chow70

Have any of you tried 100+ [ racing fuel ] octane in your F? If so, did you notice a difference in power?

I used racing fuel in my 63 AMG and you could certainly feel the difference in power, and was wondering if it was the same experience with the F?

Thanks, Chow

darbs242

iTrader: (5)

Not worth it without boost.

crazymikie

I'm surprised you felt a difference in the AMG. All street cars are tuned to run optimally on 91/93 octane. Anything more than that is typically a waste.

MRxSLAYx

Car actually runs harder on ms109. Afr is about the same, but the car proven to be about half a car to a car faster on Ms109.

darbs242

iTrader: (5)

^^^ Are you running ms9 on the strip

MRxSLAYx

Ive never ran on race gas at the strip because ive never had the need. Car will be running MS109 for its next outing though...

James7

no benefits to 100+ or race gas on a car not tuned for it ... however, if you can afford it, why not, at least you know there is almost a 0% chance you will knock when you push the car hard on a track or something ..

lobuxracer

iTrader: (2)

MS109 brings its own oxygen to the party, so there's a reason it works better. The oxygen comes from the MTBE in it (I'm not a fan of MTBE deposits). So I can see where an engine would run better with it assuming nothing else can be changed. It's extremely popular in circle track racing where carburetor size is restricted or restrictor plates are used because it gets more oxygen in the cylinder than could be achieved without oxygen in the fuel.

ToothDoc

Doesn't leaded gas also kill cats? Unless you're catless you really can't run higher than 100 octane. BTW, I ran 100 octane at the strip cuz that's all they had and noticed NO difference between 100 and 93 and I made dozens of passes...

chow70

Thanks guys, atleast you are saving me some $. I'll try it out once.

Adamgbrown

@DARBS242, Juice Q for you...
I have been entertaining the juice, but fear warranty repercusions. Is it removable for Lexus Service runs? or once its done, then bye-bye warranty?

Adam

mercurymet

Isn't Stoic for MS109 lower so despite the ecu maintaining AFR for pump gas, it is actually a higher lambda for MS109 and thus higher AFR?

So 11.7 is really 12.8 AFR for an MS109 stoic of 13.4 versus pump stoic of 14.6.

crazymikie

Air/fuel sensors measure lamba, not AFRs. So, in closed loop, you will always target stoich. Generally, the trims will move around, based on teh fuel, and cause the open loop fueling to adjust. Over time, you will always target the same lamba reading (in theory at least), as the ECU compensates for the new fuel.

ming15237

iTrader: (3)

Chow, not only do you need some driving lessons as per your last post, but you need too learn some basic fundamentals concerning factory cars and their engine tuning. Your MB would feel NO different with 91 octane as it would with 100 octane, that would be because the engine is designed to run on 91 octane! Unless the engine is tuned to run on a higher octane, there will be NO difference! This is why you are told by multiple sources that NEVER use an octane rating higher than the one your vehicle calls for, you are simply flushing money down the drain.

mercurymet

Is there a way to adjust and calibrate voltage of the sensor to mimic richer AFR than actual so the ECU adjusts and runs a little leaner?