What would be the best m30?

[6erWEBB]

Basically with all engines Ive ever messed with there seemed to be a combination of parts that, when put together, made a great combination. Of course for whatever reason the manufacturer never made them that way.

The m30 in my e24 now is a B34, And everything attached to it is stock save for a cam of unknown spec.

I heard talk a long time ago of " Man if you put a b35 head on that engine with such and such intake itd be a monster."

Is this just talk or is there some legitimacy to the statement? And if so, what would be the best combination of stock pieces to build an m30 for pre boost build performance?

-Webb

[xatlas0]

The "best" M30 depends on how far you want to take it.

If your engine is the stock unit from the 79 635, then it is not a M30B34, it is a M90, which is even better.

The "best" M30 would be a M90 block, B34/B35 crank, aftermarket rods, aftermarket pistons with the CR you want, and a B35 head.

This setup would give you ~3.7L with bigger valves for better flow, on and off boost. You need the custom pistons because the B35 head has a larger clearance volume compared to the M90 and B34 head.

[6erWEBB]

Its been swapped, the engine is from an 85 535i. I thought the m90 was a euro only thing? I do have two early (78' and 79') engines both the 3.3L laying around and have heard using the early tubes style intake allows better flow. I tried this when I put the b34 in but couldnt easily get the newer injectors and rail to fit under the tubes. Any insight on that?

Im understanding the purpose for everything except for the need for the m90 block is the bore or deck height different? And Ive never heard of clearance volume but Im guessing it means the valves go a further distance than earlier models? This would mean the cam Ive already got wouldnt work right?

Just looked at the wiki for the m30... anyway, it says the m90 is a b35 engine would that mean the head that comes on it is already the optimal one? Or is swapping to the US b35 head the benefit?

[pbonsalb]

I would use a late block. The newest one is from the 91 E34 535i. It is in the 3.4 to 3.5L range stock. There are apparently two heads, generally called early and late. The late one supposedly has 1mm larger valves and bigger ports but also lower compression

http://www.firstfives.org/faq/cylinder_head/cylinder_head_faq.htm

We have the late block in a 74 Bavaria with dual webers.

Shrick made some nice cams for these engines. There are also some aftermarket copies that are affordable and may offer slight improvements. For a turbo down the road, stay on the mild side.

Miller Performance used to turbo these cars and may have some suggestions for the best parts for forced induction use.

[Brody @ Miller]

The late blocks are garbage. They have lots of material removed. The earlier e28 blocks do not have material remove and are actually the same block as the 745, and m cars.

When BMW removed material they used cast in ribbing to make up for it. I will see if I have some
Pictures comparing them, but the early blocks are the ones we always try and use.

[JamesM3M5]

Interesting, I had no idea about the newer blocks... You do have to clearance the earlier block to fit the larger B35 crank, but nothing that hasn't been done before.

[6erWEBB]

Mmmm now thats helpful. Any info on the head difference between euro and us?

I did notice that it seems all the m90 blocks have the early style intake on them...

[bawareca]

The late blocks are garbage. They have lots of material removed. The earlier e28 blocks do not have material remove and are actually the same block as the 745, and m cars.

When BMW removed material they used cast in robbing to make up for it. I will see if I have some
Pictures comparing them, but the early blocks are the ones we always try and use.

Everything early is better ;)

[Captain Bondo]

Everything early is better ;)

Not the heads, not by a long shot.

B34 block and B35 head is the ticket.