Timing question
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#8
rotorhead
iTrader: (3)
Generally rule of thumb with porting is: later intake closing timing, = better volumetric efficiency at higher rpms. That can mean less spark advance in order to reduce knock. However, you have E85. You're not really knock limited. The later closing timing hurts the low speed torque around town, especially off boost. In that case more timing could be helpful, but it's very difficult to tune timing in those areas, even with a loading dyno. You really need combustion pressure indication, and only Barry Bordes is doing that. So we usually go by rules of thumb and accepted practice.
More porting usually means more overlap. At part load that slows your burn and makes the engine require more timing and sometimes more enrichment to keep misfire under control so the engine drives smoothly.
First thing I would do with that map is add 2 degrees each 500 rpm breakpoint, starting at 5500rpm up to 7500. I'd do that across all loads. I think you've got too little timing, but I'm throwing that out there as someone with access to very little information. This really should be done on a dyno. Can you post the split map? I don't see this as a dangerous map assuming you have decent air and water temp compensations. A lot of time what does you in is some boost spike or lean out due to a mechanical problem, not the tune itself.
Your 1500 and less vacuum area is very much a driveability/idle thing. How are you controlling idle? Can you post the map? It looks like it's a Haltech Platinum Sport. How are you controlling boost?
More porting usually means more overlap. At part load that slows your burn and makes the engine require more timing and sometimes more enrichment to keep misfire under control so the engine drives smoothly.
First thing I would do with that map is add 2 degrees each 500 rpm breakpoint, starting at 5500rpm up to 7500. I'd do that across all loads. I think you've got too little timing, but I'm throwing that out there as someone with access to very little information. This really should be done on a dyno. Can you post the split map? I don't see this as a dangerous map assuming you have decent air and water temp compensations. A lot of time what does you in is some boost spike or lean out due to a mechanical problem, not the tune itself.
Your 1500 and less vacuum area is very much a driveability/idle thing. How are you controlling idle? Can you post the map? It looks like it's a Haltech Platinum Sport. How are you controlling boost?
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