Ignition question I've been wanting to ask
02-09-2018, 11:41 AM
#1
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Ignition question I've been wanting to ask
A few years ago, I converted to the coil-on-plug LTCC system, mainly to get the high voltage out of the opti and improve reliability. I’m at about 10 lbs of boost at 6000 rpm and at a plug gap of .034, it won’t even make it to 5000 rpm before blowing the spark out (fourth gear run). I gapped them down to .025 and the other night, it still hiccupped around 6000 rpm. I’m not an electrician or engineer, but I would think that having individual coils would allow one to run a wider plug gap as opposed to a single coil and a distributor. Does having individual coils not allow you to get more voltage to the plugs? I wouldn’t go back to the old set up (especially considering the unreliability of our LT1 opti), but I notice that on race applications, they usually use a single coil and distributor. So what’s up with that? Just curious. I guess I’ll gap them down to .022 and see if that helps, but that’s getting pretty small.
11-20-2018, 11:42 AM
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Re: Ignition question I've been wanting to ask
Just a follow up in the interest of providing information. Recently my car got to where it was cutting out under any load so I changed plug wires. Solved that problem immediately. Just wondering now if back then I had a plug wire or two slowly going bad on me and just not showing a problem until it was under heavy load.
11-20-2018, 03:09 PM
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Re: Ignition question I've been wanting to ask
What plug wires were you using when the problem occurred? What wires did you replace them with?
You need upgraded wires with that much boost, and with an ignition system capable of supplying the higher voltage required to fire the plugs. Weak, aged insulation allows cross-firing between adjacent wires, and can eventually burn through the conductor.
You need upgraded wires with that much boost, and with an ignition system capable of supplying the higher voltage required to fire the plugs. Weak, aged insulation allows cross-firing between adjacent wires, and can eventually burn through the conductor.
11-21-2018, 06:21 PM
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Re: Ignition question I've been wanting to ask
Thanks for your reply. I used the 8 mm Taylor Spiro-Pro wires recommended by Bob Bailey with LTCC and replaced them with the same. I have the coils mounted so that keeping the plug wires from touching each other is easy. The old wires had a few years on them so maybe time, heat and use just took its toll. Everything is fine now and car runs very smoothly. When I first installed the LTCC, I used the LS2 coils that Bob recommends. Anything else I need to consider to boost the voltage to the plugs?
11-21-2018, 10:53 PM
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Re: Ignition question I've been wanting to ask
I have an 8-coil system, but it was done before the LTCC existed. With an engine that makes 500 HP without the nitrous, and a 300+ shot of nitrous, I run an 0.026” gap on the plugs and the MSD 8.5mm super conductors. I know Bob does not recommend those wires with his system. My MoTeC M48Pro ECU, uses the Opti cam position signals and an external MoTeC, IEX 8-channel ignition driver for the 8 LS coils. The engine has a 7,200 RPM redline.
The guys that installed the system, Second Street Speed in Perkasie, PA first installed it on a 1997 30th Anniversary SS, with a 383ci LT1 / Vortech S/C making 1,125 HP at the flywheel, and running 9.04 @ 156 MPH at close to 4,000#. The LS coils had no problem developing the required voltage. I honestly do not remember whether they were LS1 or LS2 coils, but since these engines were built around 2000, I don't think there was an LS2 coil. Maybe a truck coil? Don't know.
While you are installing your plugs with at 0.025” gap, what is the gap when you pull them out? With the first nitrous kit I put on my otherwise stock LT1, I had misfiring and eventually burned through a set of Taylor 8mm Spiro-Pro wires. Problem was the stock extended nose plugs and running a bit lean. I was burning the ground straps off the plugs.
Have you tried discussing this with Bob Bailey? He has always been very helpful when I've been trying to sort out issues on cars running the LTCC. Problem on this site is the knowledgeable LT1 forced induction guys seem to have mostly disappeared.
The guys that installed the system, Second Street Speed in Perkasie, PA first installed it on a 1997 30th Anniversary SS, with a 383ci LT1 / Vortech S/C making 1,125 HP at the flywheel, and running 9.04 @ 156 MPH at close to 4,000#. The LS coils had no problem developing the required voltage. I honestly do not remember whether they were LS1 or LS2 coils, but since these engines were built around 2000, I don't think there was an LS2 coil. Maybe a truck coil? Don't know.
While you are installing your plugs with at 0.025” gap, what is the gap when you pull them out? With the first nitrous kit I put on my otherwise stock LT1, I had misfiring and eventually burned through a set of Taylor 8mm Spiro-Pro wires. Problem was the stock extended nose plugs and running a bit lean. I was burning the ground straps off the plugs.
Have you tried discussing this with Bob Bailey? He has always been very helpful when I've been trying to sort out issues on cars running the LTCC. Problem on this site is the knowledgeable LT1 forced induction guys seem to have mostly disappeared.
11-22-2018, 08:23 AM
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Re: Ignition question I've been wanting to ask
Ok, thanks. I did send my LTCC unit to Bob to be checked and he said it checked out ok. Everything seems to be good now after the last plug/wire change so I suspect the original problem was old plug wires instead of blowing out the spark at .025.
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