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High Impedance vs. Low Impedance Injectors, why, not what?

M

Mylesofsmyles

A Member
Joined
Jan 18, 2010
I get it...there's a difference, like impedance on a speaker, but whyyyyyyyyyyyyyy would one opt for a low impedance system over a high???

Is there some to do with performancesz, or is it scarcity of a type of injector or is it just a debate of compatibility?

I don't really wanna wire in another resistor pack, nor do I care to surgically find a pretty place to mount it, so why not just get some high impedance injectors and call it a day?
 
Coils with lower resistance will create more magnetic energy than a high resistance coil at a given voltage. Greater magnetic energy will move a pintle off of its seat faster. Many years ago this was necessary for higher flow injectors that had big, heavy pintles. Times have changed and newer style high flow injectors don't have the same problem.

If you can find high impedance injectors with the flow rate you want, there's no reason to get low impedance injectors.
 
are all injectors today, mostly high impedance?

there seem to be a lot of injectors for sale but little mention of such details.
 
I just got some 850T orange tops for my +T. Car isnt finished yet, but i opted for this cause i didnt want to wire in a resistor pack, which for me might introduce just another point for failure. If this is for a +T, just get yourself some orange tops. I paid $130 for the set including cleaning, new o rings and last chance filters.
 
thanks to http://www.fuelinjectorclinic.com/injectors/technical/faq.html#1


What are the differences between low impedance/peak & hold and high impedance/saturated injectors?

Low impedance injectors (1.5 to 4.0 Ohm) have a faster trigger times due to the type of electrical signal pattern emitted by the ECU. This “Peak and Hold” pattern uses a high (6 amp) initial current pulse to open the injector, and then a lower current signal to keep the injector open. Since the “hold” or lower current part of the signal has created a weaker magnetic field, the injector will also close quicker.

High impedance injectors (10 to 16 Ohm) are triggered by a low (1 amp) constant current signal and kept open by the same constant (saturated) current for the entire cycle. Due to the lower current needed, less heat is generated during each cycle allowing the injector to stay cool and therefore increase its reliability. The down side is that the trigger time is decreased since there is less of an initial current to actuate (open) the injector.
 
Yes, they may be indeed better. You have to have peak and hold drivers if it's going to work. Myles may be able to set that up in his MS box if he wants.
 
History:
gross polluter said:
Coils with lower resistance will create more magnetic energy than a high resistance coil at a given voltage. Greater magnetic energy will move a pintle off of its seat faster. Many years ago this was necessary for higher flow injectors that had big, heavy pintles. Times have changed and newer style high flow injectors don't have the same problem.

If you can find high impedance injectors with the flow rate you want, there's no reason to get low impedance injectors.
Click to expand...
Theory:
meeki007 said:
thanks to http://www.fuelinjectorclinic.com/injectors/technical/faq.html#1


What are the differences between low impedance/peak & hold and high impedance/saturated injectors?

Low impedance injectors (1.5 to 4.0 Ohm) have a faster trigger times due to the type of electrical signal pattern emitted by the ECU. This ?Peak and Hold? pattern uses a high (6 amp) initial current pulse to open the injector, and then a lower current signal to keep the injector open. Since the ?hold? or lower current part of the signal has created a weaker magnetic field, the injector will also close quicker.

High impedance injectors (10 to 16 Ohm) are triggered by a low (1 amp) constant current signal and kept open by the same constant (saturated) current for the entire cycle. Due to the lower current needed, less heat is generated during each cycle allowing the injector to stay cool and therefore increase its reliability. The down side is that the trigger time is decreased since there is less of an initial current to actuate (open) the injector.
Click to expand...
And, performance speaking, (the WHY) a saturated injector is not only sluggish to close at high frequency, it also sends a spike through the wires to the computer. So for higher RPM use, peak + hold is the way to go. But those low impedance injectors will work OK with resistors and constant current. I have not seen a lower open time, but there are lots of variables in electro-mechanical devices.
 
Just like an audio amplifier, if you are running a single 4 ohm woofer on it, and the amplifier can only handle 8ohm loads, it will work okay for the most part and even play all day. But problems arise once you begin to drive the woofer and get the amp to near clipping. The amp will quickly heat up, and if the protection circuitry doesn't shut it down you will be looking at either smoke coming from the powersupply mosfets, or the transistor drivers themselves.

Now, onto the injectors. If you wanted to run 4 low impedence injectors , without the ballast pack the ECU will indeed run it, but once you go into anything resembling a duty cycle you are going to quickly heat up the transistor driver for the injectors. The impedence load at this point is severe, instead of lowering the impedance by 1/2 (like with the above woofer scenario) you are dividing the impedance by 4. I can't remember what the impedence of the high vs low on these injectors, but I'm pretty sure a NA injector is in the 10 ohm range per injector, and the green tops about 2-3 ohms. So dividing this by 4, you can quickly see why a ballast pack is needed. You would be practically running a short circuit with the green tops on the LH2.2/2.4 ECU.

That won't last long, if you like the smell of burning silicon, go for it. Hope this explanation makes sense.
 
Wasn't planning on using low impedance injectors without a resistor...was more interested in running the high impedance injectors instead.
 
mikep said:
History:

Theory:

And, performance speaking, (the WHY) a saturated injector is not only sluggish to close at high frequency, it also sends a spike through the wires to the computer. So for higher RPM use, peak + hold is the way to go. But those low impedance injectors will work OK with resistors and constant current. I have not seen a lower open time, but there are lots of variables in electro-mechanical devices.
Click to expand...

Although to add fuel to that fire (no pun intended) the ID1000 injectors are saturated and are considered some of the best injectors on the market.
 
Mylesofsmyles said:
Wasn't planning on using low impedance injectors without a resistor...was more interested in running the high impedance injectors instead.
Click to expand...

if you wish to run high z injectors on a low z car, you will need to remove the resistor harness.
Simply make a harness with spades to shorten the circuit.
 
scottyd said:
Although to add fuel to that fire (no pun intended) the ID1000 injectors are saturated and are considered some of the best injectors on the market.
Click to expand...
Not familiar with them, I look those up. What makes them some of the best?
BTW, it's a little confusing to call an injector "saturated" unless there is current present.
 
Injector Dynamics. They run at a ~70psi base pressure and can idle a 400whp car on E85 like its a stock car. Very easy to tune and overall very impressive but expensive.
 
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