M20 325i on M50 325i non vanos management

[Brian28]

I am swapping M20 325i running gear into my 4 pot racer. I'm planning to run it on M50 management, and would like to try the M50 stuff on the M20 engine before I lift it out of the E30 donor car. I'll do it all properly when it goes into the race car with the big connector spliced in for plug and play etc, but for now what is the minimum I need to connect up for a temporary fix? I'll be leaving the original M20 manifold and injectors in place for convenience for now, would like to be able to run with M50 loom and ECU, M50 coil on plugs, and M50 loom plugged into the M20 injector sub loom. (I've not checked the connections yet to see if they are the same). Will likely be next week sometime, any ideas welcome before I start.

Cheers
Brian

[Brianmoooore]

Red and brown/orange to battery + and - respectively, and in the round multi pin plug: Green to ignition switched live, black/yellow to 12 volts from the key starter position, and green/purple out of the engine loom to feed the fuel pump.

[Brian28]

Perfect, thanks.

[HairyScreech]

do make a thread of this on here, its something i have been looking at for a while to get a bit more economy and drivability from the e30.

i have a few links if you have not already been googling the conversion.

[Brian28]

Links would be handy please (your idea that I'm using in the first place ). I read one long thread on an american site, but posted by an English chap. The thread seemed to run out of steam before really reaching final conclusions (that I could understand anyway ) on exactly what needs to be done to properly sort cam trigger wheel and TPS, the thread stopped before the car was test driven. Any "idiots guide" links would be useful. I've sourced everything else on your PM shpping list, will make a start on engine building as soon as time allows

[HairyScreech]

gah, engage brain. - yes got it.

hows the build going?

ill dig through my notes for future use on mine and ill let you know.

[Brian28]

Thanks. Nothing at all done yet, have got the stuff together, but the 325 breaker I bought as a donor is still blocking the garage until I get time to strip it, so won't be able to get the race car in for a while yet.

[daimlerman]

What sort of advantages are you thinking about,please?

From my POV,I have one car with M50,one with M20 2.7.....

[DmcL]

M50 ECU uses a chip that is twice the capacity as that of the late E30 ECU's.. u get higher resolution in most maps, a factory MAF, coil on plug and some other nifty little benefits, i think sequential injection as well if memmory serves.

have been considering doing this myself also.. i have been tuning the standard M20 motronic ECU's for a couple years now and have peeked into an M50 file or 2 in that time, looks like it would be a worthy upgrade especially since id be able to tune it myself as well.

if u arent into tuning the standard ECU's u will need to get it tuned by someone because the standard M50 values in many of the maps will not be ideal for an M20.

[daimlerman]

M50 ECU uses a chip that is twice the capacity as that of the late E30 ECU's.. u get higher resolution in most maps, a factory MAF, coil on plug and some other nifty little benefits, i think sequential injection as well if memmory serves.

have been considering doing this myself also.. i have been tuning the standard M20 motronic ECU's for a couple years now and have peeked into an M50 file or 2 in that time, looks like it would be a worthy upgrade especially since id be able to tune it myself as well.

if u arent into tuning the standard ECU's u will need to get it tuned by someone because the standard M50 values in many of the maps will not be ideal for an M20.

Thanks,a pleasant,easy to understand answer!
I am running a Miller MAF on my 2.7,when it was 'live mapped' earlier this year,we discovered that it made little 'real world' difference to the fueling side,Miller had simply upped the fueling randomly through the rev range,smoothing it out and tweaking the timing a little found extra torque and BHP throughout the range.

However,if an M50 setup can be made to work properly,there could be some clear gains in both drivability and fuel economy to be had.

[Gunni]

fuel economy will only come from sequential injection. So a camsync sensor must be installed.

You can replace the COP´s with M42 style CNP´s (coil near plug)

Don´t expect to much though in terms of gains for economy, drivability will be way better though.
Way better then any M1.3 setup ever could.

[bss325i]

Don´t expect to much though in terms of gains for economy, drivability will be way better though.
Way better then any M1.3 setup ever could.

Even though with the M50 management being sequential and only firing one injector at a time as opposed to the Motronic 1.3 firing three injectors at a time?

[Gunni]

sequential is more about emissions then fuel conversion efficiency

[bss325i]

I guess with sequential you would get less hydrocarbons but surely you would see an improvement in economy.

[HairyScreech]

i think the real benefits from the m50 management will come from the much more accurate timing control, from the wiring diagrams the m50 runs knock sensing as well as a higher resolution, this will allow running much closer to uncontrolled combustion than the m1.3.
tighter timing control will give better economy.

M50 management is also lambda controlled, considering how rich mine has taken to running recently for no real good reason i can see a major improvement in the transient fueling.

the maf also makes for less restriction in the inlet, anything that eases the path of air into the engine will reduce pumping losses.

another fringe benefit in terms of economy is the longer dwell time of the coil on plug setup, the individual coils can produce a much higher voltage than the single coil and allow you to run wider spark gaps.
this allows a fractionally larger flame front initiation point, which can help create a faster, cleaner burn.
this is the idea behind twin spark and things like surface discharge plugs.
(i fucking love twin spark, theres a reason its banned in F1)

over all the small improvements of the M50 management combine to make a worthwhile contribution to the power and economy potential.

[Gunni]

The timing control isn´t more accurate unless you tune the ecu.
Knock sensing is only there for extremely dangerous situations, a stock M20 has none of those.

The dwell you mention is of no concern as the single coil is not running "hard" on a stock m20 or even a worked one, the coil can supply good spark up until about 1.2-1.4bar boost on a M20.
No stock engine will loose anything running just single coil.

When manufacturers make single coil cars like they did, the coil must be specced and the dwell aranged so that at peak rpm and load there is PLENTY spark energy available, this also means that at lower engine speeds there is more then required available.

The only gain I can see from a M50 management is the variable TPS giving much better transient fuelling and Lambda control when you are having a problem with the engine.