DCFIVER

30-37psi regulated

40-47psi unregulated

holmesnmanny

So it's basically the same.

JRCivic1

H22A4 ('97-01) 290cc fuel injectors would flow between 280cc and 303cc between 40 and 47psi fuel pressure respectively. With the proper programming, this injector would function in a similar fashion to the early H22A1 330cc injector, but are certainly NOT interchangeable with either stock P13/P5M ECU.

Simply put, you MUST consider the injectors as part of a system, not a stand-alone device.

Either of these two combinations would work successfully:

ANY USDM H22A1/4 engine + 330cc fuel injectors/fuel rail/fpr + resistor box + P13 ECU
ANY USDM H22A1/4 engine + 290cc fuel injectors/fuel rail/fpr + P5M ECU

NOTE: This example assumes similar fuel pump flow rates.

Now obviously, converting the older generation Prelude ('93-96) to the 290's and P5M ECU would be challenging since this requires additional emissions related systems and a way to get around the immobilizer, but converting the newer Prelude ('97-01) would be far more simple. With a set of injector clip adapters and an OBD-2 -> OBD-1 ECU adapter harness, and a quick "pin in" of a resistor box... I suspect the car would run just fine. The trouble is, WHY convert to gain essentially nothing and use older, less efficient products ?

holmesnmanny

The main difference, besides the obvious flow rate differences, is that the a1 injectors use the resistor box because they are low impedance and the a4 injectors do not use a resistor box, since they are the high impedance(saturated).

Sparksman

There are more injector options out there for peek and hold, which I see as a main reason people switch. Peak and hold have a quicker trigger time then saturated injectors for both opening and closing. If your talking only factory injectors, they do it because they are cheap and easily available. Bigger and faster, or smaller and slower. Which is better?

I own saturated high impedance k series RDX injectors for my lude. But saturated injectors have come a long way since the prelude went out of production.

People reading this should remember PSI doesnt equal volume. You will gain only so much more flow before you reach the injectors max cycle-duty and have stuck open injectors, running lean, and other fun things happening.

H22 SL33P3R

I have the h22a4 obviously with the 290cc. I am running obd1 harness. Should I convert to the other injectors and add the resistor box to get that extra fuel? I am running p28 ecu

JRCivic1

The P28 ECU's injector drivers are designed for a saturated fuel injector. I would suggest using the H22A4 290's @ 50 psi static fuel pressure and TUNE the car on a dyno.

In addition, no wiring changes would be necessary and you wouldn't have to hide a resistor box...