Can't find a VX, D15Z1 swap into CRX shell?

[Dalez0r]

Drag coefficient, frontal area, and drag area for 92 Civic CX/VX vs CRX:

CRX HF: .27 Cd, 14sq feet, 3.78 CdA
VX/CX: .36Cd, 20.56sq feet, 7.4 CdA

That's a 51% reduction in drag over the VX shell... And a few hundred pounds. Think a undertray, wheel skirts, grille block, and other sane aeromods can get that to .2Cd? That would be a drag area of 2.8sqft, or only .3 more than a Twike (2.5) and plenty less than a EV1 (3.95)

Horsepower required for level ground cruising at, say, 70mph? Assuming low rolling resistance tires of course: Stock crx drag, 11.3hp. With a (probably optimistic) .2Cd, 8.75hp

CX/VX hp for 70 stock: 20.59hp.

Real tempting to shove a little 30hp turbocharged kubota diesel in it and shoot for insane mileage... but much more work, and those things are hard to find >.<

[FritzR]

There is a VSS in the CRX HF already. It is just on the other end of the speedo cable inside the cluster. It goes through the harness to the ECU B16? red yellow wire. I've got my supermid hooked up to it.

Anyone know if this would be good enough for the z1 swap? I may consider doing one myself down the road.

[GasSavers_bobski]

Originally Posted by FritzR

Anyone know if this would be good enough for the z1 swap?

It worked flawlessly for my 'Z6 swap, though I eventually went to a transmission-mounted VSS so I could use a newer cable-free gauge cluster. For soletek's sake: I pulled the VSS off an automatic transmission in the junkyard core pile, but I'm pretty sure it came from an '02 Civic with the D17 motor. It's plastic, but the part that sticks out of the trans is only slightly larger than the original cable drive gear assembly, unlike older VSSs. It dropped and bolted in like stock... Part number 10 here.

[Dalez0r]

Someone told me my Cd and frontal area numbers may be wrong. Anyone have those numbers for the CRX?

Thanks in advance,

Dale

[GasSavers_kermit]

what else has to be done electronically to get the d15z1 running in the crx? I'm assuming that you would somehow have to graft in the vx ecu...

[GasSavers_bobski]

Originally Posted by kermit

I'm assuming that you would somehow have to graft in the vx ecu...

Right. You could run it off of other ECUs, but they wouldn't take full advantage of the engine's abilities.
There are adapter harnesses around to go from OBD-0 ('88-91 CRX) to OBD-1 ('92-95 Civic), but I'm not sure they cover the additional ECU connections used by the VX. If soldering doesn't bother you, you could cut off the HF's original ECU connectors and attach the VX's... That's what I did with my 'Z6 swap.

It would be easiest to start with an HF, since it already has MPFI and EGR wiring, as well as the EGR hardware on the firewall. An Si has the MPFI wiring, but not EGR, and a DX has neither (unless you have a CA emissions DX auto - it has EGR but not MPFI).
Converting to MPFI requires running 4 wires from the ECU to the engine bay (two to the distributor and two for the additional fuel injectors) and a bit of re-wiring in the engine bay itself. If you were strictly converting a DX to MPFI, you would need a new distributor and intake manifold, but the distributor gets replaced anyway when converting to OBD-1, and the intake manifold should be included with your motor. OBD-0 MPFI injectors require a resistor box, but Honda did away with that in the switch to OBD-1, so no need to worry about it.
Setting up the EGR wiring would require running 2 more wires from the ECU to the engine bay. One for the EGR control solenoid on the firewall, the second for the EGR lift sensor on the engine. The sensor also needs 5V power and sensor ground, but those can already be found in the engine wiring harness, so you just need to tap into them.

As for VX-specific stuff, you need two new wires for the VTEC solenoid and pressure switch, and four (in addition to the existing one) for the wide-band oxygen sensor. If you go with the CA emissions setup with a simple heated oxygen sensor, you only need 1 additional wire.

[GasSavers_kermit]

Let me make sure that I'm understanding this right...

So pretty much a d15z1 longblock should bolt right up. Is the right side motor mount the same? Then besides that I just have to rewire to OBD-I (just rearranging the wires).

Then I just need to run wires from the speedo for the VSS. Two for the VTEC solenoid, and four for the O2.

If I'm starting with a HF, then I'm done there. Otherwise I need to buy a ERG control valve and then run two more wires to the EGR control solenoid and lift sensor, and two more for a 5v and a ground. And if I'm starting with a DX, I need to run 4 wires to the engine bay.

Seems that most of the work is just wiring. How much it this setup good for mpg wise. Stock HF's get like 45 right? I imagine that with the extra 40 hp, it might have a little pick up to it too.

[GasSavers_bobski]

Originally Posted by kermit

Is the right side motor mount the same?

No. Honda changed the engine mounts all around in '92... The newer mounts won't bolt up to a CRX. You'll need to bolt the stock CRX engine mount bracket and rubber damper to the VX motor. The bolt pattern on the block should be the same, so you just need to move the old mount over to the new motor and tweak the timing belt cover to clear the bracket.

Originally Posted by kermit

Then I just need to run wires from the speedo for the VSS.

No, actually. The CRX's cable-driven speedometer and VSS should work just fine with an OBD-1 ECU. There should already be a VSS signal wire running from the gauge cluster to the ECU.
The VSS is only an issue if you want to change over to a newer gauge cluster - '94-01 Integra and '96-00 Civic clusters are popular. The trouble is that those clusters don't use a cable-driven speedometer - it's all electric. As such, you need to take the old speedometer cable and drive gear out of the transmission and replace it with a transmission-mounted VSS. The new VSS needs power, ground and it's signal wire connected to the old VSS signal wire. Simply tapping into the existing wire conveniently sends the signal to both the ECU and gauge cluster.

Originally Posted by kermit

it might have a little pick up to it too.

Yeah, but with the long HF gear set you need to get good FE, it's not going to be all that incredible.

Originally Posted by kermit

This is all for the 2nd gen CRX too, right?

Right. With the exception of the Si, all the 1st gen models use carburetors, so there would be a whole mess more work involved in converting to EFI.

[ashtond33]

Hey guys, I'm looking to do the same swap, and have started to collect parts. Has anyone found a source for the EGR control box? Majestic Honda was trying to help me find the P/N, but I had no idea what the unit actually looked like. Does anyone have pictures of the control box itself?

Thanks!

[seeodywhy]

Originally Posted by bobski

The VSS is only an issue if you want to change over to a newer gauge cluster - '94-01 Integra and '96-00 Civic clusters are popular. The trouble is that those clusters don't use a cable-driven speedometer - it's all electric. As such, you need to take the old speedometer cable and drive gear out of the transmission and replace it with a transmission-mounted VSS. The new VSS needs power, ground and it's signal wire connected to the old VSS signal wire. Simply tapping into the existing wire conveniently sends the signal to both the ECU and gauge cluster.

With the different gear ratios, if I bolt in a z1 with a hf tranny, the ecu will get the signal to operate the vtec? If so is that with all EF's or just the hf civic/crx