what pressure/GPM is the standard mazda pump
01-12-11, 02:54 PM
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what pressure/GPM is the standard mazda pump
Hello- does anyone know the figures for the standard 12A fuel pump? What pressure does it put out and how many gallons per minute? I have to replace mine like for like with a facet one.
It will be feeding an SU carb in front of a turbo running at 5PSI so perhaps something that gives a little more? The turbo kit was designed and worked well with the stock mazda pump.
I think the pump is about 4 psi?
It will be feeding an SU carb in front of a turbo running at 5PSI so perhaps something that gives a little more? The turbo kit was designed and worked well with the stock mazda pump.
I think the pump is about 4 psi?
01-12-11, 03:11 PM
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It's not enough, that's for sure. I've run the stock carb out of fuel on long uphill runs. You'll want at least 25-30 GPH at your carb's fuel pressure. Carb fuel pumps are usually rated at free flow, so you'll want something rated for more than that.
I don't like Facet pumps, personally. My recommendation is a Carter (the 72 GPH 8 PSI model). That'll flow plenty.
I don't like Facet pumps, personally. My recommendation is a Carter (the 72 GPH 8 PSI model). That'll flow plenty.
01-12-11, 05:11 PM
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Cool- cheers guys.
I have has facets on two previous 12a powered cars in the past and they have never let me down. But I have heard some don't like em.
As for what the carb requires I have found this about SU HIF carbs... (but on hotted up mini's.. same size carb though)
'Required pressure is 2.7-3.0psi with a flow-rate in the order of 15-18 gallons per hour. And unless the car is being driven flat out all the time - a pressure regulator is highly advisable to avoid rough-running at idle (caused by over-rich mixture as the carb is shaken about) and flow valve seat damage.'
Elford who made the turbo conversion in my car just used the standard mazda pump. But that would mean too much pressure I would have thought and problems as above.
so pressure a regulator might be a good idea then.
.
I have has facets on two previous 12a powered cars in the past and they have never let me down. But I have heard some don't like em.
As for what the carb requires I have found this about SU HIF carbs... (but on hotted up mini's.. same size carb though)
'Required pressure is 2.7-3.0psi with a flow-rate in the order of 15-18 gallons per hour. And unless the car is being driven flat out all the time - a pressure regulator is highly advisable to avoid rough-running at idle (caused by over-rich mixture as the carb is shaken about) and flow valve seat damage.'
Elford who made the turbo conversion in my car just used the standard mazda pump. But that would mean too much pressure I would have thought and problems as above.
so pressure a regulator might be a good idea then.
.
01-12-11, 05:55 PM
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Check the return line to your tank in the engine compartment.
Stock it has a one way flow valve/regulator in it that sets fuel pressure to about 2.5 PSI.
Its a silver cylinder in the rubber line with an arrow for direction of flow.
If Elford left that in, then your pressure will be around 2.5 psi no matter what pressure of carb pump you put in.
Stock it has a one way flow valve/regulator in it that sets fuel pressure to about 2.5 PSI.
Its a silver cylinder in the rubber line with an arrow for direction of flow.
If Elford left that in, then your pressure will be around 2.5 psi no matter what pressure of carb pump you put in.
01-12-11, 06:51 PM
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Problem is its a elford engine being fitted into a vauxhall viva (see oldschool/other rotary section- i just post question in here as its a 1st gen pump question)
I will get a regulator as well- I dont want to run the risk of my old pump going kaput right when I need fuel most- on boost. But I don't want constant needle valve problems on the carb either. It seems there are no high flow/low pressure 3psi pumps out there?
I will get a regulator as well- I dont want to run the risk of my old pump going kaput right when I need fuel most- on boost. But I don't want constant needle valve problems on the carb either. It seems there are no high flow/low pressure 3psi pumps out there?
01-12-11, 06:52 PM
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None that I know of, because it's easy to regulate the pressure down, but you can't regulate it up.
If you're boosting your car, you'll want to get a flow rate higher than that 18 GPH figure, because you're going to be jetting it richer than one would on an NA Mini. For our Camden supercharger projects we've always used a Holley FPR (in your case, you'd get the 1-4 PSI variant) and the aforementioned Carter 72 GPH fuel pump, and it works great. You could also use a Holley fuel pump if you wanted to, or any other pump with a high enough flow rate.
If you're boosting your car, you'll want to get a flow rate higher than that 18 GPH figure, because you're going to be jetting it richer than one would on an NA Mini. For our Camden supercharger projects we've always used a Holley FPR (in your case, you'd get the 1-4 PSI variant) and the aforementioned Carter 72 GPH fuel pump, and it works great. You could also use a Holley fuel pump if you wanted to, or any other pump with a high enough flow rate.
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