Quote:
Originally Posted by MissionPerformance
E60 mixture on stock HPFP is the maximum limit of the pump's flow ability at about 42lb/min oxygen consumption. At E50, you are coming very close to the limits of the pump, and your Duty Cycles on both HPFP and Injectors will eventually overload the DME. Again, you can do a dyno or two, few street pulls and such without any issues. But put the car on a 30 minute torture test on a real track, and you will see what happens. Call me old fashioned, but I just do not see any reason to risk your motor just to say you can run E50 blend and then deal with issues each time your blend ratio changes.
With a mild blend of E20-E30, you are not over stressing the pump too much, and also you have the advantage of not having to deal with issues when you go down to E10 blend and such.
Another huge risk of high Ethanol % blends is over fueling scenario. Lets say you run a full tank of clean E50 blend, and everything is fine. Now you go to a gas station and fill up to E50 mixture based on your own calculation. But you do not realize that the E85 pump you are at only has E50 fuel to begin with (nearly every E85 station has disclaimer stating that actual ethanol rating of their E85 can be anywhere between 45 to 85%). So in the end of the day, you no longer have E50 in the tank, but E30ish. If you don't give your computer enough time to adapt fuel trims, guess what happens. You will flood your motor and thus bend a rod from over rich mixture. That has happened so many times in the S55 community in the past. If B58s had a factory fitted ethanol sensor, then this would not be an issue and you could run any mix of E85 (with good enough fuel system), but without it, you are just risking your motor. On top of this, E85 has way different knock characteristics and our DME is not equipped to precisely detect the E85 knock, though that is another can of worms. So once again, what is the point of wild E85 mixtures on a system that cant detect E85 content of fuel?
Now, as it has been covered so many times in the past, full E85 is possible even on stock HPFP, given you tank the boost and skyrocket the timing. B58 is a high compression motor, and because of the way BMW designed it, its actually likes more boost vs timing. Doing log after log, and closely monitoring knock sensor input (not knock count), its clear that engine is much happier with lets say 21psi and 7degrees vs 15psi and 17 degrees.
If you look at the log provided above from the BM3 site, you will see your timing in the 13 degrees, and boost at only 16psi. That is only 2.5psi increase over stock MPPSK, but double the timing. That is why you are seeing only 41lb/min. You can do you own research, but since engine is basically a pump and performance can be calculated by the air it consumes, using a base function that is true w
ithin few % error, you are only making 410hp. As a contrast, stock MPPSK consumes 1000kg/h 36.7kg/h which translates to 367hp. That is nearly identical to a number of MPPSK results posted on members on these boards. Now, take your vehicle, pump the boost to 21psi, lower the ignition to 7-8degrees at 6200 and you will see oxygen consumption of 47kg or their about.
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do you have a dyno showing that more boost and less timing makes more power?
thank you!
I have bm3, but would switch for more power and better performance.