BC

For some additional ability to clean my large pool of injectors, as well as just some playing around in testing, I rigged up what amounts to an entire fuel system from a 928 off of the car.

The fuel rails, FPR, the pump and filter are all rigged up so I can put a battery on the pump and start cycling the injectors with a fuel/seafoam mix (I may add ethanol to clean everything up later). Also maybe some other solvents.

So I have the injectors in the rail and I fire them with 12v one at a time, off/on, on for a while, off.

What I found was strange. I want to continue testing, but:

1) Unless I have the pressures wrong (and I will add a pressure gauge as soon as I can get back out there), at stock pressure, the 4 hole 24lb injectors basically send non-atomized streams of fuel to the back of the valves. Hard, uniform, streams of fuel. 4 of them.

2) Dirty injectors seem to atomize better temporarily - as in creating what I feel would be a better atomized "fog" of fuel. But it goes back and forth between that and the streams. That could cause some very strange running of the engine if its on more than one injector.

3) A loud injector seems to be a clean injector, and a quiet injector seems to be a dirty one.

I really want to test the pintle-type 24lb injectors now. If they atomize better, they may be better than all of these blue-top 24lb ones that we are using.

If you can place the 4 holes properly, you can have two streams each port spraying at the back of the intake valve. I guess thats better than spraying everything at the middle of the port where the separation wall is.

daddyov8

understand the theory your looking at re getting the fuel into a uniform fog for better burn.

Can't help worndering why they design injectors that don't fire in that way and why do car manufacturers ask for them with straight jets?

On the latest lean burn eco engines they've done a lot of work on fuel efficiency including getting the most burn for each cycle to save using fuel, these engines are now very efficient in terms of how little fuel they use to make a certain hp, wonder if the injectors used in these engines differ at all as our quest for power is the same as that for economy just with more of everything being burnt at once. I

There may be an obvious answer for this?

Rob Edwards

What sort of LH brain and fuel map are you using to drive them?

BC

On this rig that I created from some large tuperware bins and wood, I am just firing the injectors with a 12v signal. No computers.

BC

Me too. These blue tops are for ford engines, really.
Maybe. But because of the large area of difference in where we are using these newer style injectors, and the age of the motor they are being used in, I think it does get more complex.

Tom. M

I would hazard a guess that these types of injectors are designed to use the airflow to disperse/atomize the mixture before it gets into the combustion chamber....
Newer direct injection injectors might behave differently ..

BC

Newer direct injection units need to operate at 100s or 1000s of times the pressure that our normal ones operate at.

I am sure there is some sort of air-induced mixing going on, especially at higher revs - where you will find higher air speeds, and more temperature in the port to partially evaporate the fuel.

I am going to test the pintle-type injectors and see what I find. If they spray better I may use them instead, at least on this motor.

danglerb

I'd say try some different injectors and pressures, squirting a stream doesn't sound right.

Take a look at a spray bottle for insight, the kind with a stream and spray setting.

BC

It looked like this:



Not this:

danglerb

Does not look right.

cfc928gt

Where you using an 85/86 fpr or the 87+? I do think you need a gauge on it. I 'cleaned' an old set of four hole design III injectors using an air compressor into a fuel hose attached to the injector. Then used a 9 volt battery to open the injector. The air pressure wasn't too high and it was four streams as well, not a mist. Put them in the car and they seemed to work great.

Bill Ball

I think the pattern changes dramatically from a single long pulse versus very fast short pulses, as under real conditions. So, you can clean them this way, but you can't evaluate the spray pattern unless you cycle them rapidly. Also, holding them open for very long may not be good for the solenoid.

17prospective buyer

Maybe that's it Bill. Different operating conditions.

However, we did diesel injector pop testing here at the college with a pump and pressure gauge assembly for bench testing injectors, and the spray pattern looked more like a jet or jets of fuel than a mist, and that was at approx. 2700PSI (point of opening). However maybe it's just different in the engine environment where the pulses are for ms.

Bill Ball

So, those pictures from witchhunter show a 2-hole pattern and 4-hole. Are you saying your 4-hole injectors look like the 2-hole pattern in that they are more defined streams with little diffusion?

BC

FPR is an adjustable unit. With a gauge I will turn it up to the proper pressures if too low.