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Old 08-30-2010, 11:45 AM
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Changing alternator output via voltage sense wire.

If I'm reading correctly the standard CS type alternators use a voltage sensing wire to vary the output of the alternator.

Looks like caspers "voltage booster" Is just a switched resistor that limits voltage to the sensing wire under WOT conditions. They claim a 2.2v increase at wot over your current settings. Because this only puts a heavyier load on the car under WOT conditions it won't cook or damage your battery.

I figure I could do the same with a WOT switch and a resistor to the sensing wire. Any suggestions or input on the size or resistor or diode needed to gain roughly 2-3v?

I have recently switched over to e85 and my fuel pumps output gains considerably around 15v vs 12.5 or so it sees now. At 18v it puts out 30% more flow.

I was thinking of just wiring this phone charger into the circuit. When I got WOT It will trip the normally closed switch open and only the 9v supply will be left on the alternator sense wire.

http://www.ecrater.com/p/6875423/car...dc-adapter-for



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Last edited by ForceFed86; 08-30-2010 at 12:07 PM.
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Old 08-30-2010, 08:38 PM
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Sounds like a unique idea. The 9v adapter idea should work and I cant see why it wouldnt. At WOT you'd be forcing the alternator to see a low voltage and therefore output more when you need to OVER voltage the fuel pump (up the pump to 24vdc and Im sure it'll really output a ton).

Will the increased pump voltage do anything for you though? A good pump should be able to output more than enough even at WOT.
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Old 08-30-2010, 09:48 PM
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Well I'm running fuel injection and a supra TT denso fuel pump. Only have a single in-tank pump. Just swapped over to e85 so I'd like to get the voltage up to be on the safe side. For the money these little pumps really flow well. They blow the 255 walbro's out of the water.

Many folks out there are making 400+ whp on e85 with a 255 walbro and and good wiring. I'd just like to be on the safe side. Think I'll be around 450.

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Old 09-08-2010, 10:18 PM
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It's a worker.... My battery was a little low so the alt. was charging at the time. Idle voltage settles to 13.9. Still jumps to 15.2 under boost. (or could be rigged to a WOT switch) I used a boost switch set to 20 psi. My injector duty cycle went from 63% DC at 16psi @ 6500rpm to 56% at 15.9psi @ 6500 with no other changes.

Here is the wiring.




Here is the video.



It gets loud because I am tapping the boost source at my WG. So when you hear the exhaust get loud the WG is open and the switch is closed activating the voltage boost.

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