12v to 13.5v?

[dejacky]

I'm doing the "12v" mod for my supra TT fuel pump, but after viewing the flow advantage of 13.5v instead of 12v, I want to provide 13.5 volts to my fuel pump. I noticed my battery reads 12.6volts so it's still too low. Does anyone know of any cost-effective (and safe) methods of boosting voltage from my battery to 13.5v for my fuel pump?

 

[CRE]

You reading the power with the car turned off? The voltage in a healthy electrical system is usually around 13.5v.

 

[dejacky]

You reading the power with the car turned off? The voltage in a healthy electrical system is usually around 13.5v.

Yes, I disconnected the positive terminal and simply measured from the battery directly with a volt-meter.

 

[CRE]

Yeah, test it with the car running.

And unless you're pushing 500RWHP+, you're wasting your time with the "12v mod". It only reduces power at lower loads.

 

[blue_spra]

A car battery will read 12.6 volts with the engine off. With the engine running the voltage of the electrical system is typically between 13.5 and 14.4 volts because the source of electricity when the engine is running is the alternator, not the battery.

 

[dejacky]

You reading the power with the car turned off? The voltage in a healthy electrical system is usually around 13.5v.

A car battery will read 12.6 volts with the engine off. With the engine running the voltage of the electrical system is typically between 13.5 and 14.4 volts because the source of electricity when the engine is running is the alternator, not the battery.

Thanks for your input guys, so is it better to power the fuel pump from the alternator instead of directly from the battery or does it not make a difference when the car is running?

 

[CRE]

Congratulations, Blue Spra... you've officially taken the fun out of learning. He was supposed to try it, see the difference and say "WOW! How the heck did that happen!?"

Then, later that same day, someone in the library complains as someone reading a technical manual in the back exclaims "Hey! NEATO!" just loud enough to be distracting.

You're a jerk.

Thanks for your input guys, so is it better to power the fuel pump from the alternator instead of directly from the battery or does it not make a difference when the car is running?

Shouldn't be any difference. Always best to test at the target though.

Oh, as for where to power the pump from... what's wrong with the stock circuit?

 

[blue_spra]

There's no need to run wiring so close to the heat of the engine by running off of the alternator. Connecting to the battery will give you the same results because there is already a cable running from the alternator to the battery.

They are both one in the same electrical circuit. The reason the alternator is the source of electricity when the engine is running is because it produces a higher voltage than the battery when the engine is running.

 

[Poodles]

12V mod will do nothing but overwork the pump... it's a mod that needs to be done ONLY on certain cars (if you're over the fuel requirements of one walbro I would say)

 

[dejacky]

Thank you guys for explaining this to me, everything makes sense now. My car is 2JZ-GE na-t with 550cc rx7 injectors, so the extra bit of fuel will help with my dbb pt67 turbo!

 

[jdub]

My car is 2JZ-GE na-t with 550cc rx7 injectors...

And that make this thread in the wrong section...please pay better attention next time. Thread moved.

 

[improved]

From what I read, the Walbro pump is supposed to operate at a consistent 12V. Operating continously at 12V will not overwork it. Perhaps, I'm mis-reading your statement.

The stock fuel pump would seem less apt to operating continously at 12V.

Matt-

Matt-

12V mod will do nothing but overwork the pump... it's a mod that needs to be done ONLY on certain cars (if you're over the fuel requirements of one walbro I would say)