D15Z1 running DPFI Setup and VAFC.
 

I currently have have a 1990 Honda Civic EF Hatch that motor just recently went out and I picked up a D15Z1 engine for cheap to replace it. I'm planning on swapping just the longblock and retain all original DX components DPFI, PM5 ECU and 4 Speed MT. I will be using an Apexi VAFC for Vtec activation and some fine tuning. I'm not too concern of maximizing the MPG potential of the D15Z1 but more on simplicity on the swap and will it harm the engine running it with this configuration. Thank guys in advance!

In general that sounds like a pretty bad idea and while it'll probably run it will run very badly, if I were to guess. The fuel maps and injection are so completely different from the two motors. You'll have some fun seeing how the ports on the intake manifold match up with the head on your motor.

To be honest, I would suggest you just get a different long block. What's a d15b longblock cost? Free - $50 I would guess, and everything would be much simpler. Either that or get a VX injection system and ECU for 100 bucks and use that. Either way I think would be simpler than trying to hack together two fundamentally different systems.

It will work just fine. You won't be able to set up a lean burn mode, so basically you can run the car in vtec just about all the time. I'd just run the dpfi setup and use the vafc to open the solenoid about 1800-2000 rpms. The high swirl mode will help the car idle smoother. (when vtec not engaged)

You don't think the compression difference will cause any problems? Or the cam profiles being very different?

Perhaps I overreacted at the mere thought of a d15z1 being wasted in such a fashion.

I was initially looking for just a replacement D15B motor and most have really high mileage and others just ask too much for it. I got the D15z1 for practically free from a friend and I know it has decent mileage. Since I only have the longblock the conversion to MPF1, OBD1, VX o2 Sensor will just add up on the cost and complexity. I do realize that converting using those said parts would be more optimal I just figure to ask other for feedback. While I'm still in the process of the swap.

This is exactly how I was considering on running the setup. Hopefully I should be able to gain a little bit of HP and MPG.

There's really not much difference in the compression 9.2:1 D15b and 9.3:1 on the D15z. Cam profiles from what I've read is not much different since it was just setup for VTEC-E to operate the 12 to 16 valve operation IMO.

I've been reading about D15z1 and correct me if I'm wrong from what I understand the main factor for the better fuel economy from this motor is primarily from the VTEC-E head and its valve operation, more precise fuel injection from its wideband 02 sensor, EGR system and ECU Lean Burn Mode. IMO keeping it DPFI would be more of the dumb version of lean burn. I dont expect to match the MPG of full OE Spec D15Z1 conversion but hopefuly I will gain some from the original D15B2 motor. Wishful thinking perhaps?

From experience driving it, I would say the main factor is the lean burn system. However, that takes into account that I trained myself in maximizing the use of lean burn in normal driving conditions.

There's a Honda white paper out there somewhere that spells out the increases in %s and attributes them to various technological advances, but as you said, it's mainly VTEC and lean burn, which are all part of a very large system. VTEC-E by itself I imagine will do very little without leanburn, though it should be better than nothing.

Finding an HF transmission will probably help worlds more. You should be able to dig one up for free.

My best guess would be that you'll get similar mileage to the d15 without any further modifications to the car. My heavy 92 lx would get 38 pretty much all the time, maybe 40 with a very light foot That's pretty stellar in my book for a 2400lb car. It's all the incremental differences in the car including weight, gearing, and engine tuning that got the VX to get into the high 40's and even low 50's.

Just a suggestion. The intake manifold on your original engine will bolt up, no problems. you wont' mess up the engine, the fuel maps will be based on your original ecu,
I would not do V-tec E; i think you will run very lean because your 4th gen ECU will not work like your 5 gen V-tec valve system.

Can a 92-95 Civic VX engine be put into a 89 Civic HB? - Honda-TechCan a 92-95 Civic VX engine be put into a 89 Civic HB? - Honda-Tech