1.8L vs 2.0L fuel injectors Options

[Geezer914]

I am planning to rebuild my 1.8L to a 2056L using the stock L jet fuel injection. Can you replace the 1.8 injectors with the 2.0 injectors? Would there be an avantage in performance?

[Mark Henry]

No and No

[SLITS]

There are two problems:

1.) The electrical connections to the injectors are different (difference between D-Jet and L-Jet).

2.) The 1.8 injectors flow 190.2 cc/min and the 2.0 injectors flow 380 cc/min (not a problem, but just information)

If you can change the electrical connectors to D-Jet, the 2.0 injectors would work fine. I don't personally know if this is possible until I look at a harness.

[Cap'n Krusty]

There are two problems:

1.) The electrical connections to the injectors are different (difference between D-Jet and L-Jet).

2.) The 1.8 injectors flow 190.2 cc/min and the 2.0 injectors flow 380 cc/min (not a problem, but just information)

If you can change the electrical connectors to D-Jet, the 2.0 injectors would work fine. I don't personally know if this is possible until I look at a harness.

Uhhhhhhhhh, no, Slits. The injectors are electrically different. You coul;d use 2.0 bus or 912E injectors, though. D-jet to D-jet, L-jet to L-jet.

The Cap'n

[SLITS]

Sorry Cap'n ... my spec sheet says all are low impedance (2.5 ohms) as I remember. Just another case of mis-information as I don't know the voltage of each.

Regardless, the 912E and Bus injectors are low cc/min also. I would assume that the ECU lengthens the pulse width to accomodate proper fuel delivery for the size of engine.

[JamesM]

Sorry Cap'n ... my spec sheet says all are low impedance (2.5 ohms) as I remember. Just another case of mis-information as I don't know the voltage of each.

Regardless, the 912E and Bus injectors are low cc/min also. I would assume that the ECU lengthens the pulse width to accomodate proper fuel delivery for the size of engine.

This is correct, electrically they should be pretty close but flow is way different. I was under the impression that L-jet adapted pretty well to displacement changes so I am not sure why you want to switch them, even if you were going for big power I would think the l-jet intake would limit you just as much as the injectors would. L-jet injectors are still available new and the locking connector is a lot nicer then d-jet stuff, I would chose the l-jet injectors for pretty much all custom applications. The 2.0 injectors are huge for a type 4. On a properly setup system you would maybe be at 50% duty cycle max. Even on a fully programmable system the only thing you would get is an idle that is harder to tune.

[Valy]

Use 220cc/ min or 240cc/min injectors or else the ljet will lose power around 4k rpm
The 912e injectors are the same as yours, just urban legend around them being higher flow. Check Bosch catalog.

[ClayPerrine]

Use 4 injectors from a Nissan 280ZX (mid 80s vintage). The injection on the 280ZX is a Nippondenso Built licensed copy of the Bosch L-Jet, so it uses the same impedance injectors, and they definitely flow more than the stock 914 L-jet injector.

Plus, they are waaaaaay cheaper than the 912E injectors.

[Mark Henry]

Sorry Cap'n ... my spec sheet says all are low impedance (2.5 ohms) as I remember. Just another case of mis-information as I don't know the voltage of each.

Regardless, the 912E and Bus injectors are low cc/min also. I would assume that the ECU lengthens the pulse width to accomodate proper fuel delivery for the size of engine.

This is correct, electrically they should be pretty close but flow is way different. I was under the impression that L-jet adapted pretty well to displacement changes so I am not sure why you want to switch them, even if you were going for big power I would think the l-jet intake would limit you just as much as the injectors would. L-jet injectors are still available new and the locking connector is a lot nicer then d-jet stuff, I would chose the l-jet injectors for pretty much all custom applications. The 2.0 injectors are huge for a type 4. On a properly setup system you would maybe be at 50% duty cycle max. Even on a fully programmable system the only thing you would get is an idle that is harder to tune.

L-jet injectors have limited flexibility when it comes to custom injection because they are saturated injectors, that's one of the reasons PEFI manufactures tend to favour high impedance injectors or peak and hold low impedance.
I've used 914 D-jet injectors on a couple of SDS equipped T4's with no idle issues, my teen ran at >35% duty cycle at idle.

My SDS has L-jet style connectors and they plug into D-jet injectors no problem.

[Cap'n Krusty]

L-jet uses a resistor pack in the circuit to drop the operating voltage to the injectors, D-jet doesn't. Doesn't matter to me what your book says, I don't think they're interchangeable. That means BMW, Nissan, Jaguar, and other L-jet injectors won't work either, no matter ho much you want them to. BTW, is that the same book that says 914s use the SR-15X?

The Cap'n

[Valy]

Use 4 injectors from a Nissan 280ZX (mid 80s vintage). The injection on the 280ZX is a Nippondenso Built licensed copy of the Bosch L-Jet, so it uses the same impedance injectors, and they definitely flow more than the stock 914 L-jet injector.

Plus, they are waaaaaay cheaper than the 912E injectors.

I checked those out and they are 265cc/min. Seems to me a bit too much for a 2056cc engine.

Bosh has some cheap available injectors with 214cc/min and 236cc/min. Look for those in the range of 028015015x and check that they are top-fed with hose.
 Bosch_FI_data0280150.pdf ( 1.19mb ) Number of downloads: 191

[Mark Henry]

L-jet uses a resistor pack in the circuit to drop the operating voltage to the injectors, D-jet doesn't. Doesn't matter to me what your book says, I don't think they're interchangeable. That means BMW, Nissan, Jaguar, and other L-jet injectors won't work either, no matter ho much you want them to. BTW, is that the same book that says 914s use the SR-15X?

The Cap'n

I have no idea if you can interchange them as well, but my SDS has the resistor pack as well to make it low impedance. All you have to do is remove the resistor pack to make it high impedance.
Kind of says to me the the L-jet might be a high impedance system that is turned into a low impedance system. Just guessing, but I was told by Ross the L-jet injectors would work with SDS but were a terrible choice.

Would I fool around with d-jet injectors on a l-jet with a new engine?
No.

[Geezer914]

Well, I guess I can scrap that idea! Thanks for the replys

[JamesM]

L-jet uses a resistor pack in the circuit to drop the operating voltage to the injectors, D-jet doesn't. Doesn't matter to me what your book says, I don't think they're interchangeable. That means BMW, Nissan, Jaguar, and other L-jet injectors won't work either, no matter ho much you want them to. BTW, is that the same book that says 914s use the SR-15X?

The Cap'n

D-jet DOES use resistors on the injector circuit as well, they are just internal to the ECU rather then an external pack. If you open a D-jet ECU they are attached to the top edge of the case. I have measured them from 6.8-7.2 ohms depending on the ECU, and have reused them in megasquirt installs as they are the exact value the megasquirt calculators tell you to use with 2.5ohm resistors. I would bet money that if you measured an l-jet resistor pack it would have a similar value.

Still though, I dont think i would try swapping them on a stock setup though as it would be to much of a PITA to tweak everything else to work with the different flow.

[Valy]

Well, I guess I can scrap that idea! Thanks for the replys

No need to scrap it. It will work just fine and its been done before.
L-jet is much more friendly than D-Jet.
The issue with the injectors is simple:
1. L-jet injects 2 times in a cycle and D-jet injects just once for a short period. For this reason D-jet injectors have about twice the flow of equivalent L-jet.
2. Wire connectors are a bit different.
3. resistance is the same. All the talk about the resistor pack is not relevant as both L-jet and D-jet have resistors in series to the injectors but D-jet has them internally.
4. If you want a 2L or 2056cc L-jet, just get a bit bigger injectors or pump-up the fuel pressure to compensate the difference in volume. I gave you a list of injectors that you can use for reference. This is required since L-jet has a fixed injection cycle after ~4K RPM, regardless of the AFM reading. This cycle assumes a certain air volume (1.8L) that in your case became bigger.
5. You'l need to touch a bit the AFM as well to calibrate the dynamic ratio. All the calibrations should be done after the engine is up and running and there are tons of info on how to do it right.
Is that simple.

[ClayPerrine]

L-jet uses a resistor pack in the circuit to drop the operating voltage to the injectors, D-jet doesn't. Doesn't matter to me what your book says, I don't think they're interchangeable. That means BMW, Nissan, Jaguar, and other L-jet injectors won't work either, no matter ho much you want them to. BTW, is that the same book that says 914s use the SR-15X?

The Cap'n

I agree, the D-Jet and L-Jet injectors are NOT interchangeable. But if you need bigger D-Jet injectors, go looking for a Mercedes V-8 engine that used D-Jet. They are much bigger injectors. But then again, they are going to be rare too.

[Mark Henry]

Is that simple.

Yeh right...simple (IMG:style_emoticons/default/rolleyes.gif)

My advice, if you want to go this route, is to put the 100% stock L-jet on and go from there. Always remember that FI does not add HP.

I would't even consider trying this without a good wide band O2 meter and a head temp meter.