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In Reply to: Re: I get it now posted by WH on May 22, 2001 at 21:13:37:
Here was what my problem was earlier. I thought you said you had an 1980 programmable injection. Ok, so what you are saying is you have a motronic system that you could stick on your car. Here is my thought. First of all, what car and what year is the '80s f/i that you are talking about. If it is motronic 1.0 then it is an easy swap. If it is 1.3 from the E32 and E34 then it is a lot harder. Ok here is the benifit and things you would have to do each one.
First Motronic 1.0
Well basically, it bolts on, but you will need to put on a different tranny bell housing to accomodate the flywheel reference sensors. You will also need the motronic flywheel. At the same time you will most likely need the thermostat housing for the coolant temp sensors. Also, you might need the injectors, but I can't remember. Otherwise, it just bolts on.
The Motronic 1.3
This is harder because you will need to change the crank hub and use a lot of the front engine stuff of the M30 b35 motor. Other then that, I can help you go through what you need to do the conversion.
I personally would stay with the motronic 1.0 because it is much easier to work with than the 1.3. Even though the 1.3 will give you more power, I would say that the extra cost is not worth it.
Let me know privately if you need more help.
Rob
M535i SIG Chief Technical Advisor
www.m535i.org
Since he has a 81' euro spec 3.5 liter motor, there are a couple other items to do as well....
First you can do all that Rob says about changing the transmission bellhousing so as to fit the motronic sensors. Then you'll need the flywheel, injectors,ecu and wiring harness too!
I said the flywheel and possibly the injectors, so I thought the wiring harness was self explainitory
BUT you will also need to change the engines cam as l-jet cams don't work w/motronics very well (no place to mount the rotor?). Also the upper front timing cover etc will need to be changed so you can mount the ignition cap.... then buy new plug wires and possibly an ignition coil too...
I believe it might be possible to run it with the other cam. The reason I say this is that the motronic is just a cap and rotor that is driven off of the cam anyway. If you just take out the gutts of the distributor and make it into just a cam driven cap and rotor, I think you might be able to get it to work. Now I have never done this so this is just a WAG from what I know about these motors and f/i.
But if this does not work yes you will need to get a new cam.
But will you actually have that much better power?? Euro 3.5l engines even w/l-jet in stock form made 218hp and 228 ft/lb torque....
Here is where you are getting things mixed up. The Euro motronic 1.0 put out 218bhp so you aren't loosing anything by running motronic. While the l-jet put out the same, the later runs much better.
The later US 3.5l's made significantly less (something like 188hp stock)... but yes with a chip upgrade it gets much closer....upwards of 210hp, but I haven't seen a chip upgrade that is significantly higher than 220hp. That is, at least without adding a 282 schrick cam to the engine etc.....
Now here is where everything is wrong. The US 3.5L made 182 stock, but the US only motor because it had 8.0:1 compression. The Euro motor with 10:1 compression made 218. The use the same engine management, but the US is more adaptable. If you are using the early motor, the motronic does not drain power, in fact you might even gain some by having the car run correctly at all times. Basically, the 1.3 motronic also does not take away power. The reason why the 1.3 motor only made 208 is because of the compression ratio. If you up the compression then you gain power. The simple fact is you are starting with a motor with decent compression and so the engine managment system is not going to significantly change the starting power, but the motronics does not requires as much maintainance as the l-jet and also is very easy to make more power out of. I mean with a chip in the US 3.5L motronic 1.0 motor gives you 206bhp and that is with 8.0:1 compression. The later 1.3 motor you put in a chip and you are making 222bhp. The reason why this is happening is because the motronic is able to adapt. The reason why the later motor has a bigger jump is because it takes more inputs per second than the earlier motronic. The reason why l-jet won't give lots of power is because it won't adapt. Hope this clears up my point.
Rob
M535i SIG Chief Technical Advisor
www.m535i.org
WH
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