100 Octane Usage
And the car certainly "feels" smoother, stronger, faster to me when I have it loaded up with race gas. These engines love it.
race gas works ms109 works. its like crack for this car.
The best would indeed be to be able to monitor whether the car starts to knock and is pulling timing. I wonder whether DashCommand or Throttle could help with that.
The best would indeed be to be able to monitor whether the car starts to knock and is pulling timing. I wonder whether DashCommand or Throttle could help with that.
And the car certainly "feels" smoother, stronger, faster to me when I have it loaded up with race gas. These engines love it.
If you're gonna claim timing advance , you can't dispute a log that shows it. There are plenty of variables that will effect a trap.
I'm gonna assume you're not running a dedicated fuel system either, so mixing the 100 with your remaining 93 and driving thru the pits to the starting line isn't exactly flushing a true 100octane to your rail.
I'd still like to see your slips though, as they should show the highest corrected trap of any stock C63 to date, if what you say has a chance at being accurate. Any 93oct run car should be a full 3mph off your best slip, at minimum.
Last edited by Mike450; Jun 28, 2015 at 06:04 PM.
Yes higher octane does burn slower this allows you to start the combustion event earlier. Typically any higher compression or boosted motor will not reach maximum brake torque before detonating with 93 octane, meaning there is power to gain with additional octane. Yes higher octane makes less btu's meaning you'll consume more fuel to make the same power - not sure why that was even brought up - kind of a given. This is why e85 cars consume approx 30% more fuel because the octane is so much higher. The quanity of fuel is minimum and ecu can compensate for that as it's well within 5%. I agree anything over 100 octane probably has no futher gain as the stock ecu has probably given all the timing it will with a stock tune, but its not going to hurt either. Just stay unleaded if you like your oxygen sensors.




If you're gonna claim timing advance , you can't dispute a log that shows it. There are plenty of variables that will effect a trap.
I'm gonna assume you're not running a dedicated fuel system either, so mixing the 100 with your remaining 93 and driving thru the pits to the starting line isn't exactly flushing a true 100octane to your rail.
I'd still like to see your slips though, as they should show the highest corrected trap of any stock C63 to date, if what you say has a chance at being accurate. Any 93oct run car should be a full 3mph off your best slip, at minimum.
The Best of Mercedes & AMG




I don't know if I have a 113mph car, because those were the only passes I ran it on 93 octane. Every other pass was on 100 octane gas, and every other (22 total) was in the 116's.
Have seen similar results on race gas with my old 996TT, but of course boost changes everything...
Nice. 3 mph on MS109....isnt MS109 105 octane? I assume this was still stock as the mods list looks to be just plugs.
I understand what you are saying , although that data is also subject to interpretation and how each individual graph affect each other, or you could be missing some data point that you did not or could not measure. I enjoy the car by how it feels and how far it goes. Does not all that data secondary to just how the car drives.
If not, then Blkrokt's spreadsheet is still the only actual datapoint in the thread.




Same day, same mods, same conditions, runs done 18min apart. The only change was switching to race gas.
I would data log it next time at the track on Thu (first time this year with my winter mods), but I have exactly zero interest in running pump gas. Take it or leave it. I think there are enough people who support this, and enough real-world experience shared by others.
Last edited by BLKROKT; Jun 29, 2015 at 11:03 PM.




(Typical Values) Specific Gravity: .722 @ 60°F
Oxygenated: Yes
Color: Clear
Motor Octane: 101
Research Octane: 109
R+M/2: 105
Reid Vapor Pressure: 6.17
Oxidation Stability (min.) 1440+
Distillation:
10% evap @ 147.0°F
50% evap @ 167.8°F
90% evap @ 213.3°F
E.P. @ 263.8°F
Production: Elmendorf, Texas USA
Availability: Sealed Drums
Rev: 02/04
You are correct. Only changes I had made were plugs at that time from my prior runs.
Data like shift points, timing, knk, iat's, MAP, clutch slip, etc ... all of which are variables that will determine how fast you get down a track and give you a view into why you ran what you ran.
Did your car shift at 7krpms in 1/2 or 3 gear, or did it shift at 6700? Did the TCM invoke torque management in 2nd gear? Did you have an unusual IAT on your first run that resulted in stKnk? Did your 113mph run see 4 degrees of STknk from a the not so-93 octane you were running?
You won't know any of that if you don't log, but you'll be faster/slower because of it. And most of it has nothing to do with fuel.
There are broad effects from the most minuscule variables that a PCM or TCM sees, that can results in significant changes during a measured event such as DR. That's all I'm trying to convey here, but I see some feathers are rustled. I apologize, that is not my intention.
Last edited by Mike450; Jun 29, 2015 at 07:46 PM.
I'll sponsor - a complete test report gets a case of beer! There you have it, the gauntlet is down!!




Who wants to go pound the **** out of their car on pump gas because we think they knock on the top end so you have to continually redline the snot out of it and datalog your results?
........crickets.
As a true self described "pedantic" data person, one would believe it'd be data you would like to see. As far as I can tell, it'd be the only data actually.
now we are being a bit dramatic aren't we?

Those engines are able to deal with a lot of abuse without damage - timing and AFR is just two parameters it can work with. If you throw in real crap and a cylinder cannot be stopped knocking, the engine actually turns that cylinder off.
So, not really a risk, but work it is. And useful it would be......




Great! Not sure about the tools you mention, but why don't you play with them some and I'll try my luck with Torque.
Maybe we can come up with something that way. I am actually curious to learn about this. I may also be able to get some things out of MHP (for example help in interpreting some data we collect). I have a good connection to them.




And the car certainly "feels" smoother, stronger, faster to me when I have it loaded up with race gas. These engines love it.
I have ran the same car, back to back without changing a darn thing, and gotten different times/speeds...an awesome launch vs. a good launch again can yield differences of 0.2-0.4 seconds and traps of 3-5mph...
Just my 2 cents.
Carry on.





