Re: 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 am not disagreeing with you...

Isn't there a rule of thumb for engine power output increases due only to raising compression (no other changes)? I thought it was something like 3-5% hp gain for a rise in CR by one. So if the E34 engine that makes 206hp had it's compression upped to 9.3:1 (over the stock 8.0:1) it would increase power output to about 215-220hp. Or close to the original output of the euro spec l-jet system.

It would be interesting to see exactly how much power difference you would have by taking a 3.5l euro l-jet fitted engine and fit a 1.3 version motronics on it.... Maybe 10hp more?, I think it would be heavily biased upon having a custom chip burnt....

I did see an increase of roughly 10% over the l-jet hp out on my driver euro 3.5l w/SDS EM2 fuel injection system added. But this was mostly due to removing the AFM from the intake path......

I guess in my mind a properly tuned engine with either l-jet or motronics is capable of making close to the same hp. It just that the motronic fuel management system is able to cope with changes and adapt to them without major adjustment. L-jet will just need more owner modifications.....

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

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