Coil selection for coil per cylinder application

Strictly Attitude

solid fixture here in the forum
OK so all the regulars who have kept up with my build or helped me out (Big Thanks). I am searching my options for coils to use in a coil per cylinder setup. I have acquired an expensive EFI ECU that has coil drivers built in that is run off a 60-2 trigger wheel and a cam sensor similar to how the LS engine gets it's info. Now I am looking for donor coils that won't break the bank. Ok so for starters I have contacted a few companies and started asking a few questions. I am not expecting the best answers here as they sell coils that are way beyond my needs as of right now. I need coils to get the project going and I don’t really want to spend $360 on coils designed to spark under 36psi boost conditions. Would it be nice yes but is it necessary for my build right now nope. A good set of donor coils for $100 or less is more where I want to be right now. Then down the road I can replace them one at a time if I want or when I add boost or nitrous.

My ECU is designed with 8 IGBT/8TTL or mixed according to the manual which means I’m confused what will work. This is where Grumpy drops 10 links and a load of info on me :shock: ;) :D . I think I will help to simplify this also and put what info I have down to share also.

Let’s start with definitions

IGBT - The insulated-gate bipolar transistor (IGBT) is a three-terminal power semiconductor device primarily used as an electronic switch which, as it was developed, came to combine high efficiency and fast switching. ... transistor
Article based on automotive ignition using IGBT ... 003911.pdf

TTL - Transistor–transistor logic (TTL) is a class of digital circuits built from bipolar junction transistors (BJT) and resistors. It is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by transistors (contrast with RTL and DTL). ... stor_logic

I have looked on line to find more info but it there seems to be more forum info that really does not answer my questions or give me the information I want or am looking for. So hopefully this thread will narrow it down I have some assumptions I have made on these coils such as TTL coils are driver built in coils such as LS coils which I hear are a good coil even though from my talks with lance I do not need a coil with a built in driver as my ECU has drivers built in. Ok but if it is going to be cheap good coil why would I not run them? There is also CDI which is Captive Discharge Ignition such as MSD thrown into the mix also to make things a little more confusing. I would like to make a list and post it of IGBT coils donor and aftermarket to use best to worst well as best I can with the info available. Then a list of TTL coils donor and aftermarket again best to worst. And of course CDI coils. Now to make things complicated on this subject we have waste spark strategies thrown into the mix where you fire more than on plug at once allows use of less coils (cheaper alternative). That could be another list or add on for these lists.


Staff member




my first thought here would be to visit a salvage yard and grab the complete wiring,connectors and coil packs off a late model low mileage wreck, AFTER discussing the price BEFORE you go and remove them with the salvage yard operator, I doubt youll pay more than $80-$100

$60 for 8 new replacement coils seems like a bargain ... 67229.html
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Strictly Attitude

solid fixture here in the forum
It sure does grumpy might be a pain to change over to accept a spark plug wire? From what I see the ign-1 is 45 each so I can get 8 or 1 hmmm lol


Staff member
seems like fabricating a custom,mounting bracket for the individual mount coils that plug directly on the plugs would be both a rather minor challenge and by far the less expensive option, but of course the individual engine design and ignition selected would dictate the type of coil best designed to work,
I doubt that it would take much more than an hour of careful measuring and a bit of cardboard and duct tape to come up with a functional design for a bracket that holds all four coils per cylinder bank and if you were a bit creative something made from perforated steel and bent so a top sheet surface covered the coils could be made to look rather trick,
especially if it was powder coated or chrome

A simple bracket off of the valve cover would mount them easily, in most cases




the big advantage of the individual coil ignition with spark plug wires rather than direct mount comes into play when the cylinder head design would place the coils too close to exhaust heat sources , unlike the hemi design


Active Member
I've benefited a ton from all the great information on this forum and found this thread to be one that I might be able to contribute something back to, so I can share at least some things that I learned with my Coil-Near-Plug + Sequential Multiport Holley HP-based engine build that might save someone else some time in the future.

This will probably be mostly a pretty chaotic "brain dump" / a download from my OneNote notebooks where I've cataloged a lot of data that I used for my build and not as organized as this forum's posts usually are...

For anyone already going with a modern aftermarket EFI system from one of the major vendors like Holley, FiTech or Fast, many of them can be extended to support coil-on-plug injection and their port injected offerings can normally support sequential multiport injection, as long as you provide them with both a crank sensor and a cam sync sensor.

For me, anyway going with used LS ignition coils was a no-brainer as they're readily available inexpensively, and at least the post LS1 coils are all pretty good. I picked up a set of D514a coils taken off of a Silverado truck for $125 with the brackets and mini wiring harness. These coils came on LS2s and LS7s in the Corvette, GTO, Chevy Avalanche and some other SUVs/ trucks.

A few things I've learned about the various LS ignition coils:

  • The coil packs should be thought of in two major revisions, the LS1 / LS6 early coils and the later, improved LS2, LS3, LS4, LS7 (and LQ4, LQ9, etc..) coils:
    • The LS1 & LS6 coils are inferior to later LS2, LS3, LS4, LS7 and LQ9 coils and have different connectors, harnesses, and wiring pinouts (Higher failure rates, take longer to become fully saturated, and produce less energy)
    • -LS1 coils had 40 milliamps peak secondary current;
    • LS2 truck coils 120 milliamps to put some numbers to it.
    • A dyno test that I lost the link to saw an increase of 6-8 RWHP & 2-18 RWTQ by ONLY switching from LS1 to LS2 ignition coils.
  • Coils are available as generally round (Delphi) or generally Square ("Melco/ Mitsubishi")
  • D585 Truck Coils (2nd gen truck coils cam on LQ9) with Heat Sinks:
    • The original D585 coils have an over-hyped reputation online; they can output a lot of energy, but require a bunch of energy and are dangerous in that if you run them with too long of a dwell time (over 4.5 ms)
    • they can auto-fire which generally means a dramatically advanced, unintended ignition event with the real risk of causing major detonation and engine damage.) -
    • They require a longer dwell time to produce maximum output, too, so they ARE more appropriate for lower RPM builds vs. a high RPM engine, too.
  • All the "truck" coils came with a slightly longer plug wire.
  • The different coils require different dwell times:
    • LS1 coils don't fully saturate until 8ms, but spark energy doesn't increase much past 6ms, D585 truck heat sink coils -never go over 4.5ms or they'll auto-fire; get a good dwell table for them because they're not super linear with voltage increases either.
    • D514a 4ms recommended for running; 5 ms is ok for cranking because the lower voltage means less energy; this coil is charged to max current in 4ms.
  • IGN1-A Pantera EFI / Holley "Smart Coils" / A gazillion other names: The IGN1-A coils are the mac daddy of aftermarket coils PERIOD and require a TON of energy and some appropriately large sized wires feeding them, they're renamed by everyone and they're huge and have heat sinks on them. They usually go for around $100 per coil and are MASSIVE overkill for pretty much any NA engine, AFAIK...

Dump of coil part numbers:
  • GM#12573190 ACDelco D514A LS2/LS7 Corvette, GTO, Avalanche- smaller and more efficient than truck coil- These are my coils.
  • GM#10457730 ACDelco D585 LS2 Truck 2002-2005 Escalade, 2000-2006 Yukon, 1999-2006 Silverado, 2001-2005 Trail Blazer -Has a big heat sink to dissipate more heat and support longer dwell; these are the auto-firing coils!
  • Melco version of the D585 truck coils #12558693 (ACDelco D581) & Delphi #19005218 -Melco are better (Delphi uses a 10.5" wire; Melco 9.2") Round=Delphi; Square=Melco; "Melco=Mitsubishi
  • GM#12611424 ACDelco D510C LS? --seem to be also known as D513A
  • GM#12558948 ACDelco D580 LS1/LS6 -EWWW! Avoid!
  • LS9 coils electrically the same as LS2 and later but bolt to the LS9 valve covers
  • 1999-2006 GM Trucks & SUVs: Round (old Delphi: 88894394) 19005218(Delphi); Square 12558693 (Melco/Mitsu) (2nd design see 88894393)
  • 2007-2013 GM Trucks & SUVs: Round 12573190; Square 8125706160
  • LQ9 ==D585 with heat sink $44 (2nd gen truck coils
Connecting Holley HP / Dominator ECUs to the LS ignition coil wiring harnesses:
You need to decided if you are going to do a bit of the wiring crimping and hardness wiring yourself, if you want a plug-and-play option, OR if you're going with a high amp ignition coil like the D585 or IGN1-A coils and will need the larger 12ga wires in Holley's "Big Wire" CoP/CNP sub-harness:

1. Standard Holley Universal Coil-on/Near Plug Harness: Minor DIY, Typical Amp Requirements: This connects from the Holley HP or Dominator ECU to the factory LS2/LS3/LS4/LS7/LQ9/LQ4 coil pack harness; but you have to wire the pins into your HP / Dominator ECU yourself: PN 558-307. $147

2. Plug-and-Play Harness, Typical Amp Requirements: PN 558-312, which I believe is plug-and-play between the Holley HP or Dominator ECUs and an LS2/LS3/LS4/LS7/LQ9/LQ4 coil pack harness. (I used 558-307, so I can't confirm that this works.) $198

3. Plug-and-Play Harness; Big Amp Requirement Coils: The Holley "Big Wire" C-N-P harness: PN 558-318 for $222.

If you like building your own harness you could or course build a big wire one yourself for probably $30-$40 and then you can also customize the length of the wire runs to make it all nice and clean. The standard Holley Universal harness was a "happy middle ground" option for me.

As far as mounting the coils, you're largely on your own for mounting the coils onto the valve cover, or you can buy one of the various relocation brackets and mount them on the frame rails or on the top of the fender wells, which is where mine are ending up; just know that the brackets are different for basically each coil.

I went with the ICT Billet bracket for the D514a coils from Amazon for $47 and am quite happy with it; it seemed good for mounting to the frame or to the fender wells; it's also loads lighter than the OEM cast iron bracket.
ICT Billet d514a relocation bracket.jpg

LS ignition coil list.jpg

HotRod article on LS coil conversion:

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Active Member
On Cam / Crank Sensor Options:
Personally, I looked at the kits, and their solution for a crank trigger WAS just way too expensive. I get saving money by using an LS ECM and then reprogramming it, but I did a FIRST Fuel Injection TPI build in a 1979 Corvette and the support of Holley EFI and getting a brand new ECU an harness just made sense and there are some way cheaper options than the EFI connections special crank sensor and trigger wheel and timing cover. (I don't think the EFI connection setup and timing cover would've fit under my C3 Corvette short water pump, either.)

When it comes to going with a cam and sync sensor, there's a LOAD of options, too.

Holley is pushing their "Dual Sync" distributors, which are $423 on their best "Holley Days" sale, plus then you really need to buy their $58 blank cap because you're not using it's built in ignition module; that solution with CNP / CoP made no sense to me.
MSD then has their "Cam sync plug" that just goes in the distributor hole to provide only the cam sync signal and to drive the oil pump for $315, but again, the price really makes no sense to me for what it is:

IMHO, the best solution for simple 1x cam sync is to use the GM cam sync distributor that came on the SBC Vortec engines and 4.3L V6 EFI engines with all the cap and actual distributor parts removed and a dust cap placed on the top so you're just utilizing the cam sync signal and sending it to your EFI ECU. You can pull one from the junk yard for cheap, or buy one ready-to-go from EFIconnection for $135; a simple hall effect sensor.

Picture showing the EFI Connection Vortec 1x Cam Sync Sensor installed:
Where I had to grind the bottom of the vortec cam sync sensor to get it to clear the top of the rear of my FIRST intake: Vortec Cam Sync Sensor Issues small.jpg

-I had to grind down part of the underside of the case to get it to clear the rear runners on my FIRST intake and get it to seat properly, but I don't think it would be an issue on most intakes.

For me, one of the points of going to the cam sync sensor and a 58x crank trigger wheel and sensor was increased timing accuracy, so this was also a great time to get rid of the stock plastic collar that made the connection between the distributor shaft and the oil pump shaft. I also replaced the stock oil pump with a Melling SharkTooth standard pressure and volume oil pump which still sees a small boost in both pressure and volume vs. a standard pump AND reduces pulsations through that oil pump-to-distributor shaft connection and theoretically might reduce some inaccuracies in the cam sync sensor.

Crank Triggers:

For crank triggers; I couldn't find what I thought to be a good deal that made sense. When I was looking the MSD Flying Magnetic 4x trigger wheel was out and not supported well by or recommended by Holley as lots of customers with CoP or CNP were experiencing EMI / electronic noise issues. They have since come out with a newer version using a hall effect sensor that supposed addresses the EMI / Noise issues but it's just under $400 if I remember correctly.

Holley has a whole kit of a crank trigger system for SBCs for $521 that includes a 36x wheel, mounting brackets, and the hall effect sensor and pre-wired pig tail connector. But, WOW what a price!

An interesting option for someone already planning to spring on an ATI Dampner is that you can just buy an ATI dampner with the crank trigger shell of your choosing built-in for a little bit more. I already had my ATI dampner for my build and acquired it used for 1/2 of new price, so this as not in the cards for me, but an interesting option that really simplifies going with a crank trigger a LOT, IMO.

Again the EFI Connection option just made no sense to me, even after looking at Holley's $521 kit...

Holley and a few other random folks sell what are essentially simple steel "Universal" crank triggers; Holley now only sells a 36-1 tooth version, but used to sell a slightly more accurate 58x crank trigger. Their Universal 36-1 wheel is $245, but then you're on your own on machining the holes in the right place and coming up with a bracket to mount and space out the hall effect sensor.

I went with the now discontinued Holley SBC 58x (60-2) (Part# 556-110)crank trigger kit, that included everything you need for $226.76, steel wheel, bracket, hall effect sensor, bracket and shims. -I don't have any real complaints with the trigger wheel except I would've liked to see some of the material removed for rotating weight reduction; the aluminum MSD definitely has the weight advantage vs. everything else.
Picture of Holley 60-2 Crank Trigger wheel kit installed:
SBC Crank Trigger and Sensor -small.jpg

The Holley instructions don't state which side of the engine to mount the sensor on, but with my similar-to-stock accessory setup for a C3 corvette, my PS pump needed to use the mounting holes on the right-side of the timing chain cover and this was the best I could do with the engine out. You have to shim the hall effect sensor with a feeler gage and the included shims. -I'm kind of scared that the sensor bracket will hit the frame where it is once it's back in the engine bay, but I'll find out the "fun way" this winter. -The stock PS bracket just BARELY cleared the crank trigger wheel but my aluminum Summit bracket had to be ground down quite a bit in the front to clear.

-This is a place where you could go with one of the cheaper Universal crank trigger wheels and fab up your own bracket and use an off-the-shelf hall effect sensor that your EFI system supports.

I wanted the accuracy of the 58x style, 8.5" diameter wheel; Holley discontinued it because the sensor needs to be setup VERY accurately given the 1/8" thickness of the trigger wheel and a number of customers using it in high RPM race engines had lots of problems with it losing crank signal as the crank pushes (forward?) at high RPM. -With my long-runner TPI engine, I figured the increased accuracy was a good trade-off as high RPM use isn't going to be a thing... ;-)

Tip1: Just remember to go with a crank trigger tooth count and sensor technology (magnetic vs. hall effect) that your particular EFI system supports. The Holley HP and Dominator ECUs will support basically anything and everything but the newest generation "Terminator / Maxx" ECUs and Sniper ECUs have limitations in the types of sensors that they support, so check with your EFI system before purchasing the trigger wheel or sensor.

Tip2: Also remember that if you go with a crank trigger that sets between the harmonic balancer / dampner and the crank pully, you'll need to space all those pullies the same amount as the trigger wheel thickness.

Tip3: With the Holley ECUs anyway you also need to install the trigger wheel so that the gap is within a certain # of teeth after the gap while cylinder #1 is at TDC and note which tooth the sensor is pointing to with #1 at TDC and enter this into a parameter in the ECU. (I think you have to be somewhere between 3 & 20 teeth after the gap with #1 @ TDC with the 58x sensor and Holley HP.)

Tip4: Any EFI system or "smart" standalone ignition control box is going to be sensitive to EMI / electronic "noise"; non-resistor spark plugs and electronic control systems and sensors, especially magnetic pickup sensors are a BAD combo, plus a bit of resistance means a longer spark duration which helps at low RPM.
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Active Member
On spark plug gaps and determining ignition energy requirements for your engine:

I'm curious on other folks' learnings, but my understanding is that there's the potential for some very small gains power gains, from increasing spark plug gaps, getting the plug closer to the center of the chamber as increasing the gap can get things started with a larger flame kernel that means less distance and crank degrees required to reach the outer reaches of the chamber or less total distance from the plug to the outer reaches of the chamber if the plug is centered, but only if you decrease the ignition advance to make up for the reduced travel of the flame front from the flame kernel to the chamber's edge.

BUT a larger gap can also extend the ability to run a lean mixture and potentially make small contributions to improving fuel economy if enabling a very lean burn at low throttle positions / highway cruise. (I'm one of the weirdos who actually DOES care about fuel economy out of my old gen1 SBC.)

-How do you know how much ignition energy your engine needs, though?

I stumbled across the following chart from Dr. David Redszus, but it does imply a traditional spark plug electrode and doesn't account for the reduced energy required to jump a gap with a thinner Platinum or Iridium style electrode:

If you really like to "Geek Out" and want to model your particular engine's spark requirements based upon Paschen's Law, which was built for exactly this purpose, the bottom of the Mega Squirt webpage linked to below will let you enter a tradition spark plug electrode gap, intake pressure from your MAP sensor, your engine's static compression ratio, and your intake air temperature to produce a fairly accurate estimate of the voltage required to jump the gap:
Online Spark Plug Voltage Requirement Calculator Tool:

It doesn't take into account loss of spark energy traveling through plug wires or through resistors in resistor plugs, it can't adjust for thin wire electrodes, it doesn't take into account CYLINDER PRESSURES (it's estimating them based upon MAP, CR and IATs only) and I think it's all based upon a curve built based upon observations with pump gasoline, so doesn't take into account air fuel ratios or fuel type, which is definitely a factor, but it's good for plugging in some worst-case numbers for your engine and then comparing that to your ignition coil's rating and making sure you have plenty of excess coil capacity.

Real Example:
My 10.2:1 CR, NA, TPI SBC:
If I leave the stock intake air pressure of 101.3 kPA alone, and enter an 11:1 CR, and a VERY high 70 deg C (158F) intake air temperature (I'm in Seattle; we set our record high temperature of all time last summer @ 120F; I do have a cold air intake but let's assume I didn't; 158F might actually be possible), and a .045" spark plug gap and the calculator says that I'd need 20.5kV to jump the spark plug gap.

BigJoe Sherman used to run big 0.050" - 0.055" spark plug gaps when looking for max power on the dyno sometimes, so if I up the gap to .055", the calculator estimates 23.1kV required at the plug.

My coils support 40kV and because they're individual coils per cylinder, that 40kV ability is still available at the dwell time that my coils require at my peak RPM of 6,100 so I've got large "cushion" between what I need and what I have.

I wish I had a calculator that worked based upon cranking pressure and VE% @ peak torque RPM and then adjusted for IATs, but it is easy enough to enter this info and just "gut check" what you have.

On getting the plug closer to the center of the combustion chamber the easy way; pictures of a standard tip, extended tip, and "extra extended tip" NGK spark plug: Extended and extra Extended spark plugs.jpg



The Grumpy Grease Monkey mechanical engineer.
Staff member
great info posted above, but a warning is needed here!
always check mechanical piston to electrode clearance's with extended tip plugs,
as the chances increase dramatically of piston to spark plug contact ,
as the plug extends deeper into the combustion chamber



Active Member
great info posted above, but a warning is needed here!
always check mechanical piston to electrode clearance's with extended tip plugs,
as the chances increase dramatically of piston to spark plug contact ,
as the plug extends deeper into the combustion chamber

Great reminder!



Active Member
Wow NewbVetteGuy, now that's some great detailed info !!!
Yea... I'm a bit of an information hoarder. I have these huge digital notebooks with many sections, sub-sections, and pages and I just keep adding to them and just need to get them out somewhere else where they can do other people good before I have some data corruption issue and lose them.