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Thread: Grounding Battery Behind Passenger -> Block

  1. #1

    Default Grounding Battery Behind Passenger -> Block

    Reading all the threads about EMI and the importance of grounding, I want to make sure I have my battery to block grounded correctly through the firewall. I've got a Red Top behind the passenger seat, with a positive 1 AWG running to a battery cutoff switch, to the dash, through a bulkhead fitting in the firewall to the starter. My alternator charge wire goes directly to this bulkhead.

    Right now, there's just a 1 AWG ground going from the battery into one of the structural components of the subframe, with no wire running directly from the battery to the engine block. There are two grounds from the engine to the frame:
    #1) A grounding strap from the valve cover bolt to the firewall.
    #2) A grounding wire from the block to the frame near the radiator.

    1. What gauge ground should I use from the battery to the block?
    2. Does it matter where I ground the block?
    3. Can I use a bulkhead connector, or do I need to run an intact cable through the firewall with a grommet?
    4. Right now, the alternator wire runs between the intake and the head on the passenger side. Should I move it to run above the header, secured by the valve cover bolts? Obviously this exposes it to more heat, but reduces the risk of EMI with the valve cover/valvetrain shielding the Sniper.

  2. #2

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    Does the car start okay with that wiring setup? The starter draws a lot of amps and it sounds like you're pulling those amps through the chassis? That might work if you have a fully welded frame, but it usually doesn't work on a factory car with spot welded floor pans. If you don't have a full frame in the car then run a #4 welding cable from the connection on the frame in back to the ground connection on the frame by the engine. That will tie everything together.

    Does your master cutoff kill battery power to the Sniper? If so, you might want to bypass that. The Sniper will work better if it's always connected to the battery. That way it can keep the internal clock correct.

  3. #3

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    4 AWG Welding Cable will work. Quality welding cable at 4 AWG is actually most likely better than the 0/1/2 AWG stuff most people buy. It's super flexible and works great. Bulkhead connector is fine for the ground. Anywhere on the block is probably fine. I did mine at the fuel pump block off plate for what it's worth. Check out this video for some great tips. https://youtu.be/BQdQBesuJCs
    69 Camaro
    400 SBC, ProCharger D1SC

  4. #4

    Default

    Quote Originally Posted by andyf View Post
    Does the car start okay with that wiring setup? The starter draws a lot of amps and it sounds like you're pulling those amps through the chassis? That might work if you have a fully welded frame, but it usually doesn't work on a factory car with spot welded floor pans. If you don't have a full frame in the car then run a #4 welding cable from the connection on the frame in back to the ground connection on the frame by the engine. That will tie everything together.

    Does your master cutoff kill battery power to the Sniper? If so, you might want to bypass that. The Sniper will work better if it's always connected to the battery. That way it can keep the internal clock correct.
    I'm wiring the Sniper directly to the battery, so bypassing the cutoff. I'm assuming the pull/drain is not significant when powered off? I.E. Will I need to run a battery tender if I only run the car every few weeks in the winter?

    The car has a full cage with down bars welded to the subframe near both grounding straps, so no problem at all running the starter. Here's pictures of the car/cage work: https://lateral-g.net/forums/showthread.php?t=45491

    I talked to Chris at EFI Pro and he mentioned that the Sniper is self contained with all the sensors and computer grounded via the main Sniper ground, not the block, so I think I'm okay without the #4 welding cable to try to start and I'll add it if I run into EFI gremlins. Thanks for the great answer! JP
    Last edited by Widebody 69; 09-17-2019 at 04:59 PM.

  5. #5

    Default

    Quote Originally Posted by andyf View Post
    Does the car start okay with that wiring setup? The starter draws a lot of amps and it sounds like you're pulling those amps through the chassis? That might work if you have a fully welded frame, but it usually doesn't work on a factory car with spot welded floor pans. If you don't have a full frame in the car then run a #4 welding cable from the connection on the frame in back to the ground connection on the frame by the engine. That will tie everything together.

    Does your master cutoff kill battery power to the Sniper? If so, you might want to bypass that. The Sniper will work better if it's always connected to the battery. That way it can keep the internal clock correct.
    Internal clock? Please elaborate.

  6. #6
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    Quote Originally Posted by bingo2 View Post
    Internal clock? Please elaborate.
    RTC = Real Time Clock (in Data Monitor & Datalogger). In other words, ECU time & date.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  7. #7

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    The ground wire from battery to block is not for the Sniper. It's to provide an easy path for any stray electricity to get back to the battery rather than traveling through your Sniper. Watch that video, and do yourself a favor and add the ground. No shortcuts.
    Last edited by gregs69rs; 09-17-2019 at 08:22 PM.
    69 Camaro
    400 SBC, ProCharger D1SC

  8. #8

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    Greg, thank you again for the great advice. I just grabbed 20' of nice 4 AWG and the relevant grommets & connectors, and will run directly from the battery to the block. Much appreciated! Cheers, Jason

  9. #9

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    Quote Originally Posted by bingo2 View Post
    Internal clock? Please elaborate.
    Run a datalog and look at the file name. The date & time should be correct.

  10. #10

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    Quote Originally Posted by andyf View Post
    Run a datalog and look at the file name. The date & time should be correct.
    Mine always say 11/13/2011 9:23PM for the .dlz files. Every once in a while the .dl files will reflect an accurate time & date. What does that indicate? My Sniper is wired directly to my battery. The battery is an Optima Red Top and my 175 amp Tough Stuff alternator keeps it topped up. Whenever running, whether idle or full throttle, the 3.5" tells me 14.2-14.4V.
    Last edited by HeavyChevy; 09-18-2019 at 04:14 PM.

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