None of the Fuel Injector Clinic line gets released if it cant pass the Bosch Test.

 

Sounds like y'all need to give in and figure out a slick dual injector driver / phaser / install solution for the stock ECU. Not likely a mega-massive injector will ever idle or DD well.

 

Well, I don't know about mega-massive, but if the 1250cc, 1450cc, 1650cc sizes fit your needs, and you are willing to use a proper peak-and-hold injector driver downstream from the stock ECU, I would think you could get good idle and DD from the Low-Z injectors that size.
Or if you are using a stand-alone ECU with good built-in peak-and-hold injector drivers (like the vipec i88), same idea.
I think it was said earlier that new developments, like this ASNU technology, would only be applied to High-Z injectors from now on. I don't know why this should be. It should still be true that with a good peak-and-hold driver, that the low Z injectors should open quicker for better control at idle and DD (because of the high peak current), and have less heating (because of the low hold current).

I look at injector opening in terms of the power (watts) available to throw the injector open. More power available to throw it open should be better. Then when the thing is open you can reduce the power just to hold it there.

Power is I^2 x R

In a driver like the one in the i88, you can set Peak current as high as 4 amps. Then you set hold current to 1 amp. This would be for an approx 2 ohm injector.

That peak power would be 4^2 x 2 = 16 x 2 = 32 watts


A high-Z injector might be 6 ohms, the saturated current would be around 2 amps.

That power would be 2^2 x 6 = 4 x 6 = 24 watts

So the peak-and-hold Low Z setup opens with more power, then it throttles back the power to reduce heating - seems like it wins everywhere, you just need a proper driver box to do it.

Here is the chart Vipec gives for a typical peak and hold event. They don't have any numbers on it but the idea is that the "Peak current" can be as much as 4 amps, and the "Hold current" is about 1 amp. The curved shape depicts the rise time, which you would also have with a saturated setup.

 

So when you say 1250cc, 1450cc, 1650cc sizes you're refering to FIC injectors yea?

 

Yes, the FIC "Blue Max".
As I remember there were some mixed opinions about the 1450cc Blue Max in another injector thread here not too long ago, but it wasn't said what was being used for an injector driver. For all I know they might have been using a "saturated" driver and resistors.

Wow, well after brushing up on solenoids a bit, I see that power isn't really it. The strength of a solenoid "BL" is linearly proportional to Current (Amps), also linearly proportional to total number of turns. Heating would be proportional to power though, and heating might determine determine how many turns you can have room for in the coil, due to wire gauge needed.
So number of turns, LowZ vs HighZ: winner not clear.
Peak current: LowZ the winner by a factor of about 2.
Heating due to average power consumption: LowZ the winner (lower average power consumption).

 

When you read the FAQs on the FIC web site, it seems pretty clear that the newest High-Z injectors work better than the available Low-Z injectors. But it isn’t clear why – except that the OEM design efforts are all directed at High-Z now because that is cheaper for them, due to lower cost of the simpler driver in the ECU. So I guess that’s what we’ve got now, regardless of which one is inherently better, given the same level of technology and design effort! The FIC FAQs are really pretty good. They always have been good, but I see there’s been a lot of updating there from a couple years ago.

 

Hey Talon, I guess something to remember for most is that the stock ECU drivers are saturated and not nifty peak-hold type, therefore the current is going to be constant and the LowZ + resistor pack needs to be compared to HighZ without. That's where MrFreds comment about resistor tolerance comes into play. To your point this isn't an issue with a higher end controller.

Another detail is that impedance is commonly measured as ohms, but in an AC circuit like an injector driver one needs to consider inductance, capacitance, and driven frequency to get instantaneous current to plug into your solenoid equations if you're trying to model power consumption. Maybe it's all happening so fast that it can be ignored though.
https://en.wikipedia.org/wiki/Electrical_impedance

Then you've got the mass of the valve (pintle, disk, ball), type & geometry of magnetics, spring pressure and rate, tolerances that it all got put together with, effect of materials and design on heat transfer, tolerance to aforementioned heating, etc... Lastly, how nice does all this plays with the ECU in question?

The OEMs are driven pretty hard to get cost out, CAFE up, emissions down, etc. I'd bet we all are winning from them choosing HighZ even if we don't really know why.

 

A good portion is the spray patterns are improved as is the accuracy and required latency times. That is the is the main difference between the 2 is the high impedance coils react faster than the low impedance ones.

 

Yes, and from what I gather, the main contributer to this in an injector circuit is inductance, mostly in the injector itself, which figures because the solenoid coil in an injector is exactly an inductor! If you are a speaker builder, or a circuits guy, you know that having an inductor in series with a resistance is a way to filter out high frequencies (reduce them). We see this in our case as the “on” event having a rise time, it is not a straight vertical step, it is a curve or a ramp. I’m not going to try to model this. But I know it is not something you would ignore. That’s why Vipec drew their cartoon of it they way they did – the pic I posted up in post 78. The current is still in the “rise time” region, on it’s way to what would be 5 or 6 amps if they let it go that high, but they whack it at 4 amps, or whatever you set it to below that, in the iVTS software.
With high-Z injectors the current will still have the rise time “feature” (problem actually), but the current will naturally never reach a high enough value that it needs to be whacked. If the pulse width is long enough to get past the rise time, the current levels off, and inductance is no longer having an affect, at that point it is just the ordinary resistance of the coil in the injector determining the current. For example, the 2150cc FIC injectors, DC resistance measures 8.5 ohms, at 13.5 volts the current would level off at only 1.59 amps!

Yes and this is where things get really complicated, and as time goes along, these things are refined and improved. Every so often a formerly exotic technology or material like Neodymium magnets becomes cheap and easy enough to use on a mass scale, so something new can be better than something old, even if there is something about the new device that is not inherently as good as the old device. Maybe that is what we have here, maybe not, I don’t really know. But I would take FIC’s word for it that the latest high-Z injectors are the best thing we have available at the moment, and the system cost explanation they give seems to me like it’s probably the reason why OEMs went this way with their development efforts.

 

How about these Moran injectors they are low impedance anyone heard anything good about these for idle? Looking to get the 275lb/hr / 2890cc set.

 

I think you'll struggle, especially if you wish to maintain street manners.
Why not a set of 1300 and a set of 2000's staged.

Maintain immaculate drivability, great economy in stop/start driving and still have enough fuel.

 

The Moran billet Atomizer injectors require a driver box, but are well worth it as they have an amazing spray pattern and protrude into the cylinder more for a better burn.

 

We just put 6 in one of the GTRs. Let's say the jury is out on these and leave it at that. If it were a 600 cubic inch big block with twin 106s and methanol...sure no doubt.

 

What size are those? Wes the sales rep at Moran said the 275lb/hr size would be more bearable.

 

235lb/hr