Injector breakdown

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Injector breakdown

Postby Smokem1 » Wed Feb 10, 2010 10:29 am

Marker - part name
Black - shim
Red - compression spring
Green - compression pin
Blue - intermediate disk
Image

Image

Marker - part name
Black - feed passage
Red - alignment pins
Green - pin opening/pintle
Image

Image

Marker - part name
Black - pintle seat
Red - sac/blind-hole
Image
Sac nozzle with cylindrical blind-hole.

Marker - part name
Black - pintle seat
Red - sac/blind-hole
Image
Sac nozzle with micro blind-hole.

Marker - part name
Black - pintle seat
Red - nozzle tip
Image
VCO nozzle.

Marker - part name
Red - needle guide
Green - feed passage
Blue - fuel gallery
Image
Last edited by Smokem1 on Thu Dec 23, 2010 6:46 am, edited 3 times in total.
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Postby RSWORDS » Wed Feb 10, 2010 5:57 pm

For someone that has no clue on injector parts that helps me ALOT when y'all get into your detailed disscussions! Thanks!
Image
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Re: Injector breakdown

Postby peobryant » Fri Feb 12, 2010 1:14 am

My brother wire EDM'd an injector in half and brought it home. I'll see if I can get a few pictures of it. Pretty interesting stuff.
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1992 Dodge Ram W350, Cummins Turbo Diesel, G360
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Re: Injector breakdown

Postby Smokem1 » Fri Feb 12, 2010 8:25 am

12v body area where the compression spring is installed and the return passage.
Image

12v body feed passage with edge filter removed.
Image

24v body area where the compression spring is installed and the return passage.
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24v body feed passage.
Image
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Re: Injector breakdown

Postby Smokem1 » Thu Dec 23, 2010 6:49 am

VCO - Micro blind-hole - Cylindrical blind-hole
Image

VCO - Micro blind-hole - Cylindrical blind-hole
Image

Same nozzle, difference in pintle design.
Image
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Re: Injector breakdown

Postby Smokem1 » Thu Dec 23, 2010 6:53 am

Micro-blind side by side with a VCO, both are 145° 5x0.018".
Image

Micro blind-hole
Image

Cylindrical blind-hole
Image
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Re: Injector breakdown

Postby Smokem1 » Thu Dec 23, 2010 6:54 am

A sac style nozzle alleviates a few issues that are common with the VCO nozzle. Needle steer being the main issue, and also a smaller failure rate since the pintle never contacts the spray orifices. The sac volume plays into the amount of power produced and also the amount of haze or smoke in correlation to the engine size. You can use a larger volume sac nozzle to make a bit more power, but haze will increase as will overall unburnt fuel. There is a balance to provide good hp characteristics yet retain streetability, in a maximum effort platform this would not be a concern.

Needle steer or low lift needle deviation basically is the pintle flexing during actuation, this leads to some orifices being uncovered earlier than the others. With wear this problem worsens, this uneven pattern early in the injection event was attempted to be corrected/reduced by using a secondary needle guide, found in the CR applications. However, due to the overall tolerance issues associated with the secondary guide, they 6.7L has gone back to a micro-blind nozzle to deal with the same issue, simplicity wins. These low lift areas in the injection event are much more subjective to the VCO nozzle due to the fact that the uneven flow is being controlled by the pintle seat covering the orifice, whereas in the sac nozzle the flow is being fed from the blind-hole.
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Re: Injector breakdown

Postby Smokem1 » Thu Dec 23, 2010 6:56 am

Marker - part name
Black - needle guide
Red - pin
Green - pintle tip
Image
In this picture the needle guide has 3 basic functions; to support the pintle in it's movement, to control the return rate, and also to control the allowed vertical movement of the pintle. If the tolerance is lost between the nozzle and guide, the pintle will stick open, foreign debris is often the cause. Removing material from the upper edge of the needle guide, also known as the stroke-limiting collar, will increase the allowable vertical movement. The pintle tip can also be ground to increase the dead volume in the nozzle tip if in a VCO style, or blind-hole if in a Sac style.

0.015" difference in pintle tip length
Image

0.010" removed from the stroke-limiting collar
Image
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Re: Injector breakdown

Postby Smokem1 » Thu Dec 23, 2010 6:57 am

You can see here how the external sac size does not always directly correspond with the internal volume.
Image
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Re: Injector breakdown

Postby Smokem1 » Thu Dec 23, 2010 6:58 am

The following is a close-up of a Denso 7-hole nozzle that is being used in the 12v application.
Image
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Re: Injector breakdown

Postby Smokem1 » Thu Dec 23, 2010 6:59 am

The following is a close-up of a Mack 6-hole nozzle that is being used in the 24v application.
Image

And also a borescope image of the same nozzle.
Image
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Re: Injector breakdown

Postby Smokem1 » Thu Dec 23, 2010 7:05 am

Here are some mie scattering diagrams to give a visual.

8-hole micro-blind sac type
Image

5-hole VCO
Image

5-hole micro-blind sac type
Image
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Re: Injector breakdown

Postby KTA » Fri Dec 24, 2010 12:16 pm

Why does the 8 hole have 4 strong and 4 weak fuel plumes?
Fleet of Junk: 1989 D350 627rwhp 1300 tq B-1/Hx60 twins, KTA pump/injectors, ported head, BIG fuel supply. 13.75@ 109.5mph 1/4: 1992 W350 Cab-chasis, 1993 W350 ext cab cust.370 inj Hx40/16cm 290rwhp hydroboost brakes,1984 D350 crew-cab another project.
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Re: Injector breakdown

Postby Smokem1 » Fri Dec 24, 2010 1:28 pm

4 orifices of one hone size, 4 orifices of another.
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Re: Injector breakdown

Postby dazedandconfused » Sun Dec 26, 2010 4:02 pm

Thanks for sharing this info.
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