due to 3 flats.

Quote:

Originally Posted by Bio240D (Post 2032552)
By the way, according to the fender stickers I've seen on 300D turbos, the Stock injection volume on a 617 is 51.5 cubic millimeters, and on NA engines
(616, 240D and 300D non-turbo) its 41.5 cubic millimeters. Forced Induction said that 100 cubic millimeters was just approaching stock volumes for the turbo engines. I'm assuming he's talking about some of the later model engines. 100 cubic millimeters is twice the stock 617 turbo output, and its atainable with a stock pump just by removing the start/run lockout bar in the IP.

Again, it is not only the total volume but the duration. Increasing the amount of fuel on a given element seize will enlarge the duration of injecting.
Begin is fix, end of injection moves towards late and the additional fuel can't burn completely (black smoke and heat).

Tom


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