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Hey Andre, how long (on average) does it take you to tune base fuel & ignition maps... when starting from scratch (aka default values from computer manufacturer... but not "plug in") ??
Hey Marek. The answer will understandably depend on the complexity of the engine - ie NA with fixed cam control or turbo with quad cam control are quite different. For a straightforward engine with fixed cam timing I'd normally have the fuel and ignition maps dialled in within a1-2 hours of dyno time. As you'd probably know by now, my preference is always to also confirm the tune on the road which adds a little time to the job, plus there are cold start adjustments to consider that I'd perform the following day.
For a more complex engine with cam control and boost control the time frame is more like 2-3 hours of dyno time.
No cold start or anything... just base maps.
I still don't exactly understand why you need to finish off the tune on the road??.
Im sure Andre will correct if im wrong, but i believe its to just VERIFY that everything is ok. but also, to check the cells that you couldnt access on the dyno, like the high vacuum areas, which had to be a best guess during tuning based on the trends observed in the map during the tuning process.
A dyno only SIMULATES road conditions but on a dyno sometimes you wont hit certain areas of the map that you might be able to see on the street. So its always a good practice to double check your work. A lot of tuners don't but good ones will. But it depends also on what set up you're tuning.
Hey Marek. Tommy and 13bjunkie pretty much summed it up. There are three main reasons I take this extra step:
1. It's not always possible to access the very light load areas of the mapping on a dyno. Some are worse than others and for example our Mainline rolling road does a slightly better job here than our dynapack simply because there is more inertia in the rollers. In a nut shell if you're running the car at say 3000 rpm and slowly reduce the throttle opening, at some point there isn't enough torque being produced to maintain roller speed and the engine rpm simply reduces.
2. It's pretty hard to accurately replicate real world airflow of something like 150 km/h in a dyno bay. I always like to confirm that everything is the same out on the road as it was on the dyno. I know many tuners don't bother with this but over my career I've seen enough cars roll off a dyno and need further adjustments out on the road to justify the extra time taken. This is particularly important if you're tuning something like closed loop boost control where it's tricky to really put it through its paces on a dyno.
3. It can be easier in some instances to tune aspects such as transient enrichment out on the road. The dyno tends to dull the 'feel' of transient response which is more important imho than a perfectly flat AFR on the wideband meter.
now it makes sense.