11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

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idontknow
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11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by idontknow » Mon Aug 02, 2004 12:40 pm

Ok, I hope I haven't confused you thus far.<p>I'm looking to UP the voltage on my cars fuel pump. I was looking for a transformer that would boost the voltage from 11.5-12 VDC up to 12.5-13Vdc. (The amps are currently UNKNOWN)<p>Is there a transformer made somewhere that can do this? Also, does it have only two wires...one on each side of it? One for the "in" and one for the "Out"...??<p>Please help!<p>Any links would be great to where I can purchaes this online.<p>Thanks again!<p>[ August 02, 2004: Message edited by: idontknow ]</p>

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Dave Dixon
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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by Dave Dixon » Mon Aug 02, 2004 12:45 pm

Hi there,
The bad news is that transformers only work with AC voltages. <p>The good news is that there
are a great bunch of people on this board who can offer some excellent suggestions. I'll try to get
back to you with more advice soon.
Okay group - - run with it.
Dave

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Externet
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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by Externet » Mon Aug 02, 2004 2:24 pm

Hi.
Just replace the wires feeding the fuel pump with much thicker ones. Ensure extremely good, clean, tight ground and positive conections. No twisting/crimping splices, solder them.
The voltage will raise nearly as high as the alternator puts out.
One single imperfect joint/relay/switch contact along the current path will reduce the voltage under your expectations.
Miguel
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Edd
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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by Edd » Mon Aug 02, 2004 3:02 pm

What is the logic on the upping of the supply voltage up +1 volt? Since your reference attains to its being used for automobile fuel delivery and not in some other application. If its about that minute of a voltage drop, typically an electrical fuel pump ramps up to its specified delivery pressure very quickly and just tops it off intermittently as demands require. (Some variances on Mercedes ,and possibly others, on their constant recirculating mode, but still, even they just loaf).
73's de Edd
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haklesup
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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by haklesup » Mon Aug 02, 2004 3:40 pm

Anything made to work in a car should already work equally well at both those voltages. 11.5 to 12V is what you get from the battery when the car is off and 13 to 13.5V is what you get from the alternator when the car is running.<p>Increasing DC voltage a small amount is suprisingly technically difficult unless you can add another source (like a second battery) in series so that the voltages add. In a car even this would be tricky because you need to account for charging etc.<p>Transformers generally have 4 or more wires and the black box you describe would require at least 3 wires (assuming one is a common ground, the others would be in and out) if it existed.<p>Now, if you wanted to reduce the voltage, all you need is a regulator of some kind.

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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by idontknow » Mon Aug 02, 2004 3:40 pm

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Externet:
Hi.
Just replace the wires feeding the fuel pump with much thicker ones. Ensure extremely good, clean, tight ground and positive conections. No twisting/crimping splices, solder them.
The voltage will raise nearly as high as the alternator puts out.
One single imperfect joint/relay/switch contact along the current path will reduce the voltage under your expectations.
Miguel
<hr></blockquote>

idontknow
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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by idontknow » Mon Aug 02, 2004 3:42 pm

Well, simpily changing the size wire is not that simple. Although this is a well know way to provide more voltage to the fuel pump. In fact, I have made this modification to my '87 Buick GN.<p>The reason for the install (transformer) in the "hot wire" inline is simpily to provide more voltage to the pump, thus making the fuel pump-pump more fuel.(or turn faster)<p>If transformers only deals in AC current, what is made for DC current?<p>
Anyone else have ANY suggestions or ideas?<p>Thanks to all those who replied!!!<p>[ August 02, 2004: Message edited by: idontknow ]<p>[ August 02, 2004: Message edited by: idontknow ]</p>

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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by russlk » Mon Aug 02, 2004 5:22 pm

What makes you think the pump need to deliver more fuel? The pump is designed to pump more fuel than is needed, the excess is either diverted back to the tank by a pressure regulator in the carburator (fuel injector) or the pump itself has a sensor to shut down when the pressure is high enough. Perhaps you have a defective pump, in which case raising the voltage won't help. If you are racing and running out of fuel, there is no doubt after-market pumps available with high output.<p>I had a 1940 Mercury with 3 carburators on it but the fuel pump had no problem keeping up.<p>[ August 02, 2004: Message edited by: Russ Kincaid ]</p>

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Externet
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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by Externet » Mon Aug 02, 2004 5:38 pm

Hi.
Anything else than changing the wire size is less simple.<p>If you provide more voltage to the fuel pump, it may get damaged as it is designed to work with 10 to 14V and no more. More voltage may create more fuel pressure, but the fuel presure regulator at the injector assembly will return the excess to the fuel tank anyway, gaining nothing.<p>I installed a 95psi (no typing mistake) inline fuel pump in my car, to run the 65psi minimum Vortec requierement and larger wire thickness helps starting under residual backpressure. I removed the check valve too, which made the night and day difference.<p>Your solution is to buy a larger power/pressure/volume fuel pump. Visit Kragen and ask to browse their Airtex catalog to match your needs.
Miguel :) <p><'97 Vortec wrapped in a 1962 Cadillac barge> :eek:
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Chris Smith
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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by Chris Smith » Mon Aug 02, 2004 7:26 pm

If you don’t have Fuel Injection and want more fuel, put in a fuel injector type pump in. <p>They typically produce about 90 psi VS 3 to 7 psi,...and about four to six full tanks of gas per hour VS less than one tank per hour and then your only problem will be to reduce the pressure and flow using a restriction and a feed back line. <p>I did this in a pinch 20 years back when my standard pump took a dump in the desert, and my transfer pump, a FI pump was needed to get us home. <p>I used a 223 shell in side the fuel line with its primer knocked out as a restriction and the feed back line did the rest to not blow up the Carb. <p> If your trying to increase a Fuel Injector type, don’t, you may cause the injectors to leak? They also have a pressure relief built into the bump. <p>Also if Quantity is your only issue with FI, then simply parallel Two pumps for high volume situations like drag racing or boat racing and blowers.

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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by idontknow » Tue Aug 03, 2004 8:18 am

Ok....<p>Maybe I should have put this in ~ in the orginal post...<p>We're currently running a twin-turbo 347 in a fox bodied Mustang. This is a 100% street legal, street driven car. On the dyno, we could only get 738 RWHP due to running out of fuel(aka: lean). The fuel system consists of a custom 300lph INLINE fuel pump, and a 255LPH INTANK.<p>We also tried a FMU set-up (Fuel managment unit) to help "bump" the fuel pressure under full boost. The FMU's basic design is to simply close the return line under boost, thus forcing the fuel to stay in the injector rail. <p>Without getting into needless details about the car, we're simpily looking for more volts to feed the pump. We're not interested in longivity of the fuel pumps, we have plenty laying around to replace them.<p>Finally, does anyone know of such a way to gain voltage to the fuel pump without upgrading wire size to the pump?<p>Thanks for all your replies.

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haklesup
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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by haklesup » Tue Aug 03, 2004 10:29 am

The detail about the end application helps. I was beginning to think that you did know about cars but like the fuel pump, had a bottleneck in electrical ideas.<p>Increasing the wire gague (size) may reduce a voltage drop if the current in the wire is very high. Not sure what kind of current a fuel pump uses but it probably isn't 20A. Running a second wire in parallel to the first would have the same effect as replacing it with a bigger wire and much easier to try for an experiment. In any case, the voltage will never exceed the alternator output voltage. <p>If the fuel pump is driven by a semiconductor switch in the engine controller, you will likly loose a volt or so right there. Assuming the action is purely on/off (not variable voltage) then you could add a control relay near the fuel pump. <p>Put the relay so that the contacts power the fuel pump and the coil is powered by the line which originally powered the pump. With the relay, you have isolated the pump power from the car power. You can now wire directly to the car's power sys for the full 13.5V alternator output or you can rig up two 12V car batteries in series (For 24V)and add variable regulator to bring that down to an adjustable 12V to 15V or so.<p>The relay setup is basically the same as what is typically used to power fog lamps for example.<p>You may also consider replacing the hoses that lead out of the fuel pump with larger ones or piping two fuel pumps in parallel (forget that, probably dangerous)<p>You may have plenty of fuel pumps to spare but I doubt you have many engine controllers lying around. Be very careful applying any voltage greater that 13.5V anywhere in the car as you may damage an input or chip in this expensive computer.

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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by JKMADSCI » Tue Aug 03, 2004 5:18 pm

One way to add 1 to 2 volts would be to use a sub c 3000 nimh battery. This would be good for testing your theory on fuel proportional to voltage. We use these nimh batteries in rc cars and they perform well at constant current up to 20 amps. The only thing you have to watch for is running the battery too low. If i estimate your fuel pumps at 7 amps each then the battery will last about 12 minutes before dropping to a low voltage. If this test works and you like the results, you can build a circuit to supply the extra voltage permanetly. You can use 2 batteries if you like!! 1= 1.2 2 = 2.4 apx

idontknow
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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by idontknow » Tue Aug 03, 2004 5:59 pm

I really appreciate all the advice you all have given me.<p>haklesup ~ If you would, please contact me at [email protected] <p>The theory you have about enlarging the actual fuel lines does work...both at the pump and all the way up to the injectors. Speaking of injectors, we know we have enough injector to support up to 850-900 HP...they are 93lb injectors....to give you an idea of just how large this is, conside a stock Mustang in 1993 came with 19lb injectors!<p>Again, thank you all for your ideas and thoughts.
I really appreciate you!<p>Bobby

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dacflyer
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Re: 11.5Vdc / 12Vdc to 12.5Vdc/13Vdc

Post by dacflyer » Tue Aug 10, 2004 5:53 pm

run the powerlines of the fuel pump to its own dedicated power supply...use (3) 6volt batteries or 12v + 6volt...this will give you 18V
this will probably not harm the pumps for short runs...i can rember tripling voltages on motors etc...for a while they will last...just keep a check on the temps of the pumps....don't want nothing to go FOOOOOM !

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