M50 Injectors tried in my M20

[nickphine]

I've just tried a set of M50 (erm I'm guessing M50 rather than M52 here) injectors out of a 95 520i. They're light grey so supposied to be the same flow rate as my standard 325i ones. They work fine, the car seems to run identically with them in, I can't feel any difference at all. Worst of all they tick in exactly the same way as the 325i ones so no obvious benefit. Still it's an easy upgrade/downgrade/samegrade....

I may have read somewhere that there are plastic bodied injectors from later cars, this may help with the ticking?

My new solid lead exhaust manifold might quieten them down a little!

[b12rlw]

ive bought 440cc bosch efforts for my turbo last year. they are green plastic bodied things that tick like a bunch of ticky things. just adds to the character

[nickphine]

So carbs it must be then. I just wanted my bmw to sound meaty inside as well as outside, i guess i shouldn't have removed all the sound deadening...

[HairyScreech]

do report back after a while, would be interesting to get feedback from a reasonable man as to the long term pros/cons of m50 injectors on a standard m20.

noticed any improvements in idle and low load economy?

[nickphine]

Nothing to report yet, only a quick wizz up the road, no obvious differences but i'll keep you posted.

[bmw_325i]

I've had M50 injectors for a while, and consider myself reasonable. But that could be a bit unreasonable

Idle is a bit rough and light load economy sees AFR's in mid 15's to low 16's.

Getting the right fuel pressure is quite important. Originally started with 3.5BAR but that was way too low, quite hesitant at part throttle especially when coolant temp was not cold but not hot (didn't have the AFR gauge then).

Having adjusted over a period of 6 months i have found on my engine that 3.7-3.8 was a bit on the low side and had a touch of pinging so back up at 3.9 which seems to be the sweet spot.

This is all with a Miller MAF conversion, adjustable FPR and Innovate AFR guage.

On the Miller chip at idle at 3.9BAR, AFR starts at low-mid 14's at cold start, runs up to 15-16's over the 1/4 temp mark, and then steady around stoich at normal operating temps.

Do wonder what the long term implications are of operating the fuel pump at higher pressure.

[DmcL]

the M50 injectors are slightly higher flowing than the standard M20 injectors.. also they are 4 pintle rather than single so atomise the fuel better. they can be used with an otherwise standard M20 as they dont flow loads more than the M20 injectors. if looking up the flow rate of the M50 injectors dont forget that the M50B25 runs 3.5 bar fuel pressure if memmory serves and the M20B25 runs 3.0 bar so the flow info on the M50 injectors should be at 3.5 bar, when worked out for 3.0 bar they end up marginally higher flow than the standard M20 injectors.

that is assuming you were to use M50B25 injectors on an M20B25, M50B20 injectors probably flow a little less than standard M20B25 injectors.

[bmw_325i]

DMCL - yep, that's true.

I have 0280150415 for M50B25, rated at: 18.1 LBS/HR, 190.2 CC/MIN at 3.5 BAR. 16 LBS/HR, 166 CC/MIN at 3.0 BAR.

To achieve the right AFR for the Miller 19# chip i have had to bump the fuel pressure quite a bit.