Questions regarding fuel lines/pumps

[guava]

I'm trying to do some planning and have come up with some questions. Use 300 HP as the eventual target.



What is the flow rate and or minimum PSI? (I've seen 3-5 PSI searching the forums but not the flow rate)



Where is the best place to put in a pressure gauge in the lift pump and in the injector pump?



What is the inside diameter of the fuel lines going to the lift pump?



What does a replacement lift pump run?



Surely a couple more to follow... .

 

[ARedetzke]

I can't answer any of your questions, but I have one to add: Would there be any advantage to adding a pusher type electric fuel pump to our existing setup? Maybe helping to lube the pump, (especially the ones that are turned up, or maxed out) or extend pump life.

AJ

 

[guava]

Your question follows in exactly what I want to do. I've read different solutions including an in-tank pump as well as other forms of pumps. Then there seems to be the FASS type fuel systems.



I'd like to eliminate the lift pump without breaking the bank.



With the right fuel flow data, it should be easy enough to do.

 

[Greenleaf]

While you "can't" install a pressure gauge in/on the injection pump, you can install the lift pump or supply pump gauge. You will have to obtain the 1/8" pipe tap banjo fitting in place of our bleeder screw fitting atop the factory fuel fliter mount on the side of the cylinder head.



Depending upon the integrety of your particular system along with mods to the factory set-up, you will have anywhere from 10 to 1 psi on the supply side.



As stated last week by our oun Pastor Bob, more would be better. I do not know the size of the fuel lines as mine are still factory. I would say 3/8".



If you go and add larger fuel lines, what will you do with the pick-up inside the tank? If you increase the dia. of the fuel line outside the tank, you will still have a restiction inside.



Food for thought.



BTW there are many brands of electric lift pumps out there. The FASS is one of many options. Some have filter(s) and some have fuel heaters etc. etc.



-S

 

[JLEONARD]

I'll throw in a penny's worth here.

The first gen lift pumps are generally not prone to failure as the 24 V's are. Yes they do fail from time to time, but even when they do they don't instantly take out the injection pump as they do with the 24V.

I guess the one part of the 1st gen power equation that we don't know much about, or at least it's rarely mentioned, is how much pressure or flow we really need to support various performance levels..... and how much more flow to the VE pump would help, if at all.

Jay

 

[Bob Beauchaine]

Look at my sig - 378 RWHP - no sign of fuel starvation with a factory style lift pump and a "slightly" turned up VE. At 300 RWHP fuel supply is not a major problem. Proper fuel delivery via a "built" or tuned VE, a good set of injectors and some turbo mods will get you there. 400 RWHP takes a little more work.



Bob

 

[dpuckett]

Darnit, Bob, you beat me to it. That's what I get for having something of a life for the moment. ANyway, I would like to add to the list of VE longevity concerns that the pump is only stresed when you ask for the additional fuel/ power. IE, you still use 60hp or whatever to maintain 70mph down the highway. Hence, the spillport in the pump is pulled back that same amount as it is on a stock tuned/ flowing pump. The only differnce in a 300-400hp set up is the AVAILABLE power. You have 2-3 times the power available, but still use the same power once up to cruise speed.



Stock fuel flow is 74mm/ sroke for IC models; 78mm/ storke for nonIC. Each makes 160hp/ 400lb-ft TQ. I'm not sure if power output vs fuel flow is linear, with all else being equal, or if it is exponential to one direction or another. i. e. with stock injectors, and adequate air flow, will 148mm make 320hp? More questions, I'm sorry.



Lift pump- I think the stock set up is adequate- Old Smoky has made 450hp, and still has the stock supply lines, as far as I know. I could be mistaken, though. JLEONARD is right- the LP failures are more attributed to the newer electronic models. One more beauty of mechanical controls. 300hp isnt the elusive goal it was a short time ago- heck, I'd be close if I got a charge air cooler. Based on a few 300-350hp trucks I've ridden/ driven in, and my 1/4mi speed of 80mph, I'd say mine is around 250-260hp, sans intercooler.

Daniel

 

[Greenleaf]

Good Points DP

However, if you perform wild mods inside said VE and only drive it at top speed of 55 mph, to Grandma's house two X's a week you will still wreck it even if it only requires 75 HP to top the hill enroute.



What needs to be undrestood is this; a super tuned VE will deliver like, tons more fuel @ any given RPM when compared to a factory counterpart. There are several examples, one is the fact that when you modify the gov. linkage, the pump is in a higher fuel rate be it 800 rpm's or 3400. Internal stress is internal stress. Another example is the full fuel screw. It delivers more fuel over the entire fuel band, not just WOT. Therer are other examples.



Prior to your arrival @ the last get-to-gether, I explained some of these mods to the 1st gen guys. Also discussed was the reason why the nylon washer under the AFC diaghram is to be made thinner, as opposed to removed entirely.



GL

 

[guava]

This is great information. I should point out that my question regarding the fuel lines is in part due to wanting to correctly run my transfer tank and not have any weak spots where it would cause damage to any of the pump systems.

 

[dpuckett]

Ok, I'm REALLY confused, and it appears I may have led some of the others astray in my explanations. (darn Mapquest- had it not been for them, I would have been at the BBQ an hour earlier). I was under the impression that you used the extra power and pumped the extra fuel only when you asked for it; that it required x mm of fuel to make y horsepower, regardless of what could be obtained by moving the throttle farther. Sorry to hijack this thread, just trying to clear up a lot of confusion. Seems the farther we delve into stuff like this, we end up with more questions than when we started.



-DP

 

[Bob Beauchaine]

Note that I am running a 45 gallon in bed aux tank through two 3 way mechanical valves. I have dynoed with the main and aux tank - once again no problem.



Bob

 

[DieselTweaker]

My two cents worth,,,,, I wouldnt worry about 300hp wont be that hard for you to hit at all and many guys out there are doing on a stock lift pump and lines,but If you upgrade to another pump such as an eletric pump, do away with the factory lift pump, a good eletric pump will be held back by the factory lift pump and acutally take alot of life out of the pump, also if you need some help coming up with diffrent fueling system feel free to email me and ill get you some pics of mine im not sure how much hp I'm running but it keeps up with mine.

 

[Old Smoky]

One thing to remember is that our injection pumps have a timing advance that is activated by fuel pressure. As rpm increases, the internal vane pump increases pressure, and advances the timing. So, if you have an electrical lift pump pushing 15lbs at an idle, the timing will be advanced where it "shouldn’t" be. The advantage of using mechanical pump is that as engine rpm increases, so does fuel pressure (as long as the pump is not conusming all of the fuel). I am using a low pressure pump near the tank, with the stock pump, and stock lines.



As far as the cc's of fuel to hp goes - I have found that the ratio of cc of fuel that the injection pump delivers, to hp, is not liner. Different injectors can make a big difference.

Its funny to think that we can make about 400hp on 200cc, and I've seen p-pumps with 870cc-1100cc make 500-650hp. I guess VE stands for "Very Efficient. " :-laf



Mike