My LS2/LS7 Coil Swap

Discuss the RB20, RB25 and RB26 series engines.
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WhatsADSM
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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


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raremotive
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Well done! I am glad there are guys like you around to keep contributing.

240z4u
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Nice job, looks great! I have been threatening to do this for quite some time. Glad someone else jumped in and did it.

For anyone curious, you do have some dwell adjustment in the power FC if your using datalogit.

Just one thing, how much does your motor move? It looks like you have the bracket between shock tower and motor.

Love it!

Evan

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l0nestar
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Yummy!

Post some pics of your car man!

gawdzilla
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looks good. definitely nicer than the buick setup. what did it end up costing you? a little over $300? what spark plug gap are you running now and could you widen it after the mod?

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mello88
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nice write up thanks for contributing and keeping the board alive

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BoostFab
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well done!

this is going straight to the how-to archive.!!!!!!


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WhatsADSM
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Thanks all for the kind words. For archival purposes I copied the LS2 connector schematic from the Megasquirt page just in case they take it down. This way it will still be available in my photobucket. BTW the capactitor you see in the schematic is really not needed so feel free not to put it in if you don't want... I didn't

So if you reference this picture it gets wired like this:A = Coil ground. I wired this directly to the battery - terminal for best performance.B = Signal ground. This I wired to chassis ground.C = Trigger signal. This was wired to the ECU coil trigger wire. These are the wires going *into* the stock ignitor (not the output of the ignitor which is used on other setups like the buick retrofit). The stock ignitor/coils/wiring is no longer needed. Again on my AEM EMS I verified there was an active high 0-5v signal. I assume this is the same for other EMSs and the stock Nissan ECUs since they are all driving the same ignitor, but I suggest someone verify this if possible.D = +12V. For maximum performance you should setup a ignition switched (and fused) relay and run the +12V through your relay to the coils.

Note, if there is anyone in the Milwaukee area with an RB it would be beneficial to the community if I could measure the signal from the stock ECU to the ignitor. Again I am about 90% sure it is teh same as the AEM, but it would be nice to know for sure.

Now for some of the other posts:
240z4u wrote:Nice job, looks great! I have been threatening to do this for quite some time. Glad someone else jumped in and did it.

For anyone curious, you do have some dwell adjustment in the power FC if your using datalogit.

Just one thing, how much does your motor move? It looks like you have the bracket between shock tower and motor.

Love it!

Evan
Good call... Yea my motor hardly moves, and because I am using .050 aluminum it has enough give to it that it will still flex a bit. Additionally I did slot the bolt hole a bit by the strut tower just a bit as well.

But you are correct it is something I am definately watching.
gawdzilla wrote:looks good. definitely nicer than the buick setup. what did it end up costing you? a little over $300? what spark plug gap are you running now and could you widen it after the mod?
Thanks.. Yea the coils were from an 07 Vette and I picked them up on ebay for right around $200 shipped. It included the entire set of 8 coils, and all the stock coil harness wiring from the Vette. Even included the mounting bracket from the Vette... not that I used it.

The aluminum was like $6 or so, the misc hardware was like $15. So there is about $20 in the bracket.

The plug wires were I believe $100 shipped, again from ebay.

The misc wire and connectors was about $15

So yea it is somewhere between $300 and $350.

As for teh plug gap... that is the next thing I am going to do. I wrapped up late last night and just didn't have time to open the gap. Hopefully tonight I will get a chance to open it up to .040 and see how she does. I'll keep ya posted.

Modified by WhatsADSM at 10:30 AM 7/22/2008

Modified by WhatsADSM at 10:31 AM 7/22/2008
Modified by WhatsADSM at 10:35 AM 7/22/2008

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WhatsADSM
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l0nestar wrote:Yummy!

Post some pics of your car man!
(Before some work I did)

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l0nestar
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Chromed-out 26!! Bring-Bring!

Are those Defi gages on the pillar? Looks very nice man!

.. dual catch tanks that are VTA?

What snail is that?

moso240
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Wasnt this car on Ebay awhile back? i herd he sold it for 18k if you bought man that was a nice buy if im wrong then my mistake

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WhatsADSM
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l0nestar wrote:Chromed-out 26!! Bring-Bring!

Are those Defi gages on the pillar? Looks very nice man!

.. dual catch tanks that are VTA?

What snail is that?
As for the bring-bring... "every time you see me comin' round you city bling bling" They are the SRTI gauges, which are basically a high quality knockoff of the Defis... that don't require a controller, and are a bit cheaper. After having a bunch of gauges, these are a great deal. Well priced, accurate and high quality digital steppers. Only down side I have found is that they are a little loud... I only hear them tho when I cycle power with the car off and they go through the gauge sweep at startup. Here is their site, mine are the DSD series:http://www.stri-racing.com/

The turbo is a GT4067... which is actually a *little* oversized considering its engine state now. But with the cams it'll be just about perfect. The 4067 is a GT40 thrust bearing turbo that is actually a hint bigger than the BB GT4088. They were popular for a while but now noone really runs them, which is kind of strange considering the (relatively) low cost of the turbo in relation to its potential.

and yes dual catch cans vented.
moso240 wrote:Wasnt this car on Ebay awhile back? i herd he sold it for 18k if you bought man that was a nice buy if im wrong then my mistake
Most of the swap was done by skyline king in FL.... although I actually did my own RB powered S14 about 4 years ago so I am very familiar with the swap and with everything.

Usually I am the one that mods a car and eventually wants to sell it and looses out considering all the cash I have invested. This time I figured I would consider building my own or finding one that was partially complete and was done well. So in the end I found this one, and got to be on the flip side of the transaction where I was able to get a car for much less than it would take for me to reproduce it. For this car they did the swap along with most of the drivetrain things. I just had to do the tune, and tie a bunch of loose ends (such as the ignition issue).

As for ebay. He actually had it on ebay a few times but usually the buyer never came through. So probably it sold for 18k but the guy never came through... which is stupid of him cause 18k would have been a steal! I actually got their number and called them directly to talk about it, realized they knew what they were talking about and flew out and picked it up. My transaction was actually outside of ebay, but yes it sounds like the same car.

Modified by WhatsADSM at 3:02 PM 7/22/2008
Modified by WhatsADSM at 3:03 PM 7/22/2008

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WhatsADSM
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gawdzilla wrote:looks good. definitely nicer than the buick setup. what did it end up costing you? a little over $300? what spark plug gap are you running now and could you widen it after the mod?
So as promised, I had a chance tonight to pull all the plugs and open up the gap to .040 (up from about .027). Before I would experience blow out at right around 20 psi with the .027" gap.... which I guess is fairly normal considering the power that was being run on the stock coils.

Well now even with the huge .040 gap, and even my rather conservative dwell settings I had no issues what-so-ever at 20-21 psi (didn't feel like running any more on my 93 octane). Ran smooth as can be. So the coils have considerably more spark energy than my stockers did. I'll bet these things hold me over into some HUGE numbers if I wanted them too. Seems like this should be the last ignition system upgrade I need

Overall VERY pleased with their performance so far. I'll bet they are easily as strong as many of the pricey aftermarket systems out there.

moso240
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sweet man that car looked clean i was about to pick it up for myself but didn have the cash at that moment

gawdzilla
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WhatsADSM wrote:
So as promised, I had a chance tonight to pull all the plugs and open up the gap to .040 (up from about .027). Before I would experience blow out at right around 20 psi with the .027" gap.... which I guess is fairly normal considering the power that was being run on the stock coils.

Well now even with the huge .040 gap, and even my rather conservative dwell settings I had no issues what-so-ever at 20-21 psi (didn't feel like running any more on my 93 octane). Ran smooth as can be. So the coils have considerably more spark energy than my stockers did. I'll bet these things hold me over into some HUGE numbers if I wanted them too. Seems like this should be the last ignition system upgrade I need

Overall VERY pleased with their performance so far. I'll bet they are easily as strong as many of the pricey aftermarket systems out there.
very impressive on the widened gap. definitely more spark energy there. i'd keep it as wide as possible to get the best burn. on the contrary, i still need to run pretty low gap for the splitfires (.023ish @ 18psi). I can probably run wider but haven't tried. i've found they're basically like oem except new stuff replacing old. btw we have the same turbo. mine's the precision gt4067r, i think .68 hotside or .7 i forget.

240z4u
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WhatsADSM wrote:
So as promised, I had a chance tonight to pull all the plugs and open up the gap to .040 (up from about .027). Before I would experience blow out at right around 20 psi with the .027" gap.... which I guess is fairly normal considering the power that was being run on the stock coils.

Well now even with the huge .040 gap, and even my rather conservative dwell settings I had no issues what-so-ever at 20-21 psi (didn't feel like running any more on my 93 octane). Ran smooth as can be. So the coils have considerably more spark energy than my stockers did. I'll bet these things hold me over into some HUGE numbers if I wanted them too. Seems like this should be the last ignition system upgrade I need

Overall VERY pleased with their performance so far. I'll bet they are easily as strong as many of the pricey aftermarket systems out there.
Sounds great man, congratulations again. Smart move buying someone elses project (as long as its done right). No sense in losing your *** on it, when you can buy it and a piece of someone elses!

Evan

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WhatsADSM
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gawdzilla wrote:very impressive on the widened gap. definitely more spark energy there. i'd keep it as wide as possible to get the best burn. on the contrary, i still need to run pretty low gap for the splitfires (.023ish @ 18psi). I can probably run wider but haven't tried. i've found they're basically like oem except new stuff replacing old. btw we have the same turbo. mine's the precision gt4067r, i think .68 hotside or .7 i forget.
Very cool. Yup I also have the .68 a/r (on a greddy manifold).... Out of curiosity when do you get full spool and have you ever had it dyno'd?
240z4u wrote:
Sounds great man, congratulations again. Smart move buying someone elses project (as long as its done right). No sense in losing your *** on it, when you can buy it and a piece of someone elses!

Evan
Thanks! Yea I've actually been really happy with it. After I fixed up a bunch of the loose ends it runs like a top!

If you ever decide to go down the LSX coil swap route and want some help just let me know and I'd be more than willing to help ya out...You are welcome to do it at my place if you want (I got a decent garage). Madison to Milwaukee is only about an hour and a half

240z4u
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WhatsADSM wrote:
Very cool. Yup I also have the .68 a/r (on a greddy manifold).... Out of curiosity when do you get full spool and have you ever had it dyno'd?

Thanks! Yea I've actually been really happy with it. After I fixed up a bunch of the loose ends it runs like a top!

If you ever decide to go down the LSX coil swap route and want some help just let me know and I'd be more than willing to help ya out...You are welcome to do it at my place if you want (I got a decent garage). Madison to Milwaukee is only about an hour and a half
Ill likely take you up on that at some point, I keep blowing out spark over 19psi. I also have a spare coil harness to cut up so it could be plug and play.

Thanks for the offer! Sounds like a good excuse to go to Milwaukee.

Evan

gawdzilla
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WhatsADSM wrote:
Very cool. Yup I also have the .68 a/r (on a greddy manifold).... Out of curiosity when do you get full spool and have you ever had it dyno'd?
sent you an email

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Tenchuu
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any wiring diagram on how to hook this up to stock wiring? also anyone know for suer if this will work fins with a S1 ECU? my coils are crapped out and i need to replace them. wasted spark has better documentation, but i would rather do this and eliminate the possibility of a bad igniter at the same time.

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turboredneck
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Has anyone found out if this swap would work with the factory ecu.I am running a Buick GN wasted spark on my RB20 and i am very interested in this swap.

Darius
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The ECU tells the coils when to fire so the ECU doesn't really matter in this case. The coils themselves determine whether an external ignitor is required or not. If the coils have a built-in ignitor like the LS coils, then you can ditch the external ignitor and wire the leads directly from the ECU to the coils. If the coils do not have a built in ignitor, then the ignitor needs to be retained and the coils wired from that.

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turboredneck
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Thanks for the help.

Darius
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For those of us with the S1 RB25, I thought I'd take a picture of the 6-pin weathertight plug that I installed in the harness in place of the ignitor. Several of the signal wire pins need to be rewired as shown in the photo below.

The stock ignitor is wired in order of firing order and not cylinder number. So, pins A-F are wired to cylinders 1-6, respectively.1) L/O2) L/B3) L/R4) L/Y5) GY/B6) P/W


Modified by Darius at 8:56 AM 7/9/2009

240cp
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I started wiring this in yesterday. I got it all mounted and everything so i started the wiring. Well my problem is the factory connector going into the ignitor has seven wires not six. I have the same color wires as above but with a extra black wire/yellow stripe. I thought this might have been a ground for the ignitor itself???? I have all the coils wired up accordingly just trying to figure out the signal wires from the ecu. Can anyone clarify this for me? It would be greatly appreciated.

Darius
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Yes, the B/Y wire is a ground for the ignitor. Cut it off. No longer necessary.

Wire the signal wires according to my previous post. The ignitor is not wired 1-6 as one would assume.


streeteg
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Probably some of the best info on the boards right now---Thanks for the write up

Darius
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Definitely! Especially since it seems like there are more and more people having coil issues most likely caused by age and heat cycling. Good cheap upgrade that can be done for easily under $300.

streeteg
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May consider doing it before my tune--- I love fresh spark

exodus5547097
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Just wondering if there is a swap done on s1 rb25? One last question: If done on Rb's, could I do it stock without PFC and AEM EMS?


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