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I've been thinking lately (which is always a good thing) that a 24VDC ignition system would make an interesting conversion project, as the higher voltage would allow more current to be pumped into each spark, thus yielding a more complete burn and more power.
I don't have my '02 LS1 GM manual around to look at the ignition wiring diagrams, but I was thinking of using two 12-volt batteries in series, with the car's standard 12v electrical system (starter, PCM, etc.) running off the terminals of battery 1, and then the ignition coil and charging system off the (+) of battery 1 and (-) of battery 2 to give 24 volts. I know that truck systems are like this (there is a 12V feed that comes off one of the 12V batteries) so that much will work.
I know that I would want to rewind the OEM coil packs to increase the current output, but I'm not sure of the electronics inside and how that would affect things with the switch to 24 volts.
Aside from having to refresh myself on electronics theory so I know what I'm doing, what do you think?
If you'd like to experiment with higher voltage levels with less hassle, you might wish to explore the 16 volt batteries that are on the market. Some of those units have an additional 12 volt post that can be used to power the regular OEM lighting and regular power systems while the whole 16 volt shot can be used to beef up the ignition. That might be less complicated than wiring in coverters to protect the stock harnesses and equipment.
Good luck with this experiment. I doubt that you'll see enough gain to measure on a time slip but it's this kind of pushing the envelope that makes for exciting developments. If it works for you, we'll all be doing it in six months.
Unless you're trying to fire nitro, more power is not needed. You are already getting a full burn with what you have.
More spark will not get you anymore power. As mentioned, a 3 post is perfect if you are worried you need more power.
Then you only have to buy all new 16V accessories!!! Good luck.
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Why not buy a kenne bell boost a spark, to increase voltage to just the coils, seems alot easier.
However, I have no idea what kind of setup you have on your car, but the truck coils seem to be good for 1000 hp or more, and that would be my budget upgrade
The dual battery truck systems, I believe (coming from the ford diesel information) are setup to run the glowplugs at 24 volts during warmup, and once started switch the system to a parallel 12 volt system.
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I've done this but on a single coil distributor setup. I did it by using a product similar to Kenne-Belles Boost A Spark. I put 20 volts to the coil +.
Dont believe that rubbish that "once its lit its lit". Spark quality makes a huge difference to drivability and opening up that tuning window heaps. More torque, less detonation. I would never go back to 12 volts.
The only issues are getting coils and ignitors that will work. I was considering doing this in a multicoil setup and using LS2 coils but dont know whether they will survive.
Remember its current, not voltage that you want at the spark
Also you have to remember where your starting point is. My ignition system was from an average factory ignition system setup. Where as I would say that a Buick V6 supercharged has an above average to very good from the factory setup so putting 20volts to the coils may not help as much.
I dont know how good the LS1/2 coils and ignition system is like
Thanks for the responses. Since starting this thread I've learned more about the LSx ignitions... and while they are a decent setup, the built-in igniters makes upgrading or modification a pain in the rear. I've found some info from the Mazda guys doing the LS1 coil swap, but the most has been from the MegaSquirt forum; they have the most comprehensive information on the LSx coils that I've ever found. A 24VDC ignition is still an idea, but I'll have to look into the LS1 coil design further.
Originally Posted by Dan Stewart
I have to disagree here. Current is what kills people and does the work to weld metal, not voltage. My understanding is that more current = bigger spark... that's why we have aftermarket ignition systems from Jacobs, MSD, Crane, M&W, etc. They boost the current output. Granted, voltage is important, but not as important as current. However, I'm open for correction.
Originally Posted by turbotrana
I dont know how good the LS1/2 coils and ignition system is like
The LS1 coils are not as good as the truck coils (D585's). The MegaSquirt guys have some good information on LSx coils. Check out the following links for more complete information:
I have to disagree here. Current is what kills people and does the work to weld metal, not voltage. My understanding is that more current = bigger spark... that's why we have aftermarket ignition systems from Jacobs, MSD, Crane, M&W, etc. They boost the current output. Granted, voltage is important, but not as important as current. However, I'm open for correction. [/URL]
Exactly. We are not welding metal here. We are simply creating an ignition source. To get the heat we need in the spark, without melting the electrode on the plug, we use higher voltages. Increasing current will simply cause the electrode to burn off faster.
Once you have the most spark the combustion event needs for the most complete and fastest burn, increasing the spark energy does nothing......per my previous discussions with Jacobs and why they don't make a coil for the LS1, they state that you wouldn't see any improvement over the stock coil.
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Current is what melts stuff. Power is Volts time Current. Higher the voltage, the less current required for the same amount of power transmitted. Current through a resistive load puts out heat, heat makes things all warm and melty. If you're looking to really change things up, you should be considering them both...
Thats what I used to think. I also used to think that CDI were the ignition to use (but realise now they give a crap spark). I also used to think that a high amp igniton would chew out spark plugs and dizzy caps. They dont.
Dont close your mind to new things. Experiment.
Check out www.iceignition.com.au . all this guy is doing is increasing voltage to the + side of the coil but making sure the coil and ignitors are up to it.
His ignition system was in the winners engine of the Engine Masters competion. Its not snake oil. It works
if you've had electrical engineering courses or get basic principles and are not biased by all the automotive marketing b.s. you would quickly realize that trying to get a more powerful spark from putting 24 volts to the coil would overheat it and quickly cause it to fail.
For the first few sparks, the magnetic field would be greater and you would get a better spark, but on a running engine a coil designed on 12 volts (14 volts actually) would just overheat and fail to produce a spark.
So let's redesign the coil you say, to "take advantage" of the 24 volts input and make a better spark. Well then you would have to change the primary vs. secondary windings of the coil, and also change the resistance or impedance of the coil to limit the current going through it now at 24 volts. In the end you're going to end up with the same output because the coil is designed around a thermal limit, not an electrical limit.
Have you seen the high performance coils in jegs, summitt, or jcwhitney, advertising 50,000 or 60,000 volt output? The normal is 20,000-40,000 volts. I've tried them on my boat, when you get the engine up over 3000 rpm the coil overheats and the ignition cuts out, just like a rev limiter. You can manufacturer the coil with any number of turns in the primary/secondary windings to give a desired discharge output, that's very simple. It's handling the heat generated that's the problem. The best thing they ever did was go from a single ignition coil, to coil per plug. On a v-8 that's a 1/8 improvement in saturation time for the coil to produce the spark, and it's also 1/8 less sparks a single coil would have to produce for every 2 rpm which means less heat generated--- therefore the coil has to produce less sparks per time you can make a greater primary vs secondary winding ratio to get a higher discharge and not overheat the coil.
It would be very interesting to see ignition coils having the number of primary & secondary turns published.
And let's not forget the alternator, you put two 12-volt batteries in series then how you going to charge them from an alternator putting out 14.4 volts?
Having worked with a bunch of ignitions over the years, I can tell you that the answer to the higher primary voltage question is not as simple as we might think. Firing the mixture in the combustion chamber requires energy, and the actual amount just to initiate combustion is actually much lower than you might think - much less than the advertised output figures of many aftermarket CD ignitions.
However, there is a difference between just getting the mixture lit, and getting it lit in such a way as to maximize power. The SAE published an interesting paper many years ago (I have long since misplaced my copy) that described ignition experiments on a lab engine that was running fairly lean mixtures (in the 24:1 area). They built an ignition system in which the delivered energy and the spark duration could be controlled independently. What they found was that the time required to initiate a good flame kernel was dependent upon BOTH parameters. A short, high energy spark was not as effective a longer, lower energy spark. If a flame kernel was quickly established, additional energy or duration didn't seem to make much difference. In trying to move this into the performance area, it appears that if you have some minimum amount of energy, applied at a certain rate, you will not see appreciable improvements once you go above this point. If the OEM coils are providing a marginal energy/duration, then adding energy through more primary current might make a difference. The aftermarket volt boosters are a good way to do this, but here's some things to keep in mind: if the coil driver circuit has electronic current limiting (like the old HEI system) the additional voltage AT LOW SPEEDS will cause the module to run much hotter & affect reliability. The ideal situation would be a switch that allowed the user to apply the extra voltage only for drag racing or other high-output operation. If the coil drivers do NOT have electronic current limiting, but depend instead on controlling dwell time to regulate the current in the coil (a lot of modern EFI systems do this) then the extra voltage on the primary will increase the current (and energy - it's an exponential relationship) BUT - you might overheat the coils or possibly overstress the coil driver transistors. It's a "buyer beware" situation for sure. There are some voltage boosters out there - it would be interesting to see what kind of experience users have had with them.
As far as the voltage/current issue - it takes a relatively high voltage to break down the spark gap. As cylinder pressures go up, and the mixture becomes more dense, it takes more voltage. Most people who are not able to measure actual gap breakdown voltages are surprised to find that very rarely does the voltage requirement go above 25 kV. Ads that tout 50/60/70/100 kV coils are total marketing BS (which tells you why the marketing people don't like me!). However, once the arc is actually established, the sustaining voltage across that gap might drop down into the 800-1500 volt region. As the energy in the coil is transferred to the gap, the voltage will tend to start rising slightly, until the energy is gone, and the gap goes out. So, both earlier posters are right, in a way. You have to have a certain minimum voltage to fire the gap, but once it's going, it's current that provides the heat to transfer to the fuel/air mixture. What the higher current will do (everything else being equal) is get the flame kernel going more quickly, thus making the combustion event more consistent.
This means that the "effective" timing of the engine will be closer to the actual timing. Effective timing is based upon when the pressure peaks in the cylinder, and is affected by how quickly the combustion process is intitated. if it takes a couple of extra degrees of crank rotation to get the flame started, then you've just retarded your timing by two degrees, even though your timing light shows the same "mechanical" timing.
I had an interesting conversation with a Pro Stock racer a number of years back, and he said that in their dyno testing (1200 HP Pro Stock motor) they would see several horsepower gain after a series of dyno pulls by switching to new plugs - same gap, just new. The reasoning was that the new plugs still had nice, sharp edges on the electrodes, which made it easier for the spark to jump the gap, thus initiating combustion a tiny bit earlier, which resulted in an effective slight effective timing increase, which the engine liked.
In the end, you have to try different combinations of things to find the one that works in your engine, but basically the more fuel/air/nitrous you cramming in, the more ignition you're going to need, and a voltage boosting system (that can be controlled by the user) might be the ticket. The 24 volt conversion has so many hard to resolve problems that I believe that it would be a lot of effort for very little reward.