SSinister11x

Hey all, I have always been interested in knowing how the ignition works in a LT1. Or any engine for that matter. Are there 2 ignition coils? If someone could explain how the spark works through the optispark and what other components come into play, I'd appreciate it.

OBE1 95Z28

The LT1 uses a single coil. The distributor (cap and rotor) is integrated with an optical section (hense the name opti) that provides the engine computer with visibility to the position of the camshaft. Here's a link to a detailed video out on how the opti works: http://www.youtube.com/watch?v=lFCjaz6zHfc

Injuneer

Optical cam position sensor in the Opti tells the PCM where each cylinder is in the 4-stroke cycle.

PCM uses that information to determine when to fire each cylinder, based on the timing table programmed into the PCM.... e.g. how much in advance of top dead center (TDC) should the plug fire? The timing table shows degrees of advance as a function of engine RPM and engine load, as measured by manifold absolute pressure (MAP).

PCM sends a 5V pulse signal to the ignition control module (ICM).

When it receives the 5V pulse, the ICM fires the coil.

The coil sends the high voltage to the rotor in the Opti, and the rotor sends it to the correct cylinder wire on the cap.

Complete circuitry, courtesy of Shoebox (there are minor differences, year to year, but you didn't bother to tell us what year your car is - why not add a "signature" with basic info - year, model, engine, trans and major mods?):

http://shbox.com/1/95_ign_system_schematic.jpg

SSinister11x

Thanks guys, very helpful. I have the option to get a crane Hi 6 ignition for a good price. Do you recommend it? I have a 96 SS with 130k miles. No engine upgrades.

OBE1 95Z28

No need for the ignition box with a stock setup.

TD95Z

The guy in that video looks alot like Otter from Animal House!

That clear Opti is pretty slick, too.

SSinister11x

I plan to do some long tubes and a chip, would a MSD ignition set up be fine for that as well? Thanx by the way.

OBE1 95Z28

No "chip" for a 1996, reprogramming is downloading into the computer. Typically ignition upgrades are associated with increased combustion pressure resulting from superchargers, nitrous systems, etc.