Discussion
MadMaxHSV said:
ringram said:
I run mine on 95 the manual says its best on 98, but I get hardly any/no knock (logged hours of driving)
The vxr8 307kw seems to run about 2deg more timing than the 297KW LS2 in the monaro (In fact that may be the main power difference, Piers is doing some testing on this)
Aiming to flash the timing map and log some runs tomorrow, will report back.The vxr8 307kw seems to run about 2deg more timing than the 297KW LS2 in the monaro (In fact that may be the main power difference, Piers is doing some testing on this)
I'm using Shell V-Power for a variety of reasons and the added timing of the VXR8 map should help it make better use of the octane rating. Difficult to judge but the car seems to pull better with greater response in the mid-range with smooth delivery to the redline. Hard to tell though without a dyno to backup.
There was no audible knock anywhere, but to be honest wasn't expecting any with the fuel and still running a 'factory' tune. Will be doing some logging to ensure no knock is present. If Richard has run 95 in his VXR8 with no issues I reckon even more timing could be added to get best performance running 98 or higher.
ads_green said:
PS - don't bother with fuel additives.
Any super unleaded from any supplier is going to be blended with lots of additives so I would be very careful using any octane booters.
I beg to differ......I use Millers CVL in all my cars and have done for years, one bottle with every 20 litres. The improvement in fuel economy means it pays for itself plus you can honestly feel the performance improvement. CVL is an Octane Booster and apparently the only FIA approved one out of interest. http://www.millersoils.net/1_Millers_frame_MOTORSP...Any super unleaded from any supplier is going to be blended with lots of additives so I would be very careful using any octane booters.
ads_green said:
stevieturbo said:
The higher the CR, and softer the engine, then definately use the best petrol you can get...
I made my 850 at the hubs, on regular 97 SUL.
Forced induction does make things more complicated - most FI engines run a reduced cylinder compression ratio to account for the air charge being under positive pressure rather than pulled in. You can pretty much get this ok with a non intercooled setup as the results are easier to reproduce for accurate mapping. However throw in an intercooler than it becomes incredibly difficult to get a decent map working in all situations as the effect on the air charge is so variable given the different operating conditions.I made my 850 at the hubs, on regular 97 SUL.
Perhaps difficult to tune at the ragged edge. Even I wouldnt be bothered with that...and definately not with a customers car.
I dont even take those risks with my own anymore.
stevieturbo said:
ads_green said:
stevieturbo said:
The higher the CR, and softer the engine, then definately use the best petrol you can get...
I made my 850 at the hubs, on regular 97 SUL.
I made my 850 at the hubs, on regular 97 SUL.
Forced induction does make things more complicated - most FI engines run a reduced cylinder compression ratio to account for the air charge being under positive pressure rather than pulled in. You can pretty much get this ok with a non intercooled setup as the results are easier to reproduce for accurate mapping. However throw in an intercooler than it becomes incredibly difficult to get a decent map working in all situations as the effect on the air charge is so variable given the different operating conditions.
Charge air temp sensor. I dont see what is incredibly difficult about forced induction tuning.
Perhaps difficult to tune at the ragged edge. Even I wouldnt be bothered with that...and definately not with a customers car.
I dont even take those risks with my own anymore.
FI makes the comparison of RON/MON a bit more complicated as they are measured using a NA engine.
It's not so much FI that is difficult - but intercooling gives alot of challenges. The charge air temp sensor gives you the temp but I was meaining more the compliexity of the map to use it. You still have to apply a map for the different charge temp ranges and an intercooler makes this parameter considerably more variable.
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