Engine swap

[Cyant1fical]

Just wondering, since winter is coming and I have the 30 parked up now until next year, I’m going to swap the engine, a Lad lives near me with an 1999 e39 523 looking to sell it... would that swap straight in to the 30? I know you have to change the sump and so on but would this slot in easy?

[jmc330i]

It would slot in the same as any other 24v conversion, but unless it's free, a 523i engine is a little pointless IMO - yes it's a 2.5 but it's strangled to 170bhp so is an expensive way to get 170bhp when an M20 will be easier (in terms of bolting straight in, no messing with exhausts, wiring etc etc). If you want to go 24v, you may as well start with a 190bhp 2.5 or go for a 2.8.

[Speedtouch]

They do go pretty well though, at least in my 1997 E39 523i - as quick as an E30 325i and about the same fuel economy (I'm seeing 26 mpg average, mostly country road commuting), which isn't bad for a 1.5-tonne barge.

You can change the inlet manifold for a 525i one to get it up to around the 190bhp mark, though I gather the 'strangled' 523i gives better bottom-end torque (something to do with vortex effect of a narrower inlet manifold tract).

I think the M52B25 is approx. the same weight as an M20B25, despite all-alloy construction.

[jmc330i]

The problem is how much people want for M50 manifolds etc. I would be cheaper and arguably easier to start with the right engine in the first place.

I think the M52B25 is approx. the same weight as an M20B25, despite all-alloy construction.

I've seen pics of M20s and M52s on scales and there was around a 25kg difference.

[Speedtouch]

Which is lighter, presumably the M52?

[jmc330i]

Yes, sorry I should have said that lol

[jmc330i]

Ive got an M52 to swap into my touring when I get chance. I'll try to remember to pop it on the scales at work before and after - 4cyl to 6cyl should be quite interesting.

[Speedtouch]

Indeed, that will make for an interesting comparison...

[Cyant1fical]

Hmm... interesting finds, well he only wants like 3-400 for whole car anyway as he’s to busy with his new one and it’s got the m5 alloys on which i could make my money back on them, I’d end up breaking the whole car down anyway, he’s just after a quick sale but I know it’s been well looked after now and tbh it doesn’t bother me about power as such because I’m planning a turbo for the engine anyway, I just wanted to know if it’d fit in place, thanks lads

[Scotty200]

If your thinking of turbo power a m50b25 would be a better bet as it’s a iron block vs a alloy m52