Practical Standalone Tuning: Introduction
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Introduction
06.54
| 00:00 | - In this worked example we're going to be going through the HPA 10 step tuning process as applied on this Nissan R34 GTR fitted with an EmTron KV8 ECU. |
| 00:11 | While obviously we will be focusing here on the EmTron ECU and the specifics of tuning and setting up that platform, there are some idiosyncracies around the Nissan RB26 engine, the fact that it is fitted with individual throttle bodies but still turbocharged and some of the ways that we're going to be dealing with this through the EmTron KV8 ECU will also cross over to other different brands of ECU when used on the same application. |
| 00:39 | I'll just go through the modifcations to the vehicle so that everyone can understand what we are dealing with. |
| 00:45 | The engine itself is lightly modified and it's fitted with a set of Tomei aftermarket cams and adjustable cam gears. |
| 00:53 | It's also fitted with a set of Apexi factory location low mount turbochargers. |
| 00:59 | The fuel system has been upgraded with a larger in tank pump, it's running a Sard fuel rail, adjustable fuel pressure regulator and a set of Sard 800 cc injectors. |
| 01:11 | This in itself is a little bit problematic because the Sard injectors are not one that we can get full characterisation data for. |
| 01:19 | So this makes our life a little bit harder, particularly when it comes to setting up the injector dead time or offset table, we'll see how we deal with that as we go through the worked example. |
| 01:31 | Other modifications to the engine, it's fitted with a GReddy intake kit that removes the factory mass airflow sensors. |
| 01:38 | Previously the car was tuned with Z32 airflow meters on a Apexi Power FC ECU which we have removed for the purposes of this worked example. |
| 01:49 | It's also running a larger 100 mm thick front mount intercooler and a larger exhaust system so all relatively conventional modifications for an RB26, nothing out of the ordinary there. |
| 02:04 | In terms of other key modifications, we have taken the opportunity to swtich out the factory Nissan 360° optical trigger system. |
| 02:14 | Now this is problematic on both the RB as well as the SR series of engines and while they do work reasonably well with the factory ECU, a lot of aftermarket ECUs will struggle with the 360° optical trigger system and this gets worse once we go to a more aggressive cam profile and heavier duty valve springs, this causes some harmonics which can affect the operation of the cam angle sensor given that that sensor as its name implies is fitted to the exhaust cam. |
| 02:43 | While the preferred option here would be to switch to a crank trigger system where we take engine speed information directly from a trigger wheel mounted to the front of the crankshaft and retain a cam position sensor for synchronisation input, this is a costly exercise and at the levels of modification on this engine, it's simply hard to justify. |
| 03:03 | Now of course if you were building a serious race engine where you're looking at running to 9000 or 10,000 RPM then the crank trigger system absolutely would be the right option but for a lightly modified RB26 like we're dealing with here, going to a modified trigger system in the factory location is absolutely suitable. |
| 03:24 | What we're running here is the NZ Wiring trigger systems which consists of a 24-1 tooth wheel that bolts to the front of the exhaust cam and this uses a Bosch reluctor sensor that picks up off that tooth wheel. |
| 03:38 | The 24-1 trigger wheel gives the ECU all of the information it needs because it is fitted on the camshaft, it's seeing the missing tooth once per engine cycle so not only does the ECU get engine RPM information, it also gets position information and this is all done with a single pickup so as we move through, we'll see how we go about setting that up. |
| 04:00 | As far as boost control here, we could absolutely control boost using the EmTron however the car is already fitted with a Blitz electronic boost controller which is nice and convenient and it's also working really well so the owner of the car has requested to retain that boost controller so we will be using that for our boost control. |
| 04:19 | One of the idiosyncrasies with the RB26 engine as I've mentioned is the fact that it uses individual throttle bodies and it is also running twin turbos. |
| 04:31 | This becomes a little problematic. |
| 04:33 | In a typical turbocharged engine or naturally aspirated for that matter running a single throttle body and plenum, we would run using manifold absolute pressure as the load axis for both our fuel and our ignition tables. |
| 04:45 | Now if we do this with the RB26, there are a couple of problems, first of all getting that manifold pressure reference is a little bit trickier because we don't have a common plenum which will see both boost pressure and vacuum. |
| 04:58 | So what this means is we need to tap that manifold pressure signal off all 6 throttle bodies post throttle butterfly. |
| 05:05 | Nissan actually make this easy enough for us because there is already a pressure source we can use that does exactly this. |
| 05:12 | However if we were to tune the engine conventionally using that manifold pressure signal, we'd find that it does give us some idiosyncrasies and some problems with rich and lean spots in our fuelling, it's very difficult to get consistent fuelling throughout the throttle position range at a fixed RPM if we were to use manifold pressure. |
| 05:32 | Nissan deal with this in stock form by using mass airflow sensors so that's their input. |
| 05:37 | As we've already mentioned we've ditched those which is common in aftermarket standalone ECUs. |
| 05:43 | So what we're going to be using in order to control the fuelling here is a 4D mapping system and this uses throttle position as the load axis for the main volumetric efficiency table. |
| 05:55 | The target air/fuel ratio table on the other hand still uses manifold pressure as the load axis so that we can vary our air/fuel ratio targets as our boost pressure changes. |
| 06:04 | Obviously that's key on a turbocharged engine and we will be using a secondary load table as well to make small adjustments to the fuelling once we start pushing the turbochargers a little bit harder, we'll explain in a lot more detail how that all works as we go through the worked example. |
| 06:20 | The ignition table on the other hand, this is conventional, we need to vary our ignition table based on the manifold absolute pressure and that will be the load axis there so again a few idiosyncrasies with the RB26 but as we go through the worked example you'll see that dealing with this is actually relatively easy provided you have an understanding of what we're trying to do and how to apply that. |
| 06:41 | Alright now we've got a good understanding of the car, the engine and what we're doing here, let's move on and get started with the first step of our 10 step process. |
