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Subject VR38 coils in the factory location. A recipe in progress.
Posted by Zeus on March 30, 2021 at 2:00 PM
  This message has been viewed 916 times.
Message tl;dr: I think I've figured out how to mount VR38 coilpacks in the factory VG coil location.

I've been thinking about how to get the VR38 GTR coils to fits like OEM ever since MadHatter10-6 had posted about it. So I blame him for planting that seed.

Coincidentally, I had also been sitting on a Polar Engineering GTR coil kit for a while, but I couldn't bring myself to install it for one reason and one reason alone: Needing to pull the plenum every time to remove the coils. It's a well-designed kit and still the most cost-effective way to run these coils on a VG30. That nuance in the setup though just wasn't for me.

Since I was sitting on a set of the GT-R coils, I had an opportunity to take measurements and took it upon myself to see what I could come up with.

The first challenge was that the GTR coils are much shorter than the VG coils. VG coils are 204mm long vs GT-R coils being 153mm. I considered running ignition leads, but that wasn't elegant enough as a solution.

My first attempt at solving the length issue was teaching myself Fusion360 in the hopes of 3d-printing longer stalks. While it was great to learn a new skill, the end result was a brittle piece of plastic. Won't do at all.

Plan B: I had heard about Platinum Racing Products (PRP) in Australia having GTR coil kits for almost every application (except the VG of course). So I got in contact with them about their kit for the Ford Barra specifically since it seemed to have a longer, angled stalk. During those discussions I think they realized there's likely a market for selling just the stalks, so they've since added their universal molded silicone stalks to their site: Click here

I bought one of each (straight & angled) and kept testing fitment.

While both clear the factory VG coil tubes, the straight one was clearly the winner. It's 180mm long and when paired with the GTR coil, it matches the VG coil length perfectly. Score! One problem solved.

The next challenge was how the coils would be mounted in the OEM spot. I'll spare you the minutiae of the different ways I was debating doing this, but the images below are where I landed. As it turns out, the OEM GTR coil mounting bracket can be removed (read: cut off); making its overall footprint small enough to easily fit between our intake runners. I bought a cheaper Maxima coil (exact same size as the VR38 coils) to be my sacrificial coil to cut in case this didn't work out. Luckily, it did!

The final challenge was figuring out how to secure the coils in place. As you can see in the pics above, I realized that I could repurpose the OEM VG coil brackets, but would need a means to marry the coil to the bracket. I met with a machinist this morning and gave him my specs for a solution. Hopefully the prototype adapter bracket will be ready next week and I can confirm fitment.

Now, let's be clear, did I need to do this? Nope, my car doesn't produce enough power justify coils that support 1k+ hp. I did it to simplify the ignition system to remove a known failure point (ie: PTU delete), upgrade the coils to something modern / proven, is still a Nissan part and fits in the OEM location (equal serviceability).

More to come once I get the adapter back from the machinist and can continue testing fitment.

Thanks for reading!


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