In this post I’ll show you how to generate an ignition map MegaJolt in a RPM only mode. This will most closely resemble the behavior of a weight and spring distributor.
If you were to spin a distributor through an engine’s operating RPM and then record the degrees of advance it generates, you would get a graph similar to the one below.
Here we see our engine has an operating range from about 500 to 7500rpm. Max advance of 32 degrees is achieved at about 3800rpm, and static advance is 12 degrees at about 800rpm. This is the exact terminology used to describe ignition curves of mechanical distributors. Now we just need to translate this terminology into a map or spreadsheet that MegaJolt can understand. This looks like below:
RPM bins are represented across the top while the colorful numbers represent degrees of advance. Lets say your engine is running at 2000rpm. MegaJolt will look at the table above, and say “oh! we need 29 degrees of advance!”
However, if you open the MegaJolt Configurator software, you won’t see a table like above. You’ll see one like what I have pictured below.
MegaJolt only understands maps with 100 bins. It likes to also use load sensing (MAP or TPS) to look up advance values. We can trick MegaJolt into not caring by copying our simple 10 bin map down each row.
MegaJolt will turn this into a 3d map like below. If you look at the profile of the curve/surface though, you’ll find it is exactly like the curve at the top of this post!
You could copy all of the data above manually. Luckily though, MegaJolt works off of a settings or configuration file. You can download a copy of the above generic RPM only configuration here and then load it into your own MegaJolt! Easy peasy!
For a more advanced map, try Mapping MegaJolt: MAP and RPM, or Mapping: TPS and RPM.