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Ground Web:

There are many theories on the effectiveness of an "Earth Grounding Kit." Some believe there is too much Electromagnetic Interference for the ECM to operate at peak efficiency. Nismo and HKS, both respected aftermarket performance suppliers, sell grounding kits for the 350Z. I've seen OBD-II readouts and other bits of information on the web as well that speaks to the advantages of a grounding kit. Having a BS degree, a MS degree, completed course work in DC and AC circuits and working for a company that designs and manufactures power supplies for high-end servers and central offices I've been exposed to a lot of electrical engineering work. On paper additional grounding looked like a good idea with no real downside.
So I built my own set and installed it on my new 350Z and decided to test it on a Dyno. It's important to remember that dynos are a tricky proposition. Changes in tire pressure, engine temperature, atmospheric conditions, etc. can make for different results. The best way to compare a performance modification is to make a pull before to get a 'baseline' then make a pull under as close to identical conditions as possible. Generally this means making the pulls back to back with the change in between. Even this won't offer exact results, as engines will heat soak (reduction in power) and other advantages mentioned earlier will cause performance increasers. Hopefully the two can balance out.
There were 8 other 350s dynoing the same day I did. All of them made more horsepower with each pull as the tires heated up and the oil thinned out. This was as expected. Before my first pull I disconnected the grounding kit from the battery, the chassis and the engine. After the first pull I reinstalled the grounding kit and did another pull. As the charts show, I had an increase of 3% or 6 horsepower.
Before:

After:

Before you get excited and rush off to build your own kit or buy one, we must dig a little deeper. All of the 350Zs tested that day had an increase in horsepower between pull 1 and pull 2. But none of the others had an increase of 3%. They averaged 1% to 2%. So in theory the grounding kit added 1% more horsepower. That would equate to almost 3 horsepower. Some other ground web users on other makes and models of cars have reported easier starting, smoother idling, crisper throttle response, etc. So not all of the benefits are 'dyno graphable', not bad for a $30 modification. Besides the big wires and gold terminals look great under the hood!
Supplies:
11' of 4-gauge oxygen free copper wire. thezeb.com has it for $1.09 per foot.
10 gold plated crimp style ring terminals (4 gauge 5/16 inch). Most high-end car audio stores carry these. In the southwest, Monster brand are available for $3.95 a pair and that includes the shrink tubing at Tweeters.
4 M6 x 20mm bolts, 4 M6 washers, a M6 lock nut, and 4 lock washers.
Cable Ties
Tools Required:
Something to crimp the large ring terminals
Heat gun
Wire Cutters
Razor blade utility knife
10mm socket and 10mm wrench
Procedure:
1. Read all instructions before starting.
2. Cut wire into five lengths:
Cable #1 - 32" (Right Rear of Intake to Front of Engine)
Cable #2 - 28" (Left Rear of Intake to Front of Engine)
Cable #3 - 17" (Left Front Intake to Front of Engine)
Cable #4 - 26" (Negative Battery Terminal to Left Front of Intake)
Cable #5 - 20" (Body Ground to Left Front of Intake)
The cable number corresponds to the final locations as indicated in step 19.

3. Slide two pieces of heat shrink onto each wire (1.).

1.

4. Trim off 1/2" of wire insulation from each end using a utility knife (2.). Try not to cut too deep and cut the copper wires. Also a good idea to not cut off any fingers as well. Slide on 2 of the heat shrink tubes.

2.

5. Crimp the terminals on the precut cables. I use a small workbench vice (3.).

3.

6. Use a heat gun or blow drier to shrink the heat shrink over the cable ends and terminals (4.).

4.

7. Remove engine cover (5.). Two nuts and two bolts hold on the cover (4 x 10 mm). The cover comes off a little easier if the oil filler cap is removed first. Remember to replace it when the cover is off so nothing accidentally drops into the engine.

5.

8. Open the battery cover (6.).

6.

9. Remove the two bolts (2 x 10 mm) (7.) that hold the hood sensor and remove the bolt that holds the factory body ground under the hood sensor (1 x 10 mm).

7.

10. Remove the bolt (1 x 10 mm) from the upper left bracket (8.) on the side of the intake that holds a cable tie.

8.

11. Attach one end of Cable 1 (32" cable) to the upper right manifold location. Use one of the new bolts and washers. If you are not using a lock washer on top of the flat washer apply a small amount of Loctite to the threads of the bolt. I recommend Loctite 222 since your threads are going into aluminum. Route cable and use two cable ties to secure (9.).

9.

12. Attach the other end of Cable 1 (32" cable) and one end of Cable 2 (28" cable) and one end of Cable 3 (17" cable) to the front of the engine using one of the new bolts and washers (10.). Do not tighten fully until all cables are routed.

10.

13. Attached the other end of Cable 3 (17" cable) and one end of Cable 5 (20" cable) and one end of Cable 4 (26" cable) to the left front of the intake using a new bolt and washer (11.). Do not tighten fully until all cables are routed.

11.

14. Attach the other end of the Cable 5 (20" cable) to the body ground (12.) under the hood sensor switch using the factory bolt (1 x 10 mm). Re-attach the hood sensor switch.

12.

15. Loosen the negative battery terminal and rotate clock wise a few degrees and re-tighten (13.). Cut a hole just above the positive battery cable where it enters the battery compartment. The rubber is very thick and will require a sharp razor blade to make an incision all the way through. Keep it small and push the other end of Cable 4 (26" cable) through the cut.

13.

16. Attach the other end of Cable 4 (26" cable) to the negative battery post using the new 6mm locking nut (14.). Be careful not to cross thread. The threads might need to be cleaned up by backing off the factory nut first before putting on the cable and the new locking nut.

14.

17. Attach the other end of Cable 2 (28" cable) to the left rear of the intake manifold (15.). Use a new bolt and washer. If you are not using a lock washer on top of the flat washer apply a small amount of Loctite to the threads of the bolt.

15.

18. Adjust cable routing to your satisfaction and tighten the left rear intake, left front intake and front engine bolts (16.).

16.

19. This is a quick end to end connection guide per numbered cable (17.).

17.

20. Remove the oil cap, re-install engine cover, re-install oil cap, close battery cover (18.) and enjoy your handiwork.
Originally published 1-23-2003
z327
back to Tech
18.

There are many theories on the effectiveness of an "Earth Grounding Kit." Some believe there is too much Electromagnetic Interference for the ECM to operate at peak efficiency. Nismo and HKS, both respected aftermarket performance suppliers, sell grounding kits for the 350Z. I've seen OBD-II readouts and other bits of information on the web as well that speaks to the advantages of a grounding kit. Having a BS degree, a MS degree, completed course work in DC and AC circuits and working for a company that designs and manufactures power supplies for high-end servers and central offices I've been exposed to a lot of electrical engineering work. On paper additional grounding looked like a good idea with no real downside. So I built my own set and installed it on my new 350Z and decided to test it on a Dyno. It's important to remember that dynos are a tricky proposition. Changes in tire pressure, engine temperature, atmospheric conditions, etc. can make for different results. The best way to compare a performance modification is to make a pull before to get a 'baseline' then make a pull under as close to identical conditions as possible. Generally this means making the pulls back to back with the change in between. Even this won't offer exact results, as engines will heat soak (reduction in power) and other advantages mentioned earlier will cause performance increasers. Hopefully the two can balance out. There were 8 other 350s dynoing the same day I did. All of them made more horsepower with each pull as the tires heated up and the oil thinned out. This was as expected. Before my first pull I disconnected the grounding kit from the battery, the chassis and the engine. After the first pull I reinstalled the grounding kit and did another pull. As the charts show, I had an increase of 3% or 6 horsepower. Before: After: Before you get excited and rush off to build your own kit or buy one, we must dig a little deeper. All of the 350Zs tested that day had an increase in horsepower between pull 1 and pull 2. But none of the others had an increase of 3%. They averaged 1% to 2%. So in theory the grounding kit added 1% more horsepower. That would equate to almost 3 horsepower. Some other ground web users on other makes and models of cars have reported easier starting, smoother idling, crisper throttle response, etc. So not all of the benefits are 'dyno graphable', not bad for a $30 modification. Besides the big wires and gold terminals look great under the hood! Supplies: 11' of 4-gauge oxygen free copper wire. thezeb.com has it for $1.09 per foot. 10 gold plated crimp style ring terminals (4 gauge 5/16 inch). Most high-end car audio stores carry these. In the southwest, Monster brand are available for $3.95 a pair and that includes the shrink tubing at Tweeters. 4 M6 x 20mm bolts, 4 M6 washers, a M6 lock nut, and 4 lock washers. Cable Ties Tools Required: Something to crimp the large ring terminals Heat gun Wire Cutters Razor blade utility knife 10mm socket and 10mm wrench Procedure: 1. Read all instructions before starting. 2. Cut wire into five lengths: Cable #1 - 32" (Right Rear of Intake to Front of Engine) Cable #2 - 28" (Left Rear of Intake to Front of Engine) Cable #3 - 17" (Left Front Intake to Front of Engine) Cable #4 - 26" (Negative Battery Terminal to Left Front of Intake) Cable #5 - 20" (Body Ground to Left Front of Intake) The cable number corresponds to the final locations as indicated in step 19.
3. Slide two pieces of heat shrink onto each wire (1.).	1.
4. Trim off 1/2" of wire insulation from each end using a utility knife (2.). Try not to cut too deep and cut the copper wires. Also a good idea to not cut off any fingers as well. Slide on 2 of the heat shrink tubes.	2.
5. Crimp the terminals on the precut cables. I use a small workbench vice (3.).	3.
6. Use a heat gun or blow drier to shrink the heat shrink over the cable ends and terminals (4.).	4.
7. Remove engine cover (5.). Two nuts and two bolts hold on the cover (4 x 10 mm). The cover comes off a little easier if the oil filler cap is removed first. Remember to replace it when the cover is off so nothing accidentally drops into the engine.	5.
8. Open the battery cover (6.).	6.
9. Remove the two bolts (2 x 10 mm) (7.) that hold the hood sensor and remove the bolt that holds the factory body ground under the hood sensor (1 x 10 mm).	7.
10. Remove the bolt (1 x 10 mm) from the upper left bracket (8.) on the side of the intake that holds a cable tie.	8.
11. Attach one end of Cable 1 (32" cable) to the upper right manifold location. Use one of the new bolts and washers. If you are not using a lock washer on top of the flat washer apply a small amount of Loctite to the threads of the bolt. I recommend Loctite 222 since your threads are going into aluminum. Route cable and use two cable ties to secure (9.).	9.
12. Attach the other end of Cable 1 (32" cable) and one end of Cable 2 (28" cable) and one end of Cable 3 (17" cable) to the front of the engine using one of the new bolts and washers (10.). Do not tighten fully until all cables are routed.	10.
13. Attached the other end of Cable 3 (17" cable) and one end of Cable 5 (20" cable) and one end of Cable 4 (26" cable) to the left front of the intake using a new bolt and washer (11.). Do not tighten fully until all cables are routed.	11.
14. Attach the other end of the Cable 5 (20" cable) to the body ground (12.) under the hood sensor switch using the factory bolt (1 x 10 mm). Re-attach the hood sensor switch.	12.
15. Loosen the negative battery terminal and rotate clock wise a few degrees and re-tighten (13.). Cut a hole just above the positive battery cable where it enters the battery compartment. The rubber is very thick and will require a sharp razor blade to make an incision all the way through. Keep it small and push the other end of Cable 4 (26" cable) through the cut.	13.
16. Attach the other end of Cable 4 (26" cable) to the negative battery post using the new 6mm locking nut (14.). Be careful not to cross thread. The threads might need to be cleaned up by backing off the factory nut first before putting on the cable and the new locking nut.	14.
17. Attach the other end of Cable 2 (28" cable) to the left rear of the intake manifold (15.). Use a new bolt and washer. If you are not using a lock washer on top of the flat washer apply a small amount of Loctite to the threads of the bolt.	15.
18. Adjust cable routing to your satisfaction and tighten the left rear intake, left front intake and front engine bolts (16.).	16.
19. This is a quick end to end connection guide per numbered cable (17.).	17.
20. Remove the oil cap, re-install engine cover, re-install oil cap, close battery cover (18.) and enjoy your handiwork. Originally published 1-23-2003 z327 back to Tech	18.