the b34 search begins

tacomagabe · Post by **tacomagabe** » Mon Aug 01, 2011 1:07 am

In the next few months I'm going to be looking for a healthy b34 to go in the e12. I'm thinking one from an auto trans e28 might be my best bet but what do you guys think? Maybe less wear on the motor right? Anyone know any places they trust in the northwest to source one of these or is my best bet just trolling mye28?

DEMIURGE · Post by **DEMIURGE** » Mon Aug 01, 2011 10:02 am

Personally, I found an e32/e34 M30B35 engine for my second project.
Maybe, a healthy B35 will be better for your e12.
The engine management is a bit better and the power (HP) is bigger - compared to the "green" B34 engines (USA cat. edition).
And not on the last place - the chance you'll find a healthy B35 is bigger.

tacomagabe · Post by **tacomagabe** » Mon Aug 01, 2011 7:39 pm

Yeah I would go b35, But I'm eventually going to go the turbo route and the word I've heard is b35 blocks crack under FI. The engine management would get changed when I put the turbo together anyway. I kinda figured b34s are thought of as less desirable too so maybe they would be easier to find?...I donno. If I was going normally aspirated I would go for a b35 though.
Am I right to think a motor that was running an auto trans it's whole life would be fresher then a comparable manual trans car?
My reasoning is less wear on the crank and less high revs through it's life.

anthony · Post by **anthony** » Tue Aug 02, 2011 1:12 am

I have found, here in the bay area, that m30b35s are coming to pick n pulls more often. Mainly in the form of 88-90 735i. Pnp has a website that will search for the year and model.

I am getting really close to putting the bottom half of my b35 together, the head is already. I am putting the b35 pistons into a b34 block, which will bolt straight into the e12. At least that is the plan.

GripGreg · Post by **GripGreg** » Tue Aug 02, 2011 1:14 am

I'm glad I found this topic being discussed. While we're here, I have this situation; I have a 3.5 that was installed in an E12, hooked up to an automatic at Pik-A-Parts 1/2 price sale. I want to put it in my Rosallina.
But, of course, I don't know why the E12 ended up at the yard. The car looked pretty decent. Which leaves me guessing. WHY? This is the car I got the oversize front swaybar from. Stooopidly, I didn't even check the rear swaybar.

I haven't checked the compression, but, the assumption is that it's good.
Here are the numbers I found on the motor: 42594448, and 346kb.
In your opinoin, should it fit w/o a problem?
Is it an M30B34, or an M30B35??

DEMIURGE · Post by **DEMIURGE** » Tue Aug 02, 2011 5:21 am

Greg, the engine number you wrote is invalid.
Please, check it again - it has to be only with seven digits.
The second line shows you have 3.5 (34) 6-cylinder (6) engine.
When you pick-up the correct engine number - you can easily check it in RealOEM.com by yourself.
Just to be sure what engine block you have - check, please the numbers, stamped on the left side of the block, under the plenum and right to the oil filter housing. If the numbers are only 3.5 - it is e34/e32/very late e24 M30.
If the numbers are 3.2/3.5 - this is the previous e28/e23/late e24 M30.

P.S. I have e32/e34 engine with the same 346xx second line.
The engine is 3430 cc. I really don't understand why this engine is named as M30B35 (it is closer to 3.4) and the first 3.5 M30 engines with 3453 cc are named M30B34 (closer to 3.5)

DEMIURGE · Post by **DEMIURGE** » Tue Aug 02, 2011 7:36 am

tacomagabe wrote:Yeah I would go b35, But I'm eventually going to go the turbo route and the word I've heard is b35 blocks crack under FI. The engine management would get changed when I put the turbo together anyway. I kinda figured b34s are thought of as less desirable too so maybe they would be easier to find?...I donno. If I was going normally aspirated I would go for a b35 though.
Am I right to think a motor that was running an auto trans it's whole life would be fresher then a comparable manual trans car?
My reasoning is less wear on the crank and less high revs through it's life.

Gabe, my intention is the same - but I'm not sure when it will happen...
Regarding the cracking under FI - I think - it is only luck.
I've read somewhere about "turboed" e34 with it's stock engine (not with M5 engine). The output power was something about 600-700 HP. During the tests, the only broken thing was the input shaft of the Getrag transmission (I don't know it was Getrag 265 or 260). The block survived... In your case - will you dare to go over the 350-400 HP?

If not - possibly you will have no problems with B35 block. Of course - the best way is to use a fault detection device and check for minor invisible cracks which usually can't be revealed under normal use conditions.
Regarding the engine management - yes, I agree, it is obligatory to change the stock Motronic 1.3 in cases of FI. Do you think about TCD M30 tubo KIT with MS or it would be something different?
Regarding the auto transmission car - it is reasonably to think of less wear. My engine was taken from a car with auto trans. But one of the most important things - the engine history - if it was regular maintained with good oil.
Regarding "My reasoning is less wear on the crank and less high revs through it's life" - I'm sure the crankshaft will be in very good condition, the cylinder walls - with some luck - also, the weak point is the head.
Anyway, the B35 head is better for higher power than B34.

tacomagabe · Post by **tacomagabe** » Tue Aug 02, 2011 12:44 pm

I want to just get the motor in and running stock for a while while I save for the turbo components.
There is a good argument for the b35. Here is what got me thinking about the b34 http://www.mye28.com/viewtopic.php?t=91 ... hlight=b35
Anyone have any thoughts about this?

DEMIURGE · Post by **DEMIURGE** » Wed Aug 03, 2011 11:37 am

tacomagabe wrote:I want to just get the motor in and running stock for a while while I save for the turbo components.
There is a good argument for the b35. Here is what got me thinking about the b34 http://www.mye28.com/viewtopic.php?t=91 ... hlight=b35
Anyone have any thoughts about this?

Hmmm, you just read my mind...
I've decided the same - to put my B35 and run it stock, then maybe TCD stage 2 (or some other stage

).
Regarding the B34/B35 discussion in mye28.com forum - yes, I know this topic and I'm sure - almost every fellow reading and writing here is reading the mye28 also.
It is more than possible that the late blocks for e32 and e34 aren't so robust as the previous. This directly corresponds to my opinion that the older things were made to last for longer. But I repeat - if your aim is below 350 HP - it is most likely - you will have no problems of cracking issues. On the other hand - it is easy to find in the US an American "green" 3.5 engine with low compression and boost it "to the limit". Here in Europe - we have no similar chance and the only way is to get "normal" engine and to lower the CR with aftermarket pistons or to use a special gasket. The European 3.5 older M30 engines even have more compression rate, compared to the last e32/e34.

Blaise · Post by **Blaise** » Wed Aug 03, 2011 6:00 pm

GripGreg wrote:I'm glad I found this topic being discussed. While we're here, I have this situation; I have a 3.5 that was installed in an E12, hooked up to an automatic at Pik-A-Parts 1/2 price sale. I want to put it in my Rosallina.
But, of course, I don't know why the E12 ended up at the yard. The car looked pretty decent. Which leaves me guessing. WHY? This is the car I got the oversize front swaybar from. Stooopidly, I didn't even check the rear swaybar.
I haven't checked the compression, but, the assumption is that it's good.
Here are the numbers I found on the motor: 42594448, and 346kb.
In your opinoin, should it fit w/o a problem?
Is it an M30B34, or an M30B35??

It is my understanding that the M30B35 needs modified engine mounts to go into the E12. The M30B35 block has a distinct hole (with rubber plug) in the engine block, where it mounts to the tranny. It should look like this:

<table><tr><td><a href="https://picasaweb.google.com/lh/photo/v ... site"><img src="https://lh6.googleusercontent.com/-BLsK ... C01272.JPG" height="300" width="400"></a></td></tr><tr><td>From <a href="https://picasaweb.google.com/1030509870 ... ebsite">19?? 3.5L M30-out of 1972 Bavaria</a></td></tr></table>

Mike W. · Post by **Mike W.** » Wed Aug 03, 2011 10:07 pm

Blaise wrote:
GripGreg wrote:I'm glad I found this topic being discussed. While we're here, I have this situation; I have a 3.5 that was installed in an E12, hooked up to an automatic at Pik-A-Parts 1/2 price sale. I want to put it in my Rosallina.
But, of course, I don't know why the E12 ended up at the yard. The car looked pretty decent. Which leaves me guessing. WHY? This is the car I got the oversize front swaybar from. Stooopidly, I didn't even check the rear swaybar.
I haven't checked the compression, but, the assumption is that it's good.
Here are the numbers I found on the motor: 42594448, and 346kb.
In your opinoin, should it fit w/o a problem?
Is it an M30B34, or an M30B35??
It is my understanding that the M30B35 needs modified engine mounts to go into the E12. The M30B35 block has a distinct hole (with rubber plug) in the engine block, where it mounts to the tranny. It should look like this:

https://picasaweb.google.com/1030509870 ... ebsite">19?? 3.5L M30-out of 1972 Bavaria</a></td></tr></table>

There's the pic. On mounting, I know the early B35s will bolt up to E28 motor mounts, but they're different than E12, so I don't know about that part. Unless you are really going to go for high HP on a turbo I would go with a B35. For the amount of money you will have in a 400HP+ project another B34 would be a drop in the bucket, monetarly speaking.

Odometergears · Post by **Odometergears** » Sun Aug 07, 2011 9:43 am

If you are going turbo in the future, you want lower compression to start with. This means you want the B34 engine and head. As compared to the B35, you will be getting different pistons and valves with the B34. I'm using the M106 block from an E23 745 and a regular B34 head. I've got 14lbs of boost with 385lbs torque. Anymore and I am starting to worry about drivetrain breakdowns. Running a 3.07 rear, this will move the car quite well.

Peter can post the latest dyno if he sees this post.

Jeff

garethashenden · Post by **garethashenden** » Sun Aug 07, 2011 12:24 pm

I know of a 105k b34 from an '85 535iA, $350. Unfortunately it's in NH.

tacomagabe · Post by **tacomagabe** » Tue Aug 09, 2011 8:01 pm

Odometergears
Posted: Sun Aug 07, 2011 9:43 am Post subject:
If you are going turbo in the future, you want lower compression to start with. This means you want the B34 engine and head. As compared to the B35, you will be getting different pistons and valves with the B34. I'm using the M106 block from an E23 745 and a regular B34 head. I've got 14lbs of boost with 385lbs torque. Anymore and I am starting to worry about drivetrain breakdowns. Running a 3.07 rear, this will move the car quite well.

Peter can post the latest dyno if he sees this post.

Jeff

Jeff: Have you done any work on the b34 head to get to that power? I agree on the comp ratio 9 to 1 seems a little high for me. I know guys run ok boost with it, but it might not allow me the boost I might want to run. And I just want to build something I don't have to worry about. Best gas we have in WA is 92 and I don't want to have to worry about going over mountain passes on a hot day.