I'm in the process of building a ka 240sx right now with a 450hp goal. With that much horsepower, what will I need to do to the ignition to make it work better? I've heard a msd btm is good, but I don't really get how they work.

 

Well, an MSD BTM just retards ignition timing per pound of boost... something you won't need if you're shooting for 450 horsepower. You'll need something better to manage fuel/spark.

If I were you, get good condition wires, cap/rotor and stuff like that. Run some good copper plugs. On top of all of that, you could run an MSD 6AL box, which will just increase the performance of your ignition system.

 

msd box, external coil, msd cap and rotor made for the external coil, msd wires, decent plugs.

 

how do the external coils work and where can I get some?

 

A stock cap has an iginition coil inside. It's a small, weak one. Msd, also other companies, makes external coils. You can get them at summit 'n ----.

 

You will also need a modified or aftermarket cap to run an external coil, so it has a pickup on the dizzy