Fab9 LS Coil Conversion Kit - Market Study
 

Hello all,

We've had tremendous success with our Pencil Coil Conversion Kit (300 kits shipped in 5 months) but it's not for everyone and has it's place.

A couple of examples of why we're began developing our LS kit a few months back:

1. I personally discovered the performance limitation of our kit on my NB. At about 27-28PSI we are getting intermittent break up. There is still a need for a good ignition system beyond these power levels.
2. ECU compatibility - Since our Pencil Coil Kit works very well with the factory ECU most assume it's going to work just fine with any aftermarket system. This is unfortunately not the case - Our module requires a very strong ignition signal to trigger properly and some aftermarket units are unable to provide this.
3. Because LS Truck coil. Call it a marketing gimmick but the truth is they work. They might be complete overkill but hey, who want's to worry about their ignition system? We have enough to worry about on our higher HP BP engines.

Here is where the "market study" part comes in. Throughout testing we've eliminated a number of mounting locations. The rear of the engine becomes a bit difficult, specifically with the LS Truck Coils and we'd like to avoid it for a handful of reasons but the front has it's own set of manufacturing difficulties.

Questions we have for you:

1. Should we assume most customers interested in purchasing the kit have performed a coolant re-route and eliminated the upper coolant neck?
2. If compatible with the coolant neck, do you foresee any other space limiting factors near the front of the valve cover? (re-route pipes...?)
3. Is it safe to assume most customers who will be installing the kit can follow a simple pin-out to adapt it to their ECU of choice?
4. What percentage of customers will actually utilize a sequential vs wasted spark configuration? As of now we've prepared to offer it pre-wired per order for either wasted spark or sequential, you'd simply choose during check-out.

All of the mounting components will be machined from aluminum to provide a visually appealing piece that will "hold up" to the abuse these kits will see.
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All of the harnesses (just like our current kit) are assembled using marine quality shrink tubing and durable braided sheething to withstand more than your OE wiring.
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inb4 cut valvecover

I would love a harness for sequential that is compatible with ms2e. I have the coils themselves already.

Don't you dare FAB..

In for sequential and most should have a reroute at this level. Any hope of ignition wires and coils in the kit?

The way I see it you either need to undercut flyin miatas price or sell something really different, like a DIY kit thats just a bracket and plug wires since GM practically made the whole harness already. Undercutting FM is going to be hard if your kit includes new coils.

Thank you for the feedback - I should be around 1/2 of their price with CNC'd brackets, Truck coils and a pretty harness.

Are you planning on using OEM coils, or after market? I know the FM kit is expensive because they use OEM coils. Their bracket alone is about $100, and the plug wires are about $100.

Hopefully not aftermarket. They suck.
I've seen too many LS come around complaining about this and that because their aftermarket coil took a dump. OEM is the way to go.

The plug wires are like $100, but keith said the bracket is $(some price that is $10 less than the ebay bracket). Money is all in the coils, they retail for $135 each from GM, you can get them on GM parts direct for $72.01 but thats still a lot of money. Especially when you can get a rack of 4 of them with an almost completely made wiring harness for $50 from the junk yard.

I will see if I can find my invoice for my FM bracket. I am pretty sure it was right around $100, which sounds sort of expensive for 2 pieces of metal, but it does make the LS coils look stock.

I do agree with just running to the junkyard and grabbing a set of coils there with the wiring. It is where you save the bulk of the money.

I can offer it either way. I have a great connection for the OE parts. I've opted for aftermarket coils on the couple of demo kits I have out there.. The plan is to run them through their paces at a higher dwell tolerance to do some quality testing but otherwise I don't see a good reason to go with an OE branded part. Thermal failure is the enemy and an increased dwell will rapidly speed that process up.

Aftermarket is not all created equally - the major difference between the OE and aftermarket options is a thermal protection circuit and I've made sure our choice in aftermarket coil is equipped with this feature. Other aftermarket LS coils cook themselves. None of the LS coils are smart coils so they rely on the ECU to regulate dwell with load, unfortunately most DIY guys will set a flat dwell number and leave it at that (exactly why I'd like to be prepared with a thermal protection circuit).

Keep in mind the LS coil and the LS Truck coils mount differently. It takes up quite a bit more space because of the way they are mounted and a mount that is compatible with the non-truck coils will not work with an LS Truck coil.

Its not just the thermal protection, the aftermarket and even performance aftermarket coils are all weaker than the OEM truck coils. The aftermarket coils have the same spark breakup problems at high rpms that the normal LS1 coils have.

I'd like to see actual data. We did a few nights of 32psi pulls without hesitation so I don't foresee anyone hitting the limitation of spark capacity.

check LS1tech.

After replacing yet another OEM pack, I'm definitely in the market for this.

Any pics of the assembly mounted in final installation? The Ls look strong, but I question that much mass cantilevered off just two mounting points spread so far apart.

The mock up that was installed is made of aluminum stock that I welded up - We have yet to actually mount it with 3D printed brackets (Shown in RED in our previous post).

As far as mounting it will likely be 3 points and the bracket design is not final. We will incorporate something a little nicer looking with branding.

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Sorry if this is a stupid question, but if they were wired for wasted spark, would I be able to run them with a LINK ecu on my '94? Or do I need the ability to adjust dwell curves?

I don't know what the dwell tables in your Link look like (I understand that they're hard coded in the firmware), but I do have extensive experience with LSx coils. They need more dwell than what a stock Miata ECU commands. I can only ASSUME that a Link (again, ASSUMING FM Miata Link, not something newer like a G3) runs dwell similar to a stock Miata ECU. Therefor, I would conclude that this would not be a good fit.

That being said, I wouldn't suggest going for the type of power that would blow out spark with a Miata Link. I admit I may be biased, but I've also replaced Miata Links and picked up tons of power and drivability.

LS coils require longer dwell than you can get with wasted spark at high RPM.

Are LS coils not good for wasted spark and stockish redline? I've never known this. I've always planned on upgrading from my Toyota COPs in the far far distant future.

Someone doesn't Math very well do they?

With a 8500rpm red line in wasted spark each coil will fire 8500 times a min or 142 times a second. That's every 7 milliseconds. With a 1 millisecond discharge rate you still have 6 milliseconds left for dwell. General rule I have heard is that due to over dwell protection built into the D585 coil you shouldn't dwell them over 4.7 milliseconds. So I see 1.3 milliseconds left.

You could theoretically spin a motor 10,526 RPM with D585 coils in wasted spark. In reality, if you factor in their maximum 80% intermittent duty cycle....you would be more than fine...In the real world....With D585s, in wasted spark, up to 8500rpm.

I'm ready for some lsx coils

I'd be interested with just the bracket. I already have the LS truck coils. FYI...I don't have a coolant reroute if that matters.

What you're missing is that *I* was the one that FM asked to measure dwell on some *actual* LS coils a few years back, and that the required dwell can go > 6 ms.

You will never win at math against me. I work in an engineering group and I'm often the go-to guy for sticky math problems. <evil laugh>

I have 3 degrees. One of which is in Mathematics. I used to tutor Engineering students. They were so cute thinking Matrix Algebra was hard.

There are only about 4 different variants of LS coils. The most powerful being the D585s which conversely require the least amount of dwell and are shown to become unstable and over saturated when dwelled longer than 5.5 ms. I run a set of D585s, in wasted spark, on a 11:1 motor with 25 PSI crammed on it and I spin it well beyond the factory reline. I dwell them according to the GM dwell table and run a very healthy spark gap. To say they "require" 6 ms of dwell is simply not accurate.

You guys are both right.

I have seen D585 coils that will eat as much dwell as you can give them. I don't think I saved any scope traces, but the coils on my car loved 7 ms of dwell. I've seen others that would trigger themselves while being dwelled somewhere in the 5 or 6 ms range.

I'm sure there are multiple revisions and manufacturers of GM coils. Frankly a coil that fires itself while being dwelled and current limiting is FRAKING STUPID. Save the coil but possibly lose an engine? Engineering at its worst.

Also, there is an elephant in the room that has not been addressed. Dwell is a function of voltage. I want to say that my voltage at coil primary, measured by oscilloscope, was 14VDC. Honestly I set that about 5 years ago and haven't touched or looked at it since.

Agreed on stupidity.
The popular Toyota COPs will fire themselves at 80 ms if V>10.5 and 330 ms if V<10.5.
They should have designed them to reduce the current to zero over a millisecond or so instead of firing.
I didn't see that same behavior on the LSx coils FM sent me for testing.

+1 on > 7 ms at low battery voltages for max secondary current, on said coils. Additionally, waste spark may overheat them at continuous high RPM operation, but I didn't test this specifically.

FAB9, do you have any updates on this product??