Installed S50 injectors

[Mystikal]

Spent some time this morning at the BMW garage, had a tech throw them in for me (yeah, I'm lazy and usually incompetent).

With the MarkD 93 and K&N cone on the dyno, I could see the stock injectors were both tired (299k kms) and realistically not able to handle the demands of the software. There were still solid power gains throughout the rev band, but the A/F curve obviously showed that the car was asking for more fuel, and the weak injectors just couldn't deliver.

The car started immediately after the swap; no eta regulator, no software change, no changes made. With the 17.5lb Design II injectors, the car fired up immediately and idled perfectly. I know a lot of the guys who swapped to 19lb ones had a little ECU self-adjusting going on with the inherent roughness.

I expected the 4000-6000RPM range would get a slight boost now, since the car is getting the amount of fuel the software is requesting. But as soon as I pulled away from the shop, the difference in torque and throttle response startled me. In any gear and at any RPM, the throttle feels completely different; it's significantly more sensitive and responsive. I proceeded to beat the snot out of the car all the way home, and the torque gain caught my attention every time I floored it, and the power above 5500 didn't go relatively limp like it used to; the car is actually worth revving above 6000 now. Overall this mod did significantly more good than I expected it to, I honestly wasn't looking for much of a palpable difference in power.

Anyways this is just another friendly reminder that if you mod ANYTHING on an M20B25, you really need to swap those puny stock injectors out for something bigger. A lot of guys go for the 19lb Mustang ones, but don't bother; you won't need that much fuel, and you'll need to make sure that you find Design-II 4-pintle ones. All of the M50/S50 injectors are 4-pintle, and there are LOTS laying around the forums from guys who upgraded to 3.5" HFMs and whatever the hell else E36 guys do. I will revisit the dyno for some hard numbers once Mark D'Sylva gets this local one up and running, I'm really curious as to what I'm making now.

[rwh11385]

Cost?

Update later with mpg. Maybe Type IIs helps with that too.


Yes. Torque. word.
Is your burn the same as mine? Or a different version?

[Mystikal]

I paid $40 for all 6 with 40k on them, and it shows. All o-rings look brand new still.

I already noticed that the MPG (well, L/100km) gauge is reading 5-15% lower in routine driving at steady state cruising, literally because I don't need to push the throttle down as much to maintain the same speed.

We have the same software, so far there is only one version of the 93 octane chip out there. Funny enough, Mark strolled into the shop while I was there, he was putting a chip into a Brilliantrot E34 M5.

[rwh11385]

damn cheap.

[Court M3]

what other mods beside chip do you have? Are you running the stock AFM or M30?

[nando]

your MPG gauge is now inaccurate because the large injectors will have to open less to flow the same amount of fuel, but the ECU doesn't know this. but if you calculate your mileage with the trip odometer, you should see a slight improvement (basically gains in efficiency, since the stock injectors run up to 90% duty cycle).

[Mystikal]

what other mods beside chip do you have? Are you running the stock AFM or M30?

MarkD 93 and K&N Cone on a stock AFM.

your MPG gauge is now inaccurate because the large injectors will have to open less to flow the same amount of fuel, but the ECU doesn't know this. but if you calculate your mileage with the trip odometer, you should see a slight improvement (basically gains in efficiency, since the stock injectors run up to 90% duty cycle).

Thanks for the info.

[rwh11385]

Jay, by the end of the summer, I'll let everyone see what 80-100 is like with Mark 93, 19#, 4.23 rear end, M30 AFM, and either stock airbox or K&N cone looks like. It's pretty flipping sweet.

But you talk more romantically about the running and changes than I ever could.

[golde30]

Re: Installed S50 injectors

...and you'll need to make sure that you find Design-II 4-pintle ones. All of the M50/S50 injectors are 4-pintle, and there are LOTS laying around the forums from guys who upgraded to 3.5" HFMs and whatever the hell else E36 guys do.

so are all the injectors on the m50/s50 motors the same? or is there an early version and a later version(design2?) ? thanks for any info, sounds like a good mod for us eprom chip upgrade users.

[Mystikal]

They're all the same.

It's funny how the Mustang ones became so popular, when the M50 ones are still very easy to find and suit the motor's requirements better. Plus they're ALL Design II.

[arsevader]

What you are seeing is probably more of an improvement from replacing tired dirty injectors with clean ones with the improved spray pattern.

You are right that the ECU doesn't know about the new injectors but it will try to maintain lambda. It will throttle back the injectors untill they are delivering the correct amount of fuel for your car.

You aren't introducing any more air into your engine so it would run rich if the ECU didn't do this. It's a good improvement over stock but not for the reason that most people think. You will probably see a slight fuel mileage improvement too.

James

[Mystikal]

What you are seeing is probably more of an improvement from replacing tired dirty injectors with clean ones with the improved spray pattern.

Very true. 307k kms on the factory ones shouldn't equal anything resembling OEM spray performance. Still, the car did make 143hp/147lb-ft stock with the tired ones, so I'm not sure. With the aggressive software I have in there now though, the more capable units are likely producing much more tangible results than if the chip was still stock.

[BS87]

4.23 rear end

Did you hack up something that i didn't hear about, or are you just doing that goofy calculation with your 4.10 again, i forget.

4.23 diff would be nuts.

[Mystikal]

4.23 rear end

Did you hack up something that i didn't hear about, or are you just doing that goofy calculation with your 4.10 again, i forget.

4.23 diff would be nuts.

4.10 + 195/60/14 tires. I ran a theoretical 3.85 with the Azenis last year, for example.

[arsevader]

With the aggressive software I have in there now though, the more capable units are likely producing much more tangible results than if the chip was still stock.

What does your software do though? Most chips/software just change the timing to a more aggressive timing. Nothing is going to make the ECU flow more fuel except to increase the air into the engine.

Another mistake people are seeming to make alot is thinking that increasing the diameter of their AFM is going to make a difference. The AFM is not the bottle neck in these engines. The intake ports are. Increasing the airflow before the intake ports isn't going to do shit.

Not to knock your upgrade, I plan on replacing my injectors soon with the newer improved ones. THey are more efficient than the stock ones just not more powerful.

It's just that there is a lot of misinformation out there in internet land.

James