Reverse Flow Meth Pump

[dreksnot]

I have a peculiar question: can I reverse the power polarity (swapping + to - and - for +) to reverse the meth flow in the pump? Or is the pump dynamics designed for only one direction? Pump in question is: Snow Performance SNO-40900

[stevieturbo]

I don't think it will make a difference ? The actual pumping head will still be doing the same things in terms of moving fluid.

That said...I've never tried. I do have an old pump sitting on the floor though so wouldn't be too hard to test. ( triple chamber DDP5800 type )

[dreksnot]

Usually with a positive displacement pump and being DC I wouldn't think it would be an issue. However, with it being PWM capable, and if there's something in the physical meth pump itself (like some flow dependent thing), and by reversing flow it would be detrimental to the actual flow or the pump life, that's what I wanted to know.

[stevieturbo]

The pump head is 3 simple chambers that move up and down via the rotation of the motor.

As it's the vertical motion that does the pumping, I can't see how direction of rotation would make any difference.

PWM makes no difference, as that just affects the speed of the motor.

A friend was doing some testing and logging for a fancy WI system recently, and you can even see each pressure spike from each chamber during the pumps rotation which works out around 1700rpm when loaded.

I had noticed the very erratic pressure myself ages ago when testing, but never really thought much into it, but as he is doing a sequential port injection system....the highs and lows can actually make a fair difference to what pressure might be available as any injector opens so he did resolve a workaround to stabilise the pressure. It's still not perfect, but a good improvement.

[dreksnot]

That was helpful. I'll try a quick reverse polarity test and most likely I'll install the pump in the orientation I want to versus the other way that I thought I had to. It'll work nicely with my WI system. I'll post pictures after install (3gal tank and pump battery well install).

[eLeSthree]

I can tell you that if you reverse the polarity on a "walbro 450" aka TI automotive 274 pump (or 3) you will not build fuel pressure... ask me how i know.

Not sure if that's helpful here.

[stevieturbo]

Originally Posted by eLeSthree

I can tell you that if you reverse the polarity on a "walbro 450" aka TI automotive 274 pump (or 3) you will not build fuel pressure... ask me how i know.

Not sure if that's helpful here.

totally different style of pump from the typical water injection pumps. Walbros etc use a turbo vane style.
Strange looking thing, a little like a tiny weird jet impeller, albeit with a flat centre

[stevieturbo]

And the WI style pumps

[stevieturbo]

And I can confirm, reversing polarity makes no difference. Water still flows in same direction.

[dreksnot]

Originally Posted by stevieturbo

And I can confirm, reversing polarity makes no difference. Water still flows in same direction.

AND...., I just tried this out and you're a 100% correct with my situation. Opposite input polarity, same flow direction. Shucks! Guess mounting in plan B position is going to happen now.

[stevieturbo]

What's the actual issue with mounting ?

[dreksnot]

Originally Posted by stevieturbo

What's the actual issue with mounting ?

I'm mounting the meth (WI) pump on the front vertical battery retention plate with the hose from the tank coming from the left side of the picture. If I could mount it like in the first picture (if the pump would have reversed flow) then the inlet would be at the bottom and better priming as well as better placement and ease as getting to the inlet filter. But, looks like I'll have to mount it orientated in the second picture and the filter will be difficultly beneath the pump and a bitch to get to. The third picture is the filter element. But, another possibility is to move the filter closer to the tank (that might be the ticket).

[stevieturbo]

Not sure if you can rotate the pump head itself....would need to look again, but I doubt it.

Although you might be able to remove the two long screws that hold the motor body casing and rotate it 180deg so it is flipped ?

I did remove mine years ago as water had gotten into the motor, but can't recall if the two screws etc are centred or offset slightly.

[dreksnot]

Originally Posted by stevieturbo

Not sure if you can rotate the pump head itself....would need to look again, but I doubt it.

Although you might be able to remove the two long screws that hold the motor body casing and rotate it 180deg so it is flipped ?

I did remove mine years ago as water had gotten into the motor, but can't recall if the two screws etc are centred or offset slightly.

Well, whatdayaknow.... your suggestion will work mighty fine!!! Thanks.