crankshaft & block dilemma

[mands]

Hi everyone

I'm Amanda, new to the forum and site. Its a great site.

I have a slight dilemma, can anyone tell me how I can tell whether I have a M5 block, crank and pistons, or a normal 325i block, crank and pistons?

Basically I've removed and stripped the bottom end. When I bought the car I was told it had a M5 bottom end and uprated head and cam, the latter it has but now need to know about the block. Can I tell off the numbers on the block or crank? The shells are out and they are standard, but is that M5 standard or 325 standard!!!!!!!!

I have currently got a standard 325i engine in the car and you can really tell the difference between the two - its well slow!

Thanks
Amanda

PS I've broken 3 nails now!!!
PPS Is it me, or does old gearbox oil smell like cat pi$$!!

[Geeman]

The M5 engine is physically larger than a 325i engine as it's an M30 based unti as opposed to an M20.

The M5 engine is a 24 valve and will have six individual throttle bodies, where as the 325 is just a 12 valve unit and has just one throttle body.

If it doesn't have these basic things, then it's NOT an M5 engine...

Hope this helps...

Giles.

[mands]

Thanks for your reply.

Apparently I was told the bottom end only was from a M5 engine, now whether he meant the crank rods and pistons were used, or the block as well. The top end I have is a 325i big valve head with stage 2 cam.

Basically I need to differenciate the numbers on my crankshaft from M5 or 325.

[Geeman]

Bottom end of an M5 will not fit with a 325i head. They're different sizes completely! The crank, rods and pistons from an M5 won't fit into a 325i block either.

You've been fleeced by someone. Hope you didn't pay big money for it.

[dazleeds]

welcome to the zone

[mands]

No it come with the car.

So it means all the power gain its feels must be coming from the top end.

I've taken out my mains and big end shells, I have very very slight scoring, I cannot feel them, I can only see it, would you reccommend I do anything about this, or just buy new shells?? Also could you reccommend what rings i should use, I want to put a better set in than the orginals, although theres nothing wrong with them, the bores are fine, no scoring. You sound like the man to ask!


Thanks

[mands]

welcome to the zone

Cheers

[E30Adam]

Giles is right, the M5 engine is worlds apart from the 325 M20 engine and parts are not compatible.

Can you post pics of your block, we'd be able to identify it in a flash?!?!

Whenever I do an engine rebuild I would ALWAYS use new big ends, shells, bolts etc regardless of how ther condition looks. Remember though that they are available in different thicknesses and are usually colour coded although the colour wears off. They should have a stamp to identify them.

I'd stick with parts from the dealer which included rings unless you are planning on sticking a big turbo to it or some other crazy mods.

HTH

[mands]

I will post some pictures tomorrow so you can have a look . Thanks v much !
mands.