diy k20z3 swap into ep3
mods, you can delete the other thread, forgot there was a diy section
ok so i have finally gotten some time to get this swap started... i apologize for some of the pictures being blurry, not sure if i had my wife's dslr on the wrong setting or what, i need a point a shoot camera lol.
shall we get started?
first of all...disconnect battery, drain coolant, tranny fluid, and oil if you want, i did not drain oil.
i also went ahead and disconnected the charge harness from the fuse box.
after removing stock airbox you are able to see alot more of what needs to be removed.
at this point i jacked the car up so i could remove the bumper, this may or may not be necessary but i found it much easier to do so. I also removed the radiator support that has the hood release mechanism on it, you have to twist it but the cable can be detached.
at this point i removed the radiator. be careful! there are several wires and plugs that are attached to the radiator fans that will not let you pull it out so dont force it!
ok from here i disconnected shift linkage. i also removed axles, i justed poped them out of transmission and halfshaft and pushed them out of the way, so i could roll the car in and out easily. also dont forget about the exhaust, i just removed the two bolts going from the manifold to the downpipe. from there just make sure you unplug everything that will keep the engine from coming out, or at this point you can disconnect the two plugs on ecu and one right next to it that are the engine harness and pull them gently through the firewall. i did this because i like to run the harness on the engine out of the car to make it look nice and neat. this isnt necessary but some of the plugs will be hard to get to with the engine in the bay. disconnect all hoses that prevent removal. this part is pretty straight forward... i hooked up the hoist and put a little bit of tension on the engine, then removed all engine mounts... total of 4 of them, front, back, left, right obviously.
ok at this point i am going to try and point out the immediate differences. pretty much everything on the k20z3 needs removed, and your a3 stuff be put on. if i wasnt sure... i put the a3 stuff on. i dont want to have to hack anything so thats what i did. the front mount is the only mount that is ok i believe. the tranny, timing side engine mount, and rear mount all need swapped over. my swap did not come with accessories, so i just put my a3 ones on with no issues. i cannot say if the z3 parts will work as i didnt have them.
z3 front of engine
a3 front of engine
notice the difference in the thermostat housing. i have not quite figured this one out, they are practically identical and should swap out but for some reason i am having a hard time putting the a3 housing on the z3, i will post definitive information as soon as i figure it out.
a3 transmission mounts/linkage
z3 transmission mounts/linkage
as we all already know, the shifter mechanism is backwards on the z3 and you need to swap over the ep3 mechanism. although if you would like to retain reverse lockout, you will need to use a rsx type s unit. although i have an idea i am going to try out, i will post up if i can get it to work. the housing that the reverse lockout solenoid bolts to is identical on the a3 and z3, the a3 not having it the holes are not tapped, and removal of the z3 solenoid will have to be done to see if and what metal needs removed etc... other than that the obvious mount difference. i also switched the slave cylinder from the a3 because of the clutch line, it is much different and i didnt feel comfortable bending them too much. the reason is the hydraulic line on the slave cylinder is on opposite sides. just to keep it neat i used a3. i also swapped the metal sticking up, i believe this is for the airbox as i intend to still use the factory airbox.
some coolant line differences on the head, these are for the heater core so just use them accordingly when reinstalling.
z3 head
a3 head
ok on to the timing chain side
a3
z3
basically make the z3 look like the a3, pictures def help with this. the crank pully looks a little smaller on the z3, but i still used the a3 belt and it seems to work fine, it is not too lose or anything.
ok so thats all for today. i started work around 12 in the afternoon, and finished at 7. with lots of beer and dip breaks, so this could easily be done much faster, but i like to take my time. having the right tools and power/air tools helps alot too.
ok next day
so i got most everything swapped from the a3 to the z3. here is a photo of what the timing chain side looks like with all the a3 accessories on z3.
i had problems with swapping the thermostat housing, but after some tweaking of the metal tube that runs to it i got it lined up where i felt comfortable with it not leaking.
to put the rear mount from the a3 onto the z3 you have to remove the exhaust manifold from the z3. there is not clearance because of the heat shields. i removed the one on the manifold and the one over the halfshaft. both need to be removed for the manifold to be removed. you also need to install the a3 manifold so the downpipe lines up.
while the manifold was off i wanted to show the differences in the two. there will be a great increase when using a header, the a3 manifold really looks like it is going to choke the z3
z3 on left
also the port sizes on the z3 are quite larger than the a3.
a3
z3
z3
a3
i used the a3 gasket because the bore was big enough for the z3 head without hindering flow and it fit the a3 manifold better.
at this point i moved to the transmission and removed the shift arm mechanisms from both of the transmissions. differences below.
a3
z3
what i did was remove the metal from the a3 housing to make it looked like the z3 housing, tapped the holes, slotted the shift arm shaft. although i goobed it up by cutting the slot in the wrong spot and when engaged let me go to 1st and 2nd and thats all. it will work you just have to do it correctly, i may do it correctly soon, im really scared of hitting reverse on the highway. i know i could just use an a2 mechanism but i just wanted to see if this would work. if you want pictures of this just pm me.
also...
i broke the stupid air assist valve on both of the engines, these things are stupid fragile so be careful. after reading up they really dont do all that much so i just bypassed it. here is how to do that.
the hose runs to the middle of the manifold , i just put a screw into it to seal it, just make sure it is a tight fit.
ok for the idle air control valve, i didnt have the correct hoses so i bypassed the coolant to it. it is still electronically controlled so i wasnt too concerned.
the lines that run to it i ran into each other
and on the throttle body i just did the same thing.
now for installing the shift mechanism from the a3 onto the z3. dont forget about the 8mm hex screw on the side of the transmission directly in front of the mechanism, this has to be removed! but two holes line up, the front two, the back left doesnt at all just fill it with hondabond or rtv. the one on the back right needs to be drilled/tapped there is a spot casted for it. i guess you could just have the two scews but why risk it it is fairly easy to tap threads.
i installed it and forgot to remove the shift cable bracket. the mechanism needs to be off when removing the bracket if you have the lockout solenoid on the a3 mechanism. if that makes any sense...but you need to use the a3 one basically.
i also used the slave cylinder and clutch line from the a3, the z3 clutch line ran a different route and i didnt like it. and i wanted it to bolt up just like i removed it. the slave cylinder inlet port is on the other side for the z3.
ok so that's all for now, some things i did not picture are wiring up the digital speed converter, this is pretty straight forward , if you cant figure that out you should NOT be doing this swap. and installing the throttle body adapter and throttle body, just forgot pictures, will show pictures of it installed tomorrow. also i ran the wiring harness on the z3. also straight forward.
all that is left is to switch shift cable bracket and reinstall into car! woot
anybody has any questions or anything feel free to pm me! will help as much as possible
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