Shoptalkforums.com

That was a great set of dyno charts. But....this is just a good illustration of what should be fairly common knowledge by now. There was critical information that was not incorporated into those charts which would show even more clearly what is happening. That information is:
fuel pressure


Yes....voltage is an issue. Notice that on most of those charts....you have the most instability above 14v and below 12v.
But.....one of the biggest stability problem (aside from voltage) with injectors at low rpm is a combination of fuel pressure pulsation and the initial "crack-open" pressure of the springs on the pintles. We see this problem with rapiding opening spring system....die springs on high speed dies, injection molding springs etc.
There is an initial amount of pressure that must be exerted by the solenoid to overcome spring pressure and unseat the pintle.
Once you get over a certain cyclic speed....this does not become less....but it becomes easier to overcome because the spring itself does not finish its full cycle and come to rest in the short amount of time at speed.

The fuel presssure can help or hurt this. There are minute pulsations when a pintle slams shut. Pressure rises...and then drops as the regulator compensates. The pintle reopens before that cycle is even complete..so there is slightly less pressure than there was to help unseat the pintle.

Low impedance injectors have less of a problem in the idle and low rpms because they have less spring pressure and less initial unseating pressure. But...they generally are much worse than high impedance injectors in the upper cyclic speed range...and upper pressure ranges.

All injectors have sealing problems at high cyclic rates...and most especially at highest pressure ratings. They are moving so fast...are not getting full seating spring pressure due to oscillation described above....and ...they are fighting high fuel pressure. At lower voltages....they fight to have enough power to open fully and at the same speed.

I would love to see this exact same set of graphs with fuel pressure overlayed....both normal, low and high. I bet this would also tell a few things about the rough areas of the graph. Ray

Do these specs help at all Ray?

http://www.injectordynamics.com/ID725.html#Dynamic

I measured the whole thing, with pico injectors and slimmer fuelrails i gain almost 15mm additional space to sidewalls, now there is about 10mm Also the whole package will be about 30mm shorter

MarioVelotta wrote:Do these specs help at all Ray?

http://www.injectordynamics.com/ID725.html#Dynamic

Yes, actually it does! You can see how the voltage variation is multiplied or leveraged as pressur rises. It looks rather subtle of these obviously high qulaity injectors. I would love to see some of the same graphing on a rangte of stock injectors.
That graphing is an excellent example of what I would consider more complete analysis. I have never seen that sam level of graphing done to stokc in jectors. It may be an eye opener...maybe not. Ray

MarioVelotta wrote:I really would like some ID injectors. I can't decide on 725 or 1000's since my 570's are about tapped.

I run the ID1000's on my 2200 cc. They idle fine, even better then the slim-line Siemens 660's I had before and they were better then the old-style Bosch motorsport 500cc's I had before that.
So no, nothing hardly is ever too big anymore imo if you have a good injector. There is a big difference in quality and techniques have moved on

i recently ran some ID1000's and a world of difference.......................................