Variable Cam Control Tuning: Step 4: Part Throttle Optimisation
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Step 4: Part Throttle Optimisation
03.07
| 00:00 | - The next 2 steps of the process are where we can finally get stuck into the actual tuning. |
| 00:04 | It might seem like we've spent a lot of time on the configuration leading up to this point however all of that work will make these next 2 steps quicker and easier and help ensure we achieve our desired results. |
| 00:17 | In reality, once you're comfortable with the cam tuning process, you will tend to complete these 2 steps simultaneously however we've separated them out here for simplicity and clarity. |
| 00:29 | The first of these 2 steps is to optimise the part throttle cam timing. |
| 00:33 | This is mostly relevant to continuously variable cam control systems however if you've decided to apply windowing to a switched cam system there'll be a little work to do here as well. |
| 00:45 | Let's start with a switched cam system example and in this instance, we're actually working a little out of order. |
| 00:51 | It would be more normal with a switched cam system to actually optimise the wide open throttle changeover point first which we'll do in the next step and then revisit this step to set that part throttle changeover. |
| 01:04 | On this basis, we'd already know the wide open throttle switchover RPM. |
| 01:08 | We can expect the cam switching point to want to be higher at low load and my preferred method for optimising this is demonstrated in the practical skills section of the course. |
| 01:19 | For a continuously variable cam control engine we now need to select the metrics that we'll be monitoring to help guide our tuning. |
| 01:26 | You'll recall that we may be looking for a reduction in fuel consumption for a given engine torque or conversely an increase in engine torque for a given amount of fuel. |
| 01:35 | Either of these scenarios will help us optimise fuel economy. |
| 01:39 | On the other hand you may be trying to reduce exhaust emissions through your cam control tuning which will require you to monitor emissions with a 5 gas analyser during the tuning process. |
| 01:50 | Irrespective of what you're trying to achieve, the process is detailed within the practical skills sections of the course so you can refer back there for a refresher. |
| 02:00 | The intention with building up our cam target maps in steady state and part throttle is that just like our fuel and ignition tables, we can expect our targets to show smooth and predictable trends with relation to both RPM and load. |
| 02:13 | By starting at low RPM and load, building up and then extrapolating these trends out into the wide open throttle operating area and high RPM range, we'll have the advantage of speeding up the tuning process when we get to the full power tuning step next. |
| 02:29 | If you're following the HPA 10 step tuning process that's taught in our Practical Standalone Tuning course, then this strategy also fits nicely into the various steps taught within that process. |
| 02:41 | Remember to try and keep smooth progression across your cam targets and limit sharp changes in cam target across small changes in RPM or load. |
| 02:50 | It's always important to remember that you're tuning a mechanical system that cannot respond instantly to cam target changes. |
| 02:58 | Once you've got your cam maps dialled in under steady state conditions, it's time to move on with the next step of our process. |
