Road Tuning: Ignition Table Configuration
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Ignition Table Configuration
03.14
Download the mentioned - Ignition Map Example
| 00:00 | The base ignition table is actually easier to configure than the fuel table mainly because the engine is much less critical on ignition timing than fueling. |
| 00:09 | What I mean by this is the engine will run quite happily with a very wide range of ignition timing. |
| 00:14 | Let's say at idle anywhere between zero and 40 degrees will probably have the engine running. |
| 00:20 | If you tried to vary the fueling by this much, the engine would just stall. |
| 00:25 | Let's start though with the axis configuration. |
| 00:28 | Generally we're going to want to retain the same axis we used for the fuel table. |
| 00:33 | This means if we used manifold pressure for the fuel map, we'd use manifold pressure for the ignition map. |
| 00:39 | The only exception here is if we are tuning a multi-throttle turbo engine. |
| 00:44 | In this case we'd want to use manifold pressure for the ignition table load axis so we can properly account for boost pressure. |
| 00:52 | Since the engine is not as sensitive to ignition timing, we don't need to be as worried about map resolution. |
| 00:58 | I'd have rpm zones every 500 rpm, and load zones every 20 kPa for manifold pressure, or 20% for throttle position. |
| 01:08 | When it comes to putting some numbers in the map this is where road tuning really differs from dyno tuning. |
| 01:15 | Since we don't have the benefit of feedback from a dyno, we need to accept that the ignition map probably isn't going to be optimal. |
| 01:23 | The only option we have is to advance the timing until the onset of light detonation, and then remove some timing to provide a safety margin. |
| 01:32 | We're going to look at tuning the numbers using this process later, but for now we need a starting point. |
| 01:38 | The starting point I use for an ignition map is based on researching OEM maps as well as what I've proven to work well on the dyno. |
| 01:47 | I've included sample ignition maps below that you can use as a starting point for naturally aspirated and turbocharged engines. |
| 01:56 | What you can see in these maps is that I'm using timing of around 15 degrees at idle. |
| 02:01 | The timing then advances smoothly up to around 32 degrees in the cruise areas of the map at around 3,000 rpm. |
| 02:09 | At high rpm and low load, the advance increases slightly to 35 degrees. |
| 02:14 | At 100 kPa which is full throttle for a naturally aspirated engine, I set the timing at 10 degrees at low rpm and increase it to 25 degrees by redline. |
| 02:26 | If we have a turbocharged engine, we need to retard the timing further as boost increases. |
| 02:32 | I find that retarding the timing by two degrees per 20 kPa is a good estimate. |
| 02:38 | This is intended to be a safe starting point which should result in no knock or detonation. |
| 02:44 | Aspects such as a very high compression ratio, or poor grades of fuel will affect the ignition the engine will accept, and you do need to use knock detection equipment to confirm the engine is not detonating. |
| 02:57 | By the end of this module, you should understand what input to use for the load axis on your tables, how to configure the axes, and what numbers to enter into the maps to get the engine started and running. |
