The comprehensive DOHC engine swap thread.

[Beej '86 325es]

I think you should be careful with ebay, there is a guy on here that will tell you the same thing. He bought a complete alloy black with head, the guy told him it was a m52. it was but it was a m52tu, Double VANOS, not and easy way to go, considring you have to have a bunch of crap from the

heh heh, yup, that was me also.

[JGood]

What's everyones estimated costs?

I'm looking to do a m50 swap for less then $3,000. Is this reasonable? What route should I take as far as engine selection, transmission, etc...?

Does VANOS make a difference worth the extra money? I'm looking to keep the motor fairly stock for a couple years (well, I'd like to get an intake/exhaust system as well as software). Right now I have a 325e which isn't exactly fast. I just want something that will be able to outrun e30 325i's. Would a 92 m50 be a good choice, or should I stick with the 93+ vanos?

Justin

[Stu]

Little info on the Z3 2.8 block, from my knowledge...

52 pounds lighter than a 325 block, remember that the 325 block is lighter than the M3 block, since the M3 block is physically larger to begin with. (block block block)

Most will tell you that the sleeved alloy block cannot be bored, though it can; but shouldn't go past 85mm. There needs to be enough sleeve material for safe operation, but 1mm overbore is fine. The pistons that come in the 2.8 block, like all pistons in OBD-2 motors, have a very nice graphite coating, and these pistons work fine.

A killer street setup for the alloy block is to use a 3.0 crank with the stock pistons machined down to desired compression; 10.9-11:1 is the shit for a street M/S50 (assuming you can get 93octane). The 3.2 crank seems to be overkill in my opinion, on the alloy block; why run such a long stroke (89.7mm) when you're only running 84mm bore? The 86mm stroke of the 3liter crank makes for a very nice package.

Don't forget that the alloy block uses cross-bolt main bearings. Very nice. :nice:

The aluminum block used to sell for about $2100 from the dealer, I'm not sure what the latest prices are though. Some might not find it worth their while to swing for the alloy block, as it is pricey and to build in stroker form requires custom machine work or custom pistons (even more $$). But, as mentioned above, it is a hefty weight-loss over the front axle, and you'll be hard pressed to find any other single modification that can drop that much weight. (carbon hoods only drop about 17-20 pounds).

GrapeDrink is right though, about losing weight out of the drivers seat. I've slimmed from 215 to ~160 and my 24v 318 scoots along much quicker than before! ;)

[Tony S]

Stu

Whats the set up on your Dads M3. Total displacement, compression, cams, approx HP.

Also does any one know which blocks to avoid as far as the Nakaskil cylinder liner issue. Not sure if the US blocks had this problem

[Stu]

Stu

Whats the set up on your Dads M3. Total displacement, compression, cams, approx HP.

Also does any one know which blocks to avoid as far as the Nakaskil cylinder liner issue. Not sure if the US blocks had this problem

His M3 used:
-alloy block, machined stock pistons, 3liter crankshaft, around 11:1 compression.
-Head was worked considerably with all of his tricks, 252/240 cams, conical valvetrain, etc.
Comes to around 2850cc, unsure of the peak horsepower. It was setup using his 'high torque rise' design, and made unbelievable midrange power and pulled steadily to high revs.

[ed94r]

Pardon my ignorance, but were you guys still able to use a SSK kit using a Getrag 260 trans without modifications to the shorter lever?

TIA, Ed

[Stu]

Pardon my ignorance, but were you guys still able to use a SSK kit using a Getrag 260 trans without modifications to the shorter lever?

TIA, Ed

Yea, you can modify the selector rod instead, to compensate for the 10-degree angle difference between the M50 and the M20 trans. I run a Z3 1.9 lever with a modified selector rod and modified trans mount. I really love it! :P

[SmokinTires]

Picking up my m50!

Hey guys!

This is my fist post on this forum!

I'm going down to pick up my m50 tomorrow morning and I can't wait. I have all kind of things inroute to my house to start this project. I've been waiting along time for this day. I did have a couple of questions about this swap though.

First, What flywheel/clutch setup do I want? I'm guessing m50 stuff, but I plan on running m20 transmission. Or will there be a problem with bellhousing sizes?

Second, If I decide to go with a M3 trans (casting number 1 222 751 9) will this affect the flywheel/clutch setup? I know I'd have to run a different drive shaft, but thats fine with me.

My only worries with this swap is from the transmission to the differential, what are all my options here? Driveshafts, guibos, etc...
And maybe the wiring scares me abit.

Sean[img][/img][img][/img]

[Brew]

Re: Picking up my m50!

Hey guys!

This is my fist post on this forum!

I'm going down to pick up my m50 tomorrow morning and I can't wait. I have all kind of things inroute to my house to start this project. I've been waiting along time for this day. I did have a couple of questions about this swap though.

First, What flywheel/clutch setup do I want? I'm guessing m50 stuff, but I plan on running m20 transmission. Or will there be a problem with bellhousing sizes?

Second, If I decide to go with a M3 trans (casting number 1 222 751 9) will this affect the flywheel/clutch setup? I know I'd have to run a different drive shaft, but thats fine with me.

My only worries with this swap is from the transmission to the differential, what are all my options here? Driveshafts, guibos, etc...
And maybe the wiring scares me abit.

Sean[img][/img][img][/img]

If you want to use the m20 transmission, you will want to use an m20 clutch and flywheel. You also will need to use the m20 starter and pilot bearing. The getrag 260 bolts right up to the m50, but you will need to shave the oil pan a bit for clearance to the flywheel. With this setup the only custom work is the transmission bracket, which is really quite simple. You can use your stock driveshaft and shift linkage.
The wiring is really simple. Just follow the pin chart by AKG. If you have an 89' + e30, you need to wire up the unloader relay. I'm pretty sure someone explained it earlier in the thread.

[Addissimo]

If you search, there are plenty of debates over going performance m20, or stock m50... Seems like unless you're going to boost your m20, the m50 is the way to go. By the time you spend $4-5k on a decent s14, you might as well buy an s52 with a few performance goodies (obd-I, schrick cams, euro headers, custom software, etc) and get 300hp. But then again, you wouldnt be redlining in the 8k range either... I donno, if you have shit loads of cash, and arent too worried about your car being in the garage, go for a built s14... It'd be badass.

[ed94r]

Stu,
One more question. When using the 260, how do you bend the selector rod? It's alloy and seems awful brittle!
Thanks,
Ed

[SmokinTires]

So then if I stick with a 260 trans, then I keep everything from the trans back? With basic mods to transmission mounts.

Were can I find this AKG wiring chart?

[e30Matt]

Stu,
One more question. When using the 260, how do you bend the selector rod? It's alloy and seems awful brittle!
Thanks,
Ed

Stick it in a vise using a few sockets to apply pressure in just the right places, then tighten 'er down. Voila. Bent selector rod. :)

[Beej '86 325es]

Stu,
One more question. When using the 260, how do you bend the selector rod? It's alloy and seems awful brittle!
Thanks,
Ed

Stick it in a vise using a few sockets to apply pressure in just the right places, then tighten 'er down. Voila. Bent selector rod. :)

My stock selector rod was pretty peuny too. Then it snapped in half and the dealership put in one that was supposively the right part number, but was about twice as thick. Maybe order a new one from the dealership...

Were can I find this AKG wiring chart?

http://www.akgmotorsport.com/e30convpins.html

Although, their list is not complete. I'd like to know the complete list though, so I could have it on hand when I do the swap this spring.

[Stu]

Stu,
One more question. When using the 260, how do you bend the selector rod? It's alloy and seems awful brittle!
Thanks,
Ed

Cut it. Rotate it so the ends have a 10-degree difference. Weld it back together.