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

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

Post by peejay »

roc wrote: Thu Nov 16, 2017 8:09 pm
peejay wrote: Thu Nov 16, 2017 7:24 pm 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?
From what I understand, they were developed by Mercury Marine for two cycle applications. I don't know if "IGN-1A" is a generic term or a specific part. DIYAutotune sells them for around $200/coil once you factor in the connector. The coils have separate grounds for the low current and high current phases.

They're the go-to coils for us rotary nerds since we need coils that can saturate quickly, because our engines fire every revolution AND can rev rather high. You need all the help you can get at 11000 sparks per minute, or 8000 sparks per minute on 20+psi boost.
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Re: LS Coils: Internet Overload: Which ones are the good ones?!?

Post by Circlotron »

Another LS coil worth considering is the ones from ICE Ignition. The most obvious difference externally is the iron core has double the thickness of an OEM one. I have measured as much as 180 milliJoules from one. Best I could measure from a factory one was about 95 milliJoules.

Core size comparison below.
Image
Image
user-23911

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

Post by user-23911 »

That's the most valid point brought up so far.

The energy is stored in the iron core as a magnetic field (magnetic flux).
The bigger and heavier the core, the more energy it can store.
likewise a small lightweight one stores less.

Bigger is always better.
peejay wrote: Thu Nov 16, 2017 8:54 pm
The coils have separate grounds for the low current and high current phases.

I think that if you study the online diagrams for those, they're all wrong......they're all cut and pasted from the original which was wrong.
There's a primary side earth and there's a secondary side earth.
2 separate coils with no common point.

https://www.google.co.nz/imgres?imgurl= ... mrc&uact=8

Not even close to being correct.
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Re: LS Coils: Internet Overload: Which ones are the good ones?!?

Post by user-23911 »

Then while googling Ign 1A coils .....this comes up.

https://www.diyautotune.com/product/ign-1a-race-coil/

These sellers still making BS claims.
............................................................................................................................................
Minimum voltage output (no load, at recommended dwell): 40,000 volts
Output energy: 103 mJ
Spark duration: 2.9 ms
Primary resistance: 0.5 ohms (not directly measurable)
Primary inductance: 4.8 mH (not directly measurable)
Secondary resistance: 8,500 ohms
Secondary inductance: 22.5 H
Turns ratio: 71.1
Maximum current: 19 amps
Maximum battery voltage: 17 volts
Nominal dwell: 3.0 ms
.............................................................................................................................................

Minimum voltage....it's actually maximum voltage, determined by turns ratio and primary clamp voltage.
103mJ?......stored or delivered to plug?
Duration?...2.9 msec???......that's determined by cylinder pressure, AFR and plug gap.It gets shorter as cylinder pressure increases.
Pri resistance and inductance....E = 0.5 LI squared so at 19A it can store 866mJ.....or can it?........no it can't.
Turns ratio 71........so with a 350v primary clamp it can make 24Kv, with a 400v primary clamp can make 28.5Kv....but no more. In order to make 40Kv you need a 563v primary clamp which is a bit too high to protect the primary switching transistor.Normally 400v max.
Nominal dwell 3mS.....time constant for the coil = L/R= 4.8mH /0.5 ohms= 9.6ms

http://www.electronics-tutorials.ws/ind ... cuits.html

With 0.5 ohm, max I at 13v = 26A
With a 9.6 mS dwell you'll get 63% of Imax
With 3msec dwell you might get 30% of Imax or about 9A.
Energy stored at 9A = 0.5 LI squared or 194mJ

Max current 19A?
Based on an Imax of 26A , that's 73%, then you'd need to dwell it for a bit more than 10 mSec (more than 3 times the nominal dwell) to do it.


So it's pretty much snake oil designed to sell to those who've got no idea.



Now how many mistakes did I make here?
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Re: LS Coils: Internet Overload: Which ones are the good ones?!?

Post by Circlotron »

You are pretty much on the money.
I think “minimum output voltage 40kV” should say “no less than 40kV”.
Output voltage vs turns ratio vs primary clamp voltage, yeah, if the coupling was perfect your figures would definitely be so. Maybe leakage reactance between the primary and secondary lets the secondary swing a bit higher than would otherwise be the case?
They don’t state at what primary current the primary inductance is measured. Might be 4.8mH at only 1 amp and of course decreases as the current ramps up. Stick your current clamp and scope on the primary feed wire and have a look. Guarantee the current trace gets steeper and the current increases, showing that the inductance is going down. At 19 amps no way is the inductance going to still be 4.8mH. My gut feeling is the energy at 19 amps is going to be in the 150-180mJ range, not 866mJ in a million years. That is still quite a lot though. For 9 amps probably close to 130mJ.
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Re: LS Coils: Internet Overload: Which ones are the good ones?!?

Post by Circlotron »

Circlotron wrote: Fri Nov 17, 2017 12:32 am Guarantee the current trace gets steeper and the current increases, showing that the inductance is going down.
Guarantee the current trace gets steeper as the current increases, showing that the inductance is going down.
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Re: LS Coils: Internet Overload: Which ones are the good ones?!?

Post by Orr89rocz »

Once you bench test them with an oscilloscope you'll have an idea as to what's going on.
Couple of guys on other forums have done this and there is a difference in some of the coils. Early ls1 style do not seem to put out the spark energy that the later model truck coils seem to, like the D581 and D585

Everyone in the boosted world seem to favor the D585, but they do have a dwell limit and will autofire once above that limit. Also it seems the ecm used to control the ignition side of things makes a difference. d585's have been used well north of 1500 hp.

I used D581. These were the square coil non heatsink. I ran dwell at 4.2 ms and they would fire 1400 hp worth of boosted power on gas. Stock ls1 computer on a 400 sbc. 30 lbs boost. It would not fire completely at stock dwell settings of like 3.5-3.6 ms.

For a na car i dont think any of this matters
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Re: LS Coils: Internet Overload: Which ones are the good ones?!?

Post by Newold1 »

Geez, you mean there are people on the internet out there selling "snake oil performance" products like IGN-1A !! Who wouda thunk!! :shock:
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Re: LS Coils: Internet Overload: Which ones are the good ones?!?

Post by Circlotron »

There are certainly people out there selling cheap knock-offs of IGN-1A coils. Might look the same but that's about as far as it goes.
user-23911

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

Post by user-23911 »

There's plenty of good coils to be found in junkyards too.
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Re: LS Coils: Internet Overload: Which ones are the good ones?!?

Post by Orr89rocz »

Newold1 wrote: Fri Nov 17, 2017 7:26 pm Geez, you mean there are people on the internet out there selling "snake oil performance" products like IGN-1A !! Who wouda thunk!! :shock:
Cant tell if sarcastic or if serious. The ign's are a great coil. Only really needed in high power boost situations
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Re: LS Coils: Internet Overload: Which ones are the good ones?!?

Post by NewbVetteGuy »

The IGN-1A and ICE coils are so much overkill and so far out of my budget, it's not even funny.

The later LS coils are so cheap and reliable and probably even more than I need.



I'll keep trying to find the D585 Truck Coils with the heat sink, but I'll settle for any of the later LS coils for my 6,500 RPM NA motor; it won't notice the difference, I'm sure. It's just that as coil pack take-offs all the coils are almost the same money so I figured I might as well start looking for the "good ones" for near the same price.

Thanks all; I'm moving on; there doesn't seem to be much of a power difference as long as my EFI can support the truck coils, and it can. I think the extra wire length might be useful with my fender mounting so I'll seek those out.


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

Post by davegt27 »

dfarr67
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Re: LS Coils: Internet Overload: Which ones are the good ones?!?

Post by dfarr67 »

The 'good' coils are the set you found at a great price. I went down this road and picked up a couple set of the square truck coils- good enough. If on a tunable ecu- you can drive the heat sink coils too hard and have issues.
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Re: LS Coils: Internet Overload: Which ones are the good ones?!?

Post by Walter R. Malik »

I don't know which ones are considered best however, I have never had a problem using the D581 coils from pre-2007 GM trucks.

NA or high boosted conditions; aftermarket systems or converted O.E.M. systems ... these coils seem to work very well for whatever reasoning.
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