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View Full Version : diy k20z3 swap into ep3



4g638u
02-20-2011, 05:59 PM
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?
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1913.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1914.jpg

first of all...disconnect battery, drain coolant, tranny fluid, and oil if you want, i did not drain oil.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1915.jpg

i also went ahead and disconnected the charge harness from the fuse box.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1916.jpg

after removing stock airbox you are able to see alot more of what needs to be removed.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1917.jpg

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.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1918.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1919.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1921.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1923.jpg

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!
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1925.jpg

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.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1930.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1931.jpg

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
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1937.jpg

a3 front of engine
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1938.jpg

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
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1942.jpg

z3 transmission mounts/linkage
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1943.jpg

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
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1944.jpg

a3 head
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1946.jpg

ok on to the timing chain side

a3
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1947.jpg

z3
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/IMG_1948.jpg

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.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1951.jpg

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.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1953.jpg

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.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1955.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1958.jpg

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
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1962.jpg

also the port sizes on the z3 are quite larger than the a3.

a3
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1961.jpg

z3
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1956.jpg

z3
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1960.jpg

a3
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1959.jpg

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.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1963.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1975.jpg

at this point i moved to the transmission and removed the shift arm mechanisms from both of the transmissions. differences below.

a3
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1965.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1966.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1968.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1969.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1973.jpg

z3
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1970.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1971.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1972.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1974.jpg

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.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1973.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1974.jpg


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.

http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1977.jpg

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.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1978.jpg


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
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1979.jpg

and on the throttle body i just did the same thing.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1984.jpg

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.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1980.jpg

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.
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1982.jpg
http://i915.photobucket.com/albums/ac353/michaelmckinley0324/ep3%20swap/day%20two/IMG_1983.jpg

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

K24cb7coupe
02-21-2011, 09:03 AM
nice write up, looks like a fun swap!

msanch24
02-21-2011, 10:56 AM
good work man! you'll surprise some people with the stock looking ep3!

Sneezin
02-21-2011, 12:56 PM
great coverage,,,+1

DeeAOne
02-21-2011, 01:58 PM
Nice write up! I might need this soon. :goodjob:

4g638u
03-18-2011, 04:14 PM
transmission shop is finally putting my car back together... almost a month later, oh well, but the bearings had gone bad causing 6th gear and gearset to constantly press against eachother wearing them down.. so all new bearings and a 6th gear set/gear , all together about 280 in parts.. not too bad. just glad i didnt have to replace alot more. will post up more pictures and stuff whenever i get it back...

4g638u
04-06-2011, 11:46 PM
got the car back.... the bearings went bad in the transmission and caused 6th gear to constantly press against eachother and wear down, so after all new bearings, a new 6th gear and gearset they put the tranny back in to find out the clutch was shot....anybody want to guess what brand clutch was in there? i'll give you a hint... the disc itself was a puck and literally in 20 pieces. so after a new clutch all is well.

i did have a few quirks that i had to work with... first the gasket that the obx tb adapter came with are garbage, they create huge vacuum leaks... so dont use them just cut your own like i did or go buy honda gaskets. OBX FTL on that part.

also i had a charging problem which i traced down to a plug that runs under the intake manifold by the starter, i had it pressed in but not clicked together causing the alternator to basically freewheel and not send any voltage throughout the system. I put the harness on the engine before i put the engine in the car and must have just overlooked it. just double check all plugs is all that i would recommend to do.

as far as the swap in the car i love it. i was really hesitant going into 6th my first couple times because i do not have an operational reverse lockout solenoid , but you really have to go to the right to get into reverse, so i think i am not going to worry about getting a rsx shifter mechanism. the ep3 is fine just dont be a moron.

i am running the k20a2 cold air kalibration and have no knock running 93 octane. i absolutely love having real vtec, it does not have the night/day vtec engagement of the b series because of the smoother powerband the k offers and the tune but it definitely is a different beast. i think it crosses at about 6k maybe a little less and i rev to about 8.6k or so, i do not drop out of vtec engagement in any gear. i have found myself going from a stop in 2nd, shifting to 4th then 6th for normal driving, the gears are so close it feels 1-2-4 in the a3.

i am really surprised that the z3 performs as well as it does with me running the more restrictive exhaust manifold and having the stock exhaust throughout. i did manage to put a spectre intake on. i just made my own to the correct angle. im sure its not the best intake to run but it gets the job done and doesnt rub on anything. i just used the universal honda kit and took out on of the straight sections. fits perfect.

next plans are a race header, having an exhaust shop run prolly 3 inch from the collector to my factory muffler. i really like the way the stock muffler looks on the ep3 and despise fart cannons. i think that will really wake the car up with a good tune. i imagine i will have to put a resonator in the pipe the shop puts in to prevent the car from being overly loud.

joeslow1212
04-08-2011, 05:41 PM
Good luck... Do it right the first time :)

CRXdelsol
04-08-2011, 07:26 PM
reps for taking the time to do a write up

jfryer496
04-14-2011, 10:17 PM
yeah thats alot of time taking pics inbetween the swap. good job

gsrteg
04-15-2011, 12:10 AM
nice write up! Glad all went well. Reps for good diy tutorial. :)

4g638u
04-20-2011, 07:16 PM
thanks for the positive comments guys! here are some photos of the finished product.

http://i915.photobucket.com/albums/ac353/michaelmckinley0324/paint%20picutres/IMG_2282.jpg

http://i915.photobucket.com/albums/ac353/michaelmckinley0324/paint%20picutres/IMG_2283.jpg

http://i915.photobucket.com/albums/ac353/michaelmckinley0324/paint%20picutres/IMG_2285.jpg

http://i915.photobucket.com/albums/ac353/michaelmckinley0324/paint%20picutres/IMG_2290.jpg

http://i915.photobucket.com/albums/ac353/michaelmckinley0324/paint%20picutres/IMG_2284.jpg