LS Coils: Internet Overload: Which ones are the good ones?!?

[NewbVetteGuy]

I've been trying to make sense of the nearly infinitely conflicting information available on the internet regarding the difference between the various OEM LS ignition coils; can anyone help me make heads or tails of this?

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")

Beyond that, almost everything seems to be disputed by someone...

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

[Tuner]

I think if you search in here for a thread nearly 10 years ago about LS coils, in which it was determined the reason "truck coils are better" was found to be the OE wires, not the coils. The specifics I don't recall, but the gist of it was some aftermarket valve covers required longer wires and the aftermarket ultra-low resistance suppression wires were not suppression enough and caused sporadic ECU disruption. The junkyard truck coils had longer wires that cleared the valve covers and the OE wire didn't upset the ECU with excess radiation. Somebody figured it out when they replaced the OE truck wires with aftermarket ultra-low resistance wires and the trouble reappeared with the wires. Someone here may recall more specifics. It may have been in the Turbo Buick forum or Yellowbullet.

[Caprimaniac]

I seem to remember the truck coils have a heat sink?

There are some differences, and don't blame me for not recalling the details..., in recistance, dwell time or whatever. Not all brands of ECU's are compatible with any kind of LS coils. Like FAST need the old stock type, not truck style.

Truck wire are longer, yes. So if you buy new coils and wire, choose those for placement on inner fender or on top of tall valve covers.

[NewbVetteGuy]

I seem to remember the truck coils have a heat sink?

There are some differences, and don't blame me for not recalling the details..., in recistance, dwell time or whatever. Not all brands of ECU's are compatible with any kind of LS coils. Like FAST need the old stock type, not truck style.

Truck wire are longer, yes. So if you buy new coils and wire, choose those for placement on inner fender or on top of tall valve covers.

Only SOME of the truck coils have heat sinks; the overwhelming majority do not. I'm trying to locate the PNs for the heat sink versions.


I also came across a few EFI systems and ECUs not supporting some of the older truck coils that pull loads of amps; newer Holley EFI supports everything.



Adam

[user-23911]

Lots and lots of BS on the net about ignition systems.

If you understand electronics and also able to read datasheets you'll understand that it's over dwelling them that kills them.
The drivers in them auto shut off once the current reaches a preset level. It's built in protection.The shut off makes them spark.
As in what happens when you turn on the ignition and don't crank it.


So it's not a case of which are the good ones, it's a case of installing and programming them correctly.


But in internet land everyone is an expert.


Once you bench test them with an oscilloscope you'll have an idea as to what's going on.
Plug it in and try it out is destined for failure.

[user-23911]

What most people don't understand about is "magnetic saturation". It ties in with dwell time. You can't keep on extending the dwell to increase the current.
That's one of the factors which limits a coil's output.

It's the same as trying to over fill a glass with beer. It'll only hold so much.

[Circlotron]

Coils are like cams in that you can describe their properties very accurately with numbers. 99% of everything I've read here and elsewhere though only talks about a particular coil's name or shape or colour or what it is OEM fitted to or what someone said about it. Practically never any real info. Then there are some really half-assed youtube "tests" that tell you absolutely nothing at all. And when someone does in fact put up some hard numbers and measurements they just get shouted down by most people that really don't have a firm understanding of the subject anyway. Q.E D.

[peejay]

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...).

Duty cycle. The majority of Corvettes will never see WOT for more than a cursory second or two in its entire life.

A truck, however, is expected to live a large percentage of its life at heavy load.

Big difference between idling a 3500lb aerodynamic missile around, and lugging around a 5500lb barn on wheels that might have 2000lb of stuff in it and a 6000lb trailer behind it. Look at the radiators used to give an idea of how much load they are expected to see. The radiator in a truck is easily 50% larger than a Corvette or Camaro has, because they're expecting that engine to be working its ass off in a truck.

This is a lot of why the automakers generally put new engines in cars first, to ensure they're up to snuff before putting them where they will be REALLY tested.

[midnightbluS10]

Aren't they using those coils on the lt1 now?


Doesn't that throw the "good coil only on trucks" out the window?

[user-23911]

There's no such thing as a good coil or a bad coil really...........you've just got to use them correctly.
They ALL work.

Just that when you do it wrong, they don't.


No 1 lesson........coils don't charge........they "flux".
Anyone who disagrees need to be shown the door........


Keep telling yourself over and over and over..........it might sink in?



Then you can move on.


To the next problem.

[steve316]

Joe 90 way to sugar coat it.

[n2xlr8n]

I researched it, as well.

I wound up buying the Delco D585 "truck" coils with the sink, because I'm using an aftermarket ECU and throwing a lot of boost at it with E85. I mounted them on a large aluminum bracket, as well, away from heat sources.

Still tuning, but so far, so good.

[peejay]

If you're really stressing over ignition, step up to the IGN-1A coils. They're monsters that will reliabily ignite at boost pressures that the D585s can't handle, which seems to be about 30psi+ boost.

[Newold1]

I think for most applications maybe except high boost or extreme power adders, the D585 GM truck coils seem to be reasonably priced and lots available for uses. I have used several sets on quite a few engines with Holley ECM's and they work fantastic at all compression and rpms up to 8500 I have tested at. JMO

[roc]

If you're really stressing over ignition, step up to the IGN-1A coils. They're monsters that will reliabily ignite at boost pressures that the D585s can't handle, which seems to be about 30psi+ boost.

Hey peejay, could you please say more about them? Are they aftermarket?