Fitting a sniper efi

Gents,
I’m intrigued as to how one would go about fitting a Holley Sniper (or similar system) to a GT40 replica fitted with twin tanks with a (switchable) pair of low pressure pumps fitted. Obviously the efi requires a high pressure fuel pump along with a return so would that mean two high pressure pumps/returns?
Any advice/pictures/diagrams greatly appreciated.
Simon
 
Two low mount Bosch 044 pumps will do the trick. Those Bosch pumps have a one way valve on top. Downside is, those Bosch pumps need a 12mm suply from the tank.
So next option would be as said by Tom, keep your own pumps, add a swirlpot and go with your injection pump from there.
Return goes back to the swirlpot.
 

Ian Anderson

Lifetime Supporter
Simon
Look at the Pollack valve after your existing fuel pumps and into a swirl,pot to feed your HP pump, return from fuel rail to swirl Pot. It sorts the return back to the tank from which the fuel is being drawn.

Ian
 

Jim Dewar

Supporter
Simon,
I used the Pollack valve when installing my Sniper, worked very well. I threw out the Sniper after 2 replacements from Holley and 9 months of torture, returned to my 4150 carb but kept the Pollak valve. My engine builder has installed many Holley Terminater X systems with great success moving the control units out of the engine bay.
The Sniper control unit is contained in the throttle body and has been problematic.
 

Davidmgbv8

Supporter
Just bought this along with the terminator x system
 

Howard Jones

Supporter
As you are deciding on an EFI system be sure to call the manufacture and talk to an engineer NOT a sales rep. Make an appointment if you have to. Before you do measure the at idle intake manifold vacuum on the engine that is slated to get the EFI. Get a copy of the cam card and be prepared to discuss your engine specs at length. You will need to know cranking pressure and calculated compression ratio as well as the advance curve and head specs.

Why? Near race spec and race engines will make very little manifold vacuum. Especially ones with radical cams. ALL of the self-learning EFI systems rely on a broad vacuum signal to create a "map". Without a near-normal vacuum signal, they can't create a valid fuel map. When I talked to one of the Holley engineers about my engine (7-8 inches of vacuum at 900 RPMs) he flat out told me that the self-learning EFI system they sell wouldn't work and I should go with their port-injected tuneable system that is the basis of the NASCAR FI system. He also told me............................

FIND A TUNER FIRST! that can create a map for you. This isn't something that first-timers can usually do. Be prepared to spend at least the cost of the system in labor to JUST tune it. More than likely double. This can turn into several thousand dollars very quickly. Especially if the first guy bull shitted you and you have to find another tuner.

I left the Holley double pumper on mine.
 

Neil

Supporter
The modern versions of the venerable Holly double-pumper are simple, reliable, relatively cheap, and require no computer. They typically run fine "out of the box" and can be fine-tuned with a screwdriver and some spare jets. I replaced a faulty Holly 850 "double-pumper" with a modernized version made by Proform. I bought the "race" version so that I could adjust the secondary idle independently. Another nice feature are the glass sight gauges that eliminate the need to remove a plug and leak gas to check its float level.


This was a truly out of the box installation of my new Proform 850 race version carburetor. The idle was too low and the secondaries needed a little adjustment but it started and RAN without any computer, fuel map, blah, blah...... I'm still running its original main & secondary jets- even for my 157.458 mph run. BTW, the whine is from my using a timing gear drive rather than a timing chain.
 
Strongly advise you don't go for Efi that is self learning. I had nightmares with a similar Fitech system. Fueling is straight forward , i used a low pressure facet feeding into a swirlpot with a high pressure pump inside.

The long and short of it is, you need a perfect sealing exhaust and a decent length tailpipe after the lambda to have any chance of it working, (not good with a gt40 exhaust). Even then it has to go on a rolling road because they only learn the the AFR's you tell it to learn to. And you wont know the right AFR's without putting it on a roller. So if you want EFI use an ECU that is mappable by a local tuner. Went back to a holley carb that actually worked! There are some people that got lucky with them, but a huge amount of people that didn't if you research some of the US forums.
 
I’ve got a brand new sniper setup in the box ready to put on my Cobra, but it runs so perfectly on the carb, I’ve been reluctant to do it all year….
 
Simon, my advise is leave it alone !!!! I've got the sniper on my cobra and have nothing but problems with it !!!!! It's been at the tuner 4 times and still has issues, I've done everything you can think of to correct it but it still has RF interference problems because of the Ford distributor location. They work fine on a Chevy or mopar ! But Ford motor no way !! And before I get a bunch of flack from guys yes I've tried everything !!!! Oh and holly is absolutely no help !!!!!
 
I recently installed a Holley Sniper setup on my GT40 replica but it is a modified Fiero chassis with a Chevy 350 engine transverse mounted with a Getrag 5 speed. That said the Sniper system works flawlessly and is a huge improvement. The only complaint I have is a weird sound made when the throttle is opened up it is a hard to describe but sounds sort of like a farting whistle. I have researched that this is a common trait of the Sniper and is caused by the way air enters the throttle body. I have gotten used to it but was concerned at first. Other than that the car runs great and has made it drivable. The computer is self learning and adjusts to the way it is driven. I am happy with it. I have no experience with the sniper on Ford engines, good luck with your car.View attachment 118479View attachment 118479
V8archie holley Sniper 2.jpg
v8archie GT40 7-20-21 e.jpg
V8archie GT40 10-18-21.jpg
 
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Terry Oxandale

Skinny Man
I don't run the Sniper, but do run Holley's EFI management, and I have one HP fuel pump, with 2 LP fuel pumps (one for each tank), circulating through a swirl pot. Not sure what problem you are facing, but I simply run the sensor to the HP pump system, and done.
 

Davidmgbv8

Supporter
So I have ordered a Sniper Terminator X and is on back order. What I am seeing, in this thread, a consistently that leaks around the pipes to muffler flange and the short overall muffler to exhaust tip are problemantic to the self learn. So whilst Jim with a 350 Chev, has good results from a good sealing exhaust system and no distributor near the computer in the standard Sniper offering, it looks like I will have a lot of tuning in my future to get a Map done. Discussed this with my buddy today that has installed several on classic mustangs and he said once a map is done then you turn off the O2 sensor. So really what am I gaining with the system, less wall wash down of fuel, easier to start when hot? Well you have the MAP sensor to run with your program but considering I may spend a few thousand more with a custom dyno tune, is this really worth it? From comments in this thread it does not appear so. Your comments please as I am thinking of cancelling my order with the Sniper X and keeping the dual sync dizzy with the hyperspark ignition and just running a 4160. I have a 302 stock bore, 9.7:1 compression, comp Xtreme roller 512/512 114 lobe separation which will give good vacuum signal. AFR 165 heads, dual plane manifold. This combo with Richard Holdener testing has dyno results of 396hp on a Deamon 650 carb.

Should I be going the simpler way with the carb vs FI?

Thank you in advance for your thoughts.
 
Richard Holdener, tests his motors with long-tubes collectors, open exhaust pipes , open air in take, electric water pump and an huge corrector factor on air temperatures,
with air filters , leaking(why actually?) exhaust and heat under the clamshell, you will be far away from the 396 hp announced...

if you fit the Deamon 650 on the engine , straight out the box, you dont need dyno sessions to tune? you dont need tho optimise to get the right air /fuel mixture? (same history as the hp..... the straight out of the box carburetors perfect functioning...as you can read on the vendors technical forums....)

if you you gonna keep the hyper spark ignition..... from what and how you will get the perfect (out of the box also?) ignition curve?

at the end..... carburetor or injection, rolling dyno will be needed to compare results and get as near as perfect for what the engine needs.
and most of the times a wide band lambda sensor is used to read results....of the mixture.
to find a guru who still can tune an engine on ear, and read spark plugs , is becoming extremely rare... and will also burn fuel for a good moment to see the results...

Paul
 

Kyle

Supporter
Holley terminator wins every time, at least with the GM motors. As far as ford I’m not sure. Most issues are user error. I can tell you the amount of parameters you can change/edit, add ons, etc are unreal. If you’re track driving and want utmost performance then take it to a dyno. If you have the time, then learn the system and do a street tune. Especially for you guys at altitude that change elevation quite quickly.
 

Davidmgbv8

Supporter
I guess my real question is both carb and FI require tuning, but when said and done, which am I better off with in the end?

I can tune a Edeldrock/Carter easily with a selection of jets and needles using a wide band 02 and driving. I have tSU’s 36 years by ear and plug readings.

I can learn to do a Holley. I know nothing regarding FI and will need to rely on a specialist. One advantage of a carb I can bring to have it engine dyno’d and get the carb tuned most the way while I build the car.
 
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