This is a Holley Sniper X Flow on a 505 inch Mopar big block. This engine is a little more radical than most street/strip builds. The owner went with higher than usual compression ratio, used Trick Flow 270 heads and installed a 264/268 solid roller cam. The nice thing about the Sniper+Hyperspark combination is that we were able to build ignition and AFR tables to make the car fairly drivable. The owner did need to swap the factory four speed for a 727 since there just wasn't anyway to drive the car with a clutch. We did this project a couple of years ago. I can drag up a few more pictures if there is any interest. It is a B body but that shouldn't matter in this forum since the focus is on the fuel system.
Holley Sniper on 700 hp big bock
- Thread starter AndyF
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Andy
Please add more pictures that car is great. I have not bought my new fuel system yet. I am very interested in what you have done.
Please add more pictures that car is great. I have not bought my new fuel system yet. I am very interested in what you have done.
Hello Andy, I have read a number of your posts and found them very interesting. (including your Duster build) I am currently installing a fairly stout 470 low deck in a street/strip 68 Dart. I have the Holley Sniper X Flow + the Hyperspark combination, but this will be my first time going with fuel injection. Any pointers in regards to the install and initial set up of the system other than what is noted in the directions? On this car and your Duster, did you start off with the Wizard as the initial setup?
I had the motor on the dyno for break in and to check for leaks (glad I did as the rear main leaked and need to be swapped out) and we made a few dyno pulls, but used a 950HP dyno carb as I didn't want to try to hook up the sniper on the dyno. Attached is the initial dyno sheet (was a little lean on the pull). Any insight you can provide on things to pay attention to and look out for on the install and initial start up? Thank you in advance!
Wiring is very important with a Sniper since you are feeding a low voltage microprocessor from a 12 volt automotive system. You really need to be super careful when installing the wiring for a Sniper. You also need a really good high pressure fuel system for a Sniper. Holley does make some drop in muscle car retrofit systems that include the pump, regulator and pre-filter inside the tank. I recommend using those whenever possible. Then you only need a high pressure filter and a single pressure line that feeds the Sniper from the tank.
Your engine must have a healthy cam to make 650 hp. In that case it is a good idea that you bought the Hyperspark distributor since you'll want to build an ignition curve with 20 or 25 degrees at idle and then 34 or 35 at WOT. Add 6 degrees of timing at low vacuum and smooth it all together.
Target AFR at idle will probably be around 13.5 to 13.8, WOT target should be 12.8, cruise target can be 14.5. Put those targets in and then smooth the table and you should be ready to go.
Your engine must have a healthy cam to make 650 hp. In that case it is a good idea that you bought the Hyperspark distributor since you'll want to build an ignition curve with 20 or 25 degrees at idle and then 34 or 35 at WOT. Add 6 degrees of timing at low vacuum and smooth it all together.
Target AFR at idle will probably be around 13.5 to 13.8, WOT target should be 12.8, cruise target can be 14.5. Put those targets in and then smooth the table and you should be ready to go.
Yes, wiring is one of my biggest concerns. The fact that the wires for the sniper unit come out the front side near the distributor where are all the plug wires run causes me some concern. I am going to run Firecore spark plugs wires and try to route the sniper wires as far away from them as I can, but there will be areas that will be close. Did you run any shielding on the sniper wires on any of your installs. If so, what did you use?
My other concern is that my battery is going to be mounted in the trunk and it will be a longer clean power wire from the sniper to the battery. Do you think I should be concerned on this long span?
In regards to the fuel system, I went with the whole Holley setup and have the tank and upgraded 400 LPH in-tank pump, so I should be good there. I did have a question on your response above regarding the fuel line. I am about to run stainless hard line for the fuel system and am debating 1/2" or 3/8". The Holley site says 3/8" inside diameter line is required. I am guessing that is equivalent to 1/2" O.D. tubing? What have you used for fuel line in the past? You also mentioned above a single pressure line from the tank. The XFlow unit I am installing requires an external regulator, so I think I need to run a return line to the tank as well?
Thanks again for your above response and insight!
Check the instructions on the in tank pump that you bought. Typically the in tank modules have a regulator built in. You don't need 1/2 inch fuel line with EFI, 3/8 inch will be more than enough. When the pressure is 60 psi you don't need a big line.
Thanks Andy! That makes sense. What about the shielding the sniper wiring? Have you done that on any build in the past?
Here is another video of the car. This video was shot during the initial start up. Headers were open since the exhaust system wasn't installed yet. The car had just been painted but the trim wasn't installed yet. Most of the interior was yet to be installed.
You should've bought the Holley 12-389 muscle car EFI module. If you bought the 12-389 then it drops into the tank and it has the regulator, pump and pre-filter built in. All you need to complete the install is a high pressure line that runs from the tank to the Sniper and a 10 micron filter somewhere in the high pressure line.
If you didn't buy this module then yes, you might need an external regulator as well as a return line.
Holley Sniper EFI 12-389 Holley EFI Fuel Tank Modules - 350 LPH - 1963-1976 A-Body Vehicles
MadScientistMat
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Keep any wire running to the EFI - aside from distributor wires which may give you zero choice in the matter - at least 2-3" away from all spark plug wires.
Just make sure the wire is large enough for its intended current. For a trunk to engine compartment run, you may want to subtract 2 to 4 from the usual wire gauge recommendation for shorter runs.
Also, don't forget the ground wires, which should also be upsized and grounded straight to the battery for best results.
External regulators with EFI (or any pump capable of delivering EFI levels of pressure even run with a carb) always need a return line. You don't want to use a deadhead arrangement as that will send line pressure to the moon upstream of the regulator. When using an in tank pump, you can mount the regulator next to (or even inside!) the tank and use a very short return line, although this arrangement is more likely to have vapor lock and a vacuum reference would be a pain. For normal automotive hard line you can ignore the wall thickness for sizing.
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