How many GPH @ 500hp and WOT?

[Matt400]

I know I read it here somewhere, can't find it...

How many GPH of fuel is required to feed the Cummins at 500hp and WOT?

 

[Hokey]

That is an interesting question I wonder how that equates to $/hour :-laf

 

[TPCDrafting]

How many GPH of fuel is required to feed the Cummins at 500hp and WOT?

Planning a road trip? :-laf

 

[JBlock]

using 500HP at WOT, man that will be a fast trip. More seriously sizing the pusher pump now are we/

 

[Matt400]

More seriously sizing the pusher pump now are we

yep. . thats the line I was thinking. I don't run 500hp but if I am going to make any changes I may as well do it once.

After reading through this thread it looks as though 60gph should be plenty to fuel a WOT operation while also providing the return flow requirements.

 

[rweis]

I think a lot of pumps are rated at 0 psi free flow. When we then up the psi the flow rate changes substancially. Just know what flow rate at what psi the pump is rated.



RASP?



Bob Weis

 

[Matt400]

RASP?

Hey Bob,

I have looked at the RASP and can't knock that set up at all other than having to cut part of the fan blades off and its kinda spendy.

I need some input as to why a second pump like a Holley Blue for example is not a good idea because that is what I am thinking.



Not to run it all the time but to be triggered to come on below a set pressure so it is an "on demand" set up. Seems nobody does that. The ones that run the Blue take off the stock lift pump.



I would like to run both so the Blue handles only high demands thus making it last much longer and act as a back up should the OE fail while keeping the system quiet.



A curve thrown into the mix is that my 03 would get an 05 style in-tank lift pump should the OE fail so I would have to plan for that in the plumbing.

 

[MD500E]

From my experience I would guess about 43-47 gph. 60 gph should be a safe bet.



Kevin

 

[rweis]

The reason I brought up the GPH @ psi is some pumps for marketing purposes will say "150 GPH". That is true with ZERO head psi. Put 15psi head pressure on them and they drop to less than 1/2 (some even less than that) the stated gph.



I have my "on demand" pump in my tool box 50k on the OEM so far, but a NIB just waiting for that point in time (which will happen).



As has been discussed a 10**6 times, ANY electrical pump will fail. Just when and the nature of the failure. The idea of a automatic, in place, backup is probably not a bad idea. Would have power and flow to consider when designing the system.



The RASP is a totally different approach is why I mentioned it. It also uses the OEM lp for a couple of seconds on startup, and as a backup if RASP failed.



One TDR member does a gravity feed out of the bed and has no pumps if I remember it right (been a while since I read that one).



I accept eventual lp failure, but do everything I can to make it as easy on a weak system point as I can. Stanadyne every gallon EVER, lp mounted on the frame by the tank, RACOR 690 (w/ 10 micron filter) right as it comes out of the tank (NO water, NO particulates in the fuel system), bypass (set @ 12 psi) after the lp so the lp runs at the low end of its range electrically with less strain (lower ampaerage draw, cooler, more constant speed), bypass to KEEP THE LP BYPASS VALVE CLOSED - a real source of failure, AN-6 lines throughout and no banjo's, all full flow fittings, fp post OEM lp, fp pre VP input. Carry a spare lp & ff and the tools. That is everything I know to do short of a RASP ($$$$).



Your "hot swap spare" is a good idea, BUT: It is a fuel SYSTEM. Examine EVERY part of the system from the fuel pump dispenser at the fuel stop to the exhaust gas comming out of the tailpipe. Make it as easy as possible with every system, sub system, sub sub system and that's all you can do. Maybe go ahead and put the in tank pump in now and be done with it. Maybe now that DC has FINALLY done the in tank LP we all should go that route. Maybe put the in tank lp in as the parallel backup?



Bob Weis

 

[2broke2smoke]

stanadyne every tank?



sounds pretty expensive ...



300 miles per tank = 100 fillups every 30,000 miles = 300 fillups by 90k (which is when my original liftpump started reading low on gauge)



so how much $ in stanadyne are you using per fillup?



if it's 3$ per tank you're at $900 by 90k



by 120k (where my truck is now) you're at 1200$ or the price of a new VP-44



does that sound about right?

 

[rweis]

I buy my Stanadyne in 5 gallon cans @ $105 from South East Power Systems Orlando store.



$105 for 640 oz = . 1641/oz * 8oz/30gal = $1. 3125/30 gal = . 0438 / gal, 18 mpg = . 0024 / mile * 25,000 / year = $60. 76 / year.



Your cost is based on your mpg.



VP cost $1200 / . 0024 / mile = 500,000 miles and I would have paid for a VP from the cost of the Stanadyne.



LP cost $132 / . 0024 / mile = 55,000 miles and I would have paid for the cost to replace a LP from the cost of the Stanadyne.



I have 50k on my Lp right now, and it may well quit tommorow, but so far 12psi very steady.



Of course the bottom line is we each do what we want to for whatever reason. Yes Stanadyne does add . 04 per gallon of fuel, and I accept that for the peace of mind.



Bob Weis

 

[Matt400]

My thoughts were not to use it as much of a spare but more for added fuel I need with a box.

Plumbed in parallel when system pressure dropped too low the extra pump would come on. . plumbed that way would also allow it to function as an automatic back up.



I am looking into the intank pump but don't want to find out too late that its a bad idea. One fella posted his 05 will drop to 0 psi with a box. If I were to do that update it would be more difficult to plumb around the pump.

 

[2broke2smoke]

excellent reasoning mr weis, i stand corrected ...