hey, does any body know how i could wire up the cooling fans for the engine to keep running for about 5 minutes after the car is turned off but also have a master control switch inside my car? is there some sort of timed switch i can buy? and just put it in line with the switch? thanx

 

there is a device meant to do just that function, called a turbo timer i think

 

It would be pointless to have the fan run after the car is off unless you have an electric water pump that will run as well. All you would effectively do is cool the fluid in the radiator only.
Ford and Chrystler cars (80's) both had the fan relays stay live with or w/o the ignition being on and were wired to the temp switch thus letting the fan run when the car is off untill the engine reached 'X' temp. This is why they had the 'warning: fan can run whenever it feels after the car is off' sticker on the radiator shroud.

 

mmm i guess it is kinda pointless.... will a 180 thermostat help with engine temps?

 

Actually it isn't pointless, or the manufacturers wouldn't do it.

GN's are one that I can think of that GM wired this way.

In any case, there is a word or phrase that describes the process, basically the difference in temperature between the radiator and engine will cause the coolant to "flow" as the temperature tries to equalize, thus cooling the engine off.

How effective it truly is, I have no idea, but there would be no reason to have more constant 12V systems in the car if there were no gains.

 

Aside from draining the battery, it's mostly pointless. The coolant is not going to circulate as if the car is running just beause the fan is running.
Chrystler made some fans run and others not on the exact same motor they used in everything they made in the 80's (the s__tbox 2.2).

As far as helping the car run coler, yes a 180° stat will help but, the fan switch on a TBI is set to kick the fan on at a 'tepid' 238° and only cools buy 10° (or roughly around there).
Any temp before that your fan will not run. Generally, people use a lower cut in temp switch (like the GN or truck ones... a search for 'fan switch' will find that answer) or parallel a grond wire to the switch so they can control the turn on of the fan.
W/o the fan kicking on at a lower temp then stock, a lower stat doesn't do much in stop-n-go traffic. It only opens sooner.

 

I never said the coolant will circulate like the engine is running. However, the heat contained in the coolant MUST equalize. (thats heat flux)

The higher the temperature difference between the radiator and the block, the faster the rate of heat exchange. Obiously the small radiator hoses won't allow a huge amount of coolant "flow", but since the thermostat is mechanical, it isn't governed by whether the car is on or off, so that is an additional path for the coolant.

I'm not wiring MY car up this way, because I don't like the idea of the fans having a mind of their own, in case I need to be underhood when the vehicle is hot, or in case the fan wiring somehow becomes damaged. Besides that, most clutched fan vehicles don't have this mechanism, but typically the engines aren't allowed to get as hot in the first place.