GRam

Just curious how running a lower than recommended octane effects timing/power output? I ask because I drove 350 miles to the nearest drag strip over the weekend to make a few passes.

I just updated to the V5 EC tune. Upon realizing I had not enough fuel to make the trip, I was forced to put about 25 litres (roughly half a tank) of 91/ethanol in, instead of the 94 non-ethanol I normally run.

Once at my destination, I added 30L of the 94, which left me at about 3/4 of a tank, and headed to the strip.
Had a gas, only had time to make 3 runs, best was 12.6 @ 112.5

Got me thinking, how much, if any, HP did I leave on the table? Buddy with a ZL1 Camaro says if his gets any little bit of knock sensor go off, then it retards timing until the car has it's battery disconnected for 24 hours.

I know doing that to ours will reset trans shift timing etc, but is the MB the same? Or once the knock sensors realize all is good with the fuel supply, it's just back to full steam ahead?

Thanks for taking the time to read the lengthy post..

AMG6.3

Personally, if you mixed the two fuel octanes you were not probably leaving anything on the table regarding HP. At the track too many variables like having 3/4 tank of fuel vs 1/2 a tank, etc.

What was your 60 foot and your DA level?

jmueller

12.6 at 112.5 with a tune is questionable especially with the P31 package. What were your 60ft times? When I was doing 1.8 60ft times that's when I was in the 12.2s. It was very very very hot here in florida too.

SROC276

I did a 12.56 @ 119mph and had an aweful 60ft at 2.3-2.5 running 19's. Probably bad technique. Running exhaust, shorty header and row boxes + tune. I have the p31 package too.

Merc63

When I put 91 in mine I can feel it suck timing. (Blower)

After I refill with a full tank of 94, it's better within 20-40km.

odonnks

Regarding ignition timing, if the ECU knock sensor detects knock caused by low fuel quality the ignition timing is retarded. This reduces HP because ignition occurs closer to or after the piston reaches TDC.

Autosport7

"TDC" - Top Dead Center
Somebody was bound to ask...