Race Gas And Timing
Apr 19, 2007, 11:17 AM
#1
Race Gas And Timing
So I have a pump gas map tuned to my car for 93 octane. AFR is 11:1 and timing starts about 6* ramping up to 16* at 21 psi.
When I know I'm going to be out racing I normally run 110 octane leaded fuel. With the XEDE would run 12:1 AFR and add about 3* timing. Never really was tuned for it. Boost would be whatever the stocker could ramp up to using the stock BCS.
What is the max timing that you guys aim for while on race gas?
What timing do you run at peak torque on race gas?
I simply want to know what the norm is. From the testing I've done it appears that low end timing can be set as high as 10* and I still dont see knock. What have you guys run into?
When I know I'm going to be out racing I normally run 110 octane leaded fuel. With the XEDE would run 12:1 AFR and add about 3* timing. Never really was tuned for it. Boost would be whatever the stocker could ramp up to using the stock BCS.
What is the max timing that you guys aim for while on race gas?
What timing do you run at peak torque on race gas?
I simply want to know what the norm is. From the testing I've done it appears that low end timing can be set as high as 10* and I still dont see knock. What have you guys run into?
Last edited by Jeff_Jeske; Apr 19, 2007 at 11:21 AM.
Apr 19, 2007, 11:24 AM
#2
I usually run 1*-3* more timing at peak torque and 3* more in the higher rpm's and then lean it our from there depending on the weather. I up the psi to around 25 or 26 too.
If I am still knock free after that and a little rich I lean it out slightly. I get best results from race gas with a mix of advanced timing and less fuel. If I just do one without the other it doesnt seem to work as well.
If I am still knock free after that and a little rich I lean it out slightly. I get best results from race gas with a mix of advanced timing and less fuel. If I just do one without the other it doesnt seem to work as well.
Apr 19, 2007, 01:25 PM
#3
IT really all depends on your engine and set-up. Some engines will enjoy more ignition advance than others on 110octane race gas.
My suggest: Run about 2-3 more pounds of boost. Lean AFR's out to about 11.8:1, and tune ignition timing for peak output. If you don't have access to a dyno, and can only perform a street tune, get ignition timing to about 2-3 degs under the knock threshold. When you are tuning ignitino timing, and see knock in a area, retard ignitin timing 2 degs in that area and advance ignitino timing 1 deg overall across the board, until you hit knock again. Then, like above, restard ignition timing 2 degs in that area and advance overall 1 deg again. Keep doing this until you are at peak ignitino advance overall. Then, retard ignition timing 2-3 degs overall in those areas. Be sure to watch AFR's as you advance timing. You will start to lean out the more you advance timing, you will need to add fuel as you see AFR's lean out. Make sure you don't run leaner than 12.0:1 on 110 octane, while tuning and no leaner than 11.8:1 on the final tune.
Of course, don't run this lean on regular pump gas. No leaner than 11.5:1 on 93. I actually tune for 11.5:1 at peak torque tapering down to 11.0:1 at peak power.
Make sure you are setting up your correction factors properly as well. i.e. Barometric compensation, temp compensation...ect.
CJ
My suggest: Run about 2-3 more pounds of boost. Lean AFR's out to about 11.8:1, and tune ignition timing for peak output. If you don't have access to a dyno, and can only perform a street tune, get ignition timing to about 2-3 degs under the knock threshold. When you are tuning ignitino timing, and see knock in a area, retard ignitin timing 2 degs in that area and advance ignitino timing 1 deg overall across the board, until you hit knock again. Then, like above, restard ignition timing 2 degs in that area and advance overall 1 deg again. Keep doing this until you are at peak ignitino advance overall. Then, retard ignition timing 2-3 degs overall in those areas. Be sure to watch AFR's as you advance timing. You will start to lean out the more you advance timing, you will need to add fuel as you see AFR's lean out. Make sure you don't run leaner than 12.0:1 on 110 octane, while tuning and no leaner than 11.8:1 on the final tune.
Of course, don't run this lean on regular pump gas. No leaner than 11.5:1 on 93. I actually tune for 11.5:1 at peak torque tapering down to 11.0:1 at peak power.
Make sure you are setting up your correction factors properly as well. i.e. Barometric compensation, temp compensation...ect.
CJ
Apr 19, 2007, 01:38 PM
#5
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we tuned a national BSP evo on race gas to 28psi peak tapering to 23-24ish using the stock BCS.
AFR was tuned to 12.2-12:1, with about 1-2 degrees more timing. not a hint of knock, car was wicked fast. this was on 116 though (i don't know the brand of fuel though)... not 110.
with race gas though, you don't want run it extra rich like you would with pump gas. i would target 12:1
while tuning, without touching the ignition, we could feel and see the car getting faster every run as we were leaning it out from 11ish to 12ish AFR.
AFR was tuned to 12.2-12:1, with about 1-2 degrees more timing. not a hint of knock, car was wicked fast. this was on 116 though (i don't know the brand of fuel though)... not 110.
with race gas though, you don't want run it extra rich like you would with pump gas. i would target 12:1
while tuning, without touching the ignition, we could feel and see the car getting faster every run as we were leaning it out from 11ish to 12ish AFR.
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Apr 19, 2007, 08:34 PM
#8
Flash on man! Flash on.
CJ
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