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Im building a procharged Ls3 and Im currently using these coils that I think are from a later model truck. Ill include a pic at the bottom
Ive heard comments saying the truck coils are the best and then I hear other people saying the ls3 corvette coils are better. Ive seen some aftermarket coils that look like painted oem units but ive never heard anything good about them or seen them on any high hp builds.
If you were building a boosted engine and wanted the best coils what would you run?
"Best" is such a loaded term and “Boosted engine” is very non-descript! So there is no right answer IMO.
For a mild boosted setup on gas/E85 just about any OEM coil will work fine.
How much adjustability do you have? Do you have an aftermarket ECU that can change the dwell times?
the IGN1A is likely one of the “best” coils out there in terms of raw power and easy installation. But its expensive and 100% not necessary for most mild boosted setups. If your running huge boost and power on alcohol, or trying to light off spark with tons of water in the cylinder etc…. Then you would benefit from something like an IGN1A coil. Otherwise run what you have and save your worries and money for more important parts.
Out of the OEM coils the D585 (round coils with heat sink on top) was argued to have the most output at dwell below 5ms. These coils are unable to go above 5ms without auto firing so they can also be dangerous in the wrong hands.
The old school square D581’s are IMO more powerful that the D585. *if* you have the ability to control dwell you can run them all the way up to 7ms or so and they will not “auto fire”.
I agree, for the average 1000hp build you can use just about anything. You can mismatch the coils and run junkyard plug wires and be perfectly fine, plenty of better places to spend the money at that point.
Ya the D581's are good and seem perfectly fine up to 1500hp or so, some guys have pushed to 1700. If you plan to make more power than that I would skip the IGN1A and go straight to an MSD Pro 600, double the price but over double the output and better control.
Stock ecu gets a little tricky unless you got it along with the engine from the orig vehicle.
And depending on which coil was used, the dwell tables (there are two) can be quite different.
LS3 tables are different than Gen 3 tables and need to be transposed to be used in a Gen 3 ecu.
Hmmm
Well this could have been handy to know. Guess I never researched it. Or looked into it.
lol I can't say I noticed a difference from old LS1 coils to LS3 coils on a 411 PCM. Will have to look into those tables for the new new start up tune.
Just wanted to give credit where it was due. Zac Brown made this video long ago. I thought it was really interesting, at that time the D585 was everyone's bandwagon response as the BEST oem coil. He tested teh firecore D585's as well and wasn't impressed. THe IGN1A were on another level though.
D585's (and these are the "high output" FireCore versions)
When I worked with Mercury Racing, their ignition requirement was for a 12K RPM Two Stroke Engine.
That required a Coil Dwell less than 2ms to produce 102mj of energy.
The LS engine can support a Coil Dwell of 8ms @14 Volts.
That coil charge time, with my IGN-1A coil, will produce 280mj of energy.
Thus a common report of 102mj was a result of specified testing parameters needed for use in a Two Stroke Engine.
Those ign-1a’s look pretty impressive, what harness would you recommend (haltech ecu that has oem coil harness connectors) and do you have a vendor or person with a decent price you’d recommend?
I have supplied the IGN-1A coil for more than twenty years.
I am the one who created that name.
I have offered LS-1Tech members a very good price if asked.
I also supply the LS "sub-harness" for these coils and valve cover brackets.
I usually run .018. Did an experiment this weekend and left the .028 factory gap in. 4.5 ms on D-585s. Worked great. I couldn't do that on my intercooled setup. Wondering if the hot air stuff vaporizes the fuel better causing it to light off easier. Also think if you spray water/meth it blows out (or drowns) spark much easier. Playing with introducing water meth next. Had to close up gaps on my last hot air car to .016 when I ran 10gph at each turbo at 19lbs.
I usually run .018. Did an experiment this weekend and left the .028 factory gap in. 4.5 ms on D-585s. Worked great. I couldn't do that on my intercooled setup. Wondering if the hot air stuff vaporizes the fuel better causing it to light off easier. Also think if you spray water/meth it blows out (or drowns) spark much easier. Playing with introducing water meth next. Had to close up gaps on my last hot air car to .016 when I ran 10gph at each turbo at 19lbs.
Box stock 3346's have certainly worked for tons of cars at .028 intercooled and not, but if I take the time to check them I set them at .025. I think messing with water is a waste of time, just run better fuel if the setup requires it. Having the engine rely on a cheap garden sprayer isn't my idea of a good time, seen a bunch of failures with them especially when cars sit for extended periods like many "fun/weekend" cars often do. Plus, if you already reached your goal what's the point of adding it when the combo can still go a lot faster without it.
All good points. I added it before finding my problem, so now its just there. But I figured I'd mention it as many others run water/meth as well and may have to gap down because of it. Also thought it was odd the rx-7 seemed to need less gap.(using the same coils off that car) Still think charge temp and vaporization has an effect of some sort. If it didn't the old F1 cars wouldn't have gone to all the effort of reheating the charge temps post IC.
I don't plan to rely on it. Similar to my Mazda I saw zero ET/MPH improvements with the water meth on/off in back to back runs, but my plugs read cooler with than without. So I figure that adds up over time. May also add some extra "insurance" as well in case of poor fuel or other issues like 100* days. I ran 7gph post IC and 3gph pre-turbo on the RX-7 around 24lbs. I have 7gph in front of each turbo now. Likely too much... but I had the nozzles and parts all in my spare bin.
Why are you at .016? Stock coil packs at 1200+hp still run .025 quite easily.
I was getting lean spikes and an occasional pop out the exhaust at .020” gap at the track. The .016” seemed to fix that. I have the D585’s. Stock dwell tables.
I was getting lean spikes and an occasional pop out the exhaust at .020” gap at the track. The .016” seemed to fix that. I have the D585’s. Stock dwell tables.
What plug? Boost? Both banks? Voltage stays consistent? I've chased spark issues that only happened under load, one time it turned out a banks coil ground was junk.
Originally Posted by Forcefed86
All good points. I added it before finding my problem, so now its just there. But I figured I'd mention it as many others run water/meth as well and may have to gap down because of it. Also thought it was odd the rx-7 seemed to need less gap.(using the same coils off that car) Still think charge temp and vaporization has an effect of some sort. If it didn't the old F1 cars wouldn't have gone to all the effort of reheating the charge temps post IC.
I don't plan to rely on it. Similar to my Mazda I saw zero ET/MPH improvements with the water meth on/off in back to back runs, but my plugs read cooler with than without. So I figure that adds up over time. May also add some extra "insurance" as well in case of poor fuel or other issues like 100* days. I ran 7gph post IC and 3gph pre-turbo on the RX-7 around 24lbs. I have 7gph in front of each turbo now. Likely too much... but I had the nozzles and parts all in my spare bin.
I do think E85 is happier when its not cold, same could be said of methanol. Depends what they look like, if you aren't getting proper heat into the plug already then going cooler isn't going to help as you just experienced. Showing zero gain spraying it in speaks a lot, I've seen the same.
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Best coils for boosted Ls? 
