m20 to m30 swap

[Hypr5]

Hey guys,

i've talked about engine swaps before and I am definately going to do one soon.
I would really like to go with the m30, but there is a SMALL consideration of the m50. If I go with the m30, will I need a bigger alternator? Since I have the m20 now, are most of the accessories the same? What else will I need to buy? I figure the engine, ECU, wiring harness... Anything else? Is it all "plug and play" or will I need custom engine mounts, accessory mounts, etc. Also is it going to be a problem to relocate the battery from the engine compartment to the backseat since I don't have "jump" posts under the hood?

Thanks for any help you guys can offer. Also, if any of you know of one for sale for a good price, let me know so I can compare my options.

BTW: With an auto tranny, what gas mileage can I expect? I get about 320 mi/ tank with my m20 with "energy consious driving", can I expect at LEAST 320mi/ tank with the m30? 22 gallons is a lot of gas to only go 320 miles. lol.

Thanks again

[Kalevera]

Why not just sell your car and buy a 535? I mean, you're going to have to mess with (beyond the stuff you already listed) the cooling system and probably the exhaust (I think). You'll probably have to get an M30 bellhousing for the 4hp-22. It seems easier to just buy a 535 than to do an engine swap of that nature. Plus, the added weight will stress any old suspension components, so you'll likely have to replace those in the near future.

I get about 20mpg in mixed driving, ~22/24 on the highway. My car has a ~ 19 gal tank, from what I remember from the owners manual.

Just my 2 cents.

Lowell

[Hypr5]

Thanks for advice.

I really dont want to deal with the hassle of selling the car and having to hunt down another. Plus I like to do the work, the projects are always fun. I've put many hard working hours into this car. 90% of the front end components are new now also, I have new driveshaft components, etc etc. In the end, IMO it just doesn't make sense to sell the car when I have one that I know and feel totally comfortable with it's history.

Is the m20 cooling system just not adequate? what exactly would need to be upgraded? I'm also pretty sure the exhaust would need to be messed with a bit, but I could get by with the one I have for a little while, couldn't I? I have plans to upgrade it in the near future.

20mpg mixed seems excellent compared to what I have now, so I wouldnt be at a loss there. thats good to know.

Thanks again.

edit: After looking at diagrams of the bellhousings, they LOOK IDENTICAL, but there ARE different part numbers located. Is this just because they are differnet engines and they have different part numbers (like many suspension components between the 525 / 535) or is there an actual difference?

[Jeff N.]

Just about the whole driveline is different. Engine, tranny, shaft, halfshafts, etc. Also, lots of ancillary parts such as the engine harness, computer, cooling system, etc. The only way to really do it would be to purchase a wrecked 535 and salvage everything you need. You'd spend way too much money doing it almost any other way. Except purchasing a 535i of course...

[winfred]

doing it with a automatic id just change the bellhousing instead of trying to install the computer controled 535 tranny, any m30 bellhousing for a 4hp22 tranny should work, the rest of the driveline should be able to handle the extra power. it shouldn't be too hard to get everything together

[Hypr5]

So the bellhousings are in-fact different?

What about engine mounts, is that a big problem? I'm not too worried about the odd parts, I just want to make sure I have everything ready before I do the swap.

Has this been done by anybody before? Can anyone reference me to who has done it so I can ask them what they had to buy and what troubles they ran into? While I know that many parts were in -fact different, I'm pretty sure that a lot (but not all) of what I have now would be sufficient.

Thanks

[winfred]

you need all of the brackets and wiring but the car is mostly the same, the only body difference i can think of is the 525 doesn't have the mount for the 535 airbox, and the m20/1st year m50 cars have the battery under the hood which may or may not be a problem

[winfred]

m20 and m30 have different bolt patterns, m50/m42 have the same pattern as m20 but with a slightly different tilt of the engine

So the bellhousings are in-fact different?

[Hypr5]

you need all of the brackets and wiring but the car is mostly the same, the only body difference i can think of is the 525 doesn't have the mount for the 535 airbox, and the m20/1st year m50 cars have the battery under the hood which may or may not be a problem

I've got a small method for relocating the batter. The actual relocation shouldn't be a problem, What I see becoming a problem is the posts to jumpstart it under the hood. <eek> And about the airbox, I'm not too worried about that as I have a 'homegrown' CAI which surely can be altered to fit on the other side of the engine.

Will my radiator be able to keep that car cool or will I have to buy a bigger one?

Again, I appreciate all the help you guys have given.

[winfred]

id atleast go with a 535 radiator, and it wouldn't be a bad idea to add on a auxilery trans cooler, with the extra power it couldn't hurt. i installed a 540 (bigger then the 535 unit) radiator in my 535 and used a external trans cooler from a e36 325, our summers are nasty in south louisiana and when my stock rad crapped i happened to have a new v8 rad instock and went for it. i am not quite done with my intake setup and want to do a little more insulating and fit the shield better to the hood