What are the stock lb-hr of my stock 325i?

[baaaaaaa]

I was just wondering what are the stock injector lb-hr in my 1991 325i?

[Dj Buttchug]

17lb i believe maybe 19lb

[baaaaaaa]

When what would be the advantage of upgrading to the 19lb mustang ones?

[Wh33lhop]

17lb i believe maybe 19lb

Nope, you speak of M50 and Ford injectors, respectively. The M20B25 in a 325i comes with 14 lb/hr injectors.

Edit: the theoretical advantage of upgrading to bigger injectors, on a stock motor at least, is twofold:

First, stock M20 injectors are single-pintle (the hole that it sprays fuel from). The 17 and 19 injectors are of a multi-pintle design which allows for better fuel atomization and mixture uniformity, increasing efficiency (power).
Second, (don't quote me on this one because it is mainly hearsay) the stock injectors are okay on the stock rev limit but with the increased rev limit of a chip (typically 7000rpm) the car will begin to lean out beyond 6500rpm, indicating duty cycle saturation. So basically, the stock injectors cannot supply enough fuel beyond 6500rpm or so to get a good air-fuel ratio. So assuming this is true, you will make better power up high with the larger injectors.

Honestly though you are fine sticking with stock injectors. I have laid out the advantages in theory but I do not think it makes THAT much of a difference on a stock motor.

[Kershaw]

it's going to make little difference on a stock motor.

afaik, the stock dme can only handle up to 17.5lb injectors. after that it's all the same.

i = 14lb
e = 19lb (iirc)

i need to fact check before i post. haha. w/e.

[CarsSuck]

i think i remember jlevie or someone state that the lb/hr rating is at a specific fuel pressure. The m20 runs lower fuel pressure than the m50, I have no clue about the fords, but operating at stock m20 pressure gives you a flow rating pretty close to the stock 14.5lb/hr.

e.g. 19lb @ 2.5 BAR = 15.2lb @ 2 BAR

Please correct me if Im wrong

[jmc1590]

You're close. Per RealOEM (and Stan Weiss' Injector Table):

M20 "i": 14.5# Injectors (0-280-150-715) @ 3.0 Bar

M50: 18.1# Injectors (0-280-150-415) @ 3.5 Bar

Ford 5.0 Yellow tops: (0-280-155-700) 18.25# @ 3.0 Bar

M50 injectors w/ stock M20 pressure regulator = 15.5#