Earthing kits - myths or truths? (modem size warning)

[Mos]

[Mos]

This was a thread posted (by me ) on another forum. Given the effort to write I thought it might be worthwhile.

Couple of comments on the article.

There is *NO* way that tiny earth braid is the only thing grounding the engine to the body of that Cuore. Perhaps that's the only earth they could find!

The cross sectional area of that braid is small, maybe 20-30A capacity - no way that will handle the starter.
There must be an additional earth conductor for the starter motor current, hidden from view.

To even imply that the role of engine mounts could be to ground the engine is ludicrous.

Electrolysis?!? Where is the current path that the earthing kits stop? (radiators are rubber mounted for this reason).

Earth points - toyota earth points primarily connect on the thread, and not on the face (which is always painted on the body). If you look at an earthing bolt for a toyota you will notice a good proportion of the thread is "squashed" to enlarge it so it engages the thread in the body with a lot of pressure, giving a good current path - some people interpret such bolts as damaged and discard them.

"Battery negative is best earthing terminal"... When the engine is not running, yes, when the engine is running the alternator ground is more important - the alt supplies the power to everything (including the battery) when the engine is running - so your extra cables maybe should run to BOTH the battery and alternator housing.

"earthing kit may have been responsible for a 1kW gain" 2%... a 1kW difference on a dyno is insignificant..

3-4kw on a circa 300kw engine (on the graph).. 1% also insignificant.. so you'll get an extra 1.5kW The only thing I can think of is better spark - thoughts?



Back to reality..
The IS200 has three ground straps (an RS200 should be no different). One carries the bulk of the starter motor current during cranking, 2nd back of the head, 3rd extension housing of gearbox. However while the engine is running, you have this massive ground connection that is used well below its capacity - the starter isn't running. Starter motors can draw up to 400A at first hit and about 140A (measured on a 4AGE) continuous (in theory a 1kW starter would draw 83Amps).

When the engine is running, the things potentially operating through the starter ground strap (and the other two ground straps, in lesser amounts) are the alternator, the coil pack currents, injector currents, ECU power supply current, all the VSVs, oxygen sensor heaters, auto box solenoids and engine control related currents (except fuel pump) (hope I've remembered them all).

The ingitors/coils and injectors run off a 20A fuse - the maximum current that can flow from this circuit through the ground strap will be 20A.
The EFI fuse is 20A but the bulk of that current capacity is the fuel pump. Even if we overestimate the ECU will draw less than 10A - so 10A running through the ground strap.
The alternator has a certain current capacity (80-120A - don't know the actual rating) which will limit the current running through the earths. This current rating is seldom reached and it certainly wont be needed during maximal engine exertions (things like wipers, windows, seats, etc).

In terms of absolute totals, you have 150A potentially running through the earth straps of the engine - in reality it's a lot less. (In addition keep in mind the engine, when running, is being powered by the alternator, so any grounds on the engine will conduct current directly to the alternator and not through any earth strap to the battery).

The continous current capacity of the three earth straps would be somewhere in the vicinity of the 150A - one 4Gish cable, and two 16G cables. The factory got it right


IF you really *really* want to run an earthing kit running extra grounds to every imaginable part of the engine makes no sense.

1) Run an extra grounding cable from one of the bolts of the starter motor to the battery negative - this gives you a direct current path for the starter motor. Keep in mind a foot of engine block has a much large cross sectional area (hence current capacity) than a foot of 10mm2 cable, so you might not actually improve anything.

2) Extra cable off one of the bolts of the housing of the alternator to the battery (or better still find where the diodes are grounded on the back of the alternator housing and run the cable directly to them - best possible). Makes little sense if the alternator is on the other side of the engine to the battery as the engine block will conduct better than a cable.

3) You could connect an extra 4G grounding cable on the other side of the engine to the chassis (probably won't do much).

None of these are likely to give you any extra power.

When grounding the engine and ECU bits keep in mind that if something doesn't ground on the engine in a certain area, it makes absolutely no sense to give this area an extra ground - you have 100kg of cast iron giving you an almost unimaginable current path - what would you improve by adding a kilo of copper?

Everything on the engine management side on the 1G-FE grounds at two points on the cam cover. You could connect extra cables to those two points to the battery (alternator makes no sense again as the block will conduct better).

Otherwise, you could be more creative and ground the components that use those two ground points and improve on the length wiring that the factory runs in the loom - IE all the ignitors/coils have a ground pin - you could each ignitor directly to the battery and/or alternator.

The ECU has a number of high current ground connection, some of which run the injector currents - you could connect the ECU grounding pins straight to the battery and alternator (but leave the sensor signal ground alone).

You could connect the grounds of the oxygen sensors directly to the battery or engine block.

The only thing that has potential to give you extra power here are the coil packs but afaik the spark delivery is more than adequate in the factory application. That's pretty much the only thing that I can think of that could've made a difference on the skyline - spark quality is more critical in boosted application.

In terms of the injectors doing something differently - you may get slightly crisper opening times... real world value?....

Thoughts anyone? on anything?

Hopefully someone will read it There is *some* grounding advice

Mos.

[MWP]

The only thing that has potential to give you extra power here are the coil packs but afaik the spark delivery is more than adequate in the factory application. That's pretty much the only thing that I can think of that could've made a difference on the skyline - spark quality is more critical in boosted application.

In terms of the injectors doing something differently - you may get slightly crisper opening times... real world value?....

Yup, sounds about right.
Spark is the only thing i can think of that could possibly be enhanced.
Injectors may open a little quicker, but int the end, that wont effect anything as the car is tuned for the injector response it has with the possibly bad grounding.

Long read Mos, but well said.

[Hydra]

Agreed, very nicely said.

But, it wont hurt to ensure there is a good ground We all know how much they can affect a car...

[The Witzl]

i read it
.... and in my experience and random thoughts on the flow paths of stray electronics in the vehicles that i own tends to suggest to me that the only time its worth "upgrading" your earth cabling is:

• When the existing cable is 20years old or older
• When you have INCREASED the current load on your system
• When your engine is just such an industrial powerhouse machine, built so tough that no electron would dare find a path through its cast iron grain structure..... yes, if it's an 18R-G

In seriousness though, I've only ever upgraded earth cabling when the electrical system has increased significantly.
For example:
# converting an AE71 to 4A-GE - i replaced the factory earth wires with larger diam cables
# In my RA28, the 250-400W worth of headlights and EFI gear, and the 85A alternator are a biggish increase over the stock 50A alternator and carby engine.... increased sizing of stock earth cables here too.

[JustCallMeOrlando]

My car I just replaced the factory cables on just as a precaution when I did the engine conversion. They're MASSIVELY oversized but I don't have to ever suspect them as being a problem. There is a 4GA running to the block at the engine mount, another 4GA running to the chassis at the front, an 8GA running from the head to the chassis and a 16GA running to the chassis just next to the battery where a whole bunch of factory earths join. Totally overkill, but inexpensive for piece of mind.

[The Witzl]

My car I just replaced the factory cables on just as a precaution when I did the engine conversion. They're MASSIVELY oversized but I don't have to ever suspect them as being a problem. There is a 4GA running to the block at the engine mount, another 4GA running to the chassis at the front, an 8GA running from the head to the chassis and a 16GA running to the chassis just next to the battery where a whole bunch of factory earths join. Totally overkill, but inexpensive for piece of mind.

Likewise, i believe it to be overkill.... but i always have spare 2g, 4g and 8g cable lying around, so fixing up the earths is ultra cheap and allows me to move the earth cabling to a move convenient/neater location.

I would NEVER buy an earth kit! Even if you went out and bought all of the components at retail price, it would still be worth much less than the ticket price of a "circle earth kit"!!

P.S. not taking into consideration the MASSIF bump in price you are all about to experience with cabling - copper prices have shot thru the roof, and everyone is raising their price. Dont be surprised if you see 4G and similarly sized cables tripple in price soon!!

[JustCallMeOrlando]

Exactly, it was cheap, as you know, so I just made sure it was never going to be a problem.

[oldcorollas]

but but... i can buy them in Autobacs and they come from a good brand



there are some other random "promotion" or "suppression" products there i should take a pic of...

there is some merit to putting thought into where sensors etc ground in terms of not introducing noise, but apart from that... i hope Cornelius never touches a car again

[WDE_BDY]

There was one in the girlfriends Mazda Demio (jap import with all the other aftermarket bits as well) when we bought it, probably about as effective as the magnetized thingy slipped over the fuel line to boost the fuel economy.

Callum

[mrshin]

"Battery negative is best earthing terminal"... When the engine is not running, yes, when the engine is running the alternator ground is more important - the alt supplies the power to everything (including the battery) when the engine is running - so your extra cables maybe should run to BOTH the battery and alternator housing.


Mos.

I've just thought of a notable exception - take a quick look at a Falcon cooling system - Ford have managed to find a way to turn the entire cooling system into a form of flow battery, thereby able to corrode from the inside out at a rate that makes the battery extremely jealous. The battery then attempts to compete with this, forming its own corrosion pile. This applies to every Falcon ever produced, and seems to baffle even the marine guys theories of electron flow!




I guess I'm just severely uncool because a while ago I bought a big pile of unloved welding cable from a local scrap metal place, and use that for earth etc. leads on cars. I mean, it's LEGO ORANGE coloured - how can it POSSIBLY conduct as well as the blue see-through stuff??

[kingmick]

fords use there water pumps as anodes!hahahahahahahaahah

[Hydra]

Hahaha, you can buy a new falcon with mud from the factory as well... Built ford tough??

[kingmick]

the new ad for ford ute with the dogs folling it and the bloke says you attacked the dogs etc.
Holden should be quick and come out one with" only glamours{hot chicks following the ute and inside the back of the ute} follow holden utes"

[chris davey]

So how much did GT Autosound pay this magazine to produce this "tech" article