Daydreamin...engine swaps...

[mancini_mark]

Hi everyone,

Well, I've got a 1990 525 with the M20 slug, but with plenty of life in it. I've been wondering what I should do come rebuild time. Is it worth my while to swap in an M30 or S50? I do know that the M20 is the lightest engine in the E34 in North America (3395 lbs curb weight), and that Metric Mechanic has a sweet 3.2 stroker that makes up to 260hp, and is probably even lighter (bored block, machined head, lightweight pistons). Also, I've got a beautiful set of Racing Dynamics headers that I'd like to re-use.

I guess my question is how much extra effort and parts would be involved in the swap? Do I also have to change the tranny, Rad & drivetrain? Ecu change is a given.

Also, what about the emissions gestapo? I'm in Ontario, Canada, and I'm not sure how they treat cars with non-original engines.

Just curious,

Mark

[DaCan23]

I'd suspect the tranny & differntial could not handle the torque increase for very long in moving to the 3.2 260HP motor, guarentee they'd go in less than 9 months. So they should be replaced with something beffier.

[Brandon J]

The differential is strong enough to support that amount of power and so is the manual trannies. The clutch might have to be upgraded. Do searches on engine swaps and you see many things discussed from upgrading supension and brakes to wiring harness compatibility. The key to doing a swap yourself is research research research. That means from all the various and odd parts (you will know the etk very well), to the hidden costs. If you don't trust your skill level, then don't do it. Sell the car and the headers and buy a 535i. Good luck with your research.

[mancini_mark]

I'm too attached to my car to sell it. I'd rather throw stupid amounts of money at mine. I'm not all that serious yet. I was just wondering in general terms.

Looks like the M50 uses the same radiator as mine, whereas M30 is different with the firewall mounted expansion tank. I think my tranny is the Getrag 260. I'm not sure whether other 5ers are the same.

When the time comes, I will seek professional help. I'd love to do it myself, but I don't have the free time that I used to (work sucks). Plus it will take me longer to figure things out. I might take the easy way out and drop in one of those hot M20's from Metric Mechanic. I might even get them to do the work, since it looks like they charge about $1,600.

Thanks again,

Mark

[DaCan23]

Whats the spec difference between the transmission of a M30 3.5 and a M20 2.5. 260HP & whatever the torque is would be an increase of about 100hp... adding that much to a 15yr old tranny, I'd be interested if it could hold, but wouldnt try it myself.

The reason why the V8s dont have the same tranny as the I6's is because of the added torque.

I'd agree w/ the buyin a 535i 5 speed versuses doin the swap.

[Brandon J]

Whats the spec difference between the transmission of a M30 3.5 and a M20 2.5. 260HP & whatever the torque is would be an increase of about 100hp... adding that much to a 15yr old tranny, I'd be interested if it could hold, but wouldnt try it myself.

The reason why the V8s dont have the same tranny as the I6's is because of the added torque.

I'd agree w/ the buyin a 535i 5 speed versuses doin the swap.

A M30 cannot bolt onto an M20 tranny. If he went the M20 260hp route, the stock M20 manual tranny will hold the power. The real culprit of breaking manual trannies is the torque. The weak point is the clutch. The V8 manual trannies do not mate up to M30s, M20s. The 3.0L V8 5spd auto is the same as the e36 M3 auto, but perhaps uses a different bell housing. It might not as the M60 and the M50 were designed around the same time.

It doesn't matter if a manual tranny is 15 yrs old. As long as it was treated well and has had its oil changed, all I would do is change the seals when it is out.

If the attachement is there for the car, then remember that whatever you are quoted for a project swap/upgrade, upgraded clutch, the total outcome will be more. You will find that you should change many aged items, like coolant hoses or water pump, as they are easier to get to when the engine is out. Just plan for those expenses as well.

[DaCan23]

My comparisons between M30 & M20 and reference to the M60 wasnt meant as swappable options, more towards durability of the trannies to handle the power. I know w/ the M60 came out there was no way they could use the M50 tranny because it wasnt strong enough.

In most cases where you add that much power 100HP you have to consider these things, like people that add NOS to a car and then 70-100HP gain used too much will blow the seals and snap things in the drivetrain. Of course those are apples to oranges as they are not made like BMW but...


A M30 cannot bolt onto an M20 tranny. If he went the M20 260hp route, the stock M20 manual tranny will hold the power. The real culprit of breaking manual trannies is the torque. The weak point is the clutch. The V8 manual trannies do not mate up to M30s, M20s. The 3.0L V8 5spd auto is the same as the e36 M3 auto, but perhaps uses a different bell housing. It might not as the M60 and the M50 were designed around the same time.

It doesn't matter if a manual tranny is 15 yrs old. As long as it was treated well and has had its oil changed, all I would do is change the seals when it is out.

If the attachement is there for the car, then remember that whatever you are quoted for a project swap/upgrade, upgraded clutch, the total outcome will be more. You will find that you should change many aged items, like coolant hoses or water pump, as they are easier to get to when the engine is out. Just plan for those expenses as well.

[Brandon J]

My comparisons between M30 & M20 and reference to the M60 wasnt meant as swappable options, more towards durability of the trannies to handle the power. I know w/ the M60 came out there was no way they could use the M50 tranny because it wasnt strong enough.

In most cases where you add that much power 100HP you have to consider these things, like people that add NOS to a car and then 70-100HP gain used too much will blow the seals and snap things in the drivetrain. Of course those are apples to oranges as they are not made like BMW but...

I understand. My reference on the tranny was that the M20 manual tranny could hold the extra power of a M20 stroker motor. Obviously the more powerful engines received the trannies that match the power. Self explanatory. However, based on what Mark was saying, he was looking into either stroking or swapping. A swap means that he should do the engine and tranny together. With the stroker, the M20 manual trannies can handle the extra power.

As far as differentials go, I use the small diff and it is connected to my S38 M5 engine/tranny. No problems whatsover even after 4 yrs.

For future reference, the only engine swap I would suggest where the stock manual tranny is used is doing a S50/S52 swap into a '91-'92 525i manual. Those model years use the same tranny as the e36 M3. Of course, the clutch should be upgraded (an M3 flywheel and clutch can be used). Hint*hint* when you are looking for parts to do an M3 engine/tranny swap. Look for used driveshafts from the '91-'92 525i manual.

[mancini_mark]

Well, I'm back down to earth now. This is going to be a good one when I get to it.

mark

[Kalevera]

LS-1 and a six speed. I was told earlier today of a guy in michigan who did this quite recently. That, a supercharger, and some tuning; supposedly the car drifts like no other. It's completely stock -- suspension, body, brakes; the LS1 fits in perfectly, with only trans and engine mounts fabbed -- everything else worked (ie, headers).

And BMW diffs don't break. Stupid people break bmw diffs because they run them out of oil or run bad oil in them.

best, whit

[Alexlind123]

Thats only 52hp more than the 535i, and they use the same automatice transmission. If the transmission can handle a chipped 535i with 251hp, i dont see why it couldnt handle 260.

[mancini_mark]

I wouldn't doubt that it can handle the power. It's a 5-speed, and I'd definitely upgrade the clutch. I'm a maintenance freak, so it's running better than new with redline oil in the tranny and amsoil in the diff. I might also think about a limited slip.

So...that's why I've been daydreaming about more power (don't we all). The car is almost completely modded with sachs kit, 17" wheels, etc, and it is in awesome condition, especially since I'm only the second owner.

The beauty of the M20 car is that it is the lightest E34, so it doesn't need as much power. Mark D now sells an M20 chip that works with the M30 AFM, 19lb injectors and is set up to run on 93 octane. So that's where I'm thinking of going first. I already have 19lb mustang injectors and the M30 AFM should be cheap. I'll also invest in an adjustable fuel pressure regulator to iron things out.

Cheers