what is a euro m30 3.5L

that is really funny Don. chances are Don already knew about it and already has the engine in his shop ... or on the way

there is a huge difference between the US b34 and the euro b34. main difference is compression. the number is the easy way to tell the difference. other than the b34 or b35, there are ways to tell the m90 described in the forum - found by search. if i remember, one of the ways are the water jackets on the side of the block.

other engines not discussed are m88 / s38 - totally different animals.
 
im hoping its not too complicated to find out what engine it is haha. i'll have photos and numbers tomorrow or saturday.
 
that is really funny Don. chances are Don already knew about it and already has the engine in his shop ... or on the way

there is a huge difference between the US b34 and the euro b34. main difference is compression. the number is the easy way to tell the difference. other than the b34 or b35, there are ways to tell the m90 described in the forum - found by search. if i remember, one of the ways are the water jackets on the side of the block.

other engines not discussed are m88 / s38 - totally different animals.

The last year of M90 motors did not have the raised water jacket I have one in my original car.Also were One year of production Motronic 1.0 so a front driven distributor can add to the mix
 
Ok, been doing some reading…the “early” m90’s had the raised water jacket 93mm bore, m88 block. After some time late 81 the block was changed to 92.5mm bore and the engine referred to as m30b35 but was euro only and not really like the m30b35 engine we got beginning in late 87. A customer I had that was building m88’s was insistent that the blocks had to have the raised water jacket…easy way to ID m90. Mount bosses are the same, the late US b35 buggered the mount bosses. Also when they changed to that casting b35 is when all the issues with cracks from the rear right head bolt hole started.
 
Ok, been doing some reading…the “early” m90’s had the raised water jacket 93mm bore, m88 block. After some time late 81 the block was changed to 92.5mm bore and the engine referred to as m30b35 but was euro only and not really like the m30b35 engine we got beginning in late 87. A customer I had that was building m88’s was insistent that the blocks had to have the raised water jacket…easy way to ID m90. Mount bosses are the same, the late US b35 buggered the mount bosses. Also when they changed to that casting b35 is when all the issues with cracks from the rear right head bolt hole started.
Not sure about the later M90 having a 92.5 mm bore. Maybe @Bert Poliakoff can weigh in on that.

The M90 is a somewhat transitional engine. It was derived from the M49 racing engine, and was basically an experiment to see if a larger bore with very close (6mm) cylinder spacing would be reliable. It used a very lightly modified M30B35 head, that was later swapped out for a 4 valve DOHC head to become the M88/S38. I think those two later engines had other modifications such as the oil pump, timing chain, etc.

The dominant feature of the M90 is the highly over-square architecture. The bore is 93 mm, but the stroke is only 84 mm. One might think this short stroke would produce a higher revving engine, but counter intuitively, it makes it max power about 1000 RPM lower than the M30B35. The real benefit is torque. M90 torque comes on at about 1500 RPM and hangs on all the way to redline, and this makes for a superbly drivable engine. It has all the grunt you need to power out of corners, in almost any gear, and it can push unreasonably high drivetrain ratios. I have an M90 that drives my 635 Euro with a Getrag 265/6 overdrive trans, and a long legged 3.07 final drive.. first gear can run to 35-40 mph, 5th gear starts at 85 mph...

Wonderful engine...
 
The numbers from BMW…

Bore 93.4

Stroke 84

Compression 9.3:1
 

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