DIY Injector mods

[djberg]

thanks to everyone contributing to this thread it's a super fun brain teaser for sure!

so last night i was bouncing this all around my head, and i came to a few conclusions... i may be completely wrong, or this could change up peoples thoughts on this topic.

1. machining the plunger(*for adding volume above the spill port, while typing this i added the "knub" into my thought process as well, this would add some volume to the 135cc, but i dont know how much), seems useless since at rest it sits above the spill port. and i personally think the spill ports purpose is to 1. faster easier finish to filling the plunger chamber when spring tension is at it's lightest pressure, 2. to create a momentum starter for the plunger to get moving with less pressure to get the full speed needed to push the stock amount of 135cc of fuel. now i dont know the i.d. of the inner hole of the spill port, but i would imagine it to be enough to move fuel easily, and the pressure in the outside of the barrel to be the same as the pressure of the fuel rail, so the pressure inside the barrel will be far more than the out side thus the fuel above the bottom of the spill port will mostly push back out until the spill port is "closed" then you will be building pressure. leaving you with the stock 135cc, until the machining of the length of the oil piston to actually change the volume at the longest point of the stroke.

2. so now that i believe the above to be true until some one gives info proving different, both lilpooh and frank have found the available area to add extra volume pushed, aka height difference between the top of the fuel plate and the hammer end of the plunger to be between .025-9" so using this info and by frank's statement that he has found them to be more commonly measured at .025"(.635mm), i will use that in my theory.

so we know that v=pi*r^2*h so filling in the blanks:

v=3.14*3.17^2*.635

thus v=20cc's

so with only internal machining and no shimming, and running the plunger to the point of "hitting the fuel plate" the max fuel you can get out of this is 155cc. but if you were to machine the "knub" at the bottom of the plunger that could buy you some volume, but no one has given the volume of that knub yet, that i have found anyways. so that knub/nipple thing could get us a bit more fuel area and change my theory.

also for clarification purposes, where are you guys measuring the longest point of the stroke from the edge of the plunger, or the center? aka the longest point with the knub not included in the measurement or the shortest?

two other questions i have, that some one might shed some light on.
1. what is the length of both springs fully compressed? this also could be a limiting factor to how far you can modify either side and affecting total volume.

2. what exactly is the measurement between the spill port edge and the top of the fuel plate? if you were to plug the spill port and move it up(to keep the same distance between the now modified plunger and the lowest point in the spill port) you could then modify the plunger and add volume that way.

 

[djberg]

also one other note to my theory that is a variable, maybe some one with more knowledge than i+googling have lol.

now obviously the spill port at it's smallest diameter is definitly smaller than the bore of the barrel, so the pressure in the barrel as the plunger moves through it's stroke is increasing but i have no way of knowing what the loss or gain in pressure is between the point of plunger at rest and the bottom of the spill port hole is, through the first part of the plunger's stroke.

if someone can get the smallest i.d. on the spill port and get the measurement between the spill port and the plunger at rest we may be able to figure this out.

 

[Cold Roller]

I can't remember what the port hole size is, but I remember that at max injector fuel pressure (27,000 psi), the force on the plug was about 8 lbs until it was covered by the plunger. The reality is it would seldom ever see that level of pressure due to stroke action.

IIRC, the plunger sits 5.6mm from the end of the bore (0.177ml) The hole would be about 5.1mm from the lowest edge. I don't have one to measure in front of me. It is possible I am mistaken and the area below the port is greater.

For those that have flowed open port injectors, 0.205ml volume gives about 0.188ml volume with the spill port loss. I didn't flow my injectors, but I have no reason not to trust the value.

The volume of the knub is not much less than the full diameter. If you are relying on that amount for volume calculations, other losses are more critical.

For moderate injectors, spring issues are a non-issue. For larger than 225 it may be an issue. The same may be said for fuel intake at the fuel plate. Although possible, there is no requirement for the spill port to be used to help fill the barrel. Since nearly all injectors and all large injectors are plugged, the fuel must be drawn into the chamber through the fuel plate.

By all means, experiment and add to the this or my other thread. The data is relatively clear on how to do this at a small to moderate size, the larger injectors and particulars surrounding them still remain in the hands of a few builders. Needless to say, there haven't been more than a handful of people that have chosen to tackle this project themselves. If anything, it may have educated more people about the inner workings of the injectors and encouraged more to actually buy modified injectors. In the past year it seems that there are less problems with modified injectors and nozzle sizing is becoming more of a known commodity. When you look at the much wider availability of turbos and knowledge surrounding them, I can say without a doubt that the past 2 years have finally got us out of the 6.0 Dark Ages.

 

[turboTwang6]

subscribed. awesome info here. :ford:

 

[djberg]

I've been running again and haven't had time to put my brain back to "injector theory".

But thanks again frank for all your info, its super helpful since I have yet to pull mine yet to get to my first reason for searching this all up taking care of stiction. Sorta got side lined when I saw what bad nipple cup orings can do to the top oring of an injector(still kinda dumbfounded by how oil can chase that profile at 2000+psi). But I wanna have nipple rings and a couple of spare nipples on hand so I only have to go in once until I replace them/DIY over bore/have someone rebuild them larger.

So the modifications you did are the same as those flowing 188 out of 205's? Just to be completely clear on the info I have to work with. And I'm not in any way saying you're wrong, that port hole on the inside may be tiny, and only a 8psi drop is completely possible. I'm also gonna try to pick one of my tenants brains on this he's a engineer for cummins(big truck engines), though I believe thier injectors are out sorced, not completely sure. But he should know the math to figure that out. How to solve for hole size, or a good guess at it anyways.

 

[Cold Roller]

So the modifications you did are the same as those flowing 188 out of 205's?

Yes. But if you read any of my other posts, I suffer from HPO pressure loss at long pulse widths with warm oil. Cold oil it maintains 4000 psi. Once it warms up I see 3000 psi. I either need a dual HPOP or need to plug the injectors to keep the pressure up. FWIW, on a mid-tune I have no problem with HPO pressure. Once the tune gets above 2.1 ms PW I start to loose some pressure.

that port hole on the inside may be tiny, and only a 8psi drop is completely possible.

No, it is not an 8psi drop. The size of the hole at max injector pressure would generate a bit over 8 lbs of force, not psi. It would still be 27,000 psi.

Cummins or common rail injectors are completely different. They fire using piezo electronics to allow flow through the injectors.

 

[djberg]

sorry let me re-state my statement about the cummins engineer. i'm going to pick his brain on the math with trying to figure out how much volume is lost through the spill port. not how these work. sorry for the confusion.

so you think you have a leak or not enough hpop? and this may sound like i'm pointing out the obvious but, did you look at the top oring/oil rail orings when you had them out last? oil around the ipr? it is like you say a very small leak. but you have a 2007 and i thought i heard about some of your fellow countrymen making like 1000hp on a stock 05+ hpop? i think i would go buy new rubber for the whole system or at least what you have not replaced lately and see what that does for ya.

just found another interesting point. http://www.powerstrokediesel.com/docs/EF_456.pdf pg 46

Main Injection Step 1
FUEL MANAGEMENT SYSTEM
46
• Pulse width controlled current energizes the
open coil, magnetic force moves the spool
valve to the open position.
• High pressure oil flows past the spool valve
into the intensifier piston chamber.
• Oil pressure overcomes the intensifier piston
spring force and the intensifier starts to
move.
• Fuel inlet check ball seats due to an
increase of fuel pressure under the plunger.
• Fuel pressure starts to build once the
plunger passes the fuel spill port of the
barrel.
• Force on the nozzle needle begins to build.

 

[djberg]

another good read, but it's covering the entire heui family. for any one interested. and no i did not read it n its entirety just skimmed looking for a certain few things will be reading in full later.

http://dieselclass.com/Fuels Files/HEUI 1-08.pdf

 

[djberg]

one more: The barrel (9) also contains the PRIME spill port.
The PRIME spill port is a small hole with a high precision tolerance.

The PRIME spill port is machined through the side of barrel (9) into plunger (7). This port momentarily vents fuel injection pressure during the downward stroke of the plunger.

http://gershon.ucoz.com/ISUZU/HEUI/HEUI_Systems_Operation_3126.pdf pg 18

 

[Cold Roller]

That is nothing new. At lower pressure all the fuel makes it out the spill port; that is why it idles just like stock. At higher pressure, and a shorter time to block the port, not all of the fuel makes it out the spill port. Again I will say that plugged ports are more efficient at delivering fuel. The spill ports main purpose is for fuel bleed-by (an escape route rather have it bleed into the oil). Secondarily, it helps smooth the idle parameters.

 

[TheReelMuhcoy]

I am gearing up to start my injector build now that the truck is all back together and (crossed fingers) running pretty reliably. I had an idea that I want to throw out there to those of you (eh hem FRANK) that have dabbled with injectors already and know a little bit about them.

Here is my thought:
To maintain the stock feel and function of the injector, and maintain the proper use of the spill port, would it be possible to install a copper shim between the fuel barrel and the fuel plate and then ONLY cut the intensifier piston to achieve desired fuel delivery?

 

[Lilpooh]

I've heard you can shim between the plate and body, then just cut the piston so you don't lose the spill ports. I don't know if there is a limit on how thick of a shim, before you run into issues.

I have made prototype shims and sent to someone to test, but never asked how well they worked.

 

[TheReelMuhcoy]

That's encouraging! What material did you make the spacer plate out of? I was thinking copper because it is commonly used for high pressure washers of sort.

 

[Lilpooh]

Made them out of D2 tool steel, on a lathe then surface grind the thickness to .0002" tolerance.

I really couldn't tell you if copper washers would work.

 

[nitrogen here 2]

Copper makes decent high pressure seals, but as a shim that takes pounding (I think) it would hammer out

 

[Whitezotti]

I have purchased both of these DIY injector nozzles from elite and put them together if anyone has questions on them ask me

 

[Whitezotti]

I'm actually selling a 170cc kit from elite if anyone is interested. Brand new!

 

[Whitezotti]

FYI you do have to fill the spill port . But a lot of tuning companies have problems tuning around them. Such as Matt from gearhead. I talked to him via email. Great guy tho

 

[Lilpooh]

FYI you do have to fill the spill port . But a lot of tuning companies have problems tuning around them. Such as Matt from gearhead. I talked to him via email. Great guy tho

He doesn't have to plug the spill ports. By cutting the piston and adding a shim, he will increase the stroke of the plunger, allowing him to gain CC without plugging the ports.

 

[Whitezotti]

" You don't have to!" But the instructions ask you to. It will run more efficent. More lopier .