Ok, I will try to keep this somewhat short and sweet while still giving the info I have, about the swap.
How I got to this point:My car was initially having issues with breaking up anytime I was going over 17psi. I had a *hunch* it was an ignition issue as opposed to a fueling issue so as I mentioned in a previous thread, I rewired power (through a switched/fused relay) and ground to the coils. I was then able to get away with a little more boost until the car would break up (about 20psi or so). So that pretty much solidified that I was experiencing issues with the ignition. So I started to look into potential upgrades, and looked into the splitfires, the GM/GNX retrofit, a CDI "booster" on the stockers, and the LSx coils. I eventually settled on the LS2/LS7 coils because they probably the best balance of all the options...
Background on LS2/LS7 coils:
Cons: - While they are not Coil-On-Plug which is the most convienient, they are the next best thing which is individual coils but using spark plug wires. On the GMs they come on (e.x. Corvette) they are referred to as "CNG" or Coil-Near-Plug, essentially the same thing as COP but with a small plug wire. So if you are looking for the "cool factor" of COP then these are not for you. - Because they are not COP you will need to purchase some cut-to-fit spark plug wires also - The dwell time on these coils should be much greater than stock to take advantage of their strong spark. I would strongly recommend that you have some way to adjust dwell such as a rom tune or EMS or something. They probably will still work with the stock ECU dwell but I am not sure if you will see any spark energy benefit.
Pros: - Because the coils are not located directly on the head they are actually kept cooler, which was a big + for me. Also having spark plug wires allows for easy checking of your timing, without having to chance a bad reading using the loop back connector. - Because they are stock on GMs they can be found for cheap and replacements are easy to come by if an issue arrises. Hell I actually bought 8 of them since they came on a Vette, they were less than a year old and they were just under $200 on ebay... it included the wiring as well, and I now have 2 extra coils as well. - They have an integrated ignitor. This means I could literally get rid of the entire old coil system on my R33 RB26, including the ignitor... or for those of you that always need to look for an ignitor for the swap you are home free because these babies have the ignitor built in. - The car version of the LS2/LS7 coil is very compact making them easy to fit, and the truck version while larger is very beefy and even has an integrated heat sink! - They have VERY strong spark energy. There is a very good write up by the megasquirt guys that includes the spark current, even with scope traces to prove it:
http://www.megamanual.com/seq/coils.htm
For more info on them including the pinouts and signals needed, again see the megaquirt page:
http://www.megamanual.com/seq/coils.htm
Well on to the quick pictures/explanation:
First I started by making a bracket and test fitting the coils to ensure good fitment. In the end I chose the vertical arrangement with a bolt/nut set mounting coils to both sides of my bracket. The coil mounting points are actually about 1/2" from the bottom of the coil itself. I lucked out and my local hardware store actually had nylon spacers in that size so I picked them up and they look great!
I used a piece of sheet 6061 Aluminum in .050 thickness and just cut it a bit and bent it, to get the shape I wanted. I used the TPS mounting plate to secure one side and a stock bolt hole by the strut for the other.... holds very well.
Here are side and top shots of the bracket I made along with the test fit in the car:
Coil Bracket Side:Coil Bracket Top:Test Fitting Side:Test Fitting Top:
Next I moved on to the wiring. Each coil gets a earth ground for the large current used to charge the coil, and a seperate signal ground. Many people ties these 2 grounds together.... To be honest if you don't mind a little extra wiring you really should isolate the 2 a bit from each other since the coil ground may have a tendency to get a bit noisy and the last thing you need is noise on the incoming trigger signal from the ECU. In my case I ran the coil ground directly to the - terminal on the battery and the signal ground to a chassis mounting point that my bracket was attached to. A 3rd pin is +12V again for the coil charging. This was ran to my ignition switched/fused relay power directly from the + battery terminal. The last pin is the trigger signal from the ECU. Because these coils have the ignitors built in they only require a TTL (0-5v) signal at low current levels to trigger the coils. I used an oscilloscope to verify my AEM EMS was using an active high 0-5v signal and it was. So in my case I was able to run the signal pin on the coils directly into the stock wiring. I assume this is the same for the nissan ECUs however I am NOT sure about that and I would suggest you scope out what your ECU is doing before you attempt the swap.
Here is a picture of the beginning of my wiring. (Note I am even running the power and grounds in a star configuration )
Here is the wiring completed, all wrapped up and I even used some pretty heat sheething (sp?) Also note I decided to use connectors for everything so that I could quickly remove the coils if need be. My setup is completely plug-and-play. If you are wondering, the 6-pin coil trigger signal connector is a 6-pin molex connector that was literally off-the-shelf at my local radio shack.
Here is a quick shot of the other side of my plug and play connector that is wired into the stock harness:
As with all non-COP setups you will need to buy wires as well. I chose the 8.5mm MSD super conductor wires. They were a bit pricey at ~$100, but they are quality wires and have a good reputation so I figured why chance it.Some wires. I believe these were #3 and #4
One thing I did notice was that with the MSDs you needed to modify the top terminal that plugs into the coil by reducing the diameter of the terminal. This allows it to fit on the LS2/LS7 coils. Otherwise out of the box the terminal is much to large and will not work. I just used a wire-strippers to close it up a bit:
Finally here are picks of the completed swap. Note that because the ignitor is no longer needed you can easily keep the spark plug cover and route all 6 wires through the hole where the stock ignitor/wiring used to be:
Finally, since these bad boys have much more juice they operate with much higher dwell. Here I am setting the dwell in the AEM. I am a little more conservative than the megasquirt page was (they run 5.5ms nominal and I run 4.5ms). I actually had it down near 3ms and they still were out performing my stockers. I may actually increase my plug gap, and if I ever run into issues with the ignition I know I still have a little room to boost it if need be:
And finally just for fun. Here was a second gear pull I figured I would catch with the digital camera... It was about 18-19psi. The reason it is so grip and go is because I have 275 DRs on. A bit hard to see, but it at least gives you an idea. The car is definately making power... and now it will be nice not to worry about my ignition over 20psi anymore:
Modified by WhatsADSM at 1:51 AM 7/22/2008