[dk79]

Did 1/4 mile run on road, 10.9 sec.
Same car on drag strip could not do better than 11.6
On the strip ran twice only 11.6 and 11.7
All runs stock, Arizona 91 octane gas.
What might be the reason?

[AHall]

Is 91 octane better than 93 octane for performance? The recommended gas is Shell 93 octane. The 0-60 and 1/4 times are good. Did you use launch control?

[Boiler Up!]

Tough to tell without seeing a log of engine parameters for each run, but with the information available I'll take a guess.

The 16* difference in ambient temp is likely the biggest factor here, exacerbated by location. Based on decent launch but lower trap speeds, I would assume that the car is pulling back the boost & timing as a precaution against knock. If a nearby weather station was detecting 91*, I would bet the staging lanes were well over 100*. The car's intake air temperature sensor would read even higher due to a heat soaked engine compartment.

I'm not familiar with how the DME is mapped to account for high ambient and intake temperatures for the M5, but my past experience with the naturally aspirated LS platform was that timing started to be aggressively pulled at and above 86*. I would assume that a highly strung forced induction platform like this uses the same type of logic to protect the motor from knock.

[Sophisticated Redneck]

Like Boiler up said, high temps plus crappy gas=lower d timing and boost. Plus your car was probably heat saturated while you waited to make your runs at the strip vs on the street when you just pull over real quick to do a draggy run.

Going to assume you went to Wild Horse Pass drag strip off the I-10 just south of Chandler.

If you want the absolute best trap times, just down the road from the drag strip less then a mile away is a Loves gas station that has 100 octane race gas. Mix it 50/50 with 91. (Don't get tempted to get the 110 race gas there, it's leaded).

Turn off your engine l, push your car and leave the hood up when you are about 15-20min from doing your next run, will help immensely with the heat saturation.

Get an app like torque and needed ob2 adapter (or a jb4 ) so to can monitor your timing,
engine temps, Intercooler temps, etc.

[onfireX5]

You were down in power at the strip based on temp, DA, etc plus it did not hook at the strip. Look at the 60’ times in both runs. Street hooked better.

[dk79]

Originally Posted by AHall

Is 91 octane better than 93 octane for performance? The recommended gas is Shell 93 octane. The 0-60 and 1/4 times are good. Did you use launch control?

Launch control used with every run.

[apsuard]

I had the exact same issue with my W213 E63. I’m guessing it is high IATS in staging. When you run on street you don’t have car idling for 30 minutes like at strip waiting to make a run. My best street run in my E63 was 10.39 at 133 with starting IATS of 58 degrees F. At the strip my best run was 10.7 at 129 with 120 degree F IATS to start. If you want consistent runs at strip you need something like a killer chiller. I was going to go with killer chiller on my E63 but I sold the car.

Also, my launches always sucked at the strip compared to the street. Street tires (MPS4S) launch much better on the street. Drag radials would be ideal but finding a size that will work with our cars is challenging. Best option is probably R888R