Boost reference on the fuel regulator

UNBROKEN · Jun 22, 2011

The reason I run it referenced, and bear in mind I have a different motor, is that a friend did some dyno testing with and without it on a cr Cummins, picked up quite a few hp in the upper range...over 50 actually. Seems 20psi inlet pressure at the CP3 couldn't maintain enough volume once the rpm's came up. He was draining the rail and losing rail pressure...boost referenced it and the rail pressure came back up and the power came with it.
Truck made 1133 IIRC on nitrous. 900+ on fuel only.
Totally different everything than a 7.3 but that's the background on why I do it.

Charles · Jun 22, 2011

UNBROKEN said:
The reason I run it referenced, and bear in mind I have a different motor, is that a friend did some dyno testing with and without it on a cr Cummins, picked up quite a few hp in the upper range...over 50 actually. Seems 20psi inlet pressure at the CP3 couldn't maintain enough volume once the rpm's came up. He was draining the rail and losing rail pressure...boost referenced it and the rail pressure came back up and the power came with it.
Truck made 1133 IIRC on nitrous. 900+ on fuel only.
Totally different everything than a 7.3 but that's the background on why I do it.

Which is legit. And sitting on the dyno myself once or twice with this very topic in mind, I promptly came to the realization that it didn't make jack-sh*t worth of a difference on a 7.3. I varied the pressure from ~45 to over 80. Zero.... nada.... zip...

I closed the book on that one and just set it middle-of-the-road at 60 and spent time worrying about other things. Maybe some others have done similar testing, or can hop on the rollers and do some now to either support or contradict my findings.

Gearhead · Jun 22, 2011

Charles, is the refil port on your injectors enlarged? If so that may be the reason you don't need the pressure to keep up.

TARM · Jun 22, 2011

Point well taken on the gasser comparison and yes I agree reasons are completely different.

Refill time was the other part in my post. It is also something I do not know what is the exact answer and depending on mods like Matt speaks of. I simply do not have the hands on or knowledge of the answer. I am speaking of what is the min amount of pressure needed to fully refill a well worked over 400/400% running max usable pulse width @ 2500, 2700, 3000, 3200, 3400 etc RPMS as an example? That is the other reason I can see for boost ref combined with pump life. I believe Dave or someone else from Swamps had posted on this subject recently here on PSA.

Further would not a one way check valve that works with air and fluid completely address the dangers of runaway scenario? Maybe there is a reason this woudl not work. But I have found a number of small valves rated for both air, water, and oils. Any reason this would not work as the failsafe to prevent the rupture diaphragm leak back created runaway event?

I know the answer seems to be just run a Fuelab pump @ whatever reasonable psi you wish 60-75 whatever as its brushless and running @ reduced speed. I also know you have had great luck with them. The one I have has failed twice now in I think a year. Stuck on the side of the road is still stuck brushless or not. It is also the loudest damn pump I have ever heard of this size. So its going back soon to be fixed again. I think the answer for me as I am not wanting to deal with the fragility of these electric pumps in general is to work on setting up a gear driven pump. They have nothing to burn up, electronics to fry, pressure issues, heat problems etc. The shaft turns and it pumps. The flow climbs with rpms and needed flow.

For whatever reason this damn fuel system has been fighting me on the most simple crap. After messing with trying to set fuel pressure I found the gauge sent with the regulator is a POS and simple light twist or tap changes the pressure reading dramatically. Just another stupid issue that's my fault for using what is now clearly a cheap gauge.

Tom S · Jun 23, 2011

Tarm does your check valve not hold the pressure on the other side of it?

TARM · Jun 23, 2011

Well there ya go putting a kink in it. Was just to simple. Obviously that's an issue. Its going to negate the reference the first time it sees 20psi its going to hold. Thank you for pointing that out. Saved me from self-enlightenment later after spending time and money. LOL

2stangs8689 · Jun 23, 2011

Good read, as this was a question I had when contemplating a RR system, and why no boost reference.

For the guys worried about pump life, what about a Aeromotive Pump controller? Drops voltage to the pump, extending life, wear, less heat, and kicks up to a higher voltage with either a RPM reference, or a override switch?

Charles · Jun 23, 2011

2stangs8689 said:
Good read, as this was a question I had when contemplating a RR system, and why no boost reference.

For the guys worried about pump life, what about a Aeromotive Pump controller? Drops voltage to the pump, extending life, wear, less heat, and kicks up to a higher voltage with either a RPM reference, or a override switch?

It's easier just to get a good pump and let it sing. Hopefully some people can get on the dyno and see some results. Or.... better yet, just do some bench testing and note any flow changes with varying pressure and varying rpm.

Would be good to know the minimum pressures for various rpm/quantity points.

Arisley · Jun 23, 2011

Charles said:
I hope to see a sled hooked to the truck in the background. Just back up to the sled, then when the guy's hooking everything up you pop the hood, hop out and fill the intercooler, then cinch down the clamp, slam the hood, hop back in and win the 3.0 class by a landslide...

Not sure if I would be wanting to be the one sitting four feet or so away from a motor in runaway. At the end of it, the entire front of the truck might be missing. It would be a hell of a ride though.

Charles · Jun 23, 2011

Arisley said:
Not sure if I would be wanting to be the one sitting four feet or so away from a motor in runaway. At the end of it, the entire front of the truck might be missing. It would be a hell of a ride though.

Just need to calculate the necessary quantity of diesel to pour into the intercooler for a ~300 foot run +/- a few feet's worth. So what if you sit and spin at the end of the track a bit with the guy diligently waving his little red flag at you, lol.

Tree Trimmer · Jun 23, 2011

and eventually hopping up and down yelling "STOP DAMMIT"

TARM · Jun 24, 2011

Charles said:
It's easier just to get a good pump and let it sing. Hopefully some people can get on the dyno and see some results. Or.... better yet, just do some bench testing and note any flow changes with varying pressure and varying rpm.

Would be good to know the minimum pressures for various rpm/quantity points.

That is what I would like to know as it would answer the question of needed min fuel pressure. Then we would know what is needed.

Tom S · Jun 24, 2011

Has anyone ever done say a stock SD pump that ran all the time combined with say a fuel lab that would come on at 10lbs of boost via a hobbs switch and a relay?

Aljay · Jun 24, 2011

Tom S said:
Has anyone ever done say a stock SD pump that ran all the time combined with say a fuel lab that would come on at 10lbs of boost via a hobbs switch and a relay?

No I have 2 S/D style pumps running full time tho , I was able to tell the other day I was running out of fuel at WOT .
I like your idea but right now time is precious soo no time to play with this idea well time and money .

budro · Jun 24, 2011

Tom S said:
Charles how much fuel did the regulator piss out when it ruptured?

Chuck already answered, but I have a photo of mine when it ruptured in April. I had mine dumping in the valley since the install, for the run away reasons he described.

It would not leak KOEO with 65psi on the gauge, but would idling. I have no idea if the flow increased....drove it home 20 or so miles like that.