Engine Dilemma, let me explain

[Malc]

Well just before I can away for work, I'm in Calgary right now, my 1986 e28 M535 went through the point of no return, the exhaust fell off! the rear subframe bushes are gone so I really can't be bothered to fix it, especially as it was originally bought to provide some spares for the dear old bucket.

Anyway suffering from jet lag and wide awake I was pondering the following and your input would be appreciated.

1].. I would like to keep the original engine, as the numbers match
2].. Could I use the cylinder head off the M535 as i believe it has bigger valves and is of a better design
3].. I have continued to toy with the idea of using the Motronics system, but I don't really like the big "flappy paddle" air flow meter.
4].. I much prefer the E9 intake mainfold setup
5].. Mix and match is attactive
6].. I could design a circuit for a modern MAP sensor to emmulate the output of the Motronic air flow meter, there's a thought. any good sources of info regarding MAP sensors and a Motronic flappy paddle sensor?
7]... Thus "fooling" the Motronic ECU into thinking it had the "right" sensors.
8].. Use later injectors but "barb" fittings with an early 5-series injector rail, thus keeping the "correct" intake set up.

Or should I really try and get some sleep?

I should be told
Malc :wink:

 

[decoupe]

Calgary!!!!!!

Malc:

I'm in Canmore which is 60 miles west of calgary. How long are you in town? I'm in and out frequently and on Saturday, the BMW dealer has asked me to drive the Coupe in to the M Car Tour that is going through western Canada.

Doug

 

[x_atlas0]

[1].. I would like to keep the original engine, as the numbers match
2].. Could I use the cylinder head off the M535 as i believe it has bigger valves and is of a better design
3].. I have continued to toy with the idea of using the Motronics system, but I don't really like the big "flappy paddle" air flow meter.
4].. I much prefer the E9 intake mainfold setup
5].. Mix and match is attactive
6].. I could design a circuit for a modern MAP sensor to emmulate the output of the Motronic air flow meter, there's a thought. any good sources of info regarding MAP sensors and a Motronic flappy paddle sensor?
7]... Thus "fooling" the Motronic ECU into thinking it had the "right" sensors.
8].. Use later injectors but "barb" fittings with an early 5-series injector rail, thus keeping the "correct" intake set up.

Or should I really try and get some sleep?

I should be told
Malc :wink:

[2]Wouldn't using a head from a motor with a larger bore drop your CR?

Valves are the same size:
E9: http://www.realoem.com/bmw/showparts.do?model=3451&mospid=47807&btnr=11_2444&hg=11&fg=45
M535: http://www.realoem.com/bmw/showparts.do?model=DC51&mospid=47223&btnr=11_0390&hg=11&fg=25
Head design is probably the same.

You could go MegaSquirt if you hate the AFM that much, as it uses a MAP sensor instad of an AFM, and there is a kit available to convert the digital MAF signal to analog so it acts like the AFM, but it costs an arm and a leg for less than 10whp. It gives better gains with the S38.

 

[ScottAndrews]

Malc;

First of all, the intake on a Motronic car will not clear the brake booster on an E9. You will need to use an L-Jet intake.

The Motronic system uses two magnetic crank sensors on the flywheel. One senses TDC, and the other senses the individual teeth on the ring gear. I am not sure if the Motornic flywheel has the same numbe rof teeth, but if it doesn't , you will be in trouble.

The AFM isn't that bad, but if you are determined not to use it, then use a Ford Mustang MAF. THis is abou tthe same diameter as the L-Jet throttle body. You will need to calibrate it so that it matches the AFM output curve, and you will want it to be adjustable so you can tweak it for ther 3 liter engine map. I'd build a flow bench and take the air flow vs output voltage curve for the AFM. Then measure the MAF and work out the conversion.

Personally, I would use an L-Jet ECU. THIs is much easier to deal with than the Motronic, and it doesn't require any new sensors (other than the AFM/MAF).

As a bonus-the L-Jet intake runners significantly improve low end torque.

S

 

[x_atlas0]

Malc;
The Motronic system uses two magnetic crank sensors on the flywheel. One senses TDC, and the other senses the individual teeth on the ring gear. I am not sure if the Motornic flywheel has the same numbe rof teeth, but if it doesn't , you will be in trouble.

The AFM isn't that bad, but if you are determined not to use it, then use a Ford Mustang MAF. THis is abou tthe same diameter as the L-Jet throttle body. You will need to calibrate it so that it matches the AFM output curve, and you will want it to be adjustable so you can tweak it for ther 3 liter engine map. I'd build a flow bench and take the air flow vs output voltage curve for the AFM. Then measure the MAF and work out the conversion.

Personally, I would use an L-Jet ECU. THIs is much easier to deal with than the Motronic, and it doesn't require any new sensors (other than the AFM/MAF).

As a bonus-the L-Jet intake runners significantly improve low end torque.

S

The Motronic 1.0 System uses flywheel sensors. The Motronic 1.3, used on the M30B35 cars, only has a single Hall Effect sensor based on the harmonic damper to determine crankshaft position. Makes things much easier.

With the MAF, he'd need a realtime D->A converter, properly calibrated like you said.

Given how Malc seems to like to tinker, I'd say the MegaSquirt is his best bet. No AFM and he has complete control of the engine tune.