READ before using m50 injectors

[bataangpinoy]

**Read and use your common sense before you post**

In my initial post here (when i made the thread), I claimed that M50 injectors are a downgrade from stock m20. Turns out that I was in fac, misinformed. My purpose in making this thread was to provide some insight as to whether or not m50 injectors are a good upgrade for your m20. Most people just getting into an e30 (or cars in general), most people will tinker, choosing to do cheap little mods to increase the reliability or "gain" performance from their vehicle.
I've taken out my incorrect information, and simply want to provide proper insight to the m50 injector upgrade.


Initially I claimed that M50 injectors are actually a down grade. This doesnt seem to be the case.


I ran the m50 injectors on a stock m20 with the stock m20 FPR. Car felt down on power, EGT's were too hot, and it felt like I had no fuel. And then i realized that I was running my injectors at a lower fuel pressure. I have a pic somewhere of the flow test sheet of the m50 injectors i purchased. Tested injectors at 3 and 3.5 bar. Although archaic(and probably too little too late), you can inspect the condition of the spark plugs to detect air fuel mixture. My plugs were the standard bosch copper core, and were "overheated." Which may indicate a lean condition.

http://www.xbhp.com/talkies/attachments/help-me/61397d1344802496-need-suggestions-restore-original-pickup-check_spark_plug_condition.jpg

iirc, m20b25 injectors are 16# at 3 bar, while m50 at 3 bar is 14.5. *edit* other members have said m50 injectors run 15# @ 3 bar *edit*

http://www.e30tech.com/forum/showthread.php?t=112796&page=3

So what's the actual flow rate of m50 injectors?

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.

Will you make mega horse power by just upgrading your injectors?

Simply increasing the flow rate of the injectors won't, in the long term, result in more fuel (which the engine doesn't need or can use). Provided the increase is not too much the DME will learn to reduce fuel flow to achieve a 14:1 AFR.

With the stock injectors & FPR, it is possible to hit a 12.8-13 to 1 AFR across the engines"s range of operation with chip tuning. At the rev limit the injector will be operating at high duty cycle, but since the engine isn't going to spend much time there (in the general case) that doesn't matter.

THANK YOU. Even stock m20 management can pull or add fuel, you'd have to really mess with sensor in/outputs or have crazy big/small injectors to stop it from being where it wants to be.

You can take advantage of them with a chip tune, but otherwise they will operate like stock (but with a better spray pattern).

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.

What if I have a 2.5 with bolt ons or a 2.7i hybrid?

Thank you to those who have posted correct information in this thread. M50 injectors do not flow less than M20 injectors. The M50 injectors are an excellent choice for a lightly modified 2.5L or 2.7i. They can also work quite well without a specific tune. When getting in to 19lb injector territory you really need a tune for them to not run your engine way too rich.

Hope that helps ya'll getting started messing with your e30.

[ClayW]

Do you know if the FPR on the M50 is a simple swap over to the M20?

[bataangpinoy]

Tt fits into the rail, but the mounting points are different.

google image both FPR's, and compare them.

[20gmr]

i was hoping their would be at least wideband readings or something back up your claim further than it felt shity.... I agree with the numbers and figures you posted but until someone actually tests m50 injectors at 3.0 bar no one can know for sure how they flow compared to stock.

I feel that the lower pressure should get them pretty close to factory size, certainly close enough for fuel trims to get them under control. I have used several sets with and without chipping the cars and they all ran strong. I doubt im the only person who says that too

[Deadskittles]

Something to keep in mind is the percentage of the injector you are using. When you are running 14.5# injectors they are probably rarely running even 90-95% of thier max, so m50 injectors could still possibly be adequate plus they are newer (i believe) so you may get a better spray pattern and thus atomization. Food for thought

[bataangpinoy]

Something to keep in mind is the percentage of the injector you are using. When you are running 14.5# injectors they are probably rarely running even 90-95% of thier max, so m50 injectors could still possibly be adequate plus they are newer (i believe) so you may get a better spray pattern and thus atomization. Food for thought

http://www.e30tech.com/forum/showthread.php?t=100294

0280150415's? they are 18.1lb @ the M50's 3.5 bar fuel pressure. at the M20's 3 bar pressure they are about 16lb. im running a set of them, also had M30 19lb single pintle injectors in there before that.

@ the OP, tuning (ie- a chip) for the injector size u plan to run is a good idea..

[Deadskittles]

Interesting. If people really wanted an upgrade maybe they should just pick up some pink top 21.5# s52 injectors.

[Chriskbmx]

if you had a chip for 17 pound injectors you can run them at whatever duty cycle you want. I imagine the issue is running it with stock software that makes it the problem.

[jlevie]

Simply increasing the flow rate of the injectors won't, in the long term, result in more fuel (which the engine doesn't need or can use). Provided the increase is not too much the DME will learn to reduce fuel flow to achieve a 14:1 AFR.

With the stock injectors & FPR, it is possible to hit a 12.8-13 to 1 AFR across the engines"s range of operation with chip tuning. At the rev limit the injector will be operating at high duty cycle, but since the engine isn't going to spend much time there (in the general case) that doesn't matter.

[digger]

**Read and use your common sense before you post**

been getting a few pm's on facebook about this, and I decided to post this here..

M50 injectors are actually a down grade.
Do they fit? Yes.
Will your car run? Yes.
Will you run lean? Almost dangerously.


Time to use your brains here.

The FPR on the m50 pushes 3.5 BAR of fuel, allowing the injectors to flow at 17.5 lbs *only* when the fuel pressure is at 3.5 bar. (at 3 bar, they flow about 14 lbs)

The e30 FPR pushes 3.0 BAR, making the stock m20b25 injectors the better choice. Get em rebuilt.


If you want to run m50 injectors, you need to also get an FPR (or get an adjustable) that operates at the same pressure as the m50 unit (3.5 bar).
The 3 bar unit on the m20b25 won't allow the M50 injectors to flow at the 17.5 lbs.

How do I know? Cause I ran the m50 injectors on a stock m20 with the stock m20 FPR. Car felt down on power, EGT's were too hot, and it felt like I had no fuel.
And then i realized that I was running my injectors at a lower fuel pressure.

Hope that helps ya'll getting started messing with your e30.

running 17.5lb injectors at 3b instead of 3.5b will "change" them to flow 16.2lb/hr not 14lb/hr.....atleast theoretically. im sure a quick flow test would reveal the true numbers and be more accurate than the simple equation that gives a ballpark answer

also the stock ones are 14.5 to 15lb/hr best i found last time i was after a set about 7 or 8 years ago

also you cant really run dangerously lean on a stock M20B25 you will lose power but it will take a very long time to hurt something. i know guys who used to tune for 14.2:1 AFR WOT 4000-6500rpm on stock M20B25 racecars( i have no idea why you would when there is more lower usually at 13 +/- 0.5)
. slightly rich of stoich is the most "dangerous" but you need a modified engine to be worried too much.

[Roysneon]

Simply increasing the flow rate of the injectors won't, in the long term, result in more fuel (which the engine doesn't need or can use). Provided the increase is not too much the DME will learn to reduce fuel flow to achieve a 14:1 AFR.

THANK YOU. Even stock m20 management can pull or add fuel, you'd have to really mess with sensor in/outputs or have crazy big/small injectors to stop it from being where it wants to be.

[nando]

injectors are rated at 3 bar. not 3.5 bar. they are 17.5# at 3 bar, not 3.5. effectively at 3.5 bar they would be larger, not smaller

the engine will not run lean because of M50 injectors.

[88SuperETABD]

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.

[bastianshaw]

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.

[MR 325]

Thank you to those who have posted correct information in this thread. M50 injectors do not flow less than M20 injectors. The M50 injectors are an excellent choice for a lightly modified 2.5L or 2.7i. They can also work quite well without a specific tune. When getting in to 19lb injector territory you really need a tune for them to not run your engine way too rich.