Holley Sniper EFI?

[jrfinchen1]

Is anyone running a sniper kit on the Gmt400 platform? I want to do a top-end build looking for around 300 - 350HP and I'm wondering if one of the Holley kits would be a good idea because the TBI won't be able to handle it and I really don't want to do a carb swap.

 

[PlayingWithTBI]

I want to do a top-end build looking for around 300 - 350HP and I'm wondering if one of the Holley kits would be a good idea because the TBI won't be able to handle it and I really don't want to do a carb swap.

What truck/engine/trans? Are you running an electronic controlled trans like the 4L60E? On a 5.7L the bored 46mm TBI 650 CFM can most certainly support over 350 HP up to 6K RPM. The 50mm 7.4L can do more.

46mm PORTED 5.7L TBI Package Deal 650CFM | eBay

THIS IS 650CFM! 46MM TBI /Adjustable Reg Cover. TBI are known for leaky throttle shafts. 5.7L TBI as described above and below. There are multiple casting numbers used. Not all the TBI units have all the available vacuum ports as shown in the photos.

www.ebay.com

If you have a 700R4 or a stick, the EBL Flash-II and WBO2 can self learn, even with WOT. Plus you can flash your own tunes in seconds.

www.dynamicefi.com/EBL_Flash.php

 

[jrfinchen1]

What truck/engine/trans? Are you running an electronic controlled trans like the 4L60E? On a 5.7L the bored 46mm TBI 650 CFM can most certainly support over 350 HP up to 6K RPM. The 50mm 7.4L can do more.

46mm PORTED 5.7L TBI Package Deal 650CFM | eBay

THIS IS 650CFM! 46MM TBI /Adjustable Reg Cover. TBI are known for leaky throttle shafts. 5.7L TBI as described above and below. There are multiple casting numbers used. Not all the TBI units have all the available vacuum ports as shown in the photos.

www.ebay.com

If you have a 700R4 or a stick, the EBL Flash-II and WBO2 can self learn, even with WOT. Plus you can flash your own tunes in seconds.

www.dynamicefi.com/EBL_Flash.php

I have a 1992 chevy k1500 5.7/ 700r4

 

[PlayingWithTBI]

I have a 1992 chevy k1500 5.7/ 700r4

Then you can go with the EBL which expands your SA and VE tables to 6000 RPM+. The GM 16197427 is the 2nd generation of ECM/PCM which has about the same size tables but, it still uses memcal chips which need to be "burned" unless you go to flash chips or an emulator. The good thing about the EBL is it's set up to accept a WBO2.

FYI - Dave w on Gearhead-EFI.com built a TBI engine with Vortec heads, a 4 BBL manifold with a TBI adapter, a 670 CFM Throttle Body, and a computer friendly roller Comp Cam with .480/.480 lift with the 7427 PCM, and put out 355 RWHP on the dyno, which comes out to ~400 HP at the crank

Don't get me wrong, Holley, Fitech, Edelbrock, etc all have decent EFI systems - I just like PlayingWithTBI

 

[Erik the Awful]

I have a Sniper on my '89 Stepside. It runs great, but it's not without some headaches. If you go the Sniper route, know that the system cannot tolerate vacuum leaks, exhaust leaks, nor poor wiring. You must be rock solid on those things. I also bought the Hyperspark ignition so the computer can control the timing, but I'm not sure it's worth it. On the plus side, now the only thing my ECU controls is torque converter clutch lockup.

Pros:
It's truly easy to get running provided you have it installed correctly. Mine busted off immediately and after a year of driving drives very well.
They use off-the-shelf sensors for it. The TPS is the same one on your TBI setup. The wide-band O2 sensor is from a Dodge Ram 2500.
When it acts up, diagnosis is easy because the hand-held gives you data stream.

Cons:
The factory TPS they ship it with is cheap garbage.
You're gonna get nickeled and dimed in the traditional Holley way.
You're probably going to have to readjust the throttle plates. My throttle was sticking open, and it's apparently a common problem on Snipers.

What you'll need:
Get the metric to AN adapaters that plug right into your stock fuel lines and then you can plug your fuel lines right onto the Sniper with female AN to female AN adapters.
You absolutely need the throttle arm extension or your throttle attack is excessive and you can bend your throttle shaft. https://www.summitracing.com/parts/sne-20-16
Get the Summit throttle bracket. It says it doesn't fit the Sniper, but it works. https://www.summitracing.com/parts/sum-g1514

Getting the handheld's cable through the firewall is a pain in the butt. I used an antenna plug to pass it through the firewall, and then put a piece of 5/16" fuel hose over the cable to seal it into the antenna plug.

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[jrfinchen1]

I have a Sniper on my '89 Stepside. It runs great, but it's not without some headaches. If you go the Sniper route, know that the system cannot tolerate vacuum leaks, exhaust leaks, nor poor wiring. You must be rock solid on those things. I also bought the Hyperspark ignition so the computer can control the timing, but I'm not sure it's worth it. On the plus side, now the only thing my ECU controls is torque converter clutch lockup.

Pros:
It's truly easy to get running provided you have it installed correctly. Mine busted off immediately and after a year of driving drives very well.
They use off-the-shelf sensors for it. The TPS is the same one on your TBI setup. The wide-band O2 sensor is from a Dodge Ram 2500.
When it acts up, diagnosis is easy because the hand-held gives you data stream.

Cons:
The factory TPS they ship it with is cheap garbage.
You're gonna get nickeled and dimed in the traditional Holley way.
You're probably going to have to readjust the throttle plates. My throttle was sticking open, and it's apparently a common problem on Snipers.

What you'll need:
Get the metric to AN adapaters that plug right into your stock fuel lines and then you can plug your fuel lines right onto the Sniper with male AN to male AN adapters.
You absolutely need the throttle arm extension or your throttle attack is excessive and you can bend your throttle shaft. https://www.summitracing.com/parts/sne-20-16
Get the Summit throttle bracket. It says it doesn't fit the Sniper, but it works. https://www.summitracing.com/parts/sum-g1514

Getting the handheld's cable through the firewall is a pain in the butt. I used an antenna plug to pass it through the firewall, and then put a piece of 5/16" fuel hose over the cable to seal it into the antenna plug.

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Thanks very much this gave me a lot of light on Holley. I think I am going to go with the sniper kit. I have heard stuff in the past about Holley cheating out in certain areas and the customer paying an extreme amount for it. Was your engine a stock 350? What model Sniper efi did you use?

 

[wb292]

I too am thinking of using a sniper. But trying to decide if a carb would be a better choice for my 454. Reliably is super high on my priority list and I’m a bit skeptical of the sniper. I’m also hoping I can leave the stick ignition system in place and let it control the timing. Has anyone done this? Either with a carb or a aftermarket EFI?

 

[Frank Enstein]

All of the EFI units that Summit sells FiTech, Fast, Holley/MSD, DIY/Megasquirt, and the Summit brand are pretty reliable.

Just pick the one that meets your needs for the best price and go. They're all very similar and tune about the same.

Fast has one for stand alone TPI that self learns too!

I've been tuning carbs for over 40 years. I can make a carb sing and dance and do your taxes but I can't tune a carb 200+ times a second. That's where EFI wins every time.

 

[Erik the Awful]

Note: I corrected my post above to read "female AN to female AN adapters".

My engine:
350 4-bolt main TBI block, honed, but no overbore
Factory Vortec heads, 062 castings, no porting, no machining
Factory crankshaft
Speed Pro H345DCP flat-top hypereutectic pistons - 9.7:1 compression ratio
Speedway Motors 5140 steel I-beam rods, 5.7", bushed pin
Lunati 20080720, duration @ .050 211/219, lift .507/.515
Factory roller lifters, dog bones, and spider assembly
Chevrolet Performance 12499224 LS2/LS6 valvesprings
Comp Cams 787-16 steel valve spring retainers
Comp Cams 648-16 race valve locks
Proform Parts 66914C extruded aluminum roller rocker arms
Summit 226018 Stage 1 dual-plane square-bore intake manifold
Holley Sniper
Hedman headers with 2.5" dual exhaust and an x-pipe

I've kept a secret for the last few years, only letting people in on it when they mentioned they were considering a Holley. Holley used to sell refurbished Snipers on their website for about $800, and that's what I bought. The last several times I checked, they don't sell refurbished any more, so I'll let that cat out of the bag now. I bought the basic Sniper kit - if you upgrade your TBI sending unit with the Vortec fuel pump, you don't need the "Master Kit".
www.holley.com/products/fuel_systems/fuel_injection/sniper_efi/sniper_4bbl_tbi_kits/sniper_efi/

The factory TBI distributor works just fine with the throttle body missing. I just recently upgraded to the Hyperspark.

 

[Interceptor]

I've had 2 Snipers fail. Both were replaced under warranty. One failed with a stuck O2 reading and limped home rich. On the second an injector stuck wide open, one of the 4 barrels was boiling full of fuel. Washed the rings and wasted the engine. Never again.