My e34 swap, mods, experiences and advice

[Brandon J]

Hello everyone. I thought I would share some things about my experience and my e34.

The 1993 525i 5spd:
It started life as a stock M50tu.
Engine: added S50 cams, S52 springs and retainers, 540MAF, larger injectors, 3 custom chips, custom intake and heatshield
Drivetrain: lightweight aluminum (rattling) flywheel, 3.46 40%LS Blanton Diff, short shift kit
Suspension: Green RD springs and custom shocks. Changed those out for Sachs kit. Added Green RD swaybars. Then added Dinan fixed camber plates. After the suspension was completely broken-in, ~a year, I trimmed the stock bumpstops a little at a time until it was right as far as how low I wanted the car to go on the backside of a bump. The stock bumpstops are softer so I could get a more progressive "squish" rather than a harsher one from harder foam.

Extras: I then added M5 brakes, rear headrests b/c the passengers were hurting their necks, and hardwired a V1. I had 17in 7spoke e39 540i BBS wheels and they were the strongest wheels I have used. I had 16in R-compound on e31 wheels and snow tires on another set of e31 wheels.

One time, I was running the streets of Chicago with my R-compunds. I met an M-coupe at a light. I revved my puppy to ~3000rpm and dropped it. I felt the shift knob twist with the drivetrain and without tire squeal I lunged forward. 1-2-3rd gear and he M-coupe could not get passed the front door. I had to work that engine/drivetrain combo a lot to get it to perform and the rattling was annoying.

I overreved the engine one day and.....

I was lucky as I wanted to drop in an S50 or S52. For the same price of an S50 and tranny combo, I had pickings from a rolled over e34 M5.

Now S38B36:
Engine: cam gears to move torque lower in the rpm, 4 different chips I change around,
Drivetrain: I had the M5 driveshaft custom made to mate to my small diff. Now, I don't have to change rear subframes and I have a bigger litter to chose from if I ever need a diff. It can handle the power. I am running 3.91LS, short shift kit.
Suspension is the same. S38 added ~65-70lbs to the car overall.


Okay, so look how I added the suspension in stages and left the door open to add upgrades and even account for the extra weight of the M5 running gear. I would go matched spring/shock combo, then swaybars, then fixed camber plates. In that order exactly. We have long wheelbases and the camber plates make a difference in balancing the car out. Turns are actually more controlled when going over bumps. The little bit of extra height from the plates help accomodate for the S38 extra weight.

I then added staggered T-stars with 245/45-17 and 255/40-17 rear Pilot sports. Why 245/45-17 front? Well, balancing the ride, braking, and suspension, the slightly more shoulder and width rubber cushions small bumps, small imperfections on straights and turns, has more rubber contact, and the larger diameter helps move braking to the rear with the extra 255 rubber. It brakes real smooth and balanced also because the front won't lock-up pre-eminently. I have over 25k of very hard driving miles on the tires with the horrible potholes of chicago. I bet I can go another 5k miles. The front outer shoulder wear is so common on the 5-series and I countered that with camber plates. The front of my tires are worn evenly from driving because the tire is flatter during the motion that wears it out the fastest, the turns. Because of these choices, the tires now balance with the suspension and brakes.

So, overall, I have a very forgiving, sticky, good travel, balanced, keep the tire contact on the road suspension. I can dance the car easily just like Sabine. Really. I am not that good on the track, the car is. I can push the front or break the rear in a very controlled manner while driving over 60mph on a turn. Predictable, controlled, safe. My Sachs kit has over 50k miles on it.

Recommendations:
Think balance and expandability. I did the mods, but recommend to just save and buy better. More dependable, more power, smoother, and less time tinkering. I have been told I have the best combo suspension by every e34 owner who rides in it. It is tuned as a super street car, not a track car. I drove it during the winter, on horrible streets, over 150mph, as a daily driver, on the track, autocrossing, with summer/winter/R-compound/all season tires, 15in, 16in, 17in wheels, etc. If you do this suspension combo, you won't go back.

Make good choices and you will save money overall. Good tires - go Michelin or equivalent, good matched shocks/springs, matched sway bars with adjustment for balancing, good camber plates, good M5 thrust bushings. Save money by doing the work yourself.

Take what ever info you want. Ignore what ever info you don't want. I just hope this helps those of you who want it. I might have more info that I am not willing to share and I may have more mods I am not willing to share about...especially when it comes to making power with the S38. Okay, tired fingers...

Enjoy your e34 to its fullest potential!

Mine is the first white one: (thanks to snopro67 for the pic)

http://i174.photobucket.com/albums/w106/snopro67/DSCN2386.jpg

[BigKriss]

nice write up!

[Denton]

Nice!

The Sachs kit, is that RD springs and Sachs shocks? Also, what brand are your bumpstops? Did you do 3mm spring pads?

Thanks,
Denton

[repenttokyo]

thanks brandon - this is kind of what I was asking you in the other thread. I have been trying to decide between and S52 and an S38. I know that the S38 is going to be more expensive in the long run, but I also feel that it is going to be more satisfying. Will the S38 mate with the M50 5 speed transmission? Does anything need to be moved in the engine bay?

I have done a search several times, but I can't find any threads specifically about this swap.

[Jon K]

I very badly want to do an S38 swap also but for other reasons. Brandon I want to race your car! Battle of the freaked out 525i

[Brandon J]

THe only reason I was able to do the S38 swap is because I was at the right time at the right place. If the M5 parts wre not available, then I would have gotten the S52. Now if you have an M50, pre build date Aug/92, then doing an S50 or S52 swap needs more parts. But if you do have an M50, then the manual tranny can handle the power. Same manual tranny as the M3.

If you have a M50tu, then the swap is easier. You simply swap the necessary OBDI parts from your current engine over to the S52. It will bolt on to the tranny and the tranny can handle the power. You just can't add a ton more torque. You can even use your own computer and simply purchase an OBDI performance chip for the M3. I think they also make chips for OBDI conversion S52s.

So, make sure the suspension, brakes, an tires are up to the task before adding a much bigger power jump. Then look for an S52 and it really is as basic as it sounds. Swap the long blocks and the ancilliaries. When the block is out. you can do an M3 clutch and flywheel conversion. I suggest an M3 one because there is already more surface area and clamping force built in. I have driven sport clutches and they do wear out your left leg from all that foot pressure they demand. The M3 will be a little firmer, but not nearly as bad as say a sport clutch for the smaller diameter 525 clutch. Again, starting with better parts that were designed at the factory offers reliability and ease. I think an M3 flywheel and clutch conversion is cheaper than using a 525 aport clutch too.

I don't understand why more people are not doing the S50/S52 swap. Nowadays, you can even find the longblock engines for the price of a pair of camshafts. For adding power, using the extra displacement of the S50/S52 is a great base to start with.

Good Luck!


thanks brandon - this is kind of what I was asking you in the other thread. I have been trying to decide between and S52 and an S38. I know that the S38 is going to be more expensive in the long run, but I also feel that it is going to be more satisfying. Will the S38 mate with the M50 5 speed transmission? Does anything need to be moved in the engine bay?

I have done a search several times, but I can't find any threads specifically about this swap.

[bimmerd00d]

VERY nice writeup. Rarely do we find someone as knowledgeable as you that is willing to post something like this. No speculation, no drama, no armchair mechanic here. This is what we need to see more of! I've got an E34 shell here, now I just need something to throw in it. :)

EDIT: regarding the M50/M50tu trannies, '93 introduced a weaker transmission i believe, i went through 2 of them somehow. Maybe it was just me shifting like the huge american bastard that I am. I came from a bigass hefty Corvette to the '93 525i.

[Brandon J]

Took out the RD springs with custom shocks.

I installed the Sachs matched spring/shock combo. Ironically, I still use the stock spring pads and stock bumpstops. All original since build date 9/92.


Nice!

The Sachs kit, is that RD springs and Sachs shocks? Also, what brand are your bumpstops? Did you do 3mm spring pads?

Thanks,
Denton

[repenttokyo]

thanks brandon, that's really a lot of help. If I have any specific questions, would I be able to send you a PM?

[bimmerd00d]

thanks brandon, that's really a lot of help. If I have any specific questions, would I be able to send you a PM?

why not make a post so everyone can benefit from it?

[repenttokyo]

why not make a post so everyone can benefit from it?


i just don't want to burden brandon any more than necessary.

[Brandon J]

I do agree. First everyone can benefit, plus others can chime in on real world relevant experience. We can all collaborate the best practices for maintaining and modifying the e34.


why not make a post so everyone can benefit from it?

[Denton]

Took out the RD springs with custom shocks.

I installed the Sachs matched spring/shock combo. Ironically, I still use the stock spring pads and stock bumpstops. All original since build date 9/92.

Thank you!

So when you say that you would go with "matched springs/shocks, swaybars, and then camber plates" in that order, are you suggesting not to do it all at once?

Why wouldn't one do it all at once, or at least the camber plates with the springs/shocks.

Thanks,
Denton

[Brandon J]

You can definitely do it all at once. If people had to do it in stages because of cost, then follow the stage order I suggested.

The camber plates enhance the spring/shock and swaybar combo. The swaybar combo enhance the spring/shock combo. So each latter stage enhances the previous stage. If you do the plates before the swaybars, then it will try to make up work the sways have to do. It will not have the balance.


Thank you!

So when you say that you would go with "matched springs/shocks, swaybars, and then camber plates" in that order, are you suggesting not to do it all at once?

Why wouldn't one do it all at once, or at least the camber plates with the springs/shocks.

Thanks,
Denton

[repenttokyo]

A specific question: One of the things that keeps me from swapping in an S52 is that it's about 3-4k for a 50 hp increase (over my chipped M50). I am somewhat surprised that you would have gone for an S52 had you not been lucky enough to find a good priced S38 - the power difference seems quite large. Am I off base here?

[Sam-Son]

Thanks I've always been wondering about that car. Nice work. I'm thinking about an engine conversion but like repent I'm undecided between the S50 ofr the S38. Theres plenty of power to be made out of the S50 and isnt the S50 alittle more reliable and better on gas mileage?

[Brandon J]

Good question. These M50 based engines have a good 5k usable rpms, meaning you can use between 2,000-7,000rpm on the road. Now peak HP might be around 6800rpm, but that is peak. The gains are with the torque and horsepower within that 5,000 rpm range. The S52 has more torque and HP in the whole range so you can accelerate faster in all rpms and all speeds and the engine spins faster. So, 0-60 is faster, 30-60, 50-70 and so forth.

Here is an example that I hope is clear: Say the e34 needs 200hp and 190lb/ft or torque to pass a car on the highway. Well, that power may lie around 6500rpm in the smaller M50tu at wide open throttle whereas the same power may lie around 3000rpm in the S52 at wide open throttle. That is the difference of needing to shift twice...down then up with the M50tu and not shifting at all in the S52. THis makes a huge difference. Remember I did the mods to the M50tu and know how the power band is.

50hp is a lot! But remember to add all the extra torque, the flatter torque curve, how much more power you get if a chip is added to the S52 OBDI, and so forth. Realistically, the same rule applies as far as engine size with displacement because these 2 engines are based off of the same base.

Engines are dynamic, not static. So only looking at the peak number does not reveal the actual power delivery. We have to look at HP and torque in all rpms, in 25% throttle, 40% throttle, 60% throttle, etc. Also, any gains that an M50tu sees will only be bigger with the extra displacement and the hotter camshafts of the M3 engines.

A stock M50tu with a performance chip achieves around 211 Peak HP. An S52 OBDI conversion with performance chip can reach closer to 270. Then add a 540MAF and you have even more power. And that's only peak power. Torque is even better in all rpms and throttle. Since I started with only a performance chip in my old M50tu I am familiar with the power delivery, think about how the power boost felt if you added a chip. Now times that by 5-10. Remember the power delivery is much much better at peak and throught the rev range and throttle positions.

Lastly, since people were asking, you canNOT mate an S38 to a 525i tranny. I had a donor M5 and used its tranny. You might be able to mate it with the 535i one, but the gearing is different and the M5 tranny is better optimized to balance with the S38 power delivery.



A specific question: One of the things that keeps me from swapping in an S52 is that it's about 3-4k for a 50 hp increase (over my chipped M50). I am somewhat surprised that you would have gone for an S52 had you not been lucky enough to find a good priced S38 - the power difference seems quite large. Am I off base here?

[Sam-Son]

Good question. These M50 based engines have a good 5k usable rpms, meaning you can use between 2,000-7,000rpm on the road. Now peak HP might be around 6800rpm, but that is peak. The gains are with the torque and horsepower within that 5,000 rpm range. The S52 has more torque and HP in the whole range so you can accelerate faster in all rpms and all speeds and the engine spins faster. So, 0-60 is faster, 30-60, 50-70 and so forth.

Here is an example that I hope is clear: Say the e34 needs 200hp and 190lb/ft or torque to pass a car on the highway. Well, that power may lie around 6500rpm in the smaller M50tu at wide open throttle whereas the same power may lie around 3000rpm in the S52 at wide open throttle. That is the difference of needing to shift twice...down then up with the M50tu and not shifting at all in the S52. THis makes a huge difference. Remember I did the mods to the M50tu and know how the power band is.

50hp is a lot! But remember to add all the extra torque, the flatter torque curve, how much more power you get if a chip is added to the S52 OBDI, and so forth. Realistically, the same rule applies as far as engine size with displacement because these 2 engines are based off of the same base.

Engines are dynamic, not static. So only looking at the peak number does not reveal the actual power delivery. We have to look at HP and torque in all rpms, in 25% throttle, 40% throttle, 60% throttle, etc. Also, any gains that an M50tu sees will only be bigger with the extra displacement and the hotter camshafts of the M3 engines.

A stock M50tu with a performance chip achieves around 211 Peak HP. An S52 OBDI conversion with performance chip can reach closer to 270. Then add a 540MAF and you have even more power. And that's only peak power. Torque is even better in all rpms and throttle. Since I started with only a performance chip in my old M50tu I am familiar with the power delivery, think about how the power boost felt if you added a chip. Now times that by 5-10. Remember the power delivery is much much better at peak and throught the rev range and throttle positions.

Lastly, since people were asking, you canNOT mate an S38 to a 525i tranny. I had a donor M5 and used its tranny. You might be able to mate it with the 535i one, but the gearing is different and the M5 tranny is better optimized to balance with the S38 power delivery.
That's really alot of very helpful info. Now another question which seems kinda stupid but which do you think is the better engine? isn't the S52 abit more sophisticated?

[BigKriss]

For a daily driver car, I wouldn't go overboard on the suspension mods though. My setup is too stiff for my liking. I would change the springs to stock or m-tech, nothing aftermarket for the street. I wanted a good handling car, but the tradeoff for bumps is too much for my liking. Of course all this talk is subjective.

[repenttokyo]

Thanks Brandon, I didn't know anything about the details of the S52 powerband, and that makes a lot of sense. I really appreciate the information, I am glad you took the time to post.

[bimmerd00d]

Thanks Brandon, I didn't know anything about the details of the S52 powerband, and that makes a lot of sense. I really appreciate the information, I am glad you took the time to post.

Now we need some comparison sheets between the S50/S52 and S38. It would be interesting to see how they line up to eachother.

[Brandon J]

You cannot do a S38 conversion unless you have a donor M5. There are way too many parts to swap. You would need the wiring harness, tranny, driveshaft, radiator, all ancillaries, intake, full exhaust, etc. etc.

Now if you have an M50tu already, all you need is the M3 engine longblock and a chip. Obviously there might be things you want to replace (wear parts) or you may choose to use the larger injectors of the OBDII engines, but that is nothing compared to all the specific parts you need for a S38.

As far as engines are concerned, the S52 is more reliable than the S50. It came with stronger valve springs and retainers. These are known weak points in the S50 valvetrain. It is also difficult to compare an OBDI 3.0L to the OBDII 3.2L because the 3.2L will be converted to OBDI. I say, go for the extra displacement. No replacement for displacement. The extra .2L does help when using it as a base for adding power. Oh btw, I am talking about the US versions.


Thanks I've always been wondering about that car. Nice work. I'm thinking about an engine conversion but like repent I'm undecided between the S50 ofr the S38. Theres plenty of power to be made out of the S50 and isnt the S50 alittle more reliable and better on gas mileage?

[Sam-Son]

You cannot do a S38 conversion unless you have a donor M5. There are way too many parts to swap. You would need the wiring harness, tranny, driveshaft, radiator, all ancillaries, intake, full exhaust, etc. etc.

Now if you have an M50tu already, all you need is the M3 engine longblock and a chip. Obviously there might be things you want to replace (wear parts) or you may choose to use the larger injectors of the OBDII engines, but that is nothing compared to all the specific parts you need for a S38.

As far as engines are concerned, the S52 is more reliable than the S50. It came with stronger valve springs and retainers. These are known weak points in the S50 valvetrain. It is also difficult to compare an OBDI 3.0L to the OBDII 3.2L because the 3.2L will be converted to OBDI. I say, go for the extra displacement. No replacement for displacement. The extra .2L does help when using it as a base for adding power. Oh btw, I am talking about the US versions.
Wow as always a great bunch of useful info. Really thank you:)

[Sam-Son]

Brandon I was wondering if you could tell me a little more about the mods you did to the 2.5 M50. It seems that modding the M50 will be a little more affordable at this point. What kinda HP did you get and was it reliable HP? also What did those mods run you if you don't mind my asking?
Thanks
-Mike

[Brandon J]

Brandon I was wondering if you could tell me a little more about the mods you did to the 2.5 M50. It seems that modding the M50 will be a little more affordable at this point. What kinda HP did you get and was it reliable HP? also What did those mods run you if you don't mind my asking?
Thanks
-Mike
Well, look-up how much S50 camshafts and a performance chip cost and there are your parts. I would say, there was a very nice bump in power in every rpm with the cams and chip. I know Turner Motorsport had that package for a while. With all my mods I listed in this thread, I was around 240hp, but not the same torque as an M3. I would say, go for the S50 cams, vlalve springs, retainers, and chip. If you want more power, then wait and just do the engine swap. It was a fun engine, but I did have to push it hard and work the clutch a lot to get to the upper rpms all the time. I always tell people to wait and save-up for the engine swap. By the time you spend on camshafts, valve springs, retainers, and a chip, you are more than halfway in price to an engine. Knowing how power is addictive, just doing this cam upgrade will definitely make you want more.

I did not like the lightweight flywheel for the street. It was too noisy and I lost lower end torque because of less mass and inertia. A 3.46LS is a nice upgrade, but it is a little short. Unless you spin your engine to ~7200rpm, you won't reach 60mph in 2nd gear. So, just a tad too short for the street. After having these mods, I was exhausted and realized that this isn't a Honda engine that I have to spin up for the power. It turned into that.

If you must do an upgrade, I mean a must and can't afford or find a M3 engine, then go for the 2.8L swap with M3 cams. Get that extra torque from displacement and then add the camshaft, retainers, valve springs, chip. That is a good monetary compromise. Just remember that with this, you are 3/4 of the way to a whole M3 engine.

[Sam-Son]

As always Brandon I thank you very much for that wealth of knowledge and heldful info

[Booster]

Thanks Brandon, Lots of good info there. I still think I'll join JonK and do a top mount single turbo and MegaSquirt on the Non Vanos M50.All my cars are Turbo'd except the 525I and I just love the boosted feel.:D

What did you end up doing with your swapped cams,springs etc ?
Cheers,Vinny

[Brandon J]

Thanks Brandon, Lots of good info there. I still think I'll join JonK and do a top mount single turbo and MegaSquirt on the Non Vanos M50.All my cars are Turbo'd except the 525I and I just love the boosted feel.:D

What did you end up doing with your swapped cams,springs etc ?
Cheers,Vinny

I got rid of those years ago when I did the swap. Good luck with your turbo project.

[Sam-Son]

Brandon could you tell me a little bit more about the intake setup you had on the M50?

[healtoeit]

Brandon could you tell me a little bit more about the intake setup you had on the M50?
Go to my "My CAI set up" thread

It's not the one he had but he comments on it and so do a bunch of other guys here. :)

Btw, why isn't this a sticky anymore?