Question about Race Fuels??
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Junior Member
Joined: May 2013
Posts: 49
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2014 CLS63-S Model
Question about Race Fuels??
Hey Guys -- Back in the old days of cap & rotors and points & condensers, most cars allowed a certain degree of timing adjustment to accommodate the particular fuel you were burning... If your timing was off a little for the fuel/octane you were using, the engine would either "knock" or "ping" (showing my age a little here!). If on any given weekend, one wanted to take their '65 Mustang out to the drag strip using 100+octane race gas, you would need to advance your timing several degrees to get the extra power that higher octane fuel could provide. If you did not advance your timing, the HP gains would be minimal or non-existent.
As I understand it, the measurement of "Octane" is defined as the fuels ability to resist detonation. Thus, the higher octane you run, the longer you can wait before you need to fire spark plug, thus, you beginning the fuel burn at a higher cylinder compression point, thus, more power!!
Anyway, now days, all the timing is controlled through onboard computers, so my question is: Do we have to do anything (like program the ECU) to realize the true benefits of the race gas or does the computer take care of everything automatically? I mean, how much can the 'stock' computer automatically advance or retard the timing? And how long does it take the computer to make those ignition timing adjustments once you have put it into the tank?
As I understand it, the measurement of "Octane" is defined as the fuels ability to resist detonation. Thus, the higher octane you run, the longer you can wait before you need to fire spark plug, thus, you beginning the fuel burn at a higher cylinder compression point, thus, more power!!
Anyway, now days, all the timing is controlled through onboard computers, so my question is: Do we have to do anything (like program the ECU) to realize the true benefits of the race gas or does the computer take care of everything automatically? I mean, how much can the 'stock' computer automatically advance or retard the timing? And how long does it take the computer to make those ignition timing adjustments once you have put it into the tank?
MBWorld Fanatic!
Joined: Aug 2013
Posts: 1,077
Likes: 80
From: Anchorage
05 CL65
Minimal if any gains by adding higher octane without a tune to take advantage of it, just like back in the day.....
FWIW, the higher the octane, the SOONER you can fire the spark (further BTDC) to increase peak cylinder pressure thereby making more power.
FWIW, the higher the octane, the SOONER you can fire the spark (further BTDC) to increase peak cylinder pressure thereby making more power.
PLATINUM SPONSOR
Joined: Jun 2008
Posts: 3,834
Likes: 65
From: Texas
2003 CL55
Bottom line, depends on your timing maps set up in the ECU to what your gains will be. In gneral, above 93 octane does not help power , unless you have E85 timing maps programmed from the factory. For example, 2014 GM V8 engines are seeing 20 hp/40tq gains by just adding E85 but last year GM V8`s had no gains form E85, as timing maps did not increase.
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E63 Biturbo, UPD Cold Air induction kit, UPD performance crank pulley and UPD adjustable rear suspension with ride height adjustment.
CL55 UPD Cold Air Boost kit, UPD 3000 stall converter, UPD 77mm SC clutched pulley and beltwrap kit, Custom long tubes, UPD crank pulley , UPD suspension kit, UPD SC pulley, Aux. HE, Trunk tank w/rule 2000 pump, Mezeire pump, UPD 5pc idler set, Aluminum rotor hats.
www.ultimatepd.com
instagram @ultimate_pd
facebook.com/ultimatepd
