[SGTulich]

Hello fellas and greetings from Perú

I just bought a 2009 e90 335i with n54 obviously LONG BLOCK but unfortunately the engine just failed a month ago(crankshaft, rods, rod bearings and 2 pistons) and here in Perú there are few of these engines but luckily i just found a 2008 N54 engine SHORT BLOCK.

The question is: Can i swap easily the short block engine with the Long block?

As far as i know the short block has an 8 Bolt crankshaft, the same with the flywheel and flex plate

And the Long Block(my dead engine) goes with a 6 Bolt crankshaft and flywheel,

Finally the N54 short block i'm buying by fortune is coming with an 8 Bolt flywheel and flex plate. So i wonder if it's just changing the 6 Bolt flywheel and flex plate for the 8 Bolt or it needs more changes??

Thanks for your help!!

[limitdown]

A short block just means that it's a complete crankcase/bottom-end that doesn't have a cylinder head. If your existing cylinder head is undamaged, you can bolt it onto your new crankcase/short-block. Your mechanic will need specialized tools to set the timing. If he doesn't have the tools, you can find a set on eBay for around $200. The tools from Taiwan are decent quality.

I'm assuming you have a 6AT, since you're using the term flex-plate.

If the new short block you're buying comes with its own flex-plate, then it'll bolt directly to the transmission.

My old engine had an 8-bolt crankshaft and flex-plate, while my new engine has a 6-bolt crankshaft. I just had to buy a 6-bolt flex plate. You can find used ones on eBay for around $50. When you receive the item, make sure that all of the teeth are good and that the plate is truly flat. Put the plate on a very flat surface and press down on a few parts of the outer edge to confirm.

[SGTulich]

Sorry if i did not explain myself very well LIMITDOWN i meant that i found the whole engine but it is a short block engine (CRANKCASE, BLOCK AND CYLINDER HEAD), and i,d Like yo know if even the sensors are the same from my n54 dead engine, because for example this new engine i'm buying is missing some sensors, alternator, hight fuel pump and if this new engine is easy to swap, because both are N54 engines, and these are my doubts and thanks again for your help. And one more thing the crankshaft sensor would it be the same to?

[limitdown]

Everything is the same. I just swapped all of the sensors, electronics, HPFP, alternator, injectors, turbos, etc over to the new engine. You'll just need to get new gaskets for various places like the oil filter housing area. I'd also take the opportunity to preemptively change the front & rear crank seals, valve cover gasket, oil pan gasket, oil pickup tube gasket. Some of those are a major pain to get to after the engine is in place, but are super easy and cheap to replace when the engine is out.
If your "new" engine has an existing flex plate, then the engine will bolt directly to your transmission.

[LessIsMore]

The term "long block" and "short block" has nothing to do with the actual engine block specs or fitment - just means it either comes with a head and maybe some accessories, or it's only the block/crank/etc.
Your sensors and everything should bolt up to the new engine.