Thinking about upgrading my ignition on the cheap, and was debating on switching from the stock coils / ignitor setup over to a direct spark setup using a set of LS2 / Truck coils. I can get a set substantially cheaper than a set of IGN-1A's or a twin power.
The main reason for wanting to swap is I'm planning on seeing what the lil 5862 (rated at 823 cfm at 1 bar) has in it when pushed into the 22-23 psi range ( on E85). I already have a standalone so it'll be an easy upgrade.
Is anyone running or has ran the LS coils? If so how are they working / did they work for you?

 

They seem to work well, their dwell should be set in the 2.5ms range at 14v if I recall.

EDIT: Before I forget, make sure that you're getting D510Cs rather than D585s. The 585 has a very long dwell (Around 4 ms) which will put you at 50%+ duty cycle in the high rpms

 

LS2 585 truck coils are the worst you can get for a rotary

 

^ ys that?

 

There are a lot of people running LS2 truck coils with good success.

However, I was looking for info on coils recently and ran across a couple of internet sources that were indicating at higher dwell/duty cycle, some of the coils are prone to discharging prematurely. Apparently it may be the way the coils limit current. Obviously if this where to happen at high rpm/load on a highly boosted engine this would be very bad.

I haven't delved into this matter, just took note. As with any internet info, it all needs verification. So before you use these coils, I'd suggest some in-depth research.

 

https://www.rx7club.com/2nd-generati...ssues-1053645/

Ive been told that FC coils are the most robust. There are many other threads that suggest that the FC coils are more than adequate.

 

This is why I get others input before I make any major changes. After doing some research across the web looks like folks are running into the auto ignite issue when not setting the dwell correctly.

"The LS2 coils with the heat sink discharge at about 5.5-6ms" Source

So appears the ideal way to go is setting the dwell around 3-4ms and leaving it. That should alleviate any of the auto discharge issue folks are having.

 

Found even a bit more info about them, the auto-discharge isn't only on based on too much dwell time, but also too much voltage.

Found the stock GM Dwell settings for the 5.3/6.0:



Looks like on the high end they sit around 3.5 / 3.2 around 13 / 14 volts. Under normal voltage (12-14) never go higher than 5.3 and lower than 3.2.

 

The auto-discharge function is directly proportional to amperage draw. The higher the voltage, the more quickly the coil will saturate and reach the auto-discharge limit.

And when you dwell them at that short of a charge time, the output is underwhelming. In light of the auto-discharge "feature" it's best to avoid these coils all together. And that is what the LSx guys have been doing for a while.

In the end, they're just not worth the crap shoot.

 

So what do they use?

 

Many things. Just not the D585 because of the auto ignite "feature". On the inductive side, the Mercury/IGN-1A, and it's growing list of rebadged names (Holley, AEM, Pro EFI, Firecore, etc.) is a top player. Ford has some hot COP coils too that charge very fast. The car that won drag week last year, and the only car to ever run 6s every day of drag week, uses Holley rebadged IGN-1A coils. If they're good enough to burn 3000hp worth of methanol, they're hot enough for your rotary.

 

After spending a few days researching the reported issues with these. All the reported issues I've found were related to one of two things, either having the dwell set too high or issues with the ignition controller (firmware / ECU related) that pushed the dwell too high.
Personally, I'm going to give these a try. Can get four used at any local junkyard for about the same price as one aftermarket coil. Considering I already have a standalone, it's a hundred dollar upgrade to go from the stock FD wasted spark setup to a direct fire using these coils.
Once the upgrade is done going to run them at 4.5ms, believe that should still be plenty hot enough for my build.

 

Just curious, what ECU are you running?

For me personally I'd steer clear of anything which includes "auto-ignition" in its list of known potential problems. .. given the choice between $300 in coils, and potentially $3,000+ in a rebuild, I'd go with the coils

 

I run my IGN-1A at 3.5 ms / Direct Fire. Made 460 @ 18psi on E85. Not a hint of ignition break up.

 

There is another coil that came on the LS2 truck engines, it's a D581 MELCO coil and has been used for some pretty high output setups.

Like I said before internet info is sketchy and you really have to pick through it, but I've seen some indications that the D581 may be a little better output than the D585.

they can also be found in salvage yards,

But they don't have the "cool looking" heat sinks.

 

I know a few cars using these coils with ZERO issues. Dwell settings are 3.5 and under. Start with a low dwell and move up if needed. No more then 3.5. Lower the dwell the cooler the coil will be. You'll be surprised at how little charge time is needed to have a good ignition system.
If your looking for the cheapest ignition system. try using four FC leading ignitors and four FC trailing coils. Direct fire with dwell settings at 3.5. Best spark duration coils out there.

 

I'm running a Link G4 RX.

From everything I have found the actual reported issues were mainly back in 2011 (when they first started getting popular and the limits were being pushed). Everything I have found dating 2012+ has been positive as long as they are set properly.

If the issue was truly that severe you wouldn't be able to find anyone swapping them into their car. there would have also been a recall / factory TSB from GM to swap the coils.

 

This is good to hear. Unfortunately 2nd gen rx7 parts in my neck of the woods are few and far between. Everything comes from the internet / shipped. One of the factors that helped my decision to go with them is the actual availability of replacements if I ever need it. That and I free up more room in my very limited space engine bay.

 

this isn't true, as it won't happen at the factory dwell setting.

i ran LS1 coils back in the day, and they did fine, but there are better options