looking at a 633csi...

[euroshark]

Sorry guys, that's not quite correct. The US spec M30B32 had 8:1 compression just like the US spec M30B34. Early B32s up to the end of 1983 or so had a hotter cam (272 degrees instead of 260) and a lighter flywheel. They were rated 1hp less than the B34 and about 20ft/lbs less torque, so depending on the literature you are looking at 181hp and 195ft/lbs vs 182hp and 215ft/lbs (some sources say 184hp for the B32 and 185hp for the B34). You might have seen 176hp for the 3.0 liter found in Bavarias, E12 530is, and the 630CS. The euro M30B32 was rated at 199-201hp and had 10:1 compression.

The M30B35 was rated at 208hp (or 211hp, again, depending on the source) and about 230-232ft/lbs. There were no US or euro spec B35s, they were "international".

That said, I'd still be totally willing to use it in an M30 powered E30. You can get M10 pistons from IE in varying compressions and they will fit the B32 blocks since they had an 89mm bore vs the B34s 92mm bore. The M10 and M30 mostly use the same valvetrain, bottom end bearings, etc because they are essentially variants of each other.

[TDE30]

TDE30, I didn't know they had a higher compression. M30b33s are generally around 176 hp, correct? The M30b35 is rated at 182 or thereabouts if I remember correctly.

Despite their name, the E28 535is, early E24 635CSi's, and early E23 735i/L's all used the M30 B34 (which had a CR of 8.0:1 and made 184 bhp.) The E24 633CSi and E23 733i both used the M30 B32 (CR of 9.3:1 and 177 bhp.) Late 635CSi's, late E23 735i/L's, E34 535i, and E32 735i/L all used the M30 B35. The B35 was offered as a euro (read: high compression motor) for some of certain E23's and E24's, but the US only got it officially with the E32's and E34's. It had a higher compression ratio as well, something like 10.0:1 and 208-218 bhp.

Edit: Yeah, what the guy above me said. :D

[euroshark]

The E24 633CSi and E23 733i both used the M30 B32 (CR of 9.3:1 and 177 bhp.)

This is only going to be the case on carbureted and L-Jet models which should run to approximately mid 1981 in the E24 and E23, despite the widely accepted changeover being June of 1982. After they went to Motronic all of the US spec B32s and B34s were 8:1 compression. There was another M30 designation which is quite rare in the US called the "M90" which was derived from the M49 block used in the CSLs and later the M88/3 which had slightly different dimensions than the M30B34.

They had a larger bore and shorter stroke and I would consider them to be THE most desirable M30 variety (93.355mm bore and 84mm stroke vs 92mm and 86mm). These engines were found in European spec E12 M535is, 635CSis, and 735is. I guess the point I was getting at is the M90 had 9.3:1 compression as well, but again, after the M90 was phased out in 6/82 all M30 3.2 and 3.4 liter engines had 8:1 compression in the US.

[TDE30]

Eh, thanks for the correction.

I wasn't aware that the M90's were used in euro E23's and E24's, pretty cool.

[gearheadE30]

Well, I went up to look at the car and it really wasn't too pretty. The paint was bad, one of the sunroof drains had clogged and rusted throught eh passenger side c-pillar. The sunroof leaked so the interior had water damage. The car wouldn't start, obviously, but I didn't really bother trying. It had had the windows tinted, and teh tint was peeling off. The driver's door wouldn't shut for whatever reason, and the toolkit was missing all of teh tools.

On the plus side, it was a 5-speed, there was no chassis rust, it had one of the early variants of the 13-button OBC, and it had a period-correct aftermarket stereo. Most interesting were the seats, which were e24 recaros (!!) not just e24 sport seats. In the end, thhough, I just don't have the time or money right now to get the car back the condition that I would want it to be in.

If anone else is interested, the car is in Sarasota, FL, and the car is listed in the sarasota craigslist. It would be worth more in parts than anything else, and it only had 120k miles on it.