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Thread: Will the Sniper EFI work on 600 HP with low vacuum at idle?

  1. #1

    Default Will the Sniper EFI work on 600 HP with low vacuum at idle?

    I'm finishing up the restoration on my '67 Chevelle with a BBC 496 stroker. I have a Holley 750 on the new engine now. I'm interested to see if the Sniper EFI system will work vice the carb? I have read there are issues with Learning (self-tuning) and low vacuum at idle. My vacuum readings are like 3 inHg at idle. Can you custom tune if needed for this application?

  2. #2
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    Quote Originally Posted by ChevelleSSMan View Post
    My vacuum readings are like 3 inHg at idle. Can you custom tune if needed for this application?
    Yes, the Sniper EFI software will soon be available for custom tuning. Usually, if the engine has a large race camshaft (can't maintain a steady kPa value because vacuum fluctuates too much), it will idle better using Alpha-N Idle Fuel - Fuel ICF ("Combo" Load Sensing in Engine Parameters - System ICF). However, I'm waiting for the Sniper EFI software to see if this feature is available. For your application, I'd wait to purchase the Sniper EFI until you see the Sniper EFI software. The Sniper EFI software (LINK) is very similar to the Terminator/HP/Dominator EFI software.

    UPDATE: Alpha-N @ Idle is not a Sniper EFI option. The Sniper EFI "Cam Type" options are Stock, Mild, Street/Strip, Race.
    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/3000 RPM converter, FPP aluminum driveshaft, FPP 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 MT tires.

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    I hope you're able to get more information and keep this thread going. I'm about to order for a 499 big block with .590" cam, so I have the same question sitting on the same power range. I'm thinking of just giving it a go. I was told Holley didn't use vacuum for the fuel map, like FAST, and the vacuum may not play as big of a factor other than fluctuations in RPM.

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    Quote Originally Posted by Ontheloose View Post
    I was told Holley didn't use vacuum for the fuel map, like FAST, and the vacuum may not play as big of a factor other than fluctuations in RPM.
    Of course it uses vacuum, that's what the MAP sensor is for. The Base Fuel Table is two dimensional: MAP kPa (load) x RPM.

    I hope you're able to get more information and keep this thread going.
    At this time, you'll have to contact Holley Tech Service (LINK).
    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/3000 RPM converter, FPP aluminum driveshaft, FPP 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 MT tires.

  5. #5

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    Danny, question for you. We talked last Feb about the Sniper Kit and the new upgrade coming out for the EFI software that would allow better precise tuning of a low vacuum 496. Has this upgrade been released yet? I'm anxious to hear as I'm ready to purchase and convert my Chevelle over. Please advise. Thanks!

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    Quote Originally Posted by ChevelleSSMan View Post
    Has this upgrade been released yet?
    Yes, the Sniper EFI software (LINK) & CAN/USB Dongle (LINK) is now available.
    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/3000 RPM converter, FPP aluminum driveshaft, FPP 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 MT tires.

  7. #7

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    Thanks! So I could order the Sniper EFI system and it would work for my car? Would I be able to tune it correctly myself, or is it not intuitive and I would need professional help with Holley EFI products? What is the CAN/USB Dongle? Is that to hook a laptop or tablet to the system? And you are suggesting that the Alpha-N Idle feature is now available and that will help a low vacuum big block idle properly? Thanks for the help & guidance.

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    Quote Originally Posted by ChevelleSSMan View Post
    Would I be able to tune it correctly myself, or is it not intuitive and I would need professional help with Holley EFI products?
    If you have to ask, then probably not.

    What is the CAN/USB Dongle? Is that to hook a laptop or tablet to the system?
    Yes.

    And you are suggesting that the Alpha-N Idle feature is now available and that will help a low vacuum big block idle properly?
    Alpha-N @ Idle is not a Sniper EFI option. The Sniper EFI "Cam Type" options are Stock, Mild, Street/Strip, Race.
    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/3000 RPM converter, FPP aluminum driveshaft, FPP 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 MT tires.

  9. #9

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    Thanks for the info. I referenced the Alpha-N @ Idle because you suggested it would work better in the initial thread for the low vacuum engines. So, if the Sniper EFI system still does not include that technology, will the system "Learn" properly and work OK as a replacement for my 750 carb? I would love the benefits of fuel injection, but don't want to induce more headache with the system. My engine is new and runs pretty well, but I still have difficulties with vapor lock when it's hot. I also believe I could've increased performance with better computer controlled management of the AFR. Thoughts?

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    Quote Originally Posted by ChevelleSSMan View Post
    So, if the Sniper EFI system still does not include that technology, will the system "Learn" properly and work OK as a replacement for my 750 carb?
    It will Learn properly except for the idle & off idle area. You'll be in Open Loop below a particular RPM (Closed Loop Parameters). The EFI self-tuning/Learning isn't intended to idle with radical race/large camshafts.
    http://forums.holley.com/showthread....ension-Harness (Read 2nd paragraph under "Wideband O2 Sensor Notes".)

    I would love the benefits of fuel injection, but don't want to induce more headache with the system.
    Converting to EFI will be a minor headache.

    I also believe I could've increased performance with better computer controlled management of the AFR. Thoughts?
    Yes, absolutely.
    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/3000 RPM converter, FPP aluminum driveshaft, FPP 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 MT tires.

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