Austarion

I was messing around in my box of old injectors and found an old magna injector missing it's pintle (little metal bit sticking out the front). I remember I had broken it getting it out of the manifold ages back. I've also been calibrating some injectors so I had a fuel rail set up in the shed. I put the broken injector on the test setup.. Guess what, around 500ml/min... sounds promising..

So, I found the original sonata injectors (maybe 190ml/min) and proceeded to snap the pintles off (rough as guts, I know). The spray pattern was not superb (rough jet, each one different) but the flow rates were again around the 500ml/min mark. stuck them in the car, recalibrated the efi for the new flow rate and opening times, and presto, no excess duty cycle at 1 bar boost...

Phase 3:
Worked out how to dismantle some other injectors I had around (low-z injectors from an older turbo CC lancer, were around 250ml/min. Using a screwdriver and some long-nose pliers, I pried open the peened bit at the front of the injector. With the guts of the injector out, I proceeded to dremel off the entire pintle, smoothing the base in order to obtain a more consistent flow. The injector seals on the conical part, so it was reasonably safe with regards to sealing..
cleaned out any crap then put the guts back in. Using some big pliers, I bent the metal back around to lock the nozzle section in place. Finally, with the injectors sitting in the front of a shifting spanner, I hammered the top of the injector to make sure the whole thing was done up tight.

All still sounds fairly rough, But, on flow testing version three, the flow rate is around 540ml/min and the flow pattern is a very narrow jet. So long as the injectors are pointing roughly at the valve, this should be OK. I have not yet tested version 3 in the car, just on the test bench.

I figured for this that i'd spent less than $400 so set up the entire multipoint setup, I couldn't justify spending another $400 on injectors. Only thing remaining is to test the last injectors in the car, although I'm fairly confident all will be OK..

Hey what's the number on the 500cc/min magna injector? Perhaps it's a later one (TR????) because I am sure the earlier ones did not flow that much.

It was one of the bone coloured ones from the TR 2.6, they normally flow around 260cc or thereabouts. With the pintle snapped off, it was around 500cc.

how consistent is it at lower duty cycles?

On my old injectors (360cc's from a ford turbo something) I had done a full calibration, both static (always on) and pulsed (5 and 20 ms) at 9 and 15 volts. Using the numbers from that I was able to get a consistent idle mix of around 14.8-15:1, stable over different elctrical loads and engine loads.
I have only done the static calibration for the ones I've played with so far. That said, the idle mix from the ones that are in the car is still quite stable, meaning that the modified injectors must be fairly similar in operation to the unmodified versions. I would expect the idle to be a bit less accurate because the flow is significantly greater through the modified injectors.
Thinking of it from a logical perspective, the only thing that removing the pintle should do to the opening/closing times would be in the removal of mass from the moving parts (tiny amount though it is). Other than that, the rest should be similar.
I have found that the injectors I calibrated need an opening time compensation of 3ms at 9 volts but only 0.2 ms at 15 volts. 0.2 ms sounds short but it is "opening time - closing time" and as the battery voltage goes up the opening time diminishes.
The last injectors I 'doctored up' are of low impedance (2.4 ohms) and these (allegedly) are faster in operation. Once I have a low-z driver built, i'll do some further experiments.

Should throw some pictures up

Here Goes...




They were the TP magna style injectors I played with first.. Most bosch style injectors will be similar.

Cheers,
Duncan

If you do dissasemble the injectors, be sure to test them on the bench first, or replace the internal O-ring. The reason for this is that the o-ring may not be correctly seated when the injector is first reassembled. When you run pressure through them, there may be some fuel that leaks around the o-ring before it seals. If they're in your car, this would mean some fuel in the engine bay. if its in your shed and you are ready, theres no problem. It affected one in three of my injectors. If there's rust on the sealing surface, I'd be extra wary, probably clean it up first and swap the o-ring.
Always have a fire extinguisher or two handy when playing with fuel. Better safe than sad.

Had to wire up some resistors to get the injectors working, they're low impedance style.
Did a calibration last night. The cc lancer injectors with the pintle head removed measured up at 560cc/minute. The opening time compensation was 0.7 ms at 15 volts, and a theoretical 3.2 ms at 0 volts. This is nearly the same as some other unmodified injectors I calibrated a few weeks back. All the injectors were within 3.5% flow of the others, closer than the unmodified injectors I had in there before (they were about 6% different)..
Put them in the car, reprogrammed the ECU and went for a quick scoot around town, they seem to work fine. can run 14 pounds easily now without leaning out.. idle mix is still good.
560cc injectors, cost me a grand total of $0..

what a champ! :beer

Damn I wish I had a custom ECU, are these pintles just there to restrict the injector? :?

They serve two purposes, firstly as a restriction, secondly as a flow shaping device.
The angle of the very tip determines the angle of the spray cone of a normal wide fog type injector.
taking the entire pintle head off as I have done means that the spray pattern is a very narrow jet rather than a wider spray. So long as your injectors spray roughly at the top of the intake valve, the heat from the valve and the speed of the approaching droplets of fuel does a pretty good job of atomising the fuel anyway.
I'm going on a treck this weekend from Ballas to melbourne and around a bit, so I should have a reasonable idea of the economy when I get back.. It's hard to tell around town, because when you boost up as each roundabout to 14 psi, and the injectors are big enough to put $3 per minute of fuel, economy is *somewhat* diminished..
So they are intended as more than just a restriction, but it's not of too much concern..

good research
glad you have the equipment/parts/time to try this experiment out.
And glad you passed on your findings on to the rest of us, instead of keeping them to yourself.....

I admire your thoroughness of experimentation, and willingness to share your discoveries!!

Thanks!!

(even tho i won't use this info for my own car)