Upgrading from Stock? M70B50 / Auto

[Feiht]

Evening all, just wanted to drop a line and get some ideas -- in a few months looking at picking up a low miles new 91' 850 with M70B50 / Auto.

What do you consider viable upgrades like Dinan engine / transmission chips and superchargers?

This car has a detailed service history and has been maintained by and per BMW Service Guidelines, so no worries of blowing going out more than usual.

I would like to keep the outside appearance the same, but figured it could have some more potential to be found under the hood.

Or.... should I just leave it alone and let it be a testament to the classic image?

Thank you in advance!

[Imndeep]

I for one an telling you this truth, You get what you pay for. I would be perfectly happy if all my components worked like they did from the factory. On a BMW from the 90's era alone, that is tough. Let alone the pinnacle of automotive technology of that era. Sir, to have a perfectly stock working BMW 850 is a miracle. I say, it's your car , do what you bloody want! But know this, the BMW 850ci in the automotive world in bone stock condition is a unicorn. Everyone like me thinks they can improve upon what their engineering didn't think of or the bean counters cut out. I work with them, they are the financial killer of dreams. Just saying, when you modify your car there's give and take. You lower it and buy a really bitchin ultra rare piece for a front spoiler than when you get it all painted and polished and pretty, try to drive it over speed bumps and wind up trashing the that very expensive front spoiler, cause you were too friggin low! Yes, it's like that.AS for Dinan Trans chip, I didn't notice that much of a difference. You wanna chip your 8er? best bet is the Wokike chips. I got a set at the 10th anniversary of the West coast 8'ers but I wish they were Wokke chips.

[Belgiumbarry]

I bought a "good" manual '91 850i with the idea of a supercharger install…. i knew the model but wouldn't have bought it just to keep it stock with the oem 300 HP.
The build is a hobby... but a + year later car is still on the lift with all kind of troubles, both oem and charger related.
I hope we are that far now , that it's "only" a matter of mapping….. it was a long journey , but as stated for wrenching "hobby".

[XTREMETUNING]

I think you will find the road to maintaining/restoring an 8 to be long enough as others have said. With so few upgrade options available, custom work is almost always necessary, usually costing big dollars. If a stock 8 is not enough car for you, consider waiting for a CSi for turbocharged/supercharged car when they come on the market. $38k would have just bagged you a low mile Dinan twin turbo on BaT. There is no way you could build that car yourself for anywhere near that.

Good luck,

-JRW

[Feiht]

Thank you all for your thoughts.

After much consideration, I don't think I am going to do any performance increasing parts or chips in it. I do have one lingering thought though for a possible upgrade. Since this has the 4 Speed Auto... would do you think of maybe swapping the transmission for the ZF 8 Speed?

https://www.zf.com/products/en/cars/products_29289.html

This thing is a freaking unicorn, bought by a dealership owner NEW and maintained as a show room car it's entire life, being driven only to maintain it's upkeep, in a humidity and temperature controlled environment. Can't wait to drive this thing home. Finally have an excuse for weather proofing my garage!

[shogun]

Forget it, probably super complicated. Your M70 has an EML and that needs input from many, many different modules, sensors, including DME and the TCU
EML Introduction https://www.europeantransmissions.co...MW/EML-BMW.pdf
The Electronic Throttle Control System (EML) regulates the operation of the throttle valve(s).
The scope of EML design on BMW engines provides:
• Throttle valve positioning for optimum starting
• Precise idle speed regulation without the use of an external idle control valve/circuit
• Progressive throttle opening curves matched to the driving program (with EGS/AGS interface)
• Cruise control operation without additional control modules and linkages
• Automatic synchronization of the throttles (airflow balancing) for two independent banks, throughout the entire engine speed range (M70, S70, M73 engines only)
• Intake air volume control for ASC/DSC (Automatic Slip Control/Directional Stability Control) systems
• Maximum road speed limiting
• Emergency “Failsafe” operation in the event of component failures
The EML control module is a link in the total scope of Engine Management Control. The EML is interfaced with other control modules to complete the management system, which includes:
• ECM(s) - Except E46 (EML integrated in MS42.0 ECM)
• EGS/AGS
• ABS/ASC
The main components of the EML system are:
• Accelerator pedal position sensor (PWG)
• Accelerator pedal position sensor (driver’s wish sensor - integrated in throttle housing, E46 MS42.0)
• Throttle valve assembly/assemblies with electronic control motor(s) - DK/MDK
• EML control module (MS42.0 ECM - E46)
EML SYSTEM OVERVIEW
Throttle valve control is managed electronically, using an electric motor(s), without the use of mechanical linkages or cables (except E46 - MDK). The EML system uses a microprocessor to convert the input signal for the position of the accelerator pedal into output commands for control of the throttle valve. The position of the pedal is merely a request to the control module for throttle opening. The EML module processes this input request along with other pertinent operating parameters. The throttle valve
is then moved to its proper position according to specific control unit programming.

[Feiht]

Very informative Shogun. Thank you! That does seem like quite a lot to try and make communicate with a technology gap of almost 30 years to fill. I'll leave it as is. Might change the rear gearing down the road, but she's gonna remain bone stock.

I'm not as young as I used to be, 300HP and 325lbs of torque is more than enough car for me -- especially maintaining such a classic.

If one of the moderators wants to close this thread feel free to. Thank you for all the info guys, I'll be posting a picture on pickup day before the 400 Mile journey home!

[dragon850]

Performance chips for engine, trans and eml, LSD 3.91 differential, X pipe and Ferrari mufflers. Start with these mods.