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Working on a "next-level" fuel system

n8in8or said:
I should also see what the Raptor 100 should need for a suction line. I'll use the 100 gph figure of course, and also the desired 2 cfm based on me driving in a cold climate.

So 100 gph = 1.67 gpm

(1.67 gpm x .3208)/2 cfm = .2679 sq in.......that works out to a RADIUS of .3747, so that means the ideal suction tube at those criteria would have an INSIDE DIAMETER of .292" or a little under 5/16" ID. So the existing 3/8" tube is ok currently.....except that I know if necks down to a much smaller size at the factory o-ring seal. I don't know if it's really impeding pump performance right now, but it certainly isn't helping. That's interesting stuff.
Click to expand...
TYPO ALERT! I was rushing to get this posted since my lunch was ending and I totally screwed this up. Let’s try again. The .2679 sq in is correct, but past there the numbers are wrong. This actually works out to a RADIUS of .292”, which of course works out to an INSIDE DIAMETER of .584” or a little over 9/16”! So maybe the current suction tube is a bigger problem than originally thought?
 
spdgofast said:
Hey guys, I was tossing around the idea of running a return line to the fuel filler hose, not a good idea, here's some good info relevant to this thread...
Click to expand...
That is an awesome demo, thanks for posting that! Ratman had told me it was important that the return was submerged, but I had no idea how much of a difference it would actually make. And that electronic regulator is badass! I need to look that up, I bet it's a few more coins than the mechanical one.....
 
n8in8or said:
Is the surge tank just a reservoir or is it a tank with a pressurized bladder?
Click to expand...
Its a reservoir w/o bladder for this purpose w/internal reservoir pump or external pump w/regulator configuration and short travel 'feed' to your IP making sizing your feed line short & sweet.
 
Last edited:
n8in8or said:
TYPO ALERT! I was rushing to get this posted since my lunch was ending and I totally screwed this up. Let’s try again. The .2679 sq in is correct, but past there the numbers are wrong. This actually works out to a RADIUS of .292”, which of course works out to an INSIDE DIAMETER of .584” or a little over 9/16”! So maybe the current suction tube is a bigger problem than originally thought?
Click to expand...
That's Murphy, as you age he will be by more often than not...............;)
 
JayTheCPA said:
A simple device (commonly a spring loaded ball valve) where it opens and diverts fuel to the return path in order to prevent too much pressure within the line. It is similar to a check valve, except it will allow fluid to pass (one way) when the conditions are right. Purpose is to maintain up to a maximum pressure in the line and spill fluid when pressure tries to go over that point.

Here is an example:
http://www.murcal.com/Catalog/Check...-Fuel/PRV50-Diesel-Fuel-Pressure-Relief-Valve

Page 2 of this PDF has a schematic:
http://shopping.na3.netsuite.com/co...3876&c=650659&h=25bb783bfa4f3e4e145f&_xt=.pdf

Apparently the DMax uses one and the LB7 version is noted as the most robust (per Kennedy Diesel).
Click to expand...
ak diesel driver said:
Isn't a regulator with a built-in return fulfilling the same purpose as the bleed valve?
Click to expand...
JayTheCPA said:
That is my understanding . . .

But then again, I am just a bean counter and not an engineer :D
Click to expand...

So looking at those relief valves, I think those are intended for and will work the best as a safety relief device. If you look at the specs you can see where they have a pressure where they start to open and then a pressure where they're fully open. That won't make for super precise pressure regulation. In fact that's about the pressure spread I have right now that I want to correct.
 
FellowTraveler said:
Its a reservoir w/o bladder for this purpose w/internal reservoir pump or external pump w/regulator configuration and short travel 'feed' to your IP making sizing your feed line short & sweet.
Click to expand...
Hmmm, I'm not sure that would guarantee consistent pressure. It will make sure you don't starve of fuel, but without a bladder to maintain pressure I don't see how it would maintain a constant pressure. It would be just like a water tank for a home well system that has a bad bladder - the water pressure rises and falls with the pump responding to the action of the pressure switch. However an intact pressure tank with a good bladder maintains steady pressure despite the pump cycling on and off with the demand of the pressure switch. Unless I'm missing how the tank you are referencing is designed?
 
spdgofast said:
Hey guys, I was tossing around the idea of running a return line to the fuel filler hose, not a good idea, here's some good info relevant to this thread...
Click to expand...
You know you could still use the fuel filler hose for a return.....you could use it as a conduit to drop a smaller hose down to the bottom of the tank. I don’t know if there’s much of an advantage to doing that, but just a thought in case it helps.
 
Your well system example is correct.
A surge tank is to have more volume of fuel at the ready, but without a secondary pump (and regulator system) the pressure has to be maintained by the primary pump. But it makes the primary pump run at a more constant speed instead of cycling so bad.

The difference of an accumulator sytem is a bladder to equalize the system by an outside pressure source.

Pulling the fuel tank and making increased supply and lp return (along with still needing the ip return sized according to pump builder specs): a major pain in the butt. However once it is done, the knowledge that it is never again a problem is worth it on serious hot rod imo.

That draft/ return kit they showed in the second video looks pretty enticing, especially if they have multiple sizes available.
Factory assy for gauge and ip return line and 2 new tubes for supply and lp return.
 
Will L. said:
Your well system example is correct.
A surge tank is to have more volume of fuel at the ready, but without a secondary pump (and regulator system) the pressure has to be maintained by the primary pump. But it makes the primary pump run at a more constant speed instead of cycling so bad.

The difference of an accumulator sytem is a bladder to equalize the system by an outside pressure source.

Pulling the fuel tank and making increased supply and lp return (along with still needing the ip return sized according to pump builder specs): a major pain in the butt. However once it is done, the knowledge that it is never again a problem is worth it on serious hot rod imo.

That draft/ return kit they showed in the second video looks pretty enticing, especially if they have multiple sizes available.
Factory assy for gauge and ip return line and 2 new tubes for supply and lp return.
Click to expand...
I didn’t see the second video. I’ll have to find what you’re describing.
 
A DIY surge tank/swirl pot is usually plumbed into your stock fuel system with low pressure lift pump feeding the surge tank/swirl pot with a fuel return from surge tank/swirl pot back to main tank from here your IP feed line has a pump & regulator either internal or external, the return from the IP then goes to the surge tank/swirl pot not back to the main tank. 'Feed & return line sizes are critical.'
 
FellowTraveler said:
A DIY surge tank/swirl pot is usually plumbed into your stock fuel system with low pressure lift pump feeding the surge tank/swirl pot with a fuel return from surge tank/swirl pot back to main tank from here your IP feed line has a pump & regulator either internal or external, the return from the IP then goes to the surge tank/swirl pot not back to the main tank. 'Feed & return line sizes are critical.'
Click to expand...
Sounds complicated. You said you’re making one for your Cummins swap? I look forward to seeing that and learning.
 
n8in8or said:
Sounds complicated. You said you’re making one for your Cummins swap? I look forward to seeing that and learning.
Click to expand...
Think of it as more of a means to bring the fueling from the main source closer to the IP on the diesel which in turn allows for shorter line runs between your aftermarket pump & IP......

Lest we forget you are in a realm that most have just dreamed of for decades w/your 6.5td 'so new & seemingly strange things may/will come into play for the next level of your 6.5 & its performance.
 
n8in8or said:
So looking at those relief valves, I think those are intended for and will work the best as a safety relief device. If you look at the specs you can see where they have a pressure where they start to open and then a pressure where they're fully open. That won't make for super precise pressure regulation. In fact that's about the pressure spread I have right now that I want to correct.
Click to expand...


That was just one example for illustration. There are others out there that have firm open / shut points ;) Found adjustable ones too.
 
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