HELP: Euro M30b35 vs US M30b34

E28 technical advice asked and given! Troubleshooting, modifications and more.
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benloveless1
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HELP: Euro M30b35 vs US M30b34

Post by benloveless1 »

Car: 1982 BMW 525i M30b25.

So I purchased a car this weekend and it was imported from Germany into Florida many moons ago. Nevertheless, Mike Borroughs (Stanceworks) purchased the car back in 2011 when Rusty Slammington burnt down. After Rusty rose from the dead he gave the car to a friend. I contacted Mike and let him know the situation and he said he thinks the engine was swapped in it before it was imported making the engine a euro spec motor. Needless to say no one knows much history on this car or the engine. I need some clarification as to what the engine is and possibly some direction to figure out if this is a true Euro M30B35 or a US one. The car isn't running due to some electrical/ignition issues and I'm trying to sort them out. I am posting a picture regarding the "3.5 stamp" I noticed on the head. My us 535is does not have this making me wonder if it is a euro engine. Any thoughts?

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86GT635
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Re: HELP: Euro M30b35 vs US M30b34

Post by 86GT635 »

The B35 wasn't a euro engine. It was a engine that was the same for everybody in the world. In 1985, BMW had two offerings on the table- a b34 hi compression vs the US low compression catalyzed version. It was actually a option in the otherwise euro cars. You could buy a fully euro car with a low comp catalyzed engine.

They kept that program until the B35 was introduced. They are a "world engine". No difference from one installed in a car in Germany or one for USA. Does the cylinder head have a sticker with the VIN?

How about engine mounts? The really early e32s, and the 88-89 635 shared the same block but the mounts in 89 for the e32 changed to the new design that was also used in the e34.
Mike W.
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Re: HELP: Euro M30b35 vs US M30b34

Post by Mike W. »

A -473 head is typically from about '84, well before the B35 so it's not a B35 engine. Check the casting numbers, the 3.5 or 3.0/3.3 on the intake side of the block and the one on the exhaust side which is a not too difficult to decipher number something like 23F84 which would suggest June 23, 1984 date of casting. Also the displacement may be present in a very fine stamp on the flat up by the starter, which may also have the serial number of the car it came in. Lots of ways to try to figure it out, but all I can say is it's not a B35.
Amos830
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Re: HELP: Euro M30b35 vs US M30b34

Post by Amos830 »

The easiest fastest way to solve this will be to pull the head or get an inspection camera to check the piston tops through the spark plug hole.

It looks like you've either got a US b34 or a euro b34.

US b34 will have dished pistons.

EU b34 will have piano top pistons

My US b34 has a 3.5 stamp on it JUST like that.
Mike W.
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Re: HELP: Euro M30b35 vs US M30b34

Post by Mike W. »

Amos830 wrote:The easiest fastest way to solve this will be to pull the head or get an inspection camera to check the piston tops through the spark plug hole.

It looks like you've either got a US b34 or a euro b34.

US b34 will have dished pistons.

EU b34 will have piano top pistons

My US b34 has a 3.5 stamp on it JUST like that.
Don't discount a M90 or M30B32 or even something else. So many M30s have had replacement heads you have to go off the block, the head means nothing.
benloveless1
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Re: HELP: Euro M30b35 vs US M30b34

Post by benloveless1 »

Mike W. wrote:A -473 head is typically from about '84, well before the B35 so it's not a B35 engine. Check the casting numbers, the 3.5 or 3.0/3.3 on the intake side of the block and the one on the exhaust side which is a not too difficult to decipher number something like 23F84 which would suggest June 23, 1984 date of casting. Also the displacement may be present in a very fine stamp on the flat up by the starter, which may also have the serial number of the car it came in. Lots of ways to try to figure it out, but all I can say is it's not a B35.
I will look into this tomorrow and get some more pictures and information. Whatever the engine is, it's not like my US 535is I know for sure. I'll update tomorrow with more casting numbers.
benloveless1
Posts: 230
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Re: HELP: Euro M30b35 vs US M30b34

Post by benloveless1 »

86GT635 wrote:The B35 wasn't a euro engine. It was a engine that was the same for everybody in the world. In 1985, BMW had two offerings on the table- a b34 hi compression vs the US low compression catalyzed version. It was actually a option in the otherwise euro cars. You could buy a fully euro car with a low comp catalyzed engine.

They kept that program until the B35 was introduced. They are a "world engine". No difference from one installed in a car in Germany or one for USA. Does the cylinder head have a sticker with the VIN?

How about engine mounts? The really early e32s, and the 88-89 635 shared the same block but the mounts in 89 for the e32 changed to the new design that was also used in the e34.
No sticker on the head. My us 535is has one of those and I tried looking for one on this engine and found nothing.
benloveless1
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Location: Murfreesboro, TN

Re: HELP: Euro M30b35 vs US M30b34

Post by benloveless1 »

So I found out what it was:

6726854 Is the stamping on the block up by the starter. Which indicates it is production 9/1983 633csi us market engine. From what I've researched the standings on the head indicate it's never been taken apart. Thanks for all the help.
tschultz
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Re: HELP: Euro M30b35 vs US M30b34

Post by tschultz »

AKA US M30B32 if it hasn't been separated from the block.

What is the casting date of the head?
sfdon
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Re: HELP: Euro M30b35 vs US M30b34

Post by sfdon »

Wrong.....


The b35 engine was different for the United States.

The ECE version was 9.2:1 compression
The KAT (USA) version was 9.0:1 compression.

ECE version had 7 kW and 10 Nm more than KAT

Check out the ETK- Different pistons.




"The B35 wasn't a euro engine. It was a engine that was the same for everybody in the world. In 1985, BMW had two offerings on the table- a b34 hi compression vs the US low compression catalyzed version. "
Tiit
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Re: HELP: Euro M30b35 vs US M30b34

Post by Tiit »

sfdon wrote: May 06, 2022 7:48 PM Wrong.....


The b35 engine was different for the United States.

The ECE version was 9.2:1 compression
The KAT (USA) version was 9.0:1 compression.

ECE version had 7 kW and 10 Nm more than KAT

Check out the ETK- Different pistons.




"The B35 wasn't a euro engine. It was a engine that was the same for everybody in the world. In 1985, BMW had two offerings on the table- a b34 hi compression vs the US low compression catalyzed version. "
I wonder what other differences are between those b35 versions. 0.2 increase in compression ratio is worth around 1 Kw. Must have different camshaft probably.
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