DIY LTCC or similar system for LT1s

[spfautsch]

The factory wiring of the coils have 2 separate circuits bank to bank each running 15amp fuse

I would assume those fuses are probably well oversized for the D580 coil requirements. Of course, I only know what my 8183 coils draw by way of having blown fuses.

The fuses I blew were the original 10 amp that I killed intentionally, and then a 15 amp that only got taken out because I accidentally disconnected the EST wire from the breadboard and all the coils dwelled simultaneously without firing. Before I added my wideband to this circuit I took it to 6500+ rpm several times with a 15 amp.

I cut my original coil power circuit back by several feet and used heavier wire between the two banks of the new harness. The controller should be powered by this circuit so it's measuring voltage as close to the coil power as possible. The total power draw of the controller is going to be less than 0.2 amps so not much to worry about there.

Ls1`s use 0.06''

Interesting, I'm seeing one part lookup source calling for AC 41162 iridium gapped at 0.040" as the OE plugs for the first gen LS1.

Honestly, I don't think gap makes much difference. I'm currently running double iridiums gapped at .045. I have some cheap copper plugs I could gap at .055 or .060 but it's a pain to get the boots to click on 6 & 8 because of the headers and the dipstick tube so I'm going to probably pass on experimenting with different plugs.

On a side note how hard will be to repurpose the LTCC controller to signal translator from opti to ls1 based 24x signal.

We discussed that starting around page 28 of this thread. [link] My opinion really hasn't changed much about it but it would be fairly trivial to attempt if I was in the right mood. I just don't see a really compelling reason to want to try.

[Fast355]

I would assume those fuses are probably well oversized for the D580 coil requirements. Of course, I only know what my 8183 coils draw by way of having blown fuses.

The fuses I blew were the original 10 amp that I killed intentionally, and then a 15 amp that only got taken out because I accidentally disconnected the EST wire from the breadboard and all the coils dwelled simultaneously without firing. Before I added my wideband to this circuit I took it to 6500+ rpm several times with a 15 amp.

I cut my original coil power circuit back by several feet and used heavier wire between the two banks of the new harness. The controller should be powered by this circuit so it's measuring voltage as close to the coil power as possible. The total power draw of the controller is going to be less than 0.2 amps so not much to worry about there.



Interesting, I'm seeing one part lookup source calling for AC 41162 iridium gapped at 0.040" as the OE plugs for the first gen LS1.

Honestly, I don't think gap makes much difference. I'm currently running double iridiums gapped at .045. I have some cheap copper plugs I could gap at .055 or .060 but it's a pain to get the boots to click on 6 & 8 because of the headers and the dipstick tube so I'm going to probably pass on experimenting with different plugs.



We discussed that starting around page 28 of this thread. [link] My opinion really hasn't changed much about it but it would be fairly trivial to attempt if I was in the right mood. I just don't see a really compelling reason to want to try.

When I had the stock ignition system in my Vortec 350 I ran an AC Delco platinum that was gapped at 0.035" per a GM TSB. When I swapped to the Davis Unified Ignition setup I ran NGK 7164s gapped at 0.050". Saw some small torque gains across the whole RPM range. When I switched to the D585 coils gained about 15 ft/lbs across most of the powerband. If you have a hot ignition setup, especially coil near plug I recomeend a fine wire iridium plug with a 0.050" gap. The NGKs worked great and are under $6 a plug. if you have the plugs out anyway, get an index washer set and index them with the gap toward the intake valve.

[kur4o]

Injectors are also wired on the 15amp fuses. The thirstier coils are the d585. Gm doesn`t recommend changing the gap on iridiums on ls1 engines. I am not sure but they are set at 0.040'' and must not be changed. It could be something specific to iridium conducting electricity.
So if the spark plug gap is defined by the coil used, I can recommend 0.060'' gap on platinum and copper and 0.04'' on iridiums.

And yes gap can make a big difference on performance. It changes both the intensity and duration of the spark.

We discussed that starting around page 28 of this thread. [link]

I really need to reread the whole thread. I lost track of most of the stuff discussed long time ago. Even the same pic was uploaded there. I scored it from a totally different source.

[lionelhutz]

LS1's started at 0.060" and then GM released a service bulletin to drop the gap to 0.040" because of misfire complaints once the engines got some miles on them.

[spfautsch]

That seems to make sense of the conflicting info I was seeing on the big box parts website - some were 0.060 and the ACDelco "OE" parts were gapped at 0.040. So even GM's guys got it wrong out of the gate.

Just wanted to throw out another small update - I got an email from the place that made the first batch of circuit boards saying they're doing a 20% off sale until the end of December. So I'm simultaneously working on adding the ICP header and LED jumper circuits to the original 1.0 PCB design, and I also ordered a D580 and D581 coil and should have them in a few days. Once I'm sure the circuit will drive all the coils I have, I'm planning to order a fairly substantial quantity. If nothing else, I'll have a bunch of really cool bookmarks. :-)

[NomakeWan]

That seems to make sense of the conflicting info I was seeing on the big box parts website - some were 0.060 and the ACDelco "OE" parts were gapped at 0.040. So even GM's guys got it wrong out of the gate.

Just wanted to throw out another small update - I got an email from the place that made the first batch of circuit boards saying they're doing a 20% off sale until the end of December. So I'm simultaneously working on adding the ICP header and LED jumper circuits to the original 1.0 PCB design, and I also ordered a D580 and D581 coil and should have them in a few days. Once I'm sure the circuit will drive all the coils I have, I'm planning to order a fairly substantial quantity. If nothing else, I'll have a bunch of really cool bookmarks. :-)

Bwahaha. I see we both made the same "mistake" on our 1.0 designs...leaving out the ICP header. "It's fine, I can just reprogram it with a pogo adapter! ...oh wait"

Cool stuff, best of luck with the 2.0!

[spfautsch]

I see we both made the same "mistake" on our 1.0 designs...leaving out the ICP header.

Honestly the only reason I want it is in the event a fantastic new arduino bootloader is released, or someone wants to eliminate the bootloader and boot right into the firmware. Considering the age and popularity It's highly unlikely any bootloader improvements can be made, but anything's possible. In around 10 years of working with the platform I've never had a chip die due to a corrupt flash even when interrupting a flash by accidentally pulling the usb cable. Also, when flashing over UART the bootloader's memory location as well as the fuse bytes can't be touched by the programming routine anyway.

I've got a socketed setup (also arduino based) that I use to set fuses and flash the bare AVRs before they go out. Takes about 3 seconds a chip to put a bootloader and main program on one not counting required key presses.