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Old 06-12-2006, 08:07 AM   #16
Blackout
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what about installing a "is" head? i dont know what this entails but i heard this does something. is this true??
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Old 06-12-2006, 08:28 AM   #17
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would nos make a improvement and would it be practicle on the eta motor?
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1985 325e :: sold
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1984 633CSI :: sold
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2000 528i :: Mom's Car
1991 318i :: sold
E36 M sport seats, Z3 shifter, MarkD chip, Black'dout kidneys, Kamei Eyelids, Shadowlined, Side Marker Delete, All Red Tails, Smoked Turn signals, Omega Keyless entry, Rieger Lip
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Old 06-14-2006, 04:24 PM   #18
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This is not the thread for those questions. Search the forum.
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Old 06-14-2006, 04:33 PM   #19
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okk
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1983 633CSI :: sold
1984 633CSI :: sold
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2000 528i :: Mom's Car
1991 318i :: sold
E36 M sport seats, Z3 shifter, MarkD chip, Black'dout kidneys, Kamei Eyelids, Shadowlined, Side Marker Delete, All Red Tails, Smoked Turn signals, Omega Keyless entry, Rieger Lip
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Old 09-12-2006, 10:09 PM   #20
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The 325i uses Bosch 0 280 150 715 injectors, which have a rating of 149cc/min, or 14.6 lbs @ 43.5 psi(3.0 bar)

The the M30 engine in the 535i uses Bosch 0 280 150 203 injectors which have a rating of 185cc/min or 17.6lb BUT at 36.25psi(2.5 bar).......so at the m20 b25 3.0 bar that is 19.30 lbs.

The m50 (green ) injectors do flow 17.5 lbs but at 3.5bar(50.7psi) so on the m20b25 3.0 bar they flow 16.2lbs.

I have never seen proof that the stock injectors are maxed out. Alpina got 210hp using stock AFM and injectors. Most people notice a difference after swapping injectors simply because they are replacing dirty injectors with clean ones.

The M30 AFM gave Dave a 4.6 HP increase with adjustable fuel pressure and dyno tuning. The majority of the people who try this mod get drivability problems. If you want to replace the AFM have a look at an MAF. The biggest restriction in the intake is the intake manifold, followed by the head.


The stock intake is a cold air intake and is well designed so you won't get any increase from adding a cone.

Sadly, the only easy/cheap hp increase for the M20 is a chip.

Last edited by Curtis; 09-12-2006 at 10:12 PM.
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Old 09-13-2006, 12:14 PM   #21
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Thank you for adding to the information posted.

Alpina, and other German tuners did indeed build stroker motors using the stock injectors, but from what I understand all changed the fuel regulator, increasing the fuel supply.

While admittedly my personal motor had likely tired injectors during my dyno session, they did CLEARLY move into "wide-open" when combined with software changes (Mark D'Sylva). With the stock chip, the AFR ratio was almost perfectly stoich through the RPM range.

You seem to be a knowledgeable person, therefore I'm sure you must have come across the simple mathematic formulae used to calculate possible power from a fuel injector. Using these, at 80% of the injector's duty cycle (the highest use generally recommended) a stock M20 injector can only make ~140hp. Using that number and calculating further, one will find that BMW is actually running the stock injectors at 96% of their duty cycle, in a bone stock M20B25. A 14.6lb/hr injector combined with the stock 3.0 bar regulator can only physcially make 175hp. This is simple physics, it's impossible to argue with.

I hope this is sufficient proof for you that stock M20 injectors are too small to add any sort of modifications to the motor and actually gain power.
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Old 09-13-2006, 05:31 PM   #22
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^^ Unless you bump the fuel pressure, to allow more fuel in during each opening, but going to upsize injectors works.
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Old 09-13-2006, 06:43 PM   #23
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Yep. Most M20's around now could use fresher injectors anyways (as well as 4-pintle), hence the common recommendation of upgrading them rather than upline modifications.
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Old 09-26-2006, 11:55 PM   #24
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Quote:
Originally Posted by Mystikal
You seem to be a knowledgeable person, therefore I'm sure you must have come across the simple mathematic formulae used to calculate possible power from a fuel injector. Using these, at 80% of the injector's duty cycle (the highest use generally recommended) a stock M20 injector can only make ~140hp. Using that number and calculating further, one will find that BMW is actually running the stock injectors at 96% of their duty cycle, in a bone stock M20B25. A 14.6lb/hr injector combined with the stock 3.0 bar regulator can only physcially make 175hp. This is simple physics, it's impossible to argue with.
Lets say that the stock injectors are good for around 175hp, which is more then the peak hp of the car (and i'm sure most e30s are puttin out well below the original hp numbers at this age). You don't drive around at peak hp, so the injectors are running 80% or less for the majority of the time. Running at 96% for a split second when the engine hits peak hp isn't going to hurt anything and still isn't maxing out.

Also, the bsfc values used by online calculators are approximate. If we use a bsfc of 0.4 the stock M20 injector is good for the 215-220hp @ 3bar that Alpina claims. There are lots of unanswered questions about the stock injectors, but I guarantee that BMW engineers didn't make a mistake when choosing the stock injectors. Also, keep in mind that all the sites with injector calculators are trying to sell you new injectors.

Just FYI, I just used an online bsfc calculator that calculated the bsfc of the 325i engine to be more like 0.42 and not the default 0.5 used by injector calculators. (bsfc = brake specific fuel consumption - How much fuel you are using per horsepower per hour) Try the online calculators/formulas again but this time change the bsfc to 0.42 and see what you get.

19# Ford Mustang injectors are 30% bigger then the stock injectors. At WOT the ECU does not use the O2 sensor to adjust the fuel delivery, and does not know you have bigger injectors, so the car will run extremely rich. Bigger injectors require tuning, they aren't plug and play for optimum results.

Here is something else to think about from another thread:

"Under normal driving conditions the economy should be the same but under slight variations in load the O2 sensor has a harder time getting things right. Say you've driven the car hard at WOT and have back off and will now be cruising on the highway your AFR may have been 12:1 when the car started to cruise. Now your O2 sensor will try to lean if off by changing the injector pulse time (reducing it) but how much does it it reduce it by? It doesn't know you have bigger injectors so when it reduces it, it is by too much and it runs too lean. So then it tries increase the AFR by increasing the pulse time and it runs over rich again. Eventually it will get to 14.7:1 but it takes longer than would be the case with the standard injectors. The O2 sensors help but they don't not work instantaeoulsy but rather in a closed loop. "

Last edited by Curtis; 09-27-2006 at 12:29 AM.
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Old 09-27-2006, 12:35 PM   #25
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wut about for a 1991 318i?
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2000 528i :: Mom's Car
1991 318i :: sold
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Old 09-29-2006, 02:22 PM   #26
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Quote:
Originally Posted by mike85-325e
wut about for a 1991 318i?
Since we now know that the stock 325i injectors are no where near maxing out at stock hp levels, I would assume the same to be true of the 318i.

To be sure:

1) Find out stock injector size.
2) Use online bsfc calculator to calculate your engines bsfc. (most BMW engines are well below 0.45 bsfc)
3) Use online injector size calculator and use the bsfc you found in step 2 to see what size injectors are optimum for your hp level.

Last edited by Curtis; 09-29-2006 at 02:26 PM.
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Old 09-29-2006, 05:25 PM   #27
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other than injectors wut would give me the biggest gains? m30 afm? already considering the Markd chip.
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1985 325e :: sold
1983 633CSI :: sold
1984 633CSI :: sold
1985 635CSI :: Dad's Car :: FOR SALE
2000 528i :: Mom's Car
1991 318i :: sold
E36 M sport seats, Z3 shifter, MarkD chip, Black'dout kidneys, Kamei Eyelids, Shadowlined, Side Marker Delete, All Red Tails, Smoked Turn signals, Omega Keyless entry, Rieger Lip
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Old 09-30-2006, 02:31 PM   #28
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Quote:
Originally Posted by mike85-325e
other than injectors wut would give me the biggest gains? m30 afm? already considering the Markd chip.
The M30 AFM is another one of those mods that doesn't really work well. I'm not really sure how to get power out of a 91 318 4cyl engine, but you don't want to be swapping on any 6cyl engine parts as they will be completely wrong for your engine.
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Old 10-04-2006, 04:59 PM   #29
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Not a power upgrade, but the best bang for the buck is to go with a higher geared rear diff. I've got a 4.10 on my 325is and I love how it pulls. Granted, you shift more and have a lower top speed, but it makes a more noticeable difference than any other single mod I've made.
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Old 05-25-2007, 12:58 PM   #30
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ive been think about a 4.10 diff , i have a 2.7i with a shrick 284 cam, will i notice and big differece it i go with 4.10,and i found one for 50$ but it isnt limited slip ,what is the difference between both
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