Another upgrade wire thread
Thread Starter
Drifting
Joined: Feb 2017
Posts: 1,462
Likes: 106
From: Cortlandt Manor NY
Another upgrade wire thread
Maybe I’m over thinking this but want to run this past some more electronic savvy owners. Here’s my situation:
1969 corvette roadster - replaced all original wiring and upgrading different things as I rebuild and plan more in the future. Not keeping it stock so anything goes. I am still in rebuilding process of my body off but so far have the following upgrades: Fitech EFI, SPAL dual electric fans, Vintage Air A/C, electric fuel pump, MSD 6AL, high output coil, MSD distributer, CS144 alternator. Possible future upgrades include electric wiper door and lights, stereo. I have already wired the alternator with 6 gauge from starter to bus to alternator. Ran a 2/0 ground wire from battery neg post on rear frame to bus in engine bay to alternator ground.
Now I know the Fitech and MSD 6AL say to run power and ground to avoid electrical noise and get solid voltage (I assume) but they also have 99% of vehicles with battery in engine bay. If instead of the 6 gauge from starter-bus-alt I ran 2/0 (overkill but have it) from battery to bus in engine bay to alternator would it be feasible to run power and ground for Fitech and 6AL to these buses in engine bay? Power is good and for electrical noise wouldn’t it have the same electrical noise from alternator at the battery post? This way I could just run one wire for positive and one for negative along frame rail up to engine bay instead of running wires from different electronic pieces back through the interior under the carpet to the battery?
Thoughts? I know 2/0 is overkill but I have it so cost is no problem. Would shorten up all the other wiring also. Could even run a relay and separate bus for ignition 12v from either the original coil + factory wiring or ign spot on factory fuse panel. I appreciate the help.
Pat
1969 corvette roadster - replaced all original wiring and upgrading different things as I rebuild and plan more in the future. Not keeping it stock so anything goes. I am still in rebuilding process of my body off but so far have the following upgrades: Fitech EFI, SPAL dual electric fans, Vintage Air A/C, electric fuel pump, MSD 6AL, high output coil, MSD distributer, CS144 alternator. Possible future upgrades include electric wiper door and lights, stereo. I have already wired the alternator with 6 gauge from starter to bus to alternator. Ran a 2/0 ground wire from battery neg post on rear frame to bus in engine bay to alternator ground.
Now I know the Fitech and MSD 6AL say to run power and ground to avoid electrical noise and get solid voltage (I assume) but they also have 99% of vehicles with battery in engine bay. If instead of the 6 gauge from starter-bus-alt I ran 2/0 (overkill but have it) from battery to bus in engine bay to alternator would it be feasible to run power and ground for Fitech and 6AL to these buses in engine bay? Power is good and for electrical noise wouldn’t it have the same electrical noise from alternator at the battery post? This way I could just run one wire for positive and one for negative along frame rail up to engine bay instead of running wires from different electronic pieces back through the interior under the carpet to the battery?
Thoughts? I know 2/0 is overkill but I have it so cost is no problem. Would shorten up all the other wiring also. Could even run a relay and separate bus for ignition 12v from either the original coil + factory wiring or ign spot on factory fuse panel. I appreciate the help.
Pat
Burning Brakes
Joined: Jul 2016
Posts: 767
Likes: 74
From: Blaine MN
I asked this of one of my Co-workers (EE with years of experience dealing with RFI/EMI as design constraints), he says the extra wire length adds inductance (provides some filtering) but if you run the wires next to each other it'll mostly negate the gains. I'd do the bus (assuming Bus Bars in Engine Bay) method first, I'm betting you'll know if you have RFI/EMI problems (assuming the Fitech allows you to look at all your Sensor outputs, Fuel Tables etc., I'm only familiar with Accel DFI and Holley Terminator). Let us know how it works out. (the Fuel Pump probably creates the most noise, DC Motors are noisy)
Last edited by suprspooky; Oct 31, 2018 at 01:18 PM.
Thread Starter
Drifting
Joined: Feb 2017
Posts: 1,462
Likes: 106
From: Cortlandt Manor NY
Thanks for the response. As I was thinking about it some more I was wondering if I leave the 6 gauge wire from starter to alternator to charge battery. Then run the 2/0 wire from the battery to a dedicated bus in the engine bay. This should eliminate all noise and be the same as running all the wires back to the battery. I was also going to run the fuel pump from an additional fuse panel that I installed in the rear cargo area and control it with the Fitech.
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
A device under the hood using say 2' of 10 gauge wire to a terminal block with 12' of 2/0 gauge wire from terminal block to the starter to the battery will be less total resistance than say 14' of 10 gauge wire from the device under hood to the battery. So, running a big wire to a terminal block will make a better connection to the battery compared to running multiple small wires all the way back to the battery.
The stock black ground wire going to the alternator isn't grounding the alternator. It's actually there to ground the radiator support to the engine block. I wouldn't run a big ground wire to the alternator. Then, the starter current has to go through the alternator brackets and alternator. Put it to the engine block.
The stock black ground wire going to the alternator isn't grounding the alternator. It's actually there to ground the radiator support to the engine block. I wouldn't run a big ground wire to the alternator. Then, the starter current has to go through the alternator brackets and alternator. Put it to the engine block.
Le Mans Master
Joined: May 2003
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Couple of thoughts-
On the wires/lug to the alternator- the wire lug should fit the alternators stud tightly. You want the nut to hold it down- not in place.
You can look at the wire size charts BUT it's showing a rating at 70ºF- under the hood- it's hotter- rule of thumb -go up one gauge.
And look at replacing the ammeter with a voltmeter- as it will not read correctly changing the wire sizes
The battery does more than start your car- it stabilizes voltage and filters the leftover AC ripple the alternator doesn't clean up.
I'm into overkill as well...I ran two 1/0 cables from the battery - one for the alternator and one to the starter.
On the wires/lug to the alternator- the wire lug should fit the alternators stud tightly. You want the nut to hold it down- not in place.
You can look at the wire size charts BUT it's showing a rating at 70ºF- under the hood- it's hotter- rule of thumb -go up one gauge.
And look at replacing the ammeter with a voltmeter- as it will not read correctly changing the wire sizes
The battery does more than start your car- it stabilizes voltage and filters the leftover AC ripple the alternator doesn't clean up.
I'm into overkill as well...I ran two 1/0 cables from the battery - one for the alternator and one to the starter.
Thread Starter
Drifting
Joined: Feb 2017
Posts: 1,462
Likes: 106
From: Cortlandt Manor NY
For the wire/lug to alternator, you mean the bolt on back for the negative ground cable? I have a bolt on there now that tightens down on the cable,
Was planning on upgrading the anmeter with a voltmeter for true readings.
So basically I’m going to have an upgraded wire run from battery to starter to high output alternator and a second upgraded line from battery to bus.
Was planning on upgrading the anmeter with a voltmeter for true readings.
So basically I’m going to have an upgraded wire run from battery to starter to high output alternator and a second upgraded line from battery to bus.
Thread Starter
Drifting
Joined: Feb 2017
Posts: 1,462
Likes: 106
From: Cortlandt Manor NY
EFI power wires need to go to battery per the instructions.
I know thats why I was throwing the question out there. I assume the reason they want battery connections is true 12V and to avoid electronic noise. If I’m running a 2/0 cable from battery in the back to a bus in the front and going nowhere else it would be exactly like running the wires from the Fitech, MSD and whatever else all the way back to the battery?
I know thats why I was throwing the question out there. I assume the reason they want battery connections is true 12V and to avoid electronic noise. If I’m running a 2/0 cable from battery in the back to a bus in the front and going nowhere else it would be exactly like running the wires from the Fitech, MSD and whatever else all the way back to the battery?
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Le Mans Master
Joined: May 2003
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
EFI power wires need to go to battery per the instructions.
I know thats why I was throwing the question out there. I assume the reason they want battery connections is true 12V and to avoid electronic noise. If I’m running a 2/0 cable from battery in the back to a bus in the front and going nowhere else it would be exactly like running the wires from the Fitech, MSD and whatever else all the way back to the battery?
I know thats why I was throwing the question out there. I assume the reason they want battery connections is true 12V and to avoid electronic noise. If I’m running a 2/0 cable from battery in the back to a bus in the front and going nowhere else it would be exactly like running the wires from the Fitech, MSD and whatever else all the way back to the battery?
The ground? Not that big of deal- alternator is bolted to the motor- although it conducts about 60% as good as copper- there is a lot of it. I ground the motor on both sides - nice and clean wih a star washer- you should be good to go- nothing else required..Unibody cars are a bit different than a frame car.
Thread Starter
Drifting
Joined: Feb 2017
Posts: 1,462
Likes: 106
From: Cortlandt Manor NY
Thanks for the input! I always use the right size ‘hole’ for the lug. The only pain is I’ve never been able to find a decent assortment kit for them and always have to buy individual packages of each gauge and lug size.
Race Director
Joined: Apr 2007
Posts: 11,152
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From: South Western Ontario
Batteries are bulk energy storage devices. You need to use a capacitor or other filter if you want to actually filter.
The manufacturers say to put the wires directly to the battery to avoid the calls from idiots who connect them to completely unsuitable sources. The end of a 2/0 cable running between the battery and the starter is as solid as the battery.
The alternator is at least 3-phase so the ripple is 4% or less or < 0.6V approximately. Switching noise from things like relay coils or the brushes of the DC motor in the fuel pump can be much worse than this.
The manufacturers say to put the wires directly to the battery to avoid the calls from idiots who connect them to completely unsuitable sources. The end of a 2/0 cable running between the battery and the starter is as solid as the battery.
The alternator is at least 3-phase so the ripple is 4% or less or < 0.6V approximately. Switching noise from things like relay coils or the brushes of the DC motor in the fuel pump can be much worse than this.