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Practical Reflash Tuning: Introduction

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00:00 - Now that we've seen the technique of reflashing being applied on the Dyno, we're going to see what changes are necessary if we want to perform our reflash tuning out on the road or the race track without the benefit of the feedback from the Dyno.
00:15 First let's start by talking about the differences between Dyno tuning and road tuning, and the obvious one is that when we're making tuning changes out on the road or the race track, we're not going to have the benefit of the feedback from the Dyno to tell us whether we're going in the right direction.
00:33 In other words, we're not getting that instantaneous feedback in terms of horsepower or a torque figure to let us know if the change that we've just made is going in the right direction and we're making more power.
00:46 That being said, there are actually some big advantages to performing our tuning out on the road or the racetrack and this is why, even when we've got access to a quality Dyno, I always recommend as a last step to confirm that our tune is still accurate out in the real world.
01:04 Now the reason for this is, even with a well-designed Dyno bay, it's almost impossible to replicate the sort of air flow and temperatures that we're likely to see when we're driving our car at speed on the road or the racetrack.
01:19 Now, because we don't drive or race our cars on a Dyno, what we're really interested in is making sure that our tune is accurate out in these real world conditions.
01:30 This means that when we're performing our tuning on the road or the track, that we're tuning under the actual conditions the car's going to be driving in, and hence our tune is going to be accurate for those exact conditions.
01:44 When we're talking about air-fuel ratio, this aspect of our tuning is relatively straight forward.
01:51 We can easily make sure that our air-fuel ratio matches our target regardless whether we're on the Dyno or we're on the road or track.
02:00 In this case, the process is really no different and we'll look at this shortly.
02:04 One area where there is a difference though, is when we're tuning our ignition timing.
02:09 Now when we're tuning our ignition timing on the Dyno, we're using the torque or power feedback from the Dyno to let us know when we've reached MBT timing.
02:19 If we continue to advance our timing beyond the MBT, we're actually going to see our power and our torque reduce.
02:28 Now this does present a problem when we're tuning on the road, because we don't know what the engine torque is doing.
02:35 On an engine that is not knock limited, or if we're running on a very good grade of fuel such as E85 or a high quality race fuel, our engine may not be knock limited and in this case we can end up advancing our timing well beyond MBT.
02:54 While this may not be damaging to the engine, it might also result in the engine producing less torque or power than what it could if the ignition timing was optimised.
03:05 In these situations, we do need to understand that if we are going to be performing our tuning on the road or the race track, then ignition tuning will be somewhat of a compromise, and it's always best to be conservative with the ignition timing we're using, and understand that we're probably going to be leaving some power or torque on the table.
03:28 Even when we do have access to a Dyno, some tuners may choose to get their tune close out on the road or track and then finally complete the tune by hiring an hour or two of Dyno time.
03:40 Particularly when you're tuning your own car, Dyno time can be quite expensive, and this allows you to minimise your outlay because you can get most of your tuning done on the road or track in your own time, where your only real expense is fuel.
03:57 In my own experience, after tuning literally thousands of engines using the technique of reflashing, I find that by far the majority of engines I tune, particularly those running on pump fuel will be knock limited.
04:11 That's to say the engine will start to suffer from knock or detonation before we reach MBT timing.
04:17 What this means is that if our engine is knock limited, it doesn't matter where we're performing our tuning, on the road or the racetrack, or on the Dyno.
04:27 That knock threshold becomes the limiting factor for how far we can advance our timing and hence the results we can expect to achieve on the road or track are actually almost identical to what we can hope to achieve on the Dyno.
04:42 The only downside is, we don't get a power and torque figure to let us know what we've achieved.
04:49 One final aspect to consider as well is what we're actually going to be doing on the road or track when we're making our tuning changes.
04:57 Here we have some significant advantages with the technique of reflashing in comparison to tuning a stand alone ECU.
05:07 By far the majority of our reflashing tasks will involve concentrating solely on the wide open throttle area of operation and we generally don't need to pay as much attention to the closed loop idle and cruise areas as we would with a stand alone after market ECU.
05:25 This means that we can do a lot of our tuning by focusing solely on wide open throttle, full power acceleration tests on the road or the track.
05:35 Now that we understand a little more about what we're going to be doing with our road tuning and the limitations of road tuning, we can move on.

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