s52 e46

[E36M3LX]

Hey guys, I've been wanting to make a quick thread of my s52 e46 track/drift car. most of the info also applies to swapping m50/m52 or s50 into an e46. I'm also going to share how I built a custom body wiring harness for the car using the x20 engine wire harness plug. I was able to use a lot of e36 parts for this build, so i will try to explain what swaps over for anyone else who wants to do the switch.

[E36M3LX]

why switch from e36 to e46? simple.. its a bigger, better, lighter, stronger chassis. from the factory, it may be SLIGHTLY heavier than e36, but that just means there is more weight to strip out. and BMW claims the e46 chassis is 70% more rigid than e36. and maybe you already have a built e36 that you can swap a lot of parts over into the e46.

why run an m50/52 or s50/52 in an e46? less things to break and, depending which route you take, cheaper. I am a huge fan of the m54b30, but with all the e46 motors being aluminum block, a lot of people tend to favor the old iron blocks from the e36. in my opinion, m54s are cool if you are NA, but for boost, I'd recommend an iron block motor.

I managed to make money back after selling off my old e36 parts that i couldn't use on the e46. I paid $600 for the e46 and sold my old e36 diff for 300, rear old subframe for 250 and old carbon fiber hood for 200. and i still have a few parts left over that i can sell, let me know if you need anything.

[jalopi]

70% more rigid than e36

this sent me down a google search rabbit hole. i found an interesting list of cars

http://youwheel.com/home/2016/06/20/...ehensive-list/

i wonder if that figure came from comparing an e36 m3 to an e46 sedan with fixed back seats?

the rigidity difference between models with folding seats and non-folding seats is pretty substantial. i wonder how close an e36 sedan w/o folding seats comes to the e46s' numbers

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to comment on your build - is this gonna be an untagged track-only car? i remember hearing, years ago, that cali only approved of engine swaps when the donor engine came out of a newer vehicle

[E36M3LX]

this sent me down a google search rabbit hole. i found an interesting list of cars

http://youwheel.com/home/2016/06/20/...ehensive-list/

i wonder if that figure came from comparing an e36 m3 to an e46 sedan with fixed back seats?

the rigidity difference between models with folding seats and non-folding seats is pretty substantial. i wonder how close an e36 sedan w/o folding seats comes to the e46s' numbers

__________________________________



to comment on your build - is this gonna be an untagged track-only car? i remember hearing, years ago, that cali only approved of engine swaps when the donor engine came out of a newer vehicle

You would! haha that is a pretty cool article though.

this is indeed a track-only car. i think you are right about the CA motor swap thing. but if i wanted to street drive it, the only thing i would need to do is get it past CA SMOG(emissions testing) and i would be good to go. SMOG would be easy, it is very easy to find techs that will pass anything. instead of $50 every two years, it would be 200-300 every two years to pass CA SMOG.

[gdavid]

I have heard that the m/s50&52 heads can be modified to accept dual vanos with some machining and TIG welding, I have wondered it this would be a good way to get a easy to boost motor in an e46. Run the engine off of the e46 dme with a tune and reroute the coolant lines as needed to make it work.By the time it is said and done, a S54 may be a cheaper option but it is something I have thought about.

[E36M3LX]

I have heard that the m/s50&52 heads can be modified to accept dual vanos with some machining and TIG welding, I have wondered it this would be a good way to get a easy to boost motor in an e46. Run the engine off of the e46 dme with a tune and reroute the coolant lines as needed to make it work.By the time it is said and done, a S54 may be a cheaper option but it is something I have thought about.

yes i believe this can be done. i have thought about it too, but i think most people come to the conclusion that all the extra work is just not worth it. i really dont think there is much power difference in the end, it is only better power.

[E36M3LX]

so when it came time to put in the s52 from my old e36 into the new e46, i had no idea what mounts i needed. i knew that the rubber/poly/solid motor/trans mounts would work because those are interchangeable between e36 and e46, but i couldn't find info of what motor mount arms and trans cross member that i needed. i also was not sure of which driveshaft or shifter linkage i needed to use.

if you look closely in the pictures, you can see my reason for doing this swap. my old e36 was crashed hard enough to bend the frame rails more than i ever want to know. i made sure that wasn't the case with the new e46, but i did overlook a common failure point when i bought the e46.

[E36M3LX]

i ended up using e46 motor mount arms and 5 speed e46 transmission cross member. everything bolted up to the motor/trans and the s52/zf fit right into the e46. my next problem was the drive shaft and shifter stuff. i got the 4 bolt driveshaft and shift linkages from a manual trans e46 328i(330 diff and driveshaft is 6 bolt). tried installing the driveshaft but the front section was about 16mm too long, placing the csb behind the studs in the trans tunnel. also, the front half of the driveshaft where it bolts to the flex disk, the bolt pattern was too small. thankfully the rest of the driveshaft fit okay because of the play in the slip-joint and then the rear section just bolts straight to the diff.

[E36M3LX]

so to fix these two issues for the driveshaft i did some research(thanks realoem.com) and found that i could use the flex disk that rev-shit makes for e30 motor-swaps that use e36 zf transmissions. the zf trans uses a huge output flange that doesn't always match other 5 speed driveshafts. most e30, 325i e36, and most manual e46 all use the smaller flange that is too small for the bigger flange on the e36 zf trans. and then for the driveshaft center support bearing, i just drilled two holes and used two riv-nuts with bolts and also fabbed two brackets that bolt to both the pre-existing csb studs then bolts to the new riv-nuts/bolts i just installed(sorry, no pictures of that yet).

[E36M3LX]

then onto the shifter stuff... the shift carrier from a 5 speed e46 centered the shifter perfectly, but the matching selector rod was 16mm too long like the driveshaft. i am still not sure why that happened, i think maybe the different motor moved the trans back? but how did the trans x member line up perfectly? and why did the shift carrier line up perfect? anyways, easy fix, just measured, cut and welded the selector rod and shifter was good. one of the options for OE short shifter for e46 is the shifter from a manual e60 FYI.

I was also able to re-use my old broke-bitch seats and seat brackets from the e36. i just had to elongate the holes a bit.

[RandomHero27]

good write up.

[lbennyboobool]

nice

[E36M3LX]

thanks guys ^^^

[E36M3LX]

after getting the motor in and the rest of the drive train, it was time for the wiring. i have been studying automotive electrical for work so i was confident i could figure it out, but was still worried because this was my first real wiring project. that basically means there are many many many things that i wish i did differently. so please just use this as a guide(at your own risk) and i will try to explain the things i would do differently for my next chassis harness.

this info is already out there somewhere in the interwebs, but this is how i figured it out. i started with research and reading pin outs of the x20 engine harness plug. after reading all of the pins in the x20, i figured i might only need two wires from the x20 to get the s52 to start. for obd2, EWS NEEDS to be deleted from the DME via tune for the engine to start. there is no other way. also, the fuel pump needs 12 volts for the car to start. so i determined that i would try using pin 21 as the ignition or "ECU power" and pin 18 for a starter signal. after reading through wiring schematics i decided to give the ignition wire 15 amps and the starter signal wire 5 amps.

so.... EWS tuned out of DME, 12 volts to fuel pump, put a toggle switch for the ignition wire, and push-start switch for the starter wire and it started right up!! if anyone needs more specific advice for electrical just ask away, i don't know everything but i can help you not burn your car to the ground.

[E36M3LX]

so that's all that i needed to start the car, but there are also other important things you might want/need from the x20; alternator signal wire, data link connector and oil pressure. i will be running all aftermarket gauges, but used pin 23 for the oil pressure signal. it is just a ground that needs to go to a small light with two connections. the other wire for the light goes to the fuse block and i gave that wire 5 amps. FYI - stock fuel pump needs 15 amps and most aftermarket fuel pumps can handle around 30 amps.

i use pin 13 from the x20 for the signal for the fuel pump relay. some people prefer the fuel pump on its own switch, but i like the simplicity of starting my car with one switch and one button. i can easily bypass the fuel pump signal wire and jumper the fuel pump at anytime for diagnostic reasons, etc.

the alternator will not charge the battery without the alternator signal wire pin 25. that wire is basically a ground at key on, engine off, and then when the engine is running it becomes +12v. so i ran a wire from pin 25 to a small indicator light with two connections on the back and then the other wire from the light went to a +12v terminal on the fuse block. i gave that wire 5 amps. so when you are key on, engine off, the alternator light will be on because pin 25 is acting as a ground at that time. then when you start the car, pin 25 is no longer a ground and the light will turn off. if the light is still on when the engine is running, alternator is not charging.


for the data link connector, i ran 15 amps switched power to pin 22 and that allows me to use the data link connector under the hood so i can scan the car and the tuner can communicate with the DME while it is in the car.

so for my switch panel; blue light is oil pressure, green light is battery light(alternator signal wire), upper right switch is main power(key on), the two switches to the left of that are my fan and headlight/tail light switches and the button on the bottom left is the push-start.

[E36M3LX]

there are many ways to wire a car. my approach was to use two fuse blocks. one is constant power and the other is switched power. each fuse block is rated to 100 amps each so for the switched power fuse block, i used a 100 amp relay on a switch which is basically my "key on". so anything that needs key on power goes to that fuse block and anything that needs constant +12v went to the other fuse block. its really as simple as it sounds.

the brake lights were a bit of a problem. i was hoping i could use the e46 brake light switch but it was not the typical brake light switch. it looked like it probably communicates with a module and then that module sends the signal for brake lights, etc. so first thing i do is check to see if my e36 brake light switch would work, and sure enough, it was a perfect fit and was the old-school style where you can just give it constant +12v to one pin and then when the switch is open(brake pedal depressed), another pin lets the +12v out to the brake lights. i used OE brake light stuff, just re-used the connectors and grounded each housing individually to the car.

next time around i will be using better fuse blocks, better connectors, solder/heat shrink everything and i really should have put all the fuse blocks, main power fuse, fuel pump and fan relays all in one place. also i should have used way more wiring. i thought i was making wires long enough but i should have used more just so i could route the wires a little cleaner and easier. when it comes to electrical, there are many tricks to the trade!

[328 Power 04]

Good work no doubt.
I wish you would have reached out before all that hard work though.
I have ran the S52 seamlessly with the E46 MS42 or MS43 dme on stock wiring harness. This including working cruise control, DSC, everything (for those that care for it).

- - - Updated - - -

And I apologize ahead of time, it's not a way to undermine your work.
(re-read over it, and I hope it doesn't carry that vibe)

[E36M3LX]

Good work no doubt.
I wish you would have reached out before all that hard work though.
I have ran the S52 seamlessly with the E46 MS42 or MS43 dme on stock wiring harness. This including working cruise control, DSC, everything (for those that care for it).

- - - Updated - - -

And I apologize ahead of time, it's not a way to undermine your work.
(re-read over it, and I hope it doesn't carry that vibe)

not a problem man! thank you for chiming in. so what engine wire harness are you using for s52 and e46 dme?? please feel free to explain or post a link.

just a reminder; you are in the drifting sub-forum. the whole reason this chassis swap is happening is because i was prepping my e36 m3 for a roll cage. half way through ripping out the chassis wiring harness on the e36, i realized that this was going to be a lot of work and i decided i should probably be doing all of this work to a clean chassis, not a previously wrecked chassis.

and if you are referring to the wiring as "hard work", i have to disagree. i work on cars for a living and i absolutely love the electrical aspect of it. its a nice break from all the grease and wrenches.

[E36M3LX]

so now that i got the motor in and running and the drive-train is all hooked up, it was time for the suspension and radiator. e46 has a different radiator than e36 so i just re-used the radiator from the e36 and made custom mounts for it. i was able to fit it under the e46 core support, but this placed it a little lower than it would be in an e36. I made sure the hoses still fit so i can just use all OE stuff.

e36 was fully stripped down at this point so off to the crusher it goes. I had that car for more than 6 years, I was sad to see it go.

[E36M3LX]

i think every e46 is supposed to have an "x brace" similar to what some e36 have from the factory. this piece did not fit with the s52 installed, the oil pan is much bigger on the s52 . i threw it on a press and massaged a small section of the x brace for more clearance and was good to go. sorry, no pictures of this.

i was able to fit quite a bit of suspension from the e36 to the e46. i picked up some adjustable lolli pops from SLR because the e36 lolli pops don't fit. front coil overs fit with e36 spindles and brake lines were interchangeable. i needed different top hats though for the right adjustment. i just left all of my SLR stuff on the struts. FYI the ideal e36 spindle you want for e46 is from a non-m e36. i have 96-99 m3 spindles and there is too much positive caster. i had to adjust the lolli pops quite a bit to compensate. if the car doesn't feel good in drift, first thing i will be doing is e36 non m spindles so i can get the lolli pops back to where they should be.

on my e36 i was running dual calipers using massive brakes' caliper brackets with wilwood calipers. i will be re-using the rear brakes since the e36 m3 stuff will swap over and fortunately the only other thing i need to replace is the secondary caliper brackets. everything else i will be using again on the e46.

for the rear suspension i was able to re-use the rear lower camber arms, trailing arm bushings/brackets and the coil springs and shocks. rear shock mount reinforcements are also interchangeable. e46 has aluminum upper arms for the coil spring. these are known to fail with aftermarket suspension so i picked up some reinforcements for those. unfortunately, no sub-frame or diff bushings are interchangeable.

this i when i noticed the damage on one of the rear sub-frame mounting points. i've read that this is a common failure with e46 and there was actually a recall for it. i'm not sure if it is still active, but i've heard they just weld in the same weak trunk floor. luckily it was only one of the four mounting points that was like this, the others had no signs of cracking.

[protomor]

The factory recall is long over. But if this one is that demolished, the others are most certainly cracked. You just can't see it yet. Mine had a few cracks that I only found after I wire wheeled away the under coating. Get a reinforcement kit and go to town.

[Novablue454]

yeah, that's pretty bad. I'd drop that subframe before I put much more work in the car. Th "fix" is to weld in a whole new trunk floor, than do a reinforcement kit. I'v seen more than one person walk away from a chassis over that.

What's too much caster? Is there such a thing?

[E36M3LX]

thanks for the heads-up guys. I deal with mostly old cars at my work, so I have some experience with damage similar to this. luckily, it was pretty easy. i was able to tack weld the broken piece back into place from the inside the trunk. it fit perfectly into where it ripped out from. i tack welded from the inside first, then formed everything into place from the bottom and put some more tacks down from underneath. i used the sub-frame to make sure everything lined up and the fitment was good on the first attempt.

[E36M3LX]

it was a lot of welding and grinding. i made sure to follow all the cracks and stopped them from growing. I thoroughly checked all other sub-frame mounting points for cracks and miraculously, there were no other cracks to be found. after fixing the damage, on went the reinforcements.

i still need to reinforce all 4 sub-frame mounting points from inside the car. i will be sure to share how i do it. i wish i could tie it into a roll cage but i'm thinking about building the cage using the formula drift rule-book and i don't think they allow that.

[protomor]

That was fast and thorough. Thank you and yes please do keep us updated with the rest. Very interested.