Using E I/O to monitor fuel pump booster?

Ok, Ive got a magnacahrger on my 05 gto, and with the kit was a magnavolt, which is pretty much a boost-a-pump unit. It gives the fuel pump about 17 volts when boost >3psi. and rpm >4000. Anyways, I want to be able to log the voltage going to the fuel pump, but I know the inputs on the E I/O are only 0-5v. Can anyone help me out on how I can reduce the voltage so for example at 18v, I will get a 5v output. I just want to be able to know when the booster kicks in.

You need a divide by 4 voltage divider so that at 20 Vdc you will get 5 Vdc. Check out Nuts and Volts Magazine for lots of info.

thanks - thats what i was looking for.

BTW: The output of the MagnaVolt (when it is voltage boosting) is 17 no matter what you do. They have a precision DC/DC converter in there that can supply ~20 amps at 17 volts. As long as you know the turn on points you will know the output voltage.

EC