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Thread: Twin Sniper EFI units on a Roots blown engine.

  1. #1

    Default Twin Sniper EFI units on a Roots blown engine.

    Thought I would ask here first, before trying to get onto the Holley EFI guys. Also did a search & couldn't find it. I have a customer with a 6/71 blown 347W, currently using twin 600 Holley carbs. We would like to switch to EFI early next year. We want to go with the Sniper units as it suits the nostalgia look of the car. Has it been done before? Do you just order the normal units, or need to special order them, since you only really need one ECU to control both units, etc. Thanks, Aaron

  2. #2
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    The dual Sniper EFI (Sniper 2x4) is an option in the "EFI Parameters" (System Setup - Sniper EFI software). It's not in the manual yet. The soon to be released Sniper EFI software allows forced induction programming (Boost Setup, Base Fuel & Base Timing tables, etc.). The Sniper 2 bar MAP sensor (naturally aspirated) is internal with the ECU, and it's not removable in the Sniper EFI. (I confirmed this with a Holley EFI engineer.) This location is fine for a 2 bar or higher MAP sensor, on a blow-through application; but it won't work on a Roots type blower (draw-through supercharger application), because you'd need to abandon the existing MAP sensor location and connect a 2 bar or higher MAP sensor hose to the bottom side of the blower (boost). Also on a blow-through application, you'd need to abandon the throttle body mounted fuel pressure regulator, and install a remote mounted vacuum/boost referenced fuel pressure regulator. Finally, the Sniper TBI has four 100 lb/hr fuel injectors, so I'm not sure how well the low the injector pulse width would idle with eight injectors operating.
    http://documents.holley.com/techlibrary_199r11259.pdf (Holley Sniper EFI Software Help File)
    https://www.holley.com/support/resou...Fuel_Injection (Holley Sniper EFI Software Download)
    http://documents.holley.com/199r11031r.pdf (Holley Sniper EFI Instruction Manual - For my own reference.)
    http://documents.holley.com/199r11193.pdf (Holley Sniper EFI Quick Start Manual - For my own reference.)

    UPDATE: I just heard back from Holley EFI, and they're working on the dual Sniper TBI Kit now.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3

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    Quote Originally Posted by Danny Cabral View Post
    UPDATE: I just heard back from Holley EFI, and they're working on the dual Sniper TBI Kit now.
    Perfect, thanks for that.

  4. #4
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    You're welcome.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

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    Quote Originally Posted by Danny Cabral View Post
    I just heard back from Holley EFI, and they're working on the dual Sniper TBI Kit now.
    Will it be possible to "easily" upgrade from a single existing Sniper, to the twin setup when it's released? I guess the second throttle body won't have the ECU, etc. inside it, and the main one will drive it?

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    Quote Originally Posted by 540cortina View Post
    Will it be possible to "easily" upgrade from a single existing Sniper, to the twin setup when it's released?
    I won't know until it's released.

    I guess the second throttle body won't have the ECU, etc. inside it, and the main one will drive it?
    Correct, or just disconnected.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  7. #7

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    You don't need to change the fuel pressure regulator, as the injectors are not seeing any boost. But if you do, it may help with the low idle fueling from running eight 100 lb/hr injectors.

  8. #8
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    Quote Originally Posted by Blow1940 View Post
    You don't need to change the fuel pressure regulator, as the injectors are not seeing any boost.
    Correct, a boost referenced fuel pressure regulator is only required on a blow-through application (turbocharger/supercharger).
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  9. #9

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    Quote Originally Posted by Danny Cabral View Post
    Correct, a boost referenced fuel pressure regulator is only required on a blow-through application (turbocharger/supercharger).
    Danny, would you still want to use a non-boost referenced regulator running the line to the bottom of the blower to help with idle & normal driving?

  10. #10
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    That shouldn't be necessary.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

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