The high resistance (high impedance) fuel injectors fit the engine with NO modifications. They fit the stock GTV6/Milano/Spider fuel rail and injector mounts. They will also fit other hose feed fuel injector applications - use the flow rates below to determine which will suit your application. We have them in various flow rates to handle any possible Alfa Romeo 4 cyl Nord or Alfa V6 application. The most commonly needed sizes are listed below but we have sets to handle anything up to 600 hp!
Stage 1 and Stage 2 injectors are low impedance (low resistance) injectors for the factory Bosch L-Jetronic system.
All injectors Stage 2M and higher are high impedance (high resistance) injectors for modern programmable injection systems, such as SDS.
All new fuel injectors sold in FLOW-MATCHED SETS include clamps, hoses, upper seals, and lower seals.
Injector Flow Rates and Descriptions:
Stock injectors flow rate = 17.6 pounds per hour (pph) @ 36.5 psi,
Stage 1 L jet injectors = 17.6 pph @36.5 psi
Stage 2 L jet injectors 23.8 pph @ 36.5 psi
Stage 2M 22.9 pph @ 36.5 psi
Our Stage 2m injectors are a high resistance type injector usable on Bosch Motronic systems or with aftermarket ECUs not compatible with the older low resistance L-Jetronic injectors. They are ideal on hot normally aspirated street V6s with up to 250hp.
Stage 3M 28.6 pph @ 36.5 psi
Stage 3m injectors are intended for very high output engines. They can provide enough fuel for over 300 hp at stock fuel pressure. If you are building a full race normally aspirated motor or a powerful forced induction engine these are the injectors for you are likely to need.
The following large injectors are only suitable for extreme engines!
Unless you are building a high displacement or serious forced induction engine then the Stage 3M injectors are the biggest you want. The Stage 4m, 5m, and 6m injectors are only needed for either very large displacement engines or engines with well over 10 pounds of boost. Caution: some aftermarket injection systems can not pulse Stage 4M or bigger injectors fast enough to maintain good idle and emission qualities. The SDS system can do it without any problem.
Stage 4M 36 pph @ 40 psi
These injectors flow 36 pph at 40 psi which is a common setting with aftermarket injection. I find these injectors work very well with SDS fuel injection and are a great match for a hotter supercharged V6 engine.
Stage 5M 44 pph @ 40 psi
These injectors flow 44 pph at 40 psi which is a common setting with aftermarket injection.
Stage 6M 48 pph @ 40 psi
These injectors flow 48 pph at 40 psi which is a common setting with aftermarket injection.
INJECTOR FAQ:
Question 1: Are your injectors as good as the originals?
Answer 1: They are much better. They have stainless steel bodies and better nozzles. Most importantly you can get them in flow rates high enough to support virtually any Alfa V6.
Question 2: If I don't need more fuel flow, can't I just have my original injectors rebuilt?
Answer 2: Nope. There is no such thing as a rebuilt Bosch injector. The two most critical components in the injector are the internal seal & the coil and they can not be replaced. At least one major rebuilder does nothing but clean them and it says so in the fine print on their website. The best rebuilders clean them and replace the tips and inlet screens. It makes a lot more sense to buy new ones.
Question 3: Ok, what injector should I use for a 2.5L with aftermarket injection and 164S cams?
Answer 3: Stage 2ms are ideal. Any bigger is a waste of money.
Question 4: I need more fuel flow, can't I simply raise the Fuel pressure?
Answer 4: Sort of. There are a few problems with that. First of all it takes a big increase in pressure to make a small increase in fuel flow. Raising the GTV6's fuel pressure to 40 PSI only adds about 1 pound per hour of fuel flow. If you raise it above 40 the injection system will spray in more fuel but it looses efficiency. This happens because as you raise the pressure the fuel coming out of the injector it sprays farther. On the Alfa V6 if the pressure exceeds 40 psi the bottom of the spray cone strikes the bottom of the intake port causing the fuel vapor to liquefy. That's why Alfa Romeo, BMW and other L-Jetronic users altered fuel flow by changing duration and by using different sized injectors. They did not make significant changes to fuel pressure to control fuel flow!
Question 5: I have a 3.0L with 11:1 compression, race cams, headers, and L-Jetronic. Which injectors should I use?
Answer 5: Stage 2 injectors
Question 6: What flow rate is injector X?
Answer 6: First I want to say that when comparing flow rates it's VERY important to note the fuel pressure at which the injector was tested. Most injectors have flow rates published for fuel pressure about 44 psi. Some are higher. All of our flow rate numbers are for factory GTV6/Milano fuel pressure which is 36.5 psi. Obviously at higher fuel pressure the flow numbers would be higher so please take that into account when comparing our injectors to others. We know of no other vendor that flow checks injectors at correct GTV6/Milano fuel pressure. We have them flow checked at 36.5 psi and checked for leakage and quality at much higher pressures.