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Ok, here it is, the first draft. Tell me what needs to be changed. I keep feeling like it's not done, but maybe that's because my car isn't tuned...
Anyway please write up some corrections, we can make an article out of it since a lot of us seem to be doing this kind of swap lately.
Getting tuned tomorrow... look for an update!
Anyway please write up some corrections, we can make an article out of it since a lot of us seem to be doing this kind of swap lately.
Maybe I should add more here? I don't know, I wrote it a couple of weeks ago, but forgot about it. I've been getting a lot of questions about various parts of it, so I decided to just put it up so you guys can pick it apart or add to it or whatever. Just post up changes here and I'll add them to it._______How to Build an A6/Y8 Mini-Me________
Head swapping a non-VTEC D series is a pretty common mod, but most people do it with a Z6 head. I decided to use a Y8, and found that though it's similar, there wasn't a lot of information about it. I used the Y8 for a few reasons. First off, it's what I could get in a rush after destroying my stock A6, I picked up an A6 block and a Y8 head. Next, it's better than the Z6 head because it has higher compression and is generally younger/newer. If you want to boost it, the Y8 is supposed to be better than the Z6 head because of the shape of the combustion chamber. It will also bolt up to the A6 block without modification, and you can use the A6 distributor, it has the same legs as the Y8. In this build, I also decided to use D16A1 pistons, aiming for higher compression, and I converted to OBD1.
>>>>Materials and Tools<<<<
Tools marked with a * are optional, not needed for a simple head swap.
As with any job on a CRX/Civic, you'll need a good assortment of metric sockets and wrenches, and a few screwdrivers
*If you're building the motor out of the car, as I did, you want a hoist to get the motor in
gasket scraper and something to clean the block, especially if you have a stock A6 headgasket on there
torque wrench
timing light
*soldering iron, solder, wire, and heat shrink
*cylinder hone
*piston ring compressor
oil and filter, if you are doing new pistons as well make sure to get enough for a few oil changes
Coolant
Y8 head
*A6 Block
*D16A1 Pistons and rods, with new rings
*Adjustable Cam gear (be careful if you're buying used as the older Y8 gears had issues)
*4-wire oxygen sensor (Bosch Universal)
new headgasket, the Y8 headgasket and the Z6 one are identical, but the Y8 one is cheaper. I wouldn't recommend the A6 HG.
timing belt, the Z6 and Y8 belts will both work (again, I believe the Y8 is cheaper)
*P28
*D16Y8 or D16Y7 distributor
*harness side plugs for distributor, VTEC solenoid, VTEC pressure switch
*ECU harness plugs for P28 with some extra wire
*broken or useless OBD0 ECU, I used a PM5 (DX ECU)
and of course... A MANUAL!
>>>>Building the Conversion Harnesses<<<<
It's possible to use an SAFC unit or an RPM switch to acctivate the VTEC. I chose not to do this, I wanted to install the entire thing like it was meant to be done, with factory connectors and run the motor on and OBD1 P28. I also tried to make everything easily removable, I plan on getting another CRX soon and I want to be able to put this one back to stock and swap my motor over to the new car. So before you even touch the car, get all the wiring ready, it will reduce downtime. All connections should be soldered, with heat shrink over the joints. When you are done and know everything works (ie running the car) then go ahead and tape it all to make it look pretty.
First off you want to make the dizzy conversion harness. Go to a junkyard and cut off the harness side plug for the dizzy you are using. In my case this was a D16Y7 dizzy from a 98 Civic CX. It would be ideal to cut the dizzy side plug from an OBD0 car, but I couldn't find one. I decided to solder into the main harness because I didn't have another choice, and it's only 9 wires so it's easy to return to stock. Basically you just need to match colours, here are OBD0, OBD1, and OBD2 dizzy wire colours and functions, these are all verified by me after hours of verifying and checking, don't trust every post you read on Honda Tech! This wiring kept me hung up for a week getting no fuel, but I got straightened out by Ryan (the Ry in Rywire).
OBD0 OBD1 OBD2 Function
Orange Orange Yellow CYP P
Small White White Black CYP M
Orange/Blue Orange/Blue Green TDC P
White/Blue White/Blue Red TDC M
Blue/Green Blue/Green Dark Blue CKP P
Blue/Yellow Blue/Yellow White CKP M
Large White Yellow/Green Yellow/Green ICM
Black/Yellow Black/Yellow Black/Yellow IGN
Blue Blue Light Blue RPM
For the ECU conversion (you don't need this if you are already OBD1, or aren't converting) you need to get the ECU and some length of harness to work with. I pulled a P28 from a 92 EX at the yard, and instead of unclipping the harness I just cut a good length of wires to go with it. I got a junk OBD0 ECU from a friend (these should be free, don't ever pay for a PM5!) and removed the plugs by pulling it apart and desoldering them from the board. Now all you need to do is connect the wires.
For OBD0, the big, 18 pin connector is A. The other two are sort of connected, the first 20-pin one is B and the last one, 16-Pin, is C. For OBD1, They read A B D, A is the largest, a 26-pin connector, B has 16 pins, and D has 22.
The numbers are read this way: Looking at the plug on the wire side, as if it were plugged in, the top left is 1, and below it is 2, next to it is 3. So, odd numbers run across the top and evens across the bottom. It gets a little tricky doing this since you are looking at different sides of the two types of plugs, so be very careful and work slowly. If you need to, put a little masking tape to mark the plug numbers.
Here is the conversion, I skipped unused plugs.
OBD0 Function OBD1 Function
A01 INJ1 A01 INJ1
A02 PG1 A23 PG1
A03 INJ2 A03 INJ2
A04 PG2 A24 PG2
A05 INJ3 A05 INJ3
A06 PCSol A20 PCSol
A07 INJ4 A02 INJ4
A11 EACV A09 IACV
A12 FLR1 A07 FLR1 (Main Relay)
A13 IGP1 A25 IGP1 (MR/resistor box)
A14 FLR2 A08 FLR2
A15 IGP2 B01 IGP2
A16 GND B02 LG2
A18 GND A26 LG1
B01 VBP/Hazard D01 VBU/Hazard
B03 ACC A15 AC Clutch
B04 FANC A12 FANC
B05 ALT A16 ALT
B06 MIL A13 MIL (CEL)
B08 ACS B05 AC Sw
B10 CYP P B11 CYP P
B12 CYP M B12 CYP M
B13 Fusebox B09 Starter
B14 ALT D09 ALT
B15 Ignition A21 ICM
B16 VSS B10 VSS
B17 Ignition A22 ICM
B19 ELD D10 ELD
B20 SCS D04 SCS
C01 CKP P B15 CKP P
C02 CKP M B16 CKP M
C03 TDC P B13 TDC P
C04 TDC M B14 TDC M
C05 IAT D15 IAT
C06 ECT D13 ECT
C07 TPS D11 TPS
C10 BKSW D02 (Brake Switch)
C11 Mil GND (MAP) D17 MAP
C12 SG2 D22 SG2
C13 VCC1 D19 VCC1
C14 SG1 D21 SG1
C15 VCC2 D20 VCC2
C16 O2Sensor D14 PHO2sensor
You will have a few wires left on the OBD1 plugs. You need to run 3 of these into the engine bay. I soldered them onto a plug close to the harness so I could pull the harness out of the car without a long wire running to the plugs.
A04 goes to the VTEC solenoid
A06 goes to the O2 sensor
D06 goes to the VTEC pressure switch
Everything else left on the harness is for things like Automatic transmission and EGR. If you got a harness from an EX manual (where the P28 came from) you should be all set here.
Now, you need to take a break and do something else. Before you put this thing in, you need to check it at least once for continuity. DO NOT just follow the wires, you need to make sure all the connections are good. Take a break in between checks, or have someone else do it, it's very easy to make mistakes. Don't tape it all up until you run the car with it!
Last thing is the O2 sensor wiring. Now, you don't need to go to a 4-wire O2 sensor for OBD1, as long as you keep the sensor in the stock position on the manifold, on the front of the motor. I made the mistake of trying to use the 1-wire on my DC header, where it's located behind the motor. It's better to just get a 4-wire heated O2 sensor in the first place, and you won't be throwing a code 41.
The sensors all seem to have different colours. I used a Bosch universal 4-wire for a civic, and it came with a piece of paper that listed the colours and what their functions were. To avoid confusion I'll use letters.
So you will have 1 colour A wire, 1 colour B wire, and 2 colour C wires. A will be ground and B will be signal, while C is for the heating element. Put the ground to the thermostat ground, if your sensor is behind the motor it's convenient. Splice the signal (B) into the old single wire that was running to the original O2 sensor. The two Cs are non-polar, the heater doesn't need to be in a certain direction. Run one to pin A06 (should be one of your extra wires on the harness), and the other to an ECU power yellow/black wire, I used B01 (OBD1 side), you'll need to tap into it. I would suggest using some kind of quick release connectors for these, so you can take the exhaust out without removing the sensor. Don't solder it together and leave the sensor hanging there while you are going to be installing the motor or head, you could easily break it.
>>>>Getting the new motor ready<<<<
Since I blew a couple holes in my old block, I used a new one, and assembled everything out of the car. If you are just head swapping, a lot of this won't apply. Also, I'm going to assume you can pull and install a motor, that's beyond this article, and something I think 90% of CRX owners have done at one point or another.
This would be a good time to change some old parts, even if you are just head swapping. The timing belt obviously will be new, and you might as well go ahead and do the water pump. I also replaced my clutch and flywheel at this point, since I had the motor out anyway. I won't go into detail on those either, but you should consider doing what you can while it's easy to get to.
So first thing, strip down the old block. In my case this meant removing all the pulleys and the nearly new waterpump. I also took the thermostat housing piece with my relatively new thermostat off my old block. The one on the new block was in rough shape, and didn't even have a thermostat installed. You also may need to get the alternator bracket off, and maybe the AC bracket if you have it.
Now strip down the new block and clean it. Use simple green, or, if you have access to it, a parts washer. You can also pay shops to clean motors, if you want it pristine. I like to keep the motor clean because it's easier and cleaner to work with, and a clean motor in the bay lets you know when things are leaking or wrong. You also want to clean off the mating surface of old gasket material. This is a pain on the A6 block since they used papery gaskets from the factory, so there is often a lot of stuff to scrape/clean off on them.
Start reassembling the block. I put my D16A1 pistons in at this point as well. To put the pistons in, first install the rings in each one. Make sure to check the end gap on the rings as per the manual instructions. I usually do not do this, and this time it got me. I had mismarked rings for a bored D series, and I tried for hours to get them on because I didn't check them. In the end I realized they were wrong and got the right rings. If you've never done it before, installing rings and getting the pistons in can be tricky. Do the wavy oil ring first, and then the two thin ones that go around it. The next ring (second from the top) is usually more coarse and brittle than the others, so be careful with it. The top ring is the easiest. I always use Hastings rings, they come with instructions about which side faces up and which way the gaps should go, so follow them. Some manuals and instructions say to use a piston ring expander, but it's not necessary. I've put many rings on by hand, just get one end in the groove and work it around, be patient and it will go right in.
Now compress the rings around the piston with a piston ring compressor. Let the skirt hang out the bottom a little to make sure it's lined up with the cylinder walls. Set the whole thing sort of on top of the bore, with the skirt inside. Make sure you have a lot of assembly lube or oil on the cylinder walls, and on the piston between it and the ring compressor. Set something soft, like a piece of wood, on top of the piston and hit it quickly (not too hard!) and firmly, it will fall right in. If the compressor isn't tight enough, the rings will catch on the top of the cylinder and you have to start again. I also like to turn the crank so it's as far away from the rod as possible. When you're done, put the new bearings in and put the caps on. Of course, torque everything to spec. If there is one thing you don't want to be wrong on, it's this.
When putting the end cap piece on the bottom, you need to put the thrust bearings in. They do not go in the center journal, as the Haynes manual says, but in the slot between the #3 and #4 cylinders (it will be obvious when you're looking at it). Get the bottom end together and make sure everything is torqued to spec, check twice. Slap that oil pan on and get ready to mount the head.
You should probably rebuild the head before installing it, unless it's known to be good. I didn't have to, but I plan to have the motor back out and rebuild it in a few months, so I wasn't worried about it if it did turn out to have leaky seals or something. You should also have it resurfaced, as you would when replacing a headgasket. In any case, reuilding the head is beyond this article as well, if you want to know how to do it, see my article on rebuilding a D16A6.
So now you have a nice clean block and head. Lay the headgasket on the block and put the head on. I like to tighten the bolts a half turn at a time until they are all to spec, it takes a while but you know it's not going to be wrong. Of course you want to make sure you follow the correct sequence, start in the middle and work outward.
Once you get the head on, you can install the valve cover and the timing belt. The timing belt is going to be a tight squeeze, it's a real pain to fit on, but trust me, it will go. You should make sure your cam timing is perfect before you put it on, because you don't want to be doing it while the motor is in the car. Also, adjust the valve lash now. It will save your back, I've adjusted a lot of Honda valves, and it's many times easier outside of the car, when you can sit down in a chair or something, not leaning way over the low motor.
From here pretty much all you need to do is bolt up the transmission and put it in, I'll let you figure that out.
>>>>It's in the car, now what?<<<<
Now that it's in you might notice a few things. First off, the head is a bit taller than the A6 and it's close to the hood. It will fit, don't worry. You might also notice that the upper radiator hose doesn't fit. You can cut a little bit off the end and rotate it, it will fit fine. The timing belt is also very close to the side motor mount, but it shouldn't touch it.
Now you want to go around the motor and install all the harness plugs and coolant lines, the clutch cable and the distributor, and of course, all the grounds. I can't say enough how important the grounds are, clean them and check them all twice, especially the thermostat housing ground.
You will notice there are two plugs left. One is a single wire, coming off the VTEC solenoid, the other is a 2-pin plug that is identical to the coolant temp sensor, but it's behind the dizzy. Remember those extra wires from the harness? The first one is the VTEC solenoid (A04) and the second clip is the VTEC pressure switch. Run D06 to one wire on it, and ground the other, I used the thermostat ground because it's very close.
Getting tuned tomorrow... look for an update!
