Another Sniper build tread

New Delphi coolant sensor mounted to replace the Holley supplied.


Coolant and intake manifold temp now matches perfectly.

 

Fuel pressure stability...

I did notice that the fuel pressure gauge was vibrating, and looking at the Holley forums I see that this is a common occurrence for those that are running the system dead-headed with the regulator in the tank (or near the tank)

That kind of makes sense to me since there will be a delay from the injectors opening until the pressure at the regulator have fallen sufficient for it to open and react.
In addition I am using hardline with ~6 inches of rubber fuel lines which makes the system more rigid and can therefore increase the instability.

So I hooked up the scope with a pressure transducer connected to the fuel pressure port.

Fired the car up and this is what I see:

(did not calibrate the transducer, so the total pressure is slightly off, it is 60psi and not 68psi)

Idle car in neutral (so low fuel consumption)

Fuel pressure fluctuates with ~5psi as injectors are opening

1200rpm car in drive, (to add a bit of load to the engine)

Fuel pressure not stable, and 10psi ripple...
So between 53 and 63psi true fuel pressure, very sensitive to load...
Ouch,

I then blipped the throttle, from idle to ~1000rpm and down to idle with the car in drive:




I added a fuel pulse dampener from Radium Engineering and did the same test:

Idle,

still some minor ripple but quite a bit more stable

1200rpm, car in drive:

Quite a bit better, 4Psi ripple

No scope plot of blipping the throttle, but did test that and I could not see any additional ripple.


Now: Is the fuel pressure ripple an issue?
Most likely not, since the system woupd able to tune as it _should_ be systematic for a given load/tps/rpm.
However I would think it gets a bit worse at full load, but perhaps not since as the required fuel is increased the regulator duty-cycle is increased until it is open most of the time reducing the pressure drop...

I also think that if one is using hardlines it will be more ripple than those that are running hoses since those have some "give" and will to some extent act as a pulse damper in them self...

 

Postal services suck across the pond during a pandemic..

I finally got my clips for the injectors.
grateful-fred over at the Holley forums have 3D printed some nice ones that positively fixes the injector connector to the injector.
Link to his thread:
https://forums.holley.com/showthread.php?50157-3D-printed-injector-retainer-clip



Not sure what Holley was thinking when the designed the injector harness but it is really not a reliable connector for automotive use



Fitment of the clip is really easy, just two bolts per side plus the fuel lines need to be removed The clip slides over and one then use a small zip-tie to lock it into place.


I would highly recommend this solution for everyone that is a tiny bit paranoid or that worry about getting stuck on the side of the road

In other news the weather finally cleared up and I got a few miles in the Buick, still only on back roads due to salt on the roads but the drivability is really improved with the Sniper system compared to the old carb setup.

Seems like my "western Europe" road trip is a go this summer.
Did central europe with the Baltics, Poland and the northern part of Germany a couple of years ago.
Will most likely follow the Atlantic coast down to Spain this summer, so drivability and reliability is strongly preferred

 

This has been a great thread and gives me a lot of insight as I am considering an EFI system as well. I do have one question on the in-tank fuel pump... you mentioned one of the advantages of this pump (12-303) is that it does not need a return line, but all of the documentation I have read on the Sniper EFI states that a return line is required for the Sniper itself? What am I missing?

Thanks!

 

The sniper has a build in regulator. If you go return less you cap the return port on the sniper. Depending on your application you could use a small vent line as a return as long a it can keep up with the volume of your pump. I ran new 6an lines from the tank to the sniper and called it a day.