FI M30B35 E9 swap

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nobrakese28

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Hi guys,

Picked up my 71 2800CSa two weeks ago and I'm loving it.

But ultimately I would like to convert over to fuel injection for performance, reliability, and fuel economy. I already have the pedal box and 3.0cs front and rear suspension.

The engine I have in mind is a M30 out of an E34 535i. Good news is these engines are very common items at pick-a-part these days.

I was hoping some fellow members can answer my following questions:

1) Fuel pump, is there a BMW pump from a different model that will drop in to the tank? Will the fuel level sender still work?

2) What transmission is the best option? From what I remember from my E28 days, the transmission has bosses for crank sensors.

3) What oil pan do I use?

Thanks! I'm sure I will have more questions.
 
AS for Pump: Don´t try to replicate the in-tank pump of the E34 in the E9 tank. Too much of a hassle. I´d try to go with a generic pump suitable for L-Jet and the like, about 2.5-3bar pressure, available as Bosch replacement part for about 150USD) and the orginal E9 CSi external mount location, bracket and expansion tank. Since the pump sits low enough in that setup it works fine without the in tank pickup. That way you keep the regular fuel level sender and fuel pickup. You just have to figure out a way to get a fuel return line into the tank as well.
 
You might consider doing what I did. I have a '91 M30B35 in my car, but with Weber DGV carbs. I've spent a lot of time with a wideband O2 sensor getting the jetting just right, and I'm seeing mileage similar (or better) to what is listed for a '91 535i. This setup sure makes things simple, and the carbs are so well set up that you wouldn't know they were progressive downdrafts.

Where are you located? If you were nearby, I'd offer to have you ride in my car so you can see what I'm talking about.

-Scott
 
Screams- Believe it or not my CS came with a set of Weber 32/36's. I love the look of the carburetors. Are you running a OEM airbox?

Did you just you an early M30 distributor upper timing case?

I am located in Los Angeles, I will take you up on that offer!
 
I started out using the stock airbox, but found that it caused a -very- rich WOT mixture (10:1 or worse). Leaning out the main jets would fix it, but would result in a way-to-lean cruise mixture. Using simple rectangular Weber air filters completely fixed the issue.

Yes, I am using an early upper timing cover (came off my stock motor) and the adapter nut to allow the B35 camshaft to drive the distributor.

The B35 intake ports are larger than those on older M30s, so I took my grinder to the carb manifolds and matched them up.

I use a wideband O2 sensor and gauge to get jetting just right. I also found that the jetting recommended in various posts on this forum was far richer than necessary for the secondary mains. I run 140 primary main jets, and only 110 secondary mains... and could probably still go leaner. Getting this right -really- makes the engine come to life at full throttle all the way to the redline. My WOT mixture is about 12.5:1 and my cruise mixture is about 15.5:1. I'm seeing 20-21mpg on long freeway drives and 17-18mpg average with mixed driving. That's maybe a bit better than what fueleconomy.gov has for a '91 535i, perhaps due to the lower weight of the E9:

http://www.fueleconomy.gov/feg/noframes/7753.shtml

The car really goes, and I feel no need for more carb (38s or DCOEs). I'm in Sacramento, so if you ever want a ride, let me know.

-Scott

nobrakese28 said:
Screams- Believe it or not my CS came with a set of Weber 32/36's. I love the look of the carburetors. Are you running a OEM airbox?

Did you just you an early M30 distributor upper timing case?

I am located in Los Angeles, I will take you up on that offer!
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