Background:
I am tuning the fuel/ignition timing on my Roe GTS. The previous owner was at higher altitude and only had 91 octane available. The timing was way ******** and the AFRs were pig rich high 10s, low 11s. Now I'm leaning it out to 11.8-12.2 as recommended by Sean Roe and advancing the timing. The timing is a trickier subject. I am planning to try out the ignition maps from viperacr.com. Here's a link:
SOME TIPS AND INFORMATION ABOUT VIPER TUNING
I am concerned about tuning into audible knock and causing engine damage. Is this how you get to the edge of the tune and then back off?
Car specs:
96 GTS
Roe w/ 5psi pulley, VEC 3
93 octane
50/50 water/**** injection with stock jets (325 mL included with Roe kit)
AEM wideband on after bank 1 collector before cat
B&B headers, RT hi-flow cats, Bellanger exhaust
Mobil 1 15w50 (included this because someone mentioned this may be too thick - feedback?)
Log conditions:
80s ambient
70F dew point
Night
Sea level
114 IAT
Log graph:
See attached for a recent log. The AFR is still rich and I'm leaning it out. The timing is set at the values provided on '96-02-Viper-SC-L53-9D-A3-S108.cbc' from the VEC cd.
Ignition timing:
I also attached a graph showing the piggyback timing alterations for different tunes. I'm currently using the ROE timing and am considering moving to ACR91 then ACR93.
Legend:
PAT - Previous owner's
ROE - from VEC CD
ACR91 - From viperacr.com 91 octane tune
ACR93 - From viperacr.com 93 octane tune
ACR94 - From viperacr.com 94 octane tune
Path forward:
Set AFR to 11.5
Advance timing to ACR91
Advance timing to ACR93
Lean AFR to 11.8 or 12.2
Each step will be checked with runs to check for knock-free operation. I will advance the timing while in the mid 11s AFR because advancing the ignition will increase the AFR due to a longer combustion time in the cylinder.
Feedback on the plan? I also may have access to a dyno this Saturday. Others have mentioned that a dyno tune will vary from a road tune. I have access to both to get the best results.
I also have the complete log and tune files. Where is a good place to post them?
I am tuning the fuel/ignition timing on my Roe GTS. The previous owner was at higher altitude and only had 91 octane available. The timing was way ******** and the AFRs were pig rich high 10s, low 11s. Now I'm leaning it out to 11.8-12.2 as recommended by Sean Roe and advancing the timing. The timing is a trickier subject. I am planning to try out the ignition maps from viperacr.com. Here's a link:
SOME TIPS AND INFORMATION ABOUT VIPER TUNING
I am concerned about tuning into audible knock and causing engine damage. Is this how you get to the edge of the tune and then back off?
Car specs:
96 GTS
Roe w/ 5psi pulley, VEC 3
93 octane
50/50 water/**** injection with stock jets (325 mL included with Roe kit)
AEM wideband on after bank 1 collector before cat
B&B headers, RT hi-flow cats, Bellanger exhaust
Mobil 1 15w50 (included this because someone mentioned this may be too thick - feedback?)
Log conditions:
80s ambient
70F dew point
Night
Sea level
114 IAT
Log graph:
See attached for a recent log. The AFR is still rich and I'm leaning it out. The timing is set at the values provided on '96-02-Viper-SC-L53-9D-A3-S108.cbc' from the VEC cd.
Ignition timing:
I also attached a graph showing the piggyback timing alterations for different tunes. I'm currently using the ROE timing and am considering moving to ACR91 then ACR93.
Legend:
PAT - Previous owner's
ROE - from VEC CD
ACR91 - From viperacr.com 91 octane tune
ACR93 - From viperacr.com 93 octane tune
ACR94 - From viperacr.com 94 octane tune
Path forward:
Set AFR to 11.5
Advance timing to ACR91
Advance timing to ACR93
Lean AFR to 11.8 or 12.2
Each step will be checked with runs to check for knock-free operation. I will advance the timing while in the mid 11s AFR because advancing the ignition will increase the AFR due to a longer combustion time in the cylinder.
Feedback on the plan? I also may have access to a dyno this Saturday. Others have mentioned that a dyno tune will vary from a road tune. I have access to both to get the best results.

I also have the complete log and tune files. Where is a good place to post them?