READ before using m50 injectors

[lukeADE335i]

Also - if you really wanted to run the injectors at the M50 spec. 3.5 bar you could probably run a Porsche 944 fuel pressure regulator.

This is possible with the M30, so would probably suit the M20 too (since the M20 & M30 FPRs look suspiciously similar).

[mpowerful]

I have been playing with injectors a lot lately. I have personally upgraded them to 17lb gen three injectors recently. Anyway the m50 injectors do run about 15lbs at 3 bar. I wanted something capable of running a little hotter so i got these which are rated at 17lb/hr at 3 bar. I ran them for a while on a pretty much stockish tune and they ran great. No issues whatsoever. Part throttle acceleration was def much stronger than stock. My mileage however was roughly same or only marginally improved. What i did was tune them to run like 15lb injectors for all part throttle maps then added more fuel trim in wot maps to basically make them run at 17lb rates since the car pull much harder with more fuel and more ignition advance. This also prevents knock which will eventually cause damage. Knock can be delt with in 3 ways. Lower intake air temp, add more fuel, or retard ignition timing. With 17lb injectors i can run much more fuel at wot with super aggressive igntion advance without reaching over the duty cycle capability of the injectors. At wot although you arent spending long there you can get 90-95% duty cycle with stock and m50 injectors.

Anyway i have gone off point. My point is that the m50 injectors are a decent upgrade due to four pintle design but really dont flow much more than stock will. I highly recommend the gen 3 bosch injectors even if you dont get a tune and most certainly if you do.

[bataangpinoy]

m50 injectors =
166 cc @ 3bar

So that means on a m20 with a normal 3 bar regulator, the m50 injectors would be 15.81#'s instead of 17.5 (which is higher than stock m20)

You will not run lean, you'll have more fuel, your o2 will probably correct it.

you get 4 pintholes or whatever theyre called, so you get better atomization. m50 injectors are a complete upgrade. They are completely capable of fueling a modified m20. I dont have any issues with getting into 11:1 ratios with a 3" MAF at WOT.


EDIT: Yes, I have a wideband. and dyno to prove.

perhaps i had something else going on with my fueling system.

I trust my injector rebuilder, he did my sr20det injectors, and they were spot on.

why were my numbers only at 14.5 lb/hr at 3 bar? is there a variance in injector p/n for vanos vs non vanos m50?

[bataangpinoy]

thanks for the info ya'll

[mpowerful]

As injectors age there will be some variation. Usually people sell matched sets for this reason.

Anyway if you had a 2.5 with bolt-ons or a 2.7i id say go for some 19lb/hr. Unless the setup is extreme they should be more than enough.

[Wh33lhop]

I'd either use stock, rebuilt stock or upgrade to the design three 19lbs these are actually a better designed injector(4 pintle plastic body) the m50 are just bigger but the same design. Leave your injectors alone is the best thing. I do however use redline injector cleaner.

M50 injectors are 3 pintle. M20 injectors are single pintle.

[SmokeE30]

perhaps i had something else going on with my fueling system.

I trust my injector rebuilder, he did my sr20det injectors, and they were spot on.

why were my numbers only at 14.5 lb/hr at 3 bar? is there a variance in injector p/n for vanos vs non vanos m50?

That's what the engine wants, so who cares, if you later need more fuel you can raise pressure to get it.

[Quinthirty]

Just wanted to ask if you were running the 4-pintles without any chip modifications.

[bernzpeed]

I've actually put M50 injectors on my M20 with a chip and there is definitely noticeable difference. My car is an automatic or I should say was, (S52 + G260 now) and I can say there is a quicker response when stepping on the throttle.

From my experience, this is a good simple upgrade.

The guy who bought my engine was extremely happy about his purchase.

[TC Baur MD]

I replaced my rebuilt m20 injectors with the M50 injector upgrade and I believe it was one of the best upgrades I ever did. Quicker starts and better acceleration. I'm running a Mark-D 93 oct chip.

[DesertBMW]

M50 injectors will flow the same CC if you used them with 2.5bar fuel pressure regulator.
They are good efficient replacement to your old single pintle design.