Here's what I think I know:
- LS2 & later coils (LS2, LS3, LS4, LS7 and same gen truck version coils (LQ4, LQ9, etc..) are certainly superior to the earlier LS1 / LS6 coils in terms of reliability, spark quality, and ability to support longer dwell times
- Many of the early aftermarket coils had high failure rates (MSD & even the Accels)
- Connectors, Harnesses, and Wiring pinouts are different between LS1/LS6 and the later LS coils
- Coils are available as Round (Delphi) or Square ("Melco/Mitsubishi")
Some people claim that the truck motor coils are better than the car coils (why would GM put a better coil in a Silverado than a Corvette?? Makes no sense...).
Some people claim that the Melco / Mitsubishi coils are better than the Delphi's, but others then state that only the Melco / Mitsubishi coils that have the external heatsinks on them are actually significantly better.
Is it simply that the truck coils can support a hotter spark and longer dwell times and are therefore more appropriate for lower RPMs where you don't need to recharge quickly and the performance car focused coils focus on higher RPM and shorter recovery times but with a less hot spark?
There are rumors that the later coils are somehow more efficient and pull less amps while supporting almost the same voltage differential and spark duration / dwell times; anything to this?
LS1/LS6 Coils (EWW!):GM#12558948 ACDelco D580
Later LS Coils:
D514a AC Delco#, #12573190 GM#: LS2/LS7 Corvette, GTO, Avalanche, etc... -Physically smaller and supposedly more efficient than a truck coil
D585 AC Delco#, These are supposed to be the "hot" truck coils, but there are AC Delco and Melco/Mitsubishi versions and different model #'s over time. LS2 Trucks, 2002-2005 Escalade, 2000-2006 Yukon, 1999-2006 Silverado, 2001-2005 Trail Blazer. GM #10457730; Delphi (round, 10.5" wire)19005218; Melco/Mitsubishi (square, 9.2" wire) #12558693 ---These Melcos are supposed to be the best, but I've found supposed D585 Melco square coils with this # that don't have external heatsinks at all. It appears that Melco/Mitsu created a 2nd generation of this D585 coil with #88894393 (in the 1999-2006 timeframe)
The Model #'s seem to vary between the 1999-2006 timeframe and then 2007-2013, except it seems like both manufacturers are creating new revisions within the year range and new part #s.
2007-2013 GM Truck & SUV coils: Delphi (Round) 12573190; Melco/Mitsu (Square) 8125706160
From what I've found, the LQ9 motors came with the D585 coils with the heatsinks; my best guess is that these are the #88894393 coils or the #8125706160.
In general, I'm happy to get any reliable information, but I'm mostly looking for the part #'s for the square coils with the heatsinks; I can find takeoff truck coils for shockingly cheap compared to new and I'm happy to spend the time researching to find the "good ones". I will be mounting the coil packs on my front fender wells so the original mounting system really isn't important to me.
Thanks,
Adam