Help with timer building

[Reeves]

Here's what I plan to do:
I have a proximity switch that I'm going to use to see when the clutch pedal is pushed in. When this prox is on for more than 1 second (like staging) I want to activate my rev limiter and low boost setting. After the clutch is dumped (prox off) I want the rev limiter to immediately turn off, but I want the low boost setting to stay on for X amount of time (adjustable). Digi-Set and Dynotune both have nitrous relays with adjustable timers built in, but I think these are only time on relays. I need a time off relay as well and I'm having a problem finding one with 12V coil. Anyone have an idea where to find one or how to build this circuit myself?

["Top Fuel" Bender]

I can check with my neighbor
he's great with electronics like this
Were using a timer on oil scavaging pump for a twin turbo subarban that we built
It allows power to the pump when the key is on
Then when the ignition is shut off it counts down
Kinda like a turbo timer basically
Most switches and realys can be wired for normally opened or normally closed
If not wire your high boost on normally closed and run the setup backward
I think that all makes sense