Car Wiring.........

We have had many discussions about wiring cars, floating grounds, etc, so here are some pics of a recent job. First pic is "floating ground". All grounds in car come to this buss bar. Nothing grounded on chassis

Nice Monte thats how I did my grounds this time.

Monte I like that set up. Where can a guy pick up that buss bar?

More pics. Coil packs and outside grounds. There are multiple grounds out front for fuel pump, fans, water, lights. They all ground on this stud and then heavier wire runs from here to inside buss bar to cut down on wiring. Crank sensor wire is run inside main rail to isolate and eliminate RFI. Last pic is crank trigger dist modified to be a cam pickup

It's for a boat, but I have made my own from copper strap. Simply make a strap, drill some holes in it with several bolts for ground studs and mount it to the chassis on rubber isolators. I was out of copper and found this piece........but it worked nice

The Reaper?

This forum is very aggravating to me anymore. None of the pictures are loading on this thread at work. They load on some other threads. I don't get it. Most of the time the parts for sale pictures don't load.

I checked my phone so I got to see the beautiful work, just a smaller version of what I should be looking at.

Monte, you do nice work. You should get paid for it

Monte.. I see you drilled a hole in the chassis
tube.. I didnt think that was allowed... plus you
forgot the grommet.. the whole job looks good

Nearly all pro built cars have wiring, fuel, brake lines, whatever run inside the frame rails. The grommet is in it now.


Don't worry Ray........I DO.........LOL!!!

I didnt know that holes were allowed... wish I would
have known that long ago

Very nice Monte

Very nice Monte




Ray

Nice job, Yes the buss bars can be picked up at most marine supply stores. They have many sizes, at least the place I got mine at did. Boats have so neat switch panels also . I used them as shown for the grounds and for misc. hot wire interior gauge lights.

I love to see how others (Professionals) do this kind of work. I had issues in the past with the electrics on my old racer. I am trying to absorb as much as I can and apply it to the new ride (My Junk), but it won't be as nice as this.

Wiring is NOT hard, if you understand how things work. Just time consuming and hard to make look nice. Mine never looks as nice as I WANT it to.

On EFI cars I always use the unterminated universal harness and build my own, because to me, the plug and play harness looks like an octopus and I don't use near whats in a stock harness anyway. You can look at my ECU plugs and see I use the bare minimum and pull out anything unused

Bus bars.
https://www.bluesea.com/products/category/18/BusBars

Fuse blocks.
https://www.bluesea.com/products/category/16/Fuse%20Blocks

The biggest problem with most people wiring a car themselves is, they think zip ties are expensive...

Nice work Monte.

Jeff

The good ones aren't exactly cheap! haha

I am finishing up a small wiring project, and the wiring doesn't look horrible, but definitely doesn't look as good as I would have liked.

Nice work Monte!

Outstanding work Monte!

not trying to hi-jack, but is there a proper orientation to a relay? As in right side up? I thought I read somewhere that the g forces of a drag car could cause the contacts to open under acceleration.

http://www.jegs.com/i/JEGS-Performance-Products/555/10522/10002/-1

Part # 555-10522.

Just used one in a wiring project in my duster and loved it!

Monte,would having an 8ga wire off the negative battery post to the body cause noise with everything BUT the lights grounded through a buss bar?

Cut em off.......put em on........LOL!!!!

I go through enough zip ties wiring a car to do 3 harnesses. I bundle as I go to keep things tight. Then you ad wires, rearrange, whatever, you cut them off and redo. I never just add more ties. I buy the small ones by bags of a 1000

Cool! I use the exact same bus bar and ARC switch panel!
I read your posts about grounding both heads and everything else to the bus bar and wired it up that way.

Thanks for the info!

How was the install on the ARC panel? Really thinking about one of those

Great post Monte and very nice work. Found a 10% off coupon from Summit last night so I am filling my cart and found this one. http://www.summitracing.com/parts/rfw-gw15/overview/

I could see how the contacts may bounce in the non-energized position, but the magnetic force of the energized position should maintain that position? From the spec sheet I found (posted below) you would need 30g force non-energized?
Mounting position may have more to do with keeping moisture out of the assembly?

If you are worried, there are solid state replacements for the relay.

http://www.delcity.net/store/Hella-Solid...CFQ-oaQodtt0NZA


I found this data sheet:

http://www.mouser.com/ds/2/418/NG_DS_V23134-X0000-A002_0315-572885.pdf

Shock resistance (functional)
IEC 60068-2-27 (half sine) 6ms, min. 30g.8)

Note: 8) No change in the switching state >1μs. Valid for NC contacts, NO contact values significantly higher.

The Thomas and Betts that I use are about $.35~$.80 each

If you have the wire you could save some money by purchasing from a marine supply. I paid $14 buck for the same one.

I have thousands lol

Several ideas here that need to be thought about.

Read sfi spec you can have holes in tubes. The size of the hole depends on the diameter of tube. Mike, Monte's within rules.

There are many approaches to grounding. Floating grounds have their place and most of the time the term is misused. Many in the real electronic industry have different ideas. We used floating grounds in radio and tv. You have to isolate with test equipment. In the home ground requirements change every year.

If your negative battery bus is not tied to chassis it is not ground. Ground is related to earth ground and is made theough carbon in rubber tires. I could see where there may be benefits to using an isolated negative. This way no current is traveling through chassis. The main rail the crank trigger wire is in is a non current carrying ground, well actually if chrome moly a resister. Pretty slick, if you understand why you did it.

I have a huge disagreement with the railroad industry, where I work. They ground everything. Then spend millions on lightning protection. Because lightning looks for ground. But, when you got two huge conducters running for miles at ground potential, and you use it for signaling, you really have little choice.

Some day I plan a total rewire. I just don't like anyones stuff sold to wire cars. The people who do this have a limited electronic knowledge. I don't have the time or energy to do this the way I think it should be done. Some are nicer than others. None would hold up in the rail industry due to vibration. Oh wait race cars vibrate all the time.

Nice clean work Monte. I look at anybodies wiring and take issue, including my own. When you do this 24/7 and the public depends on it. You'd better be right. Always looking for a better way.

Nice Work..... Quality wiring work and circuitry seems to be so overlooked and under appreciated on a race car.......

You do beautiful work Monte…... I always learn something from your posts.

Looks awesome Monte

I think how you have done the earthing is also referred as a "star" earthing system, they do this in music studios for the whole RF thing

A couple of months ago I found this following a link from a link....

https://www.rbracing-rsr.com/wiring_ecu.html

Holey crap!!! $25k wiring job for your salt racer, wow. They seem to know their stuff though and if anyone can make it all the way through the (very long) page, the average joe on here would learn a thing or five from it

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 !

Your best friend when it comes to zip ties.

Great looking work,the only concerns we would consider is that too many grounds at the same location as with too many positives at the same location can trigger interferences if one or more accessories have an issue.This can cause a electrical nightmare to find a problem.We eliminate this issue by having separate systems for ignition,fuel and cooling as well as any computer circuts.Sometimes moving grounds or positives for these main power accessories a matter of 6" to 12" apart can cause any interference or backfeeds to diminish and not create other issues.

White zip ties are for tying up the bag of shop garbage.

If you can find them (Fastenal, etc.) we prefer metal barbed, black UV resistant zip ties. Also, a "flush cut" dykes/diagonal cutter (Knipex is my favorite) is a must for getting the tails of the zip ties cut flush with the cinch end to avoid sharp ends.

Weatherpak connectors, buss bars, and weatherproof labeling will make your life much easier.

I have that zip tie tool also.. I wish
I would use it more often.. those SHARP
cuts sure will cut you up.. my hands right
now have about 15 small cuts from those zip
tie ends(from doing the MSD box)... 99% of
the ties I use are the black UV ones.. I have
bags of zip ties of assorted sizes

It never gets grounded to chassis.

Thank you for the link! Lots to learn on that site.

Check these out Mike:

http://www.knipex.com/index.php?id=1216&...&artID=2422

If you search a bit they you can find them much cheaper than list price.

I just need to keep that zip tie tool with the
zip ties.. that way I would use the tool... I tend
to have that tool in my pliers drawer and I just
over look it.. when I was doing road trip cars at
work I had the tool with all my zip ties and used
it all the time.. we would have 100s of zip ties on
each one of those cars... I use to buy the zip ties
for the lab and I would usually buy 5K at a time of
assorted sizes

Where does the bus bar get grounded at...the engine??

Two things.

Rulebook does state holes are legal, but "Visible reinforcement around any hole in any SFI Spec chassis (not just the roll cage) mandatory." Granted, Monte didn't build the chassis and it wasn't up to him to take care of that. And powdercoating is a pain to grind up and touch up after a weld repair, especially the vein stuff.

I believe earth in an automotive system is the negative post on the battery. I've always heard that if powerlines fall on your car, the rubber tires prevent you from being electrocuted as long as you don't step out and touch the ground. Using an isolated ground system like that makes the chassis basically inert as far as the electrical system is concerned. Not having stray current running through the chassis on something with a lot of noise sensitive electronics makes sense to me. Imagine a chassis constructed from a non-conductive material, it would need to have the same design ground system.

I also enjoy doing my electrical systems from scratch rather than any kits and have specific ways of doing things. I have no problem incorporating others' good ideas and techniques. None of mine have been on anything as complex as an EFI, traction-controlled, boosted car though. Still, there's a right way of doing things even on something stupid simple.

Buy the cheapo white ones for initially assembling the harness. Better quality black ones for final assembly. Adds up when your using hundreds of them.

When we were doing the trip cars we would leave
the tie raps just started(dont tighten them).. that
way we could slide more wires in if needed.. the bulk
of the wire we ran were thermocouple wires.. when it
was wired we would organize the bundle them tighten
it up using the zip tie tool and it cuts the tag off..
and believe me the engineers always wants more stuff
added

Don't cut them off till all done ..stick a small screw driver or razor behind the lock bingo pull it back apart ..poor man's way lol

Snap on makes electronic dykes for plastic that cut zip ties easier than anything I've previously used, including guns. They're cut completely smooth with no sharp edges at all. The dykes have a very slight convex cutting edge that gets the exposed tail below the outer edge of the clamp.

All those are UV resistant. The bigger white ones are good for 120 lbs. The smaller ones a good for 18 lbs. I have a EVO 7 those things are the cats azz, you can set the lbs you want and it cuts the ties at that setting and no sharp edges to cut yourself.

Very nice, clean work, but I think something needs to be said about the definition of "floating grounds", just for some clarification. The implication is that ALL grounds go back to the buss bar ( or one point ) with one wire and don't use the cars frame ( or anything other than a wire ) in any way to do it. In your pic, I only see 5 wires ( excluding the 2 large wires on ether end of the bar ). This leads me to believe you are only running 5 separate circuits in the car, each with a separate ground wire? There are some electronic components that require grounding that don't use ground wires, but ground through another component ( engine / chassis ). These components may have a ground wire that goes directly to the floating ground, but the items they are grounding do not. Another example would be your fuel cell. NHRA requires a ground wire on your fuel cell. Would you run a ground wire from your fuel cell all the way to your floating ground buss bar - especially when it ( and items like oil, water senders generate virtually zero RFI?
A floating ground system is a very good idea when dealing with electronic components that generate high levels of RFI or that are very sensitive to the same, but I would be surprised if the frame in most race cars doesn't end up with a path to ground somewhere. Again, very nice work.

I'm confused, are you trying to say there are two types of grounds?

I ran my fuel cell ground strap right to the battery. Since they are both in the trunk. Is this wrong? I just figured ground was ground.

That`s fine and how I did mine but my battery`s are grounded to the back bumper bolts...........

Yes, there are different types of grounds.
Here is a good post I found at:

http://electronics.stackexchange.com/questions/157022/different-types-of-grounding

"They are all connections to the same place, a point of (theoretical) zero voltage but with different purposes:

Signal Ground

This is a reference point from which that signal is measured, due to the inevitable voltage drops when current flows within a circuit, some 'ground' points will be slightly different to others. There may be several signal grounds in a circuit. Imagine if you had an amplifier with a voltage gain of 100 and you were amplifying a tiny signal, if the ground for the signal was elevated by just 0.01V the output would be wrong by 1V. Typically a signal ground would be a connection to the same stage of the circuit as the signal was connected.

Chassis ground

This is the box or frame in which a circuit is built. Typically, it is ground to make a barrier between the user and the circuits inside to prevent electric shock or to shield against interference pick up or radiation. In some high current applications, it is used as a conductor to carry current, for example in a vehicle where running many thick wires to the battery would be impractical but making connection to the chassis is easy almost anywhere. Chassis ground should be connected to the other grounds, usually it is done at a point close to where the power source arrives.

Earth ground

This is a theoretical zero. It is the potential of perfectly conducting Earth beneath your feet but obviously it varies widely depending on where you are. The connection to Earth is normally along your power providers cables or by a rod driven into the ground or sometimes both. It is supposed to be a return path for current in the event of a short circuit on your AC power lines but it is also used in radio applications as a 'zero' reference to read antenna signals against."


For most of the older non-computer controlled cars, the grounding is not much of an issue, but the computer controlled cars have high impedance inputs that can sense very small changes in voltage, and are more sensitive to noise and ground loop problems.

A ground loop is where "in theory" connections to ground are suppose to be the same, but in reality there is some (although small) resistance between the ground connections. All wire has some resistance, the smaller diameter ans longer the length, the higher the resistance the wire has. So one ground may be at a different voltage than the other. The voltage difference is V=IxR so, increases in current (I) make the voltage (V) difference worse when the resistance (R) remains the same.

For example, measure the voltage from the negative battery terminal to the engine block. This would both be considered "ground", but when cranking the engine (high current draw) you will see a small voltage generated from the resistance of the negative battery cable and connections. If you see a large voltage, the battery cable or connections are bad.

My Buss bar is isolated from the car and the negative battery cable goes directly to it.

Very informative, thanks 451Mopar.

I use larger conductors and put buss bars near the loads. They'll be one for the engine and electronics, one under the dash, and one out back. Been doing it that way since the 90s when I was taught that by a friend who wired 6-7 cars a year on the side.

I don't know what it is about the wiring in a car, but i really struggle getting my head around. I think I just haven't grasped the concept. I can read an electrical drawing no problem, but working out how to run the cabling and how things are earthed and powered, I just get lost! I'll get it one day I'm sure!

I always liked the look of the nylon laced open bundle harness.

Link to a "how to lace cable harness" from 1962:

http://www.dairiki.org/hammond/cable-lacing-howto/

very good article. on and off over the years, i have been looking for something like this. thank you for posting !

How do you ground your starter motor?

Bob Lapp of Spaghetti Menders floating ground system layout.

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.

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.

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

Where do you get your weatherpack connectors from?

del-city...terminal supply, to name a few

Weatherpacks are the hot ticket, I buy them in bulk on ebay. I even use a weatherpack through the firewall.

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

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.

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

I looked at Magnafuels web page and it does look that they are using the dual relays for the amp draw as Monte posted. The dual relays are running smaller wires, where a single 70 amp would have much larger wire on the high current side. The terminals for the 70 Amp relays are larger too.

Redundancy = mostly for airplanes - for obvious reasons.

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.

Thanks for the info Darren. Trying to plan out the electrical for met Road Runner and want it as hassle free as possible.

Jeff

bump