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.

2d Ignition Map

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 vs Advance Table

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.

Table View

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!

Megajolt Configurator View

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.

• RPM Only
  This mode is often overlooked, it only uses the RPM input to calculate advance. This mode is most like a standard mechanical distributor with weights and springs. This will produce a 2-dimensional map (RPM and Ignition Advance). You only have 10 bins to work with though. See: Mapping MegaJolt: RPM only
• MAP and RPM
  This mode calculates advance given Manifold Air Pressure (MAP)  and RPM as inputs. This will produce a 3-dimensional map. In this mode there are 100 bins (10×10) to work with. MAP and RPM is ideal for most applications such as single carburetors, mechanical fuel injection, and early electronic injection (Bosch L-Jet etc.) It is the only way to go for boosted (turbo or supercharged) applications.
• TPS and RPM
  This mode calculates advance given Throttle Position Sensor (TPS) reading  and RPM as inputs. This will produce a 3-dimensional map. In this mode there are 100 bins (10×10) to work with. TPS and RPM mode ideal for situations where a steady vacuum signal is not available such as with dual carbs, or individual throttle bodies (ITB’s).
• Adjustments to Advance (Advance Correction)
  In addition to the modes above, you can add another layer of complexity to adjust ignition advance. This can be done via just about any external sensor sending a voltage signal to the MegaJolt. The most popular, and usually most effective, is through the use of an Intake Air Temperature (IAT) signal. This will act somewhat as a multiplier, giving you extra depth to each bin, producing a 4-dimensional map with 110 bins (10×10+10).

• Alternator HP Draw
  There are a few things going on here: 1. charging draw, 2. draw to spin the alternator guts (no charging)
  
  Charging draw: At its very basis, it takes shaft power for the alternator to generate electricity. At full draw, you could potentially pull 65a x 14.5v = 1.27hp. That assumes the alternator operates at 100% efficiency. In reality, an alternator’s efficiency is about 50% depending on many factors, mainly rpm and operating temperature, so lets just say from charging you’re pulling 2.52hp.
  
  **To do this, remember, you have to pull a full 65a, most of the time though, you’re probably not consuming that much power.
  
  Spinning the alternator: the interesting thing about the charging draw is that it is always quoted in a steady state. In a race situation, nothing is in a steady state. The engine is constantly accelerating up and down the rpm range. Just like a flywheel, the alternator takes horsepower to accelerate. An OE Fiat alternator is run about 2 x crank speed, so say that in 2 seconds you accelerate from 3500 to 7500rpm, you have to spin up the alternator 8000rpm. With some assumptions on the alternator’s moment of inertia, we can calculate this to take 4.13hp. This is assuming the belt transmits power at 100% efficiently.
  
  Another note on alternators, most are rated at a certain %duty cycle. They will perform with a higher instantaneous output than what they are rated at, so while a 95a alternator will put out 120a for say, 30 seconds, as heat builds their efficiency drops and they will reach a more steady state output around their rated output, in this example, 95a.

• Water Pump HP Draw
  A subject I don’t know as much about, it seems very complicated as you have varying pressures depending on open or closed thermostat, pumping efficiency at various rpm, etc. My guess would be about 2hp to pump and negligible to spin up because of its very low MOI. Of course the advantage of an electric pump is it operates at a constant rpm, where it is most efficient, with the added plus of cooling or warming the engine while the engine is not running.

Another interesting point, a 9.5mm (3/8″) V belt has a limited power handling ability, roughly 5.5hp. It is not uncommon to exceed the belt’s capacity, this means slip, heat, degraded belt performance, and eventually failure. This is why you won’t see an alternator rated over about 110a without a double-v or serpentine (poly-v) belt on an OE application.

MegaJolt.   Mega.  Jolt.  –That’s a funny name. Where does a name like MegaJolt come from? What is MegaJolt? What can MegaJolt do for me? Well, sit down, have a read, and I’ll tell you.

• First, a bit of history
  In the late 80′s, car manufacturers started to take a serious look into the inefficiencies created by mechanical distributors. Even the best units, when tested, will show +/- 2 degrees of ignition timing. The cause of this error is due to the inherent backlash and wear of mechanical components. This wasn’t the only problem though. Manufacturers noticed poor combustion at idle and started using vacuum diaphragms to further adjust timing. These systems worked well until again, being mechanical, would wear and fail.
  
  Their solution, was an electronic revolution!

• Distributorless Ignition
  An electronic distributorless ignition system (EDIS), is an ignition system without a mechanical distributor. Instead, they have multiple coils connected directly to each spark plug. A computer determines where the engine is in it’s cycle, and when to fire each coil. Is MegaJolt that computer? Well.. kinda.
  
  Though there are many different distributorless ignitions, the Ford EDIS proved to be a tinkerer’s dream. Its advantage is that its electronics were separated into different components, a high power relay to fire coils, and the engine’s computer (ECU) to control advance. One could even unplug the ECU and the ignition system would still run (albeit at a static 10 degrees of advance). This got people thinking.. What if we unplugged the ECU and put something else in its place? That something else became MegaJolt!

• What is MegaJolt?
  MegaJolt is an ignition advance controller. Sounds complicated though it really isn’t. An ignition advance controller is a device to control an engine’s ignition timing. In older cars a controller is as simple as weights and springs in a distributor. As the engine spins, the weights allow the ignition timing to advance in proportion to the engine’s RPM. To tune the advance, one could simply change the springs holding the weights and this would change how much advance the distributor would produce.

• If MegaJolt is just a box of weights and springs, what do I need it for?
  In newer cars, the ECU acts as an advance controller and to tune an ECU you need special tools. To tune MegaJolt, however, all you need is a computer (or even just a smartphone!) To put it simply, MegaJolt allows you to tune the ignition timing of a Ford EDIS without special tools.

• So, that’s it?
  Hardly! That’s only the tip of the iceberg. Since its inception, the MegaJolt project has grown immensely. Many features were added over the years, turning MegaJolt from just an advance controller to much more:
  
  It can be a rev limiter.
  It can correct for air temperature.
  It can be a pressure switch.
  It can be a data logger.
  
  The list goes on. In a way that is almost where MegaJolt goes wrong. Too many features. It is important to remember, feature-rich as it may be, that these features are only extras, and are not required. It can be as basic or as complicated as system as you want. Either way, it is the best standalone ignition advance controller out there.

If you’d like to know more, follow these links to the other posts in our series on MegaJolt:

• Modes of MegaJolt

Oh yeah.. how did it get its name? Originally there was MegaSquirt, another project for DIY fuel injection. MegaJolt was a side project for DIY spark control. If fuel injectors give you a ‘squirt,’ its only natural that ignition gives you a ‘jolt.’

Offset templates:
Rear Offset Template
Rear Offset Template A4
Middle Offset Template
Middle Offset Template A4
Lancia Offset Template
Lancia Offset Template A4

If you have guarded cores, be careful to not bend the guards, we can usually straighten them out but this is time consuming and drives the price of pulleys higher.

With any core, the cleaner the better.