good grounding

[Seight-V8]

hello all,

Just starting to make a loom for a VEMS ecu for my 4.6 engined westfield.

The westfield has one earth wire from the battery to a chassis earth, then a braided wire from the chassis earth to a gearbox bolt hole.

Is this enough to give me a really good earth grounding, or should i make another one, so i dont get any sensor interference.

How many engine earths does a normal V8 installation have?

cheers

scott

[JSF55]

Those braided ones are really not up to the job, your better of with some nice thick welding lead and crimp on our own lugs, i ran 2 on the engine, from the block to the chassis, same on the gearbox and the battery earth was direct to the chassis rail, i also made a point of earthing all the MS stuff, LC1 etc directly to the engine at one point, for some reason i can't remember at the moment

[Coops]

Vems recomend the back of one of the heads opposite corner to the engine to chassis earths,

my block to chassis earths are like this on the drivers side engine mount,


and my vems earths out on the back of the passengers head,

[Ian Anderson]

[quote="thev8kid"
and my vems earths out on the back of the passengers head,[/quote]

Mr coops That sounds like you've finally started training for brain surgery


Ian

[Coops]

mmmmmmmm sounds like a new career

[gelmonkey]

Hi Scott
Just to add my couple of pence worth I've always run an earth lead from the bottom starter motor bolt to the chassis as well as the main one from the block to the chassis.Not running F/I myself but it won't hiurt to add another good thick cable from here.A length of marine grade battery cable will do the job nicely.

[bobtail84]

I cannot say this enough... you cannot have too many earth's.... The battery is the best earth. Make sure the earth to the chassis from the battery is good and clean. Run all the sensor earth's to the battery, the ECU earth's to the battery, keep all the earth's away from noisy wiring IE: crank sensor, HT and live from alternator. Try not to connect to 1 black wire then run it to the battery, it's better to run lot's of smaller wire's then join to a terminal at the batt. This will stop you getting re-set's.

HTH

jeff

PS. ask me how I know........

[Dangerdoc]

Hi guys,

Gonna chuck in my spurt of spiel here.

Earthing is essential and we all agree on that. Now, look at some of the pics and you will see nice thick wires and very nice heat shrink and tidy work without doubt.

Now consider the actual surface area contacted. For example, a bolt that runs through a mount. Well the mount is on a rubber bush, and so overall the surface area contacted is pretty small. What is vital, really really vital, is that where paint meets paint you must clear this away and ensure a large as possible surface area. I use electrical contact grease also and have multiple earths.

If you look at a new car (aghast) wiring diagram you will see tons of small wires all coming together at key points and then bolted to chassis earthing bonded points.

So in summary, big surface area, clear away all paint, dont get fooled thinking you have a good contact where you are only really just on the thickness of the metal plate via a bolt and bush affair. Get directly bolted to the chassis and make sure engine to chassis, gearbox to chassis and chassis to battery plus battery to engine are very very good. This sounds overkill but most electrical faults that are intermittent and very hard to trace can be related to poor earthing.

It does not need to be huge cable what you are attempting to achieve is the elimination of a potential difference between surfaces. Electricity will flow the path of least resistance and you are not talking high current here as that is through the phase (positive) side.

Great idea to route the cables independently through "quiet" areas i.e. as detailed in previous posts - away from interference and electrically noisy areas.

I'll shut up now.

Doc

[Coops]

Earthing is essential and we all agree on that. Now, look at some of the pics and you will see nice thick wires and very nice heat shrink and tidy work without doubt.

Now consider the actual surface area contacted. For example, a bolt that runs through a mount. Well the mount is on a rubber bush, and so overall the surface area contacted is pretty small. What is vital, really really vital, is that where paint meets paint you must clear this away and ensure a large as possible surface area. I use electrical contact grease also and have multiple earths.

mine aint earthed through the rubber engine bush mate,
i gather thats what you was pointing at as you commented on the size of the cables and heat shrink which is my pic on my car.

[Dangerdoc]

You know, you try and stick just a little bit of your two penneth in to assist others and before you know it, pow, shot down in flames from the defensive lot.

Lets get this really clear please, the comments about cables, bush and size were in no way a direct swipe at anyone or any vehicle but a handy reference to a posted image by way of example.

It is very clear from the image that two substantial cables run from some point, unite at a nut / washer / bolt assembly over a clearly otherwise painted area and then pass towards what appears to be an engine casing assembly.

All fine in my book. Now lets disect the post. Jees I feel like Ramon, anyway - where is Ramon he was a really good source of information.

1. The cable size is academic, what is important is the generation of a potential difference i.e. voltage from two different areas of energy status. So big cables are not necessarily the best what is important is multiple sites.

2. The suface area is commensurate to a washer area over a painted surface, is the surface under the engine mount stripped bare?

3. The bolt will pass through the hole in the engine mount and usually touch in 60% of the area designed if the hole is correct diamater. The other side will be relevant to whether the paint is acting as an insulation area !

4. There will be some sort of bush which may be poly or rubber and this will act as an insulator, regardless.

5. Heat shrink just makes it look exactly as expected - a very neat job, nothin less than expected from the owner of this beastie !!!!!!!

6. The post was designed to provoke thought and understanding and really had nothing to do with what was right or wrong from a picture that had been posted.

I have a great respect for the wealth of knowledge that is clearly evident on this site and as such we need to consider reading the entire post that is made and in the context in which it was made.

Maybe I am just wasting time and need to get the admin guys to remove my profile as I am really sick and fed up reading the hit backs from time to time in here.

Hell I get that often enough with the team in a trauma case.

Hmmmmmmmmmmmmm is it really worth the grief???


Doc

You know what - no it has been a very very long day. Nope its not worth the grief. All you constructive guys take care.

Off permanently now.


Doc

[Coops]

Doc was not shooting you down was just pointing out that mine was not being earthed through the bush,
yes the paint was removed,
the cables meet at the bush bolt point yes, BUT if you look the other cable goes to the block, so its not relying on the point where they meet at the bush bolt.
and the other one to the chassis,

We dont want you to leave, but your call,
PM me and i'll get it sorted if you feel you want to go.

[csr]

You know, you try and stick just a little bit of your two penneth in to assist others and before you know it, pow, shot down in flames from the defensive lot.

Lets get this really clear please, the comments about cables, bush and size were in no way a direct swipe at anyone or any vehicle but a handy reference to a posted image by way of example.

It is very clear from the image that two substantial cables run from some point, unite at a nut / washer / bolt assembly over a clearly otherwise painted area and then pass towards what appears to be an engine casing assembly.

All fine in my book. Now lets disect the post. Jees I feel like Ramon, anyway - where is Ramon he was a really good source of information.

1. The cable size is academic, what is important is the generation of a potential difference i.e. voltage from two different areas of energy status. So big cables are not necessarily the best what is important is multiple sites.

2. The suface area is commensurate to a washer area over a painted surface, is the surface under the engine mount stripped bare?

3. The bolt will pass through the hole in the engine mount and usually touch in 60% of the area designed if the hole is correct diamater. The other side will be relevant to whether the paint is acting as an insulation area !

4. There will be some sort of bush which may be poly or rubber and this will act as an insulator, regardless.

5. Heat shrink just makes it look exactly as expected - a very neat job, nothin less than expected from the owner of this beastie !!!!!!!

6. The post was designed to provoke thought and understanding and really had nothing to do with what was right or wrong from a picture that had been posted.

I have a great respect for the wealth of knowledge that is clearly evident on this site and as such we need to consider reading the entire post that is made and in the context in which it was made.

Maybe I am just wasting time and need to get the admin guys to remove my profile as I am really sick and fed up reading the hit backs from time to time in here.

Hell I get that often enough with the team in a trauma case.

Hmmmmmmmmmmmmm is it really worth the grief???


Doc

You know what - no it has been a very very long day. Nope its not worth the grief. All you constructive guys take care.

Off permanently now.


Doc

Whilst most of what is said is correct, it'a all theory and not practice.

Your comments regarding the picture show you have little understanding of what you're looking at.

The engine in question is fitted with a 100 amp alternator and a starter that can draw up to 120 amps
- a nice fat earth lead fitted correctly is basic requirement.

Doing what you do, I expect your attention to detail is pretty good, I can tell you that the people building the car in question
have that same skill.
The schoolboy errors you point at are not pressent. Paint was removed as required and the bush is not in the least bit relevant. Have another look at the picture.

[csr]

Just thought I'd post this picture.

If you want wiring advice, the chap that did this might be the guy to talk to don't you think?