Article 3: Back to back testing of 370Z coils (Re: Coils ain't coils)
Author: 5-0 IGNITE
Back to back testing of 370Z coils
Re: Coils ain’t coils
Figure 1 - 370Z Coils On!
We all know the most ‘go to’ coil upgrade for performance engines are the Nissan R35 GTR and the Audi R8 coils. They work, they are proven and they are affordable. Currently popular on the internet right now are the rise of 370Z coils as a substitute to the R35 GTR coils. Coils themselves are slightly cheaper than the R35 unit and we got requests to test them out. An Australian manufacturer of coil conversion kits have bench tested R35 and 370Z coils and results came out identical. The coils themselves (Hanshin) looks identical on the top end with slight variation of stalk lengths and mounting points. Specifically, what was tested were;
- Hanshin (early) 22448-JF00B (Nissan R35 GTR)
- Hitachi IGC0079 (Nissan R35 GTR Coil OEM Supplier)
- Hanshin 22448-JA10C (formerly 22448-JA10A and are actually 350Z VQ35HR coils)
All presented as genuine coils and all with identical 54mJ output. As a baseline (working with what we had), the bench testing from the reputable high-quality Australian manufacturer of coil conversion kits showed that the Audi R8 outputs 45mJ.
We have had a report from a famous Australian youtuber/car modification channel that their genuine Hanshin 22448-JA10C struggled when pushed beyond 75kW at the wheels, per cylinder, as they’ve experienced spark break down issue. So far that they thought it was a counterfeit unit (but is verified genuine). As the purpose of this test is to trial 370Z coils, we ordered genuine (and actual) 370Z coils for some dyno time;
- Hanshin part number 22448-EY00A (370Z VQ37VHR coils)
Why? Because the coil head is identical across the board with only differences in the mounting tab and the stalk length. It is a good dynamic test and one can assume that they shall perform identically right?
Working alongside with Tristan @ WTFAuto, we did a baseline run with the Audi R8 coils and yield 639.3whp (79kW at the wheels per cylinder) / 550 ft lbs torque. Within 15-20 minutes in between, we swapped out to the 370Z coils with a new harness and adjusted the coil dwell time to 4ms @ 14V. Note that no other parameters were changed;
- Same tuner
- Same dyno
- Same tune (ignition and fuel map and other correction factors untouched)
- Same night (15-20mins in between the pulls)
- Dyno straps untouched
- Same boost
- Same spark plug gap (~0.9mm off the box BKR7E)
- Same and consistent fuel
- Same ECU
- Negligible difference in ambient temperature and humidity
- Dwell time updated from 3ms (Audi R8) to 4ms (Nissan) at 14V (other points also as per recommended dwell time)
Off the run with the 370Z coils, the results showed;
- 601.8whp (74kW at the wheels per cylinder, down from 79kW at the wheels per cylinder)
- Significant RF noise that we couldn’t get a torque at flywheel figure as there lots of interference at the RPM pick up point (clamped onto injector number 3). Yes, RF suppressor resistor were in there.
- AFR, lambda, dipped to 0.74 at 6000rpm on the 370Z coils VS 0.78 at the same rpm with the Audi R8 coils.
- There was no misfire and there was no spark blow out, a point to note.
Figure 2 - Road Speed VS Power VS Lambda on Both Coil Runs
Figure 3 - RPM VS Power VS Lambda on Both Coil Runs
To re-verify, we installed the Audi R8 coils back in, did the same run and yield 636.4whp (78kW at the wheels per cylinder, up from 74kW at the wheels per cylinder) with no RPM interference showing the repeatability.
Figure 4 - Verification Run
We are always under the assumption that the coils are doing its job if the spark does not blow out but yet, the results demystifies that assumption. We have lost approximately 35whp but the car didn’t misfire. AFR got approximately 0.4 point lower (in E85 scale) and one would argue that it is a sign of incomplete burn. Ignition timing wasn’t affected as the ramping onto the run showed almost identical curve, or otherwise, would have shifted.
In conclusion, we see this as an issue. If the actual genuine 370Z coil did not give a satisfactory result and performed significantly less than the Audi R8 coils along with the reported spark break down issue, by another party, with the 350Z coils at 75kw at the wheels per cylinder; it would be pretty hard to say that these are identical units to the top performing R35 GTR coils. We jokingly discussed that pretty much any coils can be run hard if we gap the spark plugs down to miniscule gap but that would decrease its efficiency and the overall power wouldn’t it?
Our best choice would be sticking to the Hitachi R35 GTR coils or the Denso Audi R8 coils which will deliver the results every time.
Finally, we would like to state that we have no affiliation with Hitachi or Nissan or Denso. We are just a customer, like you are to us. Special thanks to Tristan at WTFAuto in his support to run the test and his valuable opinion of the results and the 5-0 Ignite team, together keeping developments of the fast RBs in the land of down under.