M90 motor swap?

[euroshark]

More responsive than M1.3? Any specific reason why?

They just feel quite a bit different. Looser and less controlled maybe... The L-Jet wants to go and the M1.3 feels like it's being held back.

[slammin.e28]

M90s have flat topped pistons as well, as opposed to dished in B34s, but, let not this be confused with the "dirty" euro B34 which got piano topped, high compression pistons.

[kronus]

The earlier cars actually had L-Jetronic and were much more responsive.

More responsive than M1.3? Any specific reason why?

[slammin.e28]

Thanks F34R. Hopefully I'll get it painted and back together one of these days.

Slammin, I've got an M90 hiding out in my shed if you want it.

Oh man....please don't tempt me.....

....

[euroshark]

Thanks F34R. Hopefully I'll get it painted and back together one of these days.

Slammin, I've got an M90 hiding out in my shed if you want it.

[slammin.e28]

I lust after M90s.

[F34R]

That euro 635 is so sexy.

[euroshark]

The earlier cars actually had L-Jetronic and were much more responsive. As for being quicker than an M6 to 60, it all comes down to the torque curve. The M90 makes ~90% of it's peak torque from about 1800rpm to about 5000rpm. The M88 and S38 make more peak torque but it comes on later and more abruptly, essentially making it take longer to wind up. I can tell you they are quicker from first hand experience! Quicker than a US Spec M6 and as quick as an M635. This car was a blast... I wish I would have kept it, but at the time it had to be sold so I could buy the '83 635CSi Euro that I have now.

[VinniE30]

1.355mm Bigger bore and a 2mm shorter stroke than a B34 or B35. They are more eager to rev than the standard M30. An M90 + G265CR equipped 635CSi will beat an M6 / M635 to 60 and sometimes beyond thanks to it's excellent torque curve.

They don't appear that special to me. I guess it's more of a novelty.:)

If the only big difference is that small change in bore/stroke and compression, while having an older version of motronic, I seriously doubt it would even come close to being as fast in an E30 as a modded B35 like mine.

How do you figure it would be faster than an M6 assuming they're in the same chassis? The M88/early S38 would make much more power.

[kronus]

An M90 + G265CR equipped 635CSi will beat an M6 / M635 to 60 and sometimes beyond thanks to it's excellent torque curve.

Didn't know that! Looks like I have some drag racing to do :p

[euroshark]

1.355mm Bigger bore and a 2mm shorter stroke than a B34 or B35. They are more eager to rev than the standard M30. An M90 + G265CR equipped 635CSi will beat an M6 / M635 to 60 and sometimes beyond thanks to it's excellent torque curve.

[kronus]

M90 is a big bore, short stroke engine. 94mm pistons, the head and cam are similar to a b35. Looks like that car is still l-jetronic which is unfortunate, would take a cam swap to get motronic 1.3 but that should give a nice power boost.

M90 is known as the "dirty" euro engine.

[slammin.e28]

http://en.wikipedia.org/wiki/BMW_M88

says the m90 is a weaker version of the m88.

only 215hp.

i would rather have a m30b35 with bolt ons.

Same cam as the B35.

Pretty much M90 is a bored/stroked B34 with B35 cam. Or an M88 with a B34 head and B35 cam. This is probably a bit over simplified, but it's still a badass engine.

[CorvallisBMW]

M90s have lighter weight internals, higher compression and like to rev more than m30s. Plus they make more power IIRC than a stock m30b35.

[Robotin]

http://en.wikipedia.org/wiki/BMW_M88

says the m90 is a weaker version of the m88.

only 215hp.

i would rather have a m30b35 with bolt ons.