m90 engine?

[BMW_E30vert]

Right guys planning to convert my brother's cab to an m30b35 this coming summer, we already have a m30 from an e34 but i have a chance to purchase a m90 engine.

I know the m90 has a larger bore than the m30 but the m30 has a longer stroke, so is there a way to use both engine's to benefit from larger bore and stroke?

If not what would be the better engine to use in a e30?

[Cypriotgeeza]

http://www.bimmerforums.com/forum/showt ... M30-vs-M90

Theres a nice little thread for you to read on there! The main information you need is on page 2 mate!

Ive finally started driving my M30'd cabby and it is a proper power house man!

Looking forward to getting the hood down in the summer and giving it a good blast

[zaust]

If you want the ultimate m30 then find a e12 m535 lump and work out how to run it on a stand alone. job jobbed.

[DanThe]

Looks like you need to get that M90 bought and bolt an M30 crank in! 3.7 FTW

Some increased compression and live mapping on the Motronic would get some good power/torque over the usual anchors

[BMW_E30vert]

Been reading a lot of the threads but no proper answers, the engine is from a e12 it's the one which has a "L" painted on the block.

I may just get the engine and have a play

Dan a 3.7 m30 sounds cool I wonder how it will compare to my alpina lump

[DanThe]

Which Alpina lump?

Favorite saying mate, "theres no replacement for displacement"

[BMW_E30vert]

That's all I've been hearing from my brother since he bought the m30, I will be using a 3.3 from a e39 b10

[DanThe]

Ahh of course

I dont think it will be behind by much TBH, you will definitely have weight and economy on your side

[87mtech27]

Very informative thread link provided by CypriotGeeza. M90 in E30 is a waste IMO besides would getting this ancient engine built for E12 M535i to run on Motronic be a PITA? Much better to leave it for the 3.0 CS's and E12s but to each their own I guess.

M90 have the old skool cool banana type inlet manifold which is a way better than the later M30 inlet manifolds

Edit:

Got this from another forum:-

As I understand it, the B34 and M90 heads are effectively the same in terms of flow capability, and therefore power. If you want to refresh a head, I would either move it to a B35 or leave the M90 head and use a cam gear to change the M90 to Motronic with some other bits (upper timing cover, valve cover, throttle, intake manifold, etc) but keep in mind that you will be converting to Motronic 1.0, which is a good bit more cantankerous than Motronic 1.3. You will also have to change the bellhousing on the transmission,as the crank position sensor runs off the flywheel on 1.0, and uses some other sensors (cold start for one) that are eliminated in 1.3.

Gains really come if you go with a B35 head and custom pistons to bump the CR backup to reasonable levels due to the improved flow characteristics of the B35. Also, don't forget that you will have to compensate with a tune to get much out of this at all, as the stock Motronic system does not have enough elasticity to deal with these changes.

So, really, the work required boils down to your parts choices: M1.0 with a B34 head for minimal gains and a lot of work, or M1.3 with a B35 head for more money (pistons, B35 head, M1.3 harness/sensors/crank pulley) and more power.

[Bristol_Jer]

So very basically, the m90 block is just a bored out m30 block?

[BMW_E30vert]

The m90 block is more similar to the m88

from some research it seems you can bore out the m30 block and use the m90 Pistons

Piston will be 1mm above deck but apparently the b35 head allows this?

This could all be rumours as its just what I've read of the interweb

[87mtech27]

From my understanding the M90 block is same as M88 but with M30 head. BMW changed M30 bore and stroke various times during its life time.