Turbo on standard Motronic

[brody]

The stock ecu can handle any amount of boost. It doesn't need to know pressure, ever. Pressure means nothing with a MAF based system, it is all about flow and proper tuning.

Check out the WAR chip, it's 350 and you can tune your turbo setup and retain your stock ecu. It gives you control of your actual ecu, it's not a piggyback.

30 lbs injectors will be what yo want. 19lbs is a waste of install time and effort, 24's are borderline wasting time.

All this info about the stock ecu can't do this and that etc is funny. The motronic ecu old as it is, can do much more than anyone gives credit for. After all, BOSCH a billion dollar company developed it not a private individual or small tuner company.

You can run any size injector with motronic, you just have to have the right tuning for it.

[Lee Harvey]

I bar is doable with a chip and begi fmu, you can't do it with 19lb injectors though, and forget the m30 afm and throttle body they aren't needed and won't aid you any. 19lb injectors are too small, 24lb injectors will start and idle stock, and with the afm and fmu dialed in correctly will support 12psi happily all day long, beyond that you have to up the ante to 30lb injectors, which will not start and idle properly in open loop off cold starts, as the ecu ignores your afm tweaking and runs a generic map... designed for 14.5lb injectors... and dumps ungodly amounts of fuel since you now have 30lb injectors. 30lb injectors are still doable, and 37lb have been done, but 30lb are so excessive to manage on motronic with a piggyback chip, fmu, and afm tweaking, I wouldn't bother.

If you want cheap power and reliability with hassle free setup, there's nothing wrong with a turbo chip and fmu. Dialing it in is the only tricky part, and once you're settings are right you're basically done, just have to find the sweet spot on the afm and on the fmu. All of this is done by watching the wideband gauge you will have installed so you could do this.

As for addressing the reliability, most stock m20's with a chip are happy to hold 7-11psi on the stock headgasket and bolts, beyond that they get finnicky though, so I strongly recommend at minimum getting metric blue's, or preferrably ARP/Raceware head studs, and removing and retorqueing them one by one in specified sequence as per Bentley manual instructions. This saves you the hassle of replacing your headgasket which should hold up fine, and gives you the added protection of badass unstoppable clamping force. And if it does blow, well you'd have been replacing the head gasket anyways, so it's a worthwhile gamble to hope it holds coz it probably will and your not out any extra if you end up doing it in the future.

Let me know if you need more info on any of it, grassroots/cheapmofo ziptie builds are my forte hahaha

[nando]

... is a bad idea. :p

no way you could run 1 bar on stock management with 19# injectors. Generally you can do 6-7psi on stock management and keep it somewhat (but not very) reliable. you'll want 24# injectors minimum, I'd think, and a "turbo" chip (which really just retards the timing).

with actual tuning a stock B25 will do 1 bar no problem, but that just isn't safe on the stock computer which has no way of measuring boost pressure.

for really cheap management you could always do MS1, a basic kit is like $300. That's probably along the lines of getting a RRFPR and a turbo chip for motronic. MS1 isn't super advanced but it's mature, inexpensive and well supported. there's a couple guys in the UK with tons of MS experience, specifically www.diyefi.co.uk.

[Syncro325is]

Search turbo chip if you want to be cheap at first. Its going to cost when you want to up the boost so you may as well wait and do it right the first time. Use the search bar.

[BONNARSKI]

As money is none existant as i'm sure you'r all aware i am wanting to know what the maxiun boost a standard Motronic on my 89' 325i Sport would be abole to cope with. I'm thinking that with a suitable chip, M30 AFM, M30 19lb injectors and M30 throttle body a boost pressure of about 1 bar would be exceptable.
I plan on having the CR lowered and can sort all the various hardware and plumbing its just the engine management is the hold back. If funds would allow a full standalone would be ideal but not at the moment.

Any help appreciated, thanks