Why high fuel pressure on P7100?

turboman1

turboman1

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What is the reason behind running a lot of fuel pressure on the P7100. I mean what is the difference between running 100gph through it at 16psi or 100gph through it at 45psi?

I would think more psi would advance the timing a little but not that much. So what are the other reasons?

Thanks
Adam
 
the pump doesn't have to work as hard to make injection pressure, and I would assume you end up with a little higher pressure at the injector
 
Ok i can see that, but isn't that work pretty minimal since the pop off pressure is in the thousands?

Thanks
Adam
 
I think it has to do also with speed, at higher engine speeds there is a lot less time in milli seconds to fill the plunger, more pressure should fill faster. I am talking max hp high rpm, now between 16 and 45 psi I wouldn;t think there would be much difference.
 
I believe jim fulmer and a few other people found that there is no power gain above 45psi.. When you pressurize fluid going to another pump you are 'supercharging' the pump, so theoretically the more fuel you can squeez in the plunger before port closing, the more volume that will be displaced.
 
Isn't diesel a non compressible fluid... so how can you fit more into the barrel?

Adam
 
the seal between barrel and plunger wall isn't perfect, so if there is air in the barrel from any kind of fluid turbulence, theoretically it should be forced out or compressed.. in a perfect world there would be no air and pressure wouldn't matter.. i made 10rwhp on a dyno by changing fuel pressure from 10psi at WOT with a factory lift pump to 25-30 at WOT with an air dog..

p.s. if the barrel is full at port closing all the pressure in the world isn't going to help or hurt you..
 
I thought the air dog removed air from the diesel. Would that cause any gain?

I am just trying to figure out if it is worth it to run 45 psi over 16 psi with the same gph

Adam
 
Ive just cranked my new project this week and only seeing 10-12 psi from a Areo 1000 pump thats suppose to provide 45+. I have the same tuneup in the overflow valve that I had in the previous truck that idled at 55/60 psi. Only diff. is now that there's only the elect. pump now vers the mechanical and a 14 psi elect before. I can only assume that the OFV is not pinching the fuel back enough to create pressure, I was hoping to baseline with this setup but looks like I will have to go with a regulator. I agree I dought theres anything to gain above say 45# but that pressure needs to be maintained under load. I hope I made a good decision to get away from the mech./elct. setup that Im used to running; it worked very well for me and had no issue supporting 800+ hp, I wanted the look and simplicity of an all elect. setup. We'll see.
Ryan
 
Jim did prove that there was no gains above 45psi (for a street truck with a 12mm pump).

Raise the rpm band you want to see power in or run a 13mm pump or larger and you could be leaving more hp on the table?
 
stock600 said:
Ive just cranked my new project this week and only seeing 10-12 psi from a Areo 1000 pump thats suppose to provide 45+. I have the same tuneup in the overflow valve that I had in the previous truck that idled at 55/60 psi. Only diff. is now that there's only the elect. pump now vers the mechanical and a 14 psi elect before. I can only assume that the OFV is not pinching the fuel back enough to create pressure, I was hoping to baseline with this setup but looks like I will have to go with a regulator. I agree I dought theres anything to gain above say 45# but that pressure needs to be maintained under load. I hope I made a good decision to get away from the mech./elct. setup that Im used to running; it worked very well for me and had no issue supporting 800+ hp, I wanted the look and simplicity of an all elect. setup. We'll see.
Ryan
Click to expand...

I have 2 A1000 pumps now and pressure is 20 Idle and around 70lbs under load, the boost reference regulator works good
 
Well I got the feeling today that the sensor for the Racepak could be wrong and went to Grainger and got a liquid filled 0-100 mechanical gauge. She's 68# at idle and as high as 72# with a raised or high idle, against the trans brake or applying load I didnt see below ~ 62#. I will be getting a new sensor next week and testing this comming weekend. Ryan
P.S. I cant imagine after seeing this today having 2 of these big ass pumps feeding one little P7100? Im going to try and run it with my modified OFV and see how it does just as it was in the truck, not going to go to a regulator unless it needs one.
 
I run 11gpm thru my pump@50psi using a mechanical lift pump. Fuel is used to cool the injection pump as well . Over 50psi can run the risk of hydrostatically locking the rack, causing a run-away condition.
 
GRotman said:
I run 11gpm thru my pump@50psi using a mechanical lift pump. Fuel is used to cool the injection pump as well . Over 50psi can run the risk of hydrostatically locking the rack, causing a run-away condition.
Click to expand...

Ya I see what your saying. But at that 68# I am returning a ton of fuel to the cell; with the cap off you can see it well. I'll just see how the pressure drops under a serious load, If it keeps up well and the drop is min. like I hope I may drop the idle pressure down to 45# or so and make sure theres no drop in hp, this should ensure even more fuel flow through the pump.
 
You can probably get away with less volume in a drag race application due to running less rpm. I would still want to see the pressure around 50psi thru the run though.
 
Right.... I'll end up setting the idle pressure to what ever it needs to be to maintain a min. of ~45# under load. In the truck a 55/60# idle tune up still would pull down to say 30 under load right at the stripe, Im hoping this pump will maintain a bit better. We'll see.
 
we use the eliminator which is one size bigger than the a1000 and it will drop 10 lbs of pressure from idle to full load on the dyno. it is the smallest pump I would use on a motor over 1000 hp, the waterman mechanical setup is really the way to go and fairly easy to setup. the fuel output is increased with rpm and pressure can be controled with a return valve or a regulator
 
AirDog has a 250 gph pump that I used on my puller this year. Stuckeys use it in their drag truck and Kusileks use them in their trucks as well. All of them hold 45 psi with only a 1-2 psi drop. You then have the luxuries of your filter system, plenty of volume, the pressures needed, and of course the air removal to make the injection system work consistent. Cause with all that return fuel you are creating tons of foam in the tank that just gets shoved through the injection system.
 
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