Anybody with regulated fuel return read this!

madpowerstroke

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Hello, I know I may catch hell for this but here it goes. I talked to Rene at quick tricks one day and he told me some interesting info. He said he has been doing a lot of test trying different things out to see how it effects horsepower and track times.

So he told me he was raising fuel pressure past 65 psi to see what would happen, well truck ran sluggish and slowed in track times. So he went the other way and truck kept getting faster and faster, he stopped at 45psi, regulated return.He told me trust him and try it, well since I had my regulated return set for 65-67psi I tried it. Well geuss what it worked I lowered to 50 psi and dam, truck felt stronger and quicker. Egt's also dropped 100-150 degrees, I know this makes no sense but it works, my fuel mieage increased abou 2-3 mpg.

Since it worked fopr me I told Nate(windrunner408) well it worked for him to all of it. So I past the info to Chris (strokin 6L) and worked for him, but can't say anything about mpg.

I talked to my injector build and he told me dropping psi to 50 or even 45psi, will not hurt the injectors at all, I still feel better at 50psi tho. International says that 44 min for fuel pressure so I guess they do know their engines.

So basically what I'm saying is if you have a regulated fuel system turn it down to 50 psi and you will see a differance, and if you do get on this thread and tell everyone. Any info I find that works and doesn't hurt truck I will always share, just to make the 6.0's better. So trust me on this and try it, I know it sounds nuts but it does work. It works great for bigger than stock injector and stock.
 

faster6.0

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I tell customers to do this all the time, if your pump does not keep up with the psi demanded by the regulator at that psi,Running less psi on the regulator will increase return line psi and will Not run your pump dry as fast. 65-70 is ideal if you have a pump that will maintain the psi with enough volume. You won't see a power gain if you are maintaining the higher psi with a properly sized fuel pump and reduce the psi, either. So really only beneficial to those not maintaining psi at 65-70, but still great info.
 
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Strictly Diesel

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if your pump does not keep up with the psi demanded by the regulator at that psi, more psi on the regulator will increase return line psi and will run your pump dry as fast.
Say what? That made no sense at all!

1. Regulator isn't making any demands on the system. It's a dumb device that simply opens or closes based on pressure. The fuel injectors and programming make demands on the fuel system, the regulator simply attempts to maintain pressure by closing and reducing return FLOW (back to the tank) during times of high demand.

2. "more psi on the regulator" (that would mean turning the pressure UP) does NOT "increase return line psi". It you turn the pressure up, you are holding the diaphragm closed and reducing return flow. If you reduce return flow without changing the backpressure in the return line, you will effectively reduce return line pressure (not that we care about return line pressure).

3. Unless you have the regulator adjusted to such a low pressure that the return is always open and flowing too much fuel back to the tank, the pressure setting on the regulator has nothing to do with "running the pump dry". With a properly designed fuel system and properly located and adjusted regulator, the only thing we care about is volume. If you have enough volume for the demand (injectors and programming), you will not have pressure drop. If your demand exceeds the flow capability of your pump, you will have pressure drop. In order to "run the pump dry", you would literally have to have the pressure drop to 0psi.

The only thing I can think of that might explain what you are thinking is this example. Lets say you have a truck with the pressure regulator set at 65psi. When you go to WOT, the fuel pressure drops to 50psi. If you turn the pressure regualtor down to 50psi and go to WOT again and the pressure now holds steady without dropping, did you change anything with regard to the pump? The answer is NO. In the first run, the pump was moving enough fuel to maintain 50psi of pressure at WOT. In the second run the pump was moving enough fuel to maintain 50psi of pressure at WOT. More than likely the regulator was closed and returning no fuel during both runs, since the pump was at its limit for the demand. The only difference between the examples is that the pressure would be higher at less than WOT in the first test and the fuel pressure gauge won't be dropping in the second test. The pump didn't "run dry" in either case...and in both cases the pump isn't moving enough fuel for the specific demand of this combination...assuming 65psi is the target pressure you want to maintain.

You won't see a power gain if you are maintaining the higher psi with a properly sized fuel pump and reduce the psi, either. So really only beneficial to those not maintaining psi at 65-70.
I can't comment on the power gain with lower pressure because I've never tested it. We've always recommended 60-65psi because that's what the injector builders we've talked to wanted to see to prevent injector failures.

As for whether this is only beneficial to someone that's not maintaining pressure...see my example above again. 50psi because that's what the regulator is set at and 50psi because that's all the pump will support is still 50psi at the injectors. Either way, there has to be enough fuel volume to the fuel rails to make that pressure. If the engine really makes more power at 50psi, why don't we have people reporting that their truck feels stronger when they stomp the pedal and the pressure drops?

I think that this calls for more investigation...but I can tell you that all of the trucks we've worked on felt much better with 60psi+.
 

TooMuch03

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I am intrigued by this, but I am not understanding how the pressure to the injectors can have any impact on how the fuel burns. IMO the flow to the injectors is far more important than pressure. As long as you have sufficient flow feeding the injectors, how can having more or less pressure feeding the injectors matter?
 

faster6.0

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This is not true (at least in my case and four others so far). There is an optimal pressure to run our injectors at. Yes the minimum spec is 44psi (per International) but nonetheless, there is an optimal pressure. I have a fuel system that is totally capable of flowing 70psi of fuel all day long for my injectors and when I lowered it from 62-64 psi to 46-48psi (at the regulator after my fuel has gone through the heads), I noticed that my truck ran quieter at idle, my throttle response improved, turbo response improved, I have less smoke with a nice run to 70 mph, cruising EGTs are lower (dropped easily 20-30F and am now at about 700F at 70 mph on perfectly flat ground), my EGTs also seem to not rise as quickly as they did before when I go up a hill, and it is looking like I can go further on my tank of fuel. So whether or not lowering the fuel pressure to this level is the optimal way to do things or not, I am planning to leave my fuel pressure here. JMO of course.

do you think an egt drop is because the injectors are getting/using more or less fuel?
 
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Strictly Diesel

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I am intrigued by this, but I am not understanding how the pressure to the injectors can have any impact on how the fuel burns. IMO the flow to the injectors is far more important than pressure. As long as you have sufficient flow feeding the injectors, how can having more or less pressure feeding the injectors matter?

Conceptually it shouldn't, but we all know that concept and reality don't always match.

In all the years I've been doing fuel system work I've had a number of customers tell me that their truck ran better at Xpsi instead of Ypsi. There are those people that will just set it where we specify in the instructions and those that experiment and find the "sweet spot". Every customer that ever experimented and reported back was different. Some were lower, some were higher...but all generally settled on something in the 60-70psi range.

This tells me a few things. First, not every truck is the same (obviously). Differences in injectors (size, tolerances, age, wear, o-ring condition, etc) will certainly play into this. Second, not every customer is the same. Different people are sensitive to different sound frequencies, volume levels, vibrations and butt-dyno tolerances.

In the end, unless someone wants to do dyno testing on multiple vehicles to prove the concept...and then do long term wear results (making sure that the lower pressure isn't contributing to premature injector wear)...the final pressure people end up running will be very subjective and based entirely on how the truck "feels and sounds".
 

Ross@Flyindiesel

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trying this tonight when i get to the truck. and ive got dyno results at 60 psi and will have dyno results on the same tune and everything oct 20th so we will be able to see if there is a gain and how much, granted that the truck isnt one of those odd ball ones and seems to loose power instead of gain like everyone else.
 

windrunner408

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do you think an egt drop is because the injectors are getting/using more or less fuel?

I think that when it comes down to making clean and efficient power, it takes things being set up properly so everything works together (in harmony essentially) and doesn't end up fight anything else. I think that my EGT drop could be due to a better atomization of the fuel for a cleaner burn. I guess there could be less fuel but perhaps the flow being delivered to the injector is more laminar than before so the fuel flows into the port on the injector easier. Of course this is all purely conjecture. I just look at it from the stand point that a smart engineer put a specification out for a minimum pressure of fuel be delivered to the injectors (for a specified amount of fuel flow for a given volume) and the injector builders know that by running too low of a fuel pressure ends up resulting in not enough fuel flow to the injectors and there by leads to premature failure of the injectors and therefore probably build in a large factor of safety. I agree with Dennis below in that it is really going to take some long term standardized testing on a lot of different trucks to fully know what the deal is. I know I have talked with the injector builder of my injectors and he is fine with me running the pressure where I have it. I also figure that I have more than what is at my regulator in the fuel rails due to it being further down the line so I am going to keep it where it is for now anyways.

Conceptually it shouldn't, but we all know that concept and reality don't always match.

In all the years I've been doing fuel system work I've had a number of customers tell me that their truck ran better at Xpsi instead of Ypsi. There are those people that will just set it where we specify in the instructions and those that experiment and find the "sweet spot". Every customer that ever experimented and reported back was different. Some were lower, some were higher...but all generally settled on something in the 60-70psi range.

This tells me a few things. First, not every truck is the same (obviously). Differences in injectors (size, tolerances, age, wear, o-ring condition, etc) will certainly play into this. Second, not every customer is the same. Different people are sensitive to different sound frequencies, volume levels, vibrations and butt-dyno tolerances.

In the end, unless someone wants to do dyno testing on multiple vehicles to prove the concept...and then do long term wear results (making sure that the lower pressure isn't contributing to premature injector wear)...the final pressure people end up running will be very subjective and based entirely on how the truck "feels and sounds".

I agree completely Dennis. This is why I just post up what I noticed with my truck and if others want to try it then all the more power to them. I think the only way to really know is to do a lot of standardized testing with different trucks.

I liked my strictly diesel RR kit.
 

madpowerstroke

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I hope that this post stays, and some of the stuff gets edited. I actually thought that I was going to get nailed on here about the reducing of the fuel pressure. I'm glad that Dennis came on here to give input on all the things he has seen as far a customers and pressure.

So far 3 out 3 trucks have been made happier, and I'm not saying it will always be the case. Just something for members that have a regulated return system to try without hurting the injectors or anything else.

Like I stated before Rene did run on dyno testing fuel pressure and that is what he found on his truck, lowering gave him more power. I would like to hear from members that do try this, good or bad.

Hope this post gets back on track about what it was intended for, just to provide so info and maybe make somemore 6.0 powerstrokes alittle better.
 

PTSUPERD

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Just cleaned this thread up out of respect to Adrian. Good info here. Please keep it on track and post with respect. I must say the dogpile mentality is aging.
 

Pizza pig

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I have my FP gauge set at 60psi, it doesnt move on WOT run with thirsty 205/150s and a fuelab pump. Since it couldnt hurt, maybe ill test this out.
 

madpowerstroke

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Just cleaned this thread up out of respect to Adrian. Good info here. Please keep it on track and post with respect.

Thanks, I was typing the reply as you were cleaning it up. Like to hear from the members on here after they try this out. Like I said before won't hurt anything and it may help their trucks out.
 

hawgdoctor

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Also interested in this. Will be playing with mine to see what the results are. Will report back what seems to be the "sweet" spot for mine, and the other shop truck. Good info dennis, and still waiting on your phone call lol..... j/k I know you're a busy man.

Sent from my DROID RAZR using Tapatalk 2
 

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