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Re: Car Wiring.........
[Re: 72Swinger]
#2054873
04/15/16 11:43 AM
04/15/16 11:43 AM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
master
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master
Joined: Oct 2003
Posts: 7,506
Az
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so does the ground bus get tied to the chassis at some point, or does one run a ground from the body/chassis at the battery - then another cable to the ground bus ? i like to use a bus whenever possible, but i have experience only on the "+" bus installation. the next complete job i would like to employ both. monty, please clarify. thanks !  It never gets grounded to chassis. Where does the bus bar get grounded at...the engine?? My Buss bar is isolated from the car and the negative battery cable goes directly to it. How do you ground your starter motor?
Fastest 300
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Re: Car Wiring.........
[Re: Crizila]
#2054927
04/15/16 01:45 PM
04/15/16 01:45 PM
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Joined: Jan 2003
Posts: 2,813
Blue Ridge, VA
Plumb Wired
master
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master
Joined: Jan 2003
Posts: 2,813
Blue Ridge, VA
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Bob Lapp of Spaghetti Menders floating ground system layout.
RIP Monte Smith
aka: OutlawFish
'98 Bickel Dodge Dakota PST
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Re: Car Wiring.........
[Re: jlatessa]
#2055000
04/15/16 03:44 PM
04/15/16 03:44 PM
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Joined: Dec 2005
Posts: 11,833
Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,833
Fulton County, PA
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I've seen instances like this where both heads have connecting grounds, why would this be needed?
Thanks, Joe Spark plugs have to be grounded to fire. Ground on both heads prevents any issues with the path that voltage follows passing through the assembly to a single ground point. Either with the spark plug function, damage to engine components or RF interfering with electronics. Is it redundant? Maybe, but the conversation is about assembling a trouble-free electrical system.
If the results don't match the theory, change the theory.
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Re: Car Wiring.........
[Re: Monte_Smith]
#2057510
04/19/16 12:05 PM
04/19/16 12:05 PM
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Joined: Jan 2015
Posts: 105
South Florida
indcontrols
member
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member
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Posts: 105
South Florida
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VERY Nice looking work ! I have done many race cars with the grounding setup such as yours, works fine.
The only issue to look out for is a potential difference between the electrical devices that are mounted to the chassis (motor loads) and the chassis components themselves. It is a mechanism for corrosion, can add to the other corrosion mechanisms that are inherent and unavoidable such as dissimilar metals in contact with each other, fuel by products, lubricants, etc.
As I said, works fine for a race car, not good for a street car loaded with a zillion other luxury devices and such invasive things as trim screw penetrations, coated fabrics, adhesives, etc.
I now use a hybrid version, I complete the "ground" system such as yours, but always tie to the chassis just for the corrosion possibility especially if there is a fortune in paint work... Maybe unnecessary, but better safe than sorry. I also use versicable (braided wire) anyplace there is high temp or even the remote possibility of chafing - the fiberglass jacket is almost impervious, but it does weigh a touch more...
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Re: Car Wiring.........
[Re: indcontrols]
#2057533
04/19/16 12:37 PM
04/19/16 12:37 PM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
master
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master
Joined: Oct 2003
Posts: 7,506
Az
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VERY Nice looking work ! I have done many race cars with the grounding setup such as yours, works fine.
The only issue to look out for is a potential difference between the electrical devices that are mounted to the chassis (motor loads) and the chassis components themselves. It is a mechanism for corrosion, can add to the other corrosion mechanisms that are inherent and unavoidable such as dissimilar metals in contact with each other, fuel by products, lubricants, etc.
As I said, works fine for a race car, not good for a street car loaded with a zillion other luxury devices and such invasive things as trim screw penetrations, coated fabrics, adhesives, etc.
I now use a hybrid version, I complete the "ground" system such as yours, but always tie to the chassis just for the corrosion possibility especially if there is a fortune in paint work... Maybe unnecessary, but better safe than sorry. I also use versicable (braided wire) anyplace there is high temp or even the remote possibility of chafing - the fiberglass jacket is almost impervious, but it does weigh a touch more...  Point being, it is often impossible not to include the chassis in the ground system somewhere along the line ( point I was trying to make). The key is "most direct path with least amount of connections" - benefit of a floating ground, especially when you have sensitive electronics that require precise current / voltage. I just finished my street rod project and also went with a "hybrid" ( for lack of a better term ) grounding system. Many of the components in my system resided in a fiberglass body, so from a practical side, it behooved me to use the frame as a grounding component in some instances. I also had no critically sensitive electronics on board. Pic shows two main + and - terminals located on the fire wall. One area that is often over looked in the grounding system is the radiator. If yours isn't grounded, it needs to be. 
Fastest 300
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Re: Car Wiring.........
[Re: Monte_Smith]
#2057538
04/19/16 12:46 PM
04/19/16 12:46 PM
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Joined: Nov 2004
Posts: 6,890
North Alabama
Monte_Smith
OP
master
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OP
master
Joined: Nov 2004
Posts: 6,890
North Alabama
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The chassis IS grounded. There is a large ground cable run to the motor plate from bus bar and each cylinder head is tied together. Of course the motor is solid mounted, so this automatically makes it grounded to the chassis.............BUT, you are NOT using the chassis as a main ground path. The chassis is actually a very poor conductor, but most use it as their main ground path. Have to remember, motors and such are mounted TO the chassis usually through painted tabs and bolts. That's a POOR conductor. Some have studs welded to chassis, that's fine, but other parts are still bolted to chassis, NOT part of it
On the car pictured, the ONLY things I have grounded directly to chassis itself is the rear lights, the shift light and the Race Pak. All "noisy" items are on the bus bar and separated. The ECU power and grounds go directly to battery. I have wired all EFI cars like this since I started and do not have RFI issues. If it's good for EFI, it's good for anything
Last edited by Monte_Smith; 04/19/16 12:50 PM.
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Re: Car Wiring.........
[Re: Monte_Smith]
#2070027
05/09/16 12:41 PM
05/09/16 12:41 PM
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Joined: Jan 2003
Posts: 10,050
MN
JERICOGTX
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,050
MN
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Monte, do you wire any of the components for redundancy? Looking at Magnafuels website, and they have a diagram for wiring the pump with dual relays. Waste of time, or good idea? What about fuses?
Jeff
69 GTX
68 Road Runner
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Re: Car Wiring.........
[Re: Monte_Smith]
#2070139
05/09/16 03:38 PM
05/09/16 03:38 PM
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Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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On redundant wiring, it would depend on your application and how critical a failure may be. Normally if the correctly rated relay is used, it will be pretty dependable. The question is how redundant are you talking about?
You could have two relays in parallel connected together at the same point which would share the current load when both are working correctly, but if you loose the connection from the switch, or if they are using the same ground, fuse or circuit breaker, then the redundancy is limited.
Also, when designing a redundant system you would want some way to test or verify both paths are working correctly.
I would guess most redundant wiring would be used on endurance racing vehicles where the extra cost and weight is not a big issue.
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Re: Car Wiring.........
[Re: Monte_Smith]
#2070288
05/09/16 08:26 PM
05/09/16 08:26 PM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
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master
Joined: Oct 2003
Posts: 7,506
Az
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Magna-Fuel does show their pumps wired with two 30amp relays. Its not about redundancy, but amp draw. One 70 amp relay accomplishes same thing Redundancy = mostly for airplanes - for obvious reasons.
Fastest 300
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Re: Car Wiring.........
[Re: Monte_Smith]
#2070366
05/09/16 10:05 PM
05/09/16 10:05 PM
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Joined: Jan 2003
Posts: 10,050
MN
JERICOGTX
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,050
MN
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MagnaFuel says the ProStar 500 pump draws only 13a at 28psi. Why the need for a 70A relay?
69 GTX
68 Road Runner
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Re: Car Wiring.........
[Re: JERICOGTX]
#2070600
05/10/16 08:34 AM
05/10/16 08:34 AM
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Joined: Oct 2004
Posts: 3,097
back in Georgia
dthemi
master
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master
Joined: Oct 2004
Posts: 3,097
back in Georgia
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MagnaFuel says the ProStar 500 pump draws only 13a at 28psi. Why the need for a 70A relay? That would be stable load after start. Initial current draw at start of pump could easily be over 50amps.
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Re: Car Wiring.........
[Re: Monte_Smith]
#2070886
05/10/16 05:28 PM
05/10/16 05:28 PM
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Joined: Jan 2003
Posts: 10,050
MN
JERICOGTX
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,050
MN
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Thanks for the info Darren. Trying to plan out the electrical for met Road Runner and want it as hassle free as possible.
Jeff
69 GTX
68 Road Runner
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