m50b20 injectors in a 325 with other mods

[PeteE30Tourer]

My 325i cab has a standard engine currently apart from a chip from on here. It drives ok, but you know how it is - you always wish you had a bit more grunt, so I'm starting to think what's the best way to invest in this. I have a set of m50b20 that I bought on here and had fully refurbished. I was told originally that these were a good swap for the existing standard jets as they have a higher flow rate and better spray pattern. However, someone else then told me that I'd end up over-fueling with these unless I did other changes to match them.

So, where do I go with this? I'm looking at a new exhaust system anyway, probably with a 6-branch to get the gasses out quicker and I'd really like to get a BBTB as I fitted one on my old Touring and it drove so much better with it. So, my thought process is - more air getting in, more fuel being injected and easier access for the exhaust gas to escape would make for a better driving experience. I'm guessing I would probably have to get a custom chip for this set up though.

Opinions please?

[HairyScreech]

I was under the impression that b20 injectors were desired as the flow rate is very close to m20b25 injectors?
Haven't checked myself but its worth googleing the part numbers on both sets to see how they match up, if its only a few cc difference then the motronic won't be fueling accurate enough as standard for the difference to be noticeable. The standard ecu both under and over fuels at different ranges anyway and that's before you throw in any sensor variance and poor maintenance.
The lamba sensor version of the ecu will be able to account for small variance in closed loop mode so as long as the injectors are the same or slightly higher flow then the open loop should be fine.

However if there is a significant flow difference then you will need to chip the engine to suit.

[Speedtouch]

You may well need a custom chip to suit the different flow rate, although I don't think they differ that much.

It's relatively easy to alter this in the chip program.

[PeteE30Tourer]

I'm not sure what flow rate the standard injectors are supposed to put out, but here's the test result sheet from InjectorTune - suggests the injectors I have are all putting out 165 cc/min.



Would these require a different chip? Speedtouch - I have your mild chip at the moment, which I'm very pleased with (running with original injectors, not cleaned to my knowledge).

[Speedtouch]

Apparently, stock M20B25 injectors have a static flow rate of 14.5Lb or 154cc a minute at 3bar fuel pressure.

So, ideally, you should use a chip slightly tweaked to make the best use of your new injectors, else you won't see any benefit.

I can supply one, either Mild or Wild.

[PeteE30Tourer]

Nice one - so should I notice any difference going from my existing standard injectors with your mild chip to these m50b20 injectors with a modified mild chip?

[Speedtouch]

Yes, you should notice some gains, assuming the engine is in good condition. The standard injectors are a bit restrictive in terms of flow rate, and there are benefits in using slightly higher flow rate ones, particularly if you have other tuning bits such as BBTB, six-branch, etc.

[PeteE30Tourer]

Excellent - thanks for this. Can you PM me details to order the modified chip?

[Speedtouch]

PM sent!

Thanks,

[HairyScreech]

Another benefit should be slightly reduced low speed emissions/slightly improved low speed torque due to better fuel atomisation that multi hole injection provides.

[Suki_BiH]

i havce m50b20 injectors on m20b25 with speedtouch chip and lots of other modifications....

1400kg touring going crazy!!!!

[Speedtouch]

Seems odd that they should recommend using engine oil on the rubber O-rings, seeing as oil rots rubber!

[PeteE30Tourer]

i havce m50b20 injectors on m20b25 with speedtouch chip and lots of other modifications....

1400kg touring going crazy!!!!

Interesting. What other mods do you have? Did you use one of Speedtouch's standard chips or a special to take account of the different flow rate? I'm going for the latter, but I'm just holding off until I know if I can get a Racing Dynamics exhaust manifold first.

[maggspower]

Seems odd that they should recommend using engine oil on the rubber O-rings, seeing as oil rots rubber!

They must use a different grade, viton or the like, there are engine seal o-rings (camshaft). Not only that its quite close to fuel too.

[Speedtouch]

i havce m50b20 injectors on m20b25 with speedtouch chip and lots of other modifications....

1400kg touring going crazy!!!!

Interesting. What other mods do you have? Did you use one of Speedtouch's standard chips or a special to take account of the different flow rate? I'm going for the latter, but I'm just holding off until I know if I can get a Racing Dynamics exhaust manifold first.

I programmed him up a special chip, to take account of the different flow rate.

[HairyScreech]

As above, the o rings are viton and come into contact with oil in general use anyway via the breather hole.

[steve_k]

Hmm so they can be used then?

look's like their next on my list lol.

[HairyScreech]

they can sort of be used, as said above.

However if you want m50 injectors, a maf etc then your best bet may be to fit an m50 or to fit a full m50 management.

[Suki_BiH]

i havce m50b20 injectors on m20b25 with speedtouch chip and lots of other modifications....

1400kg touring going crazy!!!!

Interesting. What other mods do you have? Did you use one of Speedtouch's standard chips or a special to take account of the different flow rate? I'm going for the latter, but I'm just holding off until I know if I can get a Racing Dynamics exhaust manifold first.

here are all mods on my engine

http://www.e30zone.net/modules.php?name ... highlight=