Has anyone installed the Vargas shotgun yet?

[Itsbrokeagain]

so we're finally up and running, Justin managed to set some time aside over the past few days to tweak the tuning for this car and so far we're having zero issues. No misfires, hiccups, nada. Currently at the limit of 93 alone with 20.5-21 psi and getting zero corrections, or maybe -1 here and there if ive been sitting in traffic or its hot and humid.

Stock tune or JB4 I used to get all sorts of corrections with the same mods and only at 14-15psi, sometimes -4 to -7.

Both in-tank pumps running and getting 90-100psi on the lowside, but I am seeing the flunctuations that @martymil was getting when the second HPFP comes on (running stock AIC maps from Vargas), I see 3400 psi or so rail pressure and zero
droppage, but the low side flips a shit (not sure if Im at the end of range with the stock low pressure sensor). Next year mods include the Flex Fuel add-on and re-doing the LPFP hoses.

Beforehand we were running an OTS 2+ map on GCs and the car hit way too hard, lighting the tires up everywhere even into 4th. That was at 18.5 psi.

Got a half tank in it now and going to add a splash of E85 and see what she does. Quite satisfied with how the car turned out after months (and years) of setbacks. Props to Vargas and PR for providing quality parts and Justin for working his magic.

 

[martymil]

What your seeing is the hpfp pumps switching really quickly and fighting for control causing fuel pulses in the lpfp line, it happens on large hp pi only cars too.

You need to run a return line and fuel reg before the pumps and move the lpfp sensor before the reg or on the reg which will smooth the wild swings right down to almost non existant on the lpfp side

 

[Itsbrokeagain]

What your seeing is the hpfp pumps switching really quickly and fighting for control causing fuel pulses in the lpfp line, it happens on large hp pi only cars too.

You need to run a return line and fuel reg before the pumps and move the lpfp sensor before the reg or on the reg which will smooth the wild swings right down to almost non existant on the lpfp side

Got it. I guess we'll be looking into that come next year when we do the Flex Fuel addition to MHD. Going to let that development ride for a bit and allow people to refine it and the programming before we add it to the car.

What do you have your regulator set at pressure-wise?

 

[Erichale77]

@martymil Didn't you use Radium fuel pulse dampers to fix this issue?

 

[martymil]

It helped but the most effective way is the way i just mentioned and will remove 90 % of the swings and run the damper to smooth things right out if you still get them.

I run my static pressure at 75psi with no boost reference

Need to set it while car not running to stop the ecu trying to correct the lpfp pressures down to 72 psi

Easiest way is to trip your stage 3 lpfp hobbs switch to flow fuel while you adjust the reg

 

[Erichale77]

So you're not using the fuel dampers then, correct? I have external fpr coming from my pi rail now. You're saying i should place fpr before my fuel line splits off to both hpfp's and pi rail??

 

[martymil]

if you have a single shotgun and pi your hpfp pressures and lpfp pressures should be normal especially with a return line.

Leave you fpr on the return line from your pi rail as it was.

if you have a double barrel you must run a fpr and a return line before the line split to both di pumps and have the lpfp sensor on the fpr to stop the pulses from the fast switching solenoids on the di pumps.

If you still have swings I would put a damper on the overdriven pump line as close to the pump as possible for best effect.
But really anywhere between the fpr and di pumps will do.

 

[Erichale77]

Thanx for the info Martymil. I have double barrel and PI FWIW

 

[martymil]

Ahh right, do you get swings on the lpfp line ?

 

[Erichale77]

Haven't checked for that yet. I was starting to run lean above 850whp so I detuned it and decided to upgrade my fuel line and lpfp setup first. Having it installed now so i'll have more logs and dyno results soon. Plan on taking it to the 1/2 mile event in Oct here in Ocala, FL on the 20th

 

[martymil]

Yeah its only to stabilize the wild swings on the lpfp side which in turn helps settle things down on the hpfp somewhat but not totally.

As im not pushing for a huge number and keeping things under 600hp the double barrel was the perfect choice

Occasionally ill push it further, like track days and dyno days.

But anything between 5 & 600hp is barely drivable and the car trying to kill you at every turn

At least at this power level with forged internals i can see the car lasting a long time

 

[TSRfast]

I have not given up on this for the 335xi. I do think that this is possible to mount the HPFP on top of the alternator. Even using the shotgun. the key is going to be is it long enough to mount behind the alternator. I found a simple bearing mounted shaft drive used for a polishing bufferwheel. I would seem to me that if we can get the HPFP fitting on one end of this and a serpentine pulley on the other end.. To mount it to the alternator mounting holes you could use a bar plate under it as i doubt the holes line up. https://www.grizzly.com/products/Grizzly-5-8-Heavy-Duty-Portable-Shaft/H8025

Another ideas for Tony.. if you can provide the length of the shot gun.... and even make one longer I think his unit would work with some spacers and if need be a mounting plate.

This would not only be for the 335xi.. allowing RWD cars to mount on the top by the alternator would be a nice option.

Anyone figure out a work around to get the shotgun to fit XI cars? I would love to ditch PI if I had a solid solution...