Important notes about this thread:
1. The information in this thread may not apply to your year/engine S12. As such, it is recommended you use the information in this thread in conjuction with information provided in an S12 FSM/180SX FSM
2. This thread will be edited and updated from time to time with information regarding the wiring/components for different years/engine configs of S12s as they can be different. If you find something differnet in your swap from the information provided in this guide, please pm me, an mod, or chat me up on msn messenger, email addy is theultimateinsanemonkeyisinyourhouse@hotmail.com
3. As always, the writer of this guide, and the club that is hosting it on the forum are not responsible for any loss of money, time, loved ones, or valuable limbs that may arise during the long arguious (sp?) battle that is the CA18DET/S12 Swap.
Table of Contents
Section 1: Tools recomended/needed for swap
Section 2: Removing your engines
Section 3: What to do once your engine is removed
Section 4: Wiring
Section 5: Install
Section 6: Misc. recommended components
Section 7: Helpful links with more information
Section 8: Current CA18DET facts and myths
Section 1 Recommended tools for swap Welcome to the exciting world of the 18det/s12 swap. With you just starting out here is an brief list of tools/literature you will need to get going on your swap.
1. An socket set of some kind, doesnt matter which kind as long as its got like 10 mm all the way up to 22mm 23mm or so.
2. An set of open end wrenches, ranging in size as same as the sockets.
3. An set of ratcheting wrenches is recommended, but many times you can get away without.
4. An pipe that will fit over your ratchet handle that you can use as leverage for those more reluctant bolts.
5. Screw driver set with many different sets of bits.
6. Engine hoist, engine stand, jack, and jack stand.
7. S12 fsm for your appropriate year car, and 180SX fsm
8. An digital camera is nice if you run into any problems, or find out something that was originally said on the forum couldnt be done, to prove us wrong.
9. Torque Wrench.
Section 2: Engine Removal 1. Jack up car, drain rad fluid, oil, and transmission fluid.
2. Disconnect rad hoses, unbolt mount holding up driveline before transmission.
3. Set jack under tranny, raise tranny up an bit, then undo transmission mount bolts, slowly let transmission down.
4. lower car, disconnect engine harness, disconnect clutch slave, remove rad.
5. Find an place to hook engine hoist to engine, jack engine up slightly, unbolt engine mounts.
6. Meanuvre engine/transmission out of car and set in corner of shop.
Repeat process for front clip if you purchased front clip, if you have an motorset then dont worry about it.
Section 3: What to do once your engine is removed
You now have your stock engine/trans sitting in the corner of your shop and your ca18det sitting somewhere else in your shop...whats the next step? It depends on your scenario.
Scenario 1, You purchased an front clip, your CA18DET with C transmission are sitting on your shop floor.
First step, remove your 18det from its C transmission, and put your 18det on an engine stand. Next you need to replace the following, timing belt, head gasket, and water pump. Once that is done you need to take your engine off the engine stand, replace the clutch, then bolt it back up to your transmission. If you have some extra money, it is also recommended to replace the exhaust dumpipe at this time to as once the engine is in there is no real room to remove it and replace it...also you can get an larger one then stock.
Scenario 2, You purchased an motor set. First thing you need to do is put your 18det on an engine stand and replace everything that you would in scenario1. Normally with an engine set, they sell you the C transmission that came on the engine. If for some reason your engine is without the transmission just remove your stock transmission and mount it to your CA18DET.
Another thing to note is that on my engine my brackets where the same on my 18det as the ones on my 20e, which looked like this
Your brackets however may look like this, if they do, your stock ca brackets will mount to the block.
Also if you swap an S13 trans into an S12 MkII, it will bolt up to the S12's trans mount, but you will need the front half of an S13 drive shaft and bolt that up to the back half of the S12's. If you swap an S13 trans into an S12 MkI, you will need a custom trans mount. As for the driveshaft, I don't know, but the technique for the MkIIs might work. Or a custom 1 or 2 piece drive shaft may have to be purchased. (thanks to nemesis for mentioning this and needcafors13 for discovering this on his S12/KA drift car.)
Section 4: Wiring Before I go head on into wiring, I think its important to point out the things needed to make everything work. These are things you should look for if you are buying an engine set, or front clip. If you end up having to buy an used harness because you couldnt get one with your engine you will want to ask about these also.
Now naturally the system isnt to much different from the stock system...you have the engine harness, the maf, and the ecu. But you also have an ignitor and an dropping resistor. The dropping resistor looks like this
It is the silver rectangle box on the left. (note, if your harness did not come with an dropping resistor you can use an dsm dropping resistor(1st gen dsm...IE 90 Eagle talon or eclipse), the write up for that is in the myth section.) And here is an pic of an ignitor, it is the silver box with ribbed protrusions on the outside of it above the engine mount
(pic courtesy of umaii naa).
As for harness routing, this is how I have done it on my 85 lhd usdm s12.
I pretty much routed it thru the same way the 20e harness runs. There is an plastic elbow piece inside the 18det harness tho that I removed by untaping the harness, removing it, then retaping the harness. This allowed me to gain an couple of inches on my harness. Now for the fun part...the wiring.
Here are some relays wiring diagrams, The KA/s12 wiring schematic and SR/S13 wiring schematic are less important, but are a good reference, and also are nice to have if you have a friend who might want you to help them with a swap.
Another important thing to remember, that isnt always shown in the wiring diagrams is that you should have a fuse and a fusible link inbettween each relay and its power source. A lot of people right now are just using fuses, and no fusible links and are getting away ok with it, however the fusible link is a good safety precaution to keep your ecu from getting fried.
The below is previous wiring info, and should only be used in comparison with the relay diagrams, follow the diagrams tho, if the below doesnt match them, follow the diagrams instead.Yellow/red wire on the s12 harness goes to the black and red wire on the 18det harness, this is for the fuel pump relay
blue/red wire on the s12 harness goes to the reb and black wire on the 18det harness, this is ecu relay
black/red wire on the s12 harness goes to the red wire on the 18det harness, this is ecu back up power
blue wire on the s12 harness goes to the black/blue/red wire on the 18det harness, this is the main ignition power
green/black wire on the s12 harness goes to the black white wire on the 18det harness, this the ecu power
black/yellow wire on the CA18det harness, which is the idle air valve power, along with the o2 sensor which is the brown wire, both go to any 12 volt switched source.
The neutral switch on the CA which is green/orange goes to the neutral switch on the s12 harness which is also green/orange
For more clarification on the wiring, you should look at the ka/s12 swap and the s13/sr swap. The KA/S12 swap looks like this:
and the s13/sr swap looks like this:
ECU & Dash wiring The colors on the wires that run from the ECU up into the dash matched up perfectly on both the SR ECU harness and the KA dash harness:
Back to Top Wire Color Use Yellow / Red stripe
Tachometer signal
Yellow / Green stripe
Speedometer signal
Orange
Ignition start
Black (may be more than one ground)
Ground
Blue / Green stripe
AC signal
Blue / Black stripe
Water temp signal
On the mk2 s12 there is i believe 2 or 3 white plugs underneath the dash that you need to splice into certain wires into the ecu, but those wires are previously mentioned in the write up. In the mk1 there is one or 2 plugs that you need to splice wires off of.
As of right now I am a little unsure on both mk1 and mk2 plug counts. I havent started on my wiring yet, but as you can see I have almost all of the info. If you have done either swaps, please post up pics and or info for your model/year/engine of s12. If your car started with an mechanical speedometer, your speedo cable will connect right up to the 180sx C transmission, I belive that if you have an digital dash, it doesnt use an mechanical speed sending unit in the transmission so you will need to try to come up with an solution to that. Your stock tachometer tho will not work with the 18det as it sends the signal back off the coilpack differently then the 20e or 18et does from its normal coil. An solution for this is to use 4 IN4004 diodes connected to the coil side of the ignitor, then join them together to the 4 on the tacho side, and join the wire going to the tacho making sure the arrows on the diodes are pointing towards the tachometer and away from the coil.
Section 5: Install The installation of the engine should be pretty straight forward from here. Put the engine/trans back into the bay and install everything back up in the reverse order from how you removed it. There are some components that you will need, and some that are recommended which I will cover in the next section. It is recommended to install your engine, then do the wiring first tho so you dont end up taking to much distance out of the 18det harness. But once the engine is installed and the wiring is done, only thing left to do is have the exhaust made up by an local shop, and pick up a couple components to make the car run a bit better.
Section 6: Recommended Components Stock the 180SX came with an smic (side mount intercooler), now this is better then having no intercooler, but it is an good idea to upgrade to an fmic, especially if you install an boost controller and start running higher boost then stock. And if you only bought an motorset...you will prolly not even have the smic. An BOV (blow off valve) is also an good thing to have. Along with an oil cooler, and an oil catch can. It is possible to also use either the 180sx rad, or the 20e rad, here are some pics of my 180sx rad install:
It is also recommended to pick up an aftermarket oil temp gauge, and boost gauge.
Section 7: Helpful links with more information
These are all on
www.nicoclub.com in the CA section stickied by one of our own club s12 members who happens to be an moderator on nicoclub.com, needcafors13
CA18DET Engine Facts
http://forums.nicoclub.com/zerothread?id=114950 FAQ's, Common upgrades, D.I.Y. upgrades, no-no's, etc…
http://forums.nicoclub.com/zerothread?id=114953 Part Numbers / Crossover Parts between USDM and JDM CA18's
http://forums.nicoclub.com/zerothread?id=114952 CA18DET Wiring Information and FSM
http://forums.nicoclub.com/zerothread?id=114956 Catch Can Installation Info:
http://forums.nicoclub.com/zerothread?id=13750 Other links tho to look at for more information regarding variations in european and australian engines would be
http://www.sxoc.com and the australian s12 site.
Section 8: Current CA18DET Myths: There are a couple of myths floating around this forum and others about certain things regarding the 18det.
One of them is that an dropping resistor from an 1st generation dsm (IE eagle talon, or eclipse, awd turbo.) will work with the 18det harness. As of yet, no one has given me anymore solid info...IE the part number for an dsm dropping resistor, and wether or not it has to be wired up any differently, or if it will plug right into the harness.
[Edit] This myth has been resolved, an big thanks goes out to MasterZenki off of nico for doing an quick write up on how to make the dsm dropping resistor work with the ca18det harness...and here it is.
So if for some reason your harness didnt come without an dropping resistor this will work for you.
Another myth, that was floating around, but has been proved wrong is that the mk2 rsx in japan didnt come with an CA18DET. However, it did come with an 18det, and also the s12 in japan was built into the early 90s. The s12 18det differs from the 180sx 18det in that its throttle body goes over the valve cover like the 18et. The engine also has 8 intake runners and came non intercooled. The engine used one coil pack to power all 4 plugs instead of individual coil packs.
Another myth that was going around on this forum was that the 18det wouldnt bolt up to the B transmission. Despite many australian members claiming that it bolted up fine. I myself didnt know for sure...and knowing what I know about the car I thought it possible that the B tranny in australia might of been different then the usdm or canadian, but my b tranny bolted up to my block without issue.
If you have an myth, send me an pm and I will add it to this post.