Tuning an M50

[sniff diesel]

After finally getting my 325i track car to handle as I wanted, my thoughts are turning towards getting a bit more power from the M50B25 engine (non-vanos) I'm wondering what might be worth upgrading next: throttle body, exhaust manifold, hotter cams etc.

I've already got a generic large cone filter with a 4" air duct feeding it, and have removed the cats (It's an April 1992 so it doesn't need them for the MOT) and have a Peco DTM style exhaust back box.

I'm know the sensible thing to do is fit an S52 engine but I like the fact that should my M50 blow up I can replace my basic engine with a £200 one from a scrapyard, rather than a £2000 M3 lump. I'm not expecting miracles, but it would be nice to see about 220bhp. Being a track car (albeit a road legal one, doing about 1000 miles a year on the road to keep it ticking over between track days) I'm not too fussed about drivability at lower revs as it spends most of it's life about 4000 rpm and it's about 250kgs lighter than a standard 325i so shouldn't be affected by a loss of torque too much.

Just wondering what people thoughts and experiences were.

[agent006]

sniff diesel said:

I'm wondering what might be worth upgrading next: throttle body, exhaust manifold, hotter cams etc.

Yes. All of those. Whether it's cheaper than an engine change all depends on whether you're doing the work yourself.

I've spent the best part of £1500 on my M20 with cam upgrade and remap etc and i'm still barely halfway there, and barely only hafway to the power i'd have if i'd have spent the same on an M52B28. Don't be afraid of engine changes, they can often be the better value choice (note: not "cheaper").

[sniff diesel]

agent006 said:

Don't be afraid of engine changes, they can often be the better value choice (note: not "cheaper").

What I love about the M50 though is the fact that they're so cheap to replace, say for arguments sake it threw a rod through the block I'd be able to swap the engine over for about £200 and then transfer my uprated cams, TB, manifold, remapped ECU or whatever to the replacement engine; so although it may seem a wiser move to fit an M3 lump now in the longer run the running costs should be cheaper by sticking with an M50 and a few bolt on goodies. Does that make sense?

Also I may want to enter the Khumo BMW championship in a couple of years time...

[sniff diesel]

anonymous said:

[redacted]

Sounds similar to the spec of the Alpina B6 lump I've been offered; M50B25 but with a M52B28 crank taking it to 2.8l, Alpina cams, BBTB and put out 240bhp. I'm waiting to see a dyno sheet for proof of the power output before committing.

[sniff diesel]

anonymous said:

[redacted]

That's the man. By the time I've sold my original engine for say £2-300 it would end up costing no more than a pair of hotter cams for my M50. Could hopefully get it fitted in a few days myself.

Do you think it's a good option?

[sniff diesel]

Only thing putting me off ATM is the fact that it's done 150k and there's no dyno sheet to proove the power, just the guy's word that it "felt real quick"