The power output difference is not minimal (archive)

Basically, if it were minimal, then the E34 b35 motor would not be able to make without any mods but a chip 222. Also, the b34 motor in the US E28 makes 206 with a chip and 8:1 compression. If I am not mistaken, the motor that Steve has is a 9.3:1 compression ratio. This is higher then both the b34 and b35. This means that the power output of the l-jet motor has the benifit of higher compression, while the motronic can make almost as much(US b34) and more b35. The simple fact is that the better the f/i, the better the car runs. I agree you drop an SDS on the car and you will gain some serious power, but we are talking BMW f/i. Basically, I was responding to what Steve was saying about his 3.5L l-jet motor and how he was going to drive it hard and that he was probably going to do mods to it. He also said he has access to the motronic stuff. All I was saying is that the motronic will staying in tune, and will also adapt to any performance mods that are done.

Rob
M535i SIG Chief Technical Advisor
www.m535i.org

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

I'm not mixed up... Sure the motronic system is adaptable.... that's how it was designed. But the l-jet system that he has already on the engine would work fine too.. and it's FREE! The power output difference would be minimal....

I guess in my mind if you're going to do all the work to switch from l-jet to motronic (like BUY all the parts). You could always buy a nice aftermarket programable fuel injection like the SDS-EM3 and be able to 'tune' the igntion and fuel curves yourself --no chips to buy! I have done this on a euro 3.5 liter...... pretty easy took only about 3 hours to install the new system, and a week to map the fuel curves...

As for the cam... you can adapt a motronic cam to run l-jet by buying the Metric Mechanic adaptor nut (to drive the shaft for the distributor). But you can't go the opposite way around... ie you would have to machine the l-jet cam to fit the motronic rotor as there is no way to mount the rotor otherwise..... something the average home mechanic shouldn't do................

Also what 'maintainance' do you need to perform to a l-jet system?? Tuning the co? Setting the idle? I've had some l-jet powered cars I've done nothing to the system for years.....How does this compare to 'maintainance' on a motronic system?

I'm still confused with what you mean about power output.... isn't 218hp pretty damn close to 222hp for a fully chipped motronic system (either 1.0 or 1.3)??

http://www.m535i.org

Follow Ups:

Re: The power output difference is not minimal WH 15:27 5/23/2001 (1)
- Re: The power output difference is not minimal Rob Anderson 22:27 5/23/2001 (0)

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