'05 CL65: drag strip results
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From: North Scottsdale, AZ
2008 Bentley GTC, Porsche GT2/EVOMS GT700, 1968 Dodge Charger Hemi
Originally Posted by AMG2GO
Are you kidding? that's the best that is available? why is that?
it sucks!!!
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From: El Paso, TX
'03 G500, '13 G63, '17 GLS63,
Originally Posted by AMG2GO
Are you kidding? that's the best that is available? why is that?
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From: Boston
NSX
Its probably just fine for everyone else in phoenix. When they decided on that mix they probably didn't figure someone will have a garage full of cars like yours. But.... I am sure you pay more car taxes than anyone else in that city so I think you should have some say in the octane... 
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From: Maryland
'14 E63S & '14 Audi SQ5
AMG2GO:
My assumption was that the CL65 ran the 1/4 using less than 94 octane. On the East Coast the only gas station that had 94 octane was Sunoco. However, over the last 2 years most states (PA not included) have banded together to restrict an additive Sunoco uses to bump the octane from 93 to 94. The reason being that the additive is not environmentally friendly. I figured A-Train was using 93 octane and that the CL65's knock sensors would cut back the timing when it sensed less than optimal gas. So if he used 100 octane it would have advanced the timing to it's "normal" 94 octane setting. Sorry I was not clear in my earlier post...I guess you are not a mind reader!
Tom
My assumption was that the CL65 ran the 1/4 using less than 94 octane. On the East Coast the only gas station that had 94 octane was Sunoco. However, over the last 2 years most states (PA not included) have banded together to restrict an additive Sunoco uses to bump the octane from 93 to 94. The reason being that the additive is not environmentally friendly. I figured A-Train was using 93 octane and that the CL65's knock sensors would cut back the timing when it sensed less than optimal gas. So if he used 100 octane it would have advanced the timing to it's "normal" 94 octane setting. Sorry I was not clear in my earlier post...I guess you are not a mind reader!
Tom
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From: Boston
NSX
I think the ECU is probably mapped to run safely for something like 89-90 octane... and I doubt the engine will knock unless its super hot and its been ran hard with 91 octane even. This is standard fare, manufacturers always build in that "cushion".... this the cushion that aftermarket companies and chip makers exploit. They just put in a more aggressive curve.
Nonetheless this is mostly guessing on our part, and higher octane certainly doesn't hurt. If the engine is running very hot, and the ambient air temps are high, the car is turbocharged or supercharged, all these contribute to a need for higher octane under severe conditions. I am just saying that I think you'd be surprised how much of a margin is built-in from the factory.
Nonetheless this is mostly guessing on our part, and higher octane certainly doesn't hurt. If the engine is running very hot, and the ambient air temps are high, the car is turbocharged or supercharged, all these contribute to a need for higher octane under severe conditions. I am just saying that I think you'd be surprised how much of a margin is built-in from the factory.
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Joined: Sep 2005
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From: Cary, IL
2003 CL55 Kompressor Horizon Blue Metallic
I've been wondering about the octane thing myself, just based on driving around in the CL55 over the last few weeks. The 55 definitely runs more beastly in cool weather, just a 20 degree swing from 70 to 50 is huge. So I'm asking myself if it is due to the standard issue rich factor of safety, or if there is some moderate retardation going on, or a factor of both.
What has surprised me is that I don't notice pre-ignition/pinging. I expected that there would be some. Heck, LS1's ping like a rattlesnake all the time and they are normally aspirated.
That RennTechV12 notices a .4 second improvement with 100 octane would indicate to me something is going on with our ECU platforms.
Based on past unscientific hacking with Bosch Motronic systems, they will adapt where a knock sensor is active and act accordingly. To rid the ECU of what is learned, I've had to either tell the ECU to reset (sending a command to clear DTC works, even if there aren't any DTCs) or wait a while for the ECU to relearn a higher octane. But it doesn't adapt "instantly".
Unfortunately, on some platforms a knock sensor can cause a retardation of timing even if there isn't a major problem. So, I believe higher octane can help the ignition timing game even if the car was designed to run fine on low octane.
But I'm going to guess that the performance increases are due to the fact that the cars are running rich WOT, and that the 100 octane mixture has more energy by volume (which could be a stretch depending on how they got the number versus a gasohol mix). Get the 100 octane to light, and if it has a higher BTU rating ???
Since I'm rambling ... how do I get hold of Star diagnostics for laptop OBD II config? :-)
What has surprised me is that I don't notice pre-ignition/pinging. I expected that there would be some. Heck, LS1's ping like a rattlesnake all the time and they are normally aspirated.
That RennTechV12 notices a .4 second improvement with 100 octane would indicate to me something is going on with our ECU platforms.
Based on past unscientific hacking with Bosch Motronic systems, they will adapt where a knock sensor is active and act accordingly. To rid the ECU of what is learned, I've had to either tell the ECU to reset (sending a command to clear DTC works, even if there aren't any DTCs) or wait a while for the ECU to relearn a higher octane. But it doesn't adapt "instantly".
Unfortunately, on some platforms a knock sensor can cause a retardation of timing even if there isn't a major problem. So, I believe higher octane can help the ignition timing game even if the car was designed to run fine on low octane.
But I'm going to guess that the performance increases are due to the fact that the cars are running rich WOT, and that the 100 octane mixture has more energy by volume (which could be a stretch depending on how they got the number versus a gasohol mix). Get the 100 octane to light, and if it has a higher BTU rating ???
Since I'm rambling ... how do I get hold of Star diagnostics for laptop OBD II config? :-)
Last edited by mclarenm8d; Oct 21, 2005 at 01:19 AM.
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From: Portsmouth, NH
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A-Train,
If you plan on heading up to the strip again before the end of the month let me know. I was going to call them tommorow to see when they close. I think they close at the end of October. I got a C43 that I wanted to run a few times before storing it for the winter. Just looking for another benz owner to go there with.
Load your car with cement blocks and maybe we can race!! :p
Actually, anyone in the NE area with interest, toss me a PM.
If you plan on heading up to the strip again before the end of the month let me know. I was going to call them tommorow to see when they close. I think they close at the end of October. I got a C43 that I wanted to run a few times before storing it for the winter. Just looking for another benz owner to go there with.
Load your car with cement blocks and maybe we can race!! :p
Actually, anyone in the NE area with interest, toss me a PM.
