M500 build log

[Johansson]

Yup, 6 standard Bosch EFI pumps.

If I were you I would use a hydraulic pump coupled to a 4-stroke gasoline engine, no need for batteries and you can get as much fuel as you would ever need.

[metiz]

Hey Anders,

dou you have any suggestions? A 2-stroke should work too right, like a lawnmower engine or something like that

[Johansson]

Well, if you have a good enough battery and a pair of Bosch pumps you should defenitively try them first before you go for any hardcore route like a 4stroke powered fuel pump, but in the end I bet my ass that you need more fuel than any decent sized electric pump can supply.

[metiz]

I'll need about 10 liters a minute @8 bar. Most EFI pumps that I can find seem to run at about 3 bar

[Johansson]

Then I think you should go for a hydraulic pump, no cheap EFI pumps I know of can produce 8 bar.

[metiz]

I've been reading up on pumps and it seems I can hook up two or more identical pumps in series to get more pressure. Kind of like hooking up two 1.5V batteries + to - to get 3V
Which means I can buy a bunch of dirt cheap in-tank pumps and just chain them up! Two pumps should give me about 600kPa of pressure, which is just about enough to get ~3L/min.

Any thoughts?

[turbochris]

I would use a gas powered hedge trimmer w a small hydraulic pump. I think that's what Racket did. hedge trimmer I had was 18cc, had a clutch and reduction gears in it. Use the gears to drive a small hydraulic pump. Use a standard frame hydraulic pump, real easy to change pumps/displacements.

[ernie wrenn]

Still going to be regulated by bypass and pump amp draw of the motor... 600kpa do not think is possible. Be careful not to blow a seal on the second pump.

[metiz]

Even if I hook up 1000 motors in series, each 3 bar (300kPa), totalling 3000 bar, each motor will still only have a 3 bar pressure differential so I don't think It'll rupture any seals. However, I'd need at least 6 pumps, 3 pares of 2 running paralel and batteries to power them. Turbochris, what kind of pump are you talking about? All I can find are expensive ~300+ bar ones.

[ernie wrenn]

Stacking pumps will not increase the pumps pressure, it will increase the volume some. The automotive pump vanes will not seal on a increasing pressure. They are designed to produce a given amount of fuel at x pressure.

To increase pressure you must go to a gear pump. It gives you a higher pressure but a lower volume.
Vane pumps give you volume but not pressure.

As the volume or pressure increase the Amperage increases to a increasing slope. You will, at a given point, burn the fields out of the pump.

I drive one of my A/B augmenter pumps with a 7.5 Hp 12vdc 3450 rpm motor. The pump itself has a -24 supply line and a -20 discharge, if it has a restriction it will develop over 4000 psi. I run a 250 psi by-pass check valve, to reduce over pressure.

I can send pics if you need them.

ernie

[metiz]

Hey Wrenn,

I don't think I agree. In my example, asuming it works, the pressure differential at the front and back will remain 3 bar, regardless how many you hook up. The seals are rated at 3 bar.
Each pump would get their own power supply and should do no more work than any other pump in the sequense, because they are just pumping liquid up another 3 bar


This is what I base my reasoning on www.engineeringtoolbox.com/pumps-parallel-serial-d_636.html The pump-curve shows that pressure is increased 100% (theoretically) and the flowrate stays the same. That makes sense accoring to the Bernoulli equation.

[ernie wrenn]

Pumps are designed around certain parameters... case pressure being one of them. If you increased the pressure above.... say 400 psi. the thin housing stands a good chance of rupturing, the seal points are going to start leaking, internal pressures may exceed the component designs. You will have a very dangerous condition before long.

Geared high pressure pumps are designed for the pressure abuse.

[ernie wrenn]

3000 bar = 43,511.321 psi ... It will blow apart. None of the auto style pumps will stand over 500 psi., Probably much lower.

[metiz]

Jun 11, 2013 18:28:17 GMT -5 ernie wrenn said:

3000 bar = 43,511.321 psi ... It will blow apart. None of the auto style pumps will stand over 500 psi., Probably much lower.

Agreed, but that was just an example. I need a maximum of 8 bar (120psi) but with 2 pumps hooked up, that will be closer to 6 bar (~100psi) which is still ok.

Just exploring options here. I already have one pump, getting a second one and testing it shouldn't be that hard.

Can you send pics of your system?

[ernie wrenn]

Load some tomorrow..