Is it true that there is no way for the fans to work after shutdown w/pfc? I'm told one of the things you cut when installing the pfc is this function. If the car is just on the fans will work so what i've been doing is using my turbo timer to keep the car on (not running) so the fans will run.


disclaimer: i know of and read through all threads relating to the "fan mod" and lowering temps fans come on at with datalog it

 

I'm surprised at that, because the PFC still has the fan relay from the recall. It seems the fan mod should still work (the one that requires you to throw a switch minutes before turning off the car, etc...

I assume that you just want to cool down the engine bay - right? Since the water pump will not be running and there will be very little impact on the water temp inside the block.

 

I have the PFC with fan control temp settings turned down lower, and the fan mod switch for post shut off cooling. All works 100%.

The switch has to be turned on 2 minutes pre shut down for them to stay on for 10 minutes.

 

Wondering exactly why anyone would bother with running the fans after shutdown? Since no coolant/oil is flowing, it would seem that you're just moving air around, with little purpose.

The only benefit I could see is that all parts underhood that don't benefit from fluid circulation might have a tiny bit of extra life from the engine bay cooling down a bit faster, but other than that, it's not like you'd be saving your engine at all, since it's off. Right?

 

By running the fan after shutdown, you are not saving your engine, but you are cooling the turbos and preventing cokeing. Plus all the rubber parts will last longer.

 

cokeing doesn't happen on liquid/oil, cooled turbos anyways

it's just for us guys who all agree that boiling liquids and steaming metal parts cannot be good...so why not avoid heat soak by leaving fans on?

 

I guess it probably doesn't really hurt anything other than your battery life. Even at that, the impact will probably be minimal. *shrug* Meh, whatever.

 

By some of your-alls logic, opening the hood after parking the car in the garage is also a waste of time.

The fan mod post shutdown and open hood does help.
This can be verified by air and water temps after starting up the engine after it has been parked for 10 to 30 minutes in hot weather. It does extend the life of all plastic and rubber parts.

But hell, this is a free country! If you do not want to protect your investment, that is your privalege and right.

 

Check your engine temps after letting the car sit for 5 to 10 minutes without the fans on. It may be up to 110-120. Turn the engine on to drive again and the temps go down slowly.

Check your engine temps after letting the car sit for 5 to 10 minutes with the fans on. Probably 90-100. Turn the engine on to drive again and your temps will be much lower as you've already cooled down some of the coolant.

That doesn't make a difference?

How about that the higher the temps get, the more pressure the coolant system sees? If you run your fans for 10 minutes after shutdown, it will help keep the pressures lower, and cool the engine faster even though the coolant isn't being circulated.

As for the hood open, I always keep it open in the garage after getting home. Not only does it help further cool the engine bay down, but it definitely saves on rubber and plastic parts. I also have a large fan on a shelf that is on a timer to blow on the engine bay for about 30 minutes.

Maybe I'm just talking out of my ***, but my car now has 105,000 miles on the stock engine and turbos and I still drive it hard. I have had my boost set at 13 PSI for over 2 years. I definitely do attribute some of the extra life in the engine and components to the added cool down.

Okay, enough rant.

 

random experience with heatsoak. when i first got my first FD i drove it and was waiting in the car with the car on but not running. I was shocked to see the stock temp gauge start to rise *above center*, just sitting there! the 'fan mod' cured that symptom.

 

By the way, your original question, yes the fan mod still works with the PFC.

 

Summit racing Part No. PRM-18905
This wiring kit includes 160-210 degrees F adjustable thermal sensor, 30 amp relay switch, 12 ft. of 16 gauge wire, 5 ft. of 10 gauge wire, connectors, fuse block taps, fuse holder with 30 amp fuse, and instructions.



Allows you to run and fan after shutoff until the set temperature is reached with any ECU.
I use it on an auxiliary pusher fan in front of the AC condenser.
Works great and i didnt have to wire a switch back to the interior.

 

Running the fans will result in some coolant flow due to thermosiphon. IF the coolant temp is high enough to keep the t-stat open then the cooler denser coolant in the radiator will flow to the bottom of the system displacing hot coolant and forcing a flow of hot coolant to the top of the radiator. Thermosiphon should occur in a coolant cooled turbo with or without the fans on due to the high temp of the turbo as compared to the motor, if plumbed correctly that is.

Another consideration is to park facing into a breeze. Tough to do in the garage, external fans do help.

 

It is actually just convection. We used to have a cast iron 4-cyclinder generator that didn't even have a water pump. It just used the convection as described above to circulate the water. The happens in all cars after shutdown until the thermostat closes at which time everything should be at a reasonable temperature, especially if there has been a small fan running.

Some vent system at the back corners of the hood would really be nice, but i havent figured out a good way to do it and keep out rain and not look ugly.

 

The old T model ford did not have a water pump. My mechanic s fans run for 10 minutes after shut down and when he parks in the garage there is a fan on the floor that is turned for a few minuites . Can not hurt .

 

Sorry to bring this thread.. So, where can i find this post fan mod how to??

I feel like I have read it somewhere.. but not quite sure where..

My car is running kind of hot and want to do all the mods possible while I'm doing turbo simplification..

Thanks!

PHIL

 

I think I just found my answer..

http://www.scuderiaciriani.com/rx7/fan_circuit.html

 

Here's an idea for keeping the fans going after the car is switched off.. Haven't thought it through fully yet, but here goes..

Hook up your turbo timer and set it to two minutes. Hook up a second timer (with a relay) and set it to 2 and a half minutes. Arrange them so that when the turbo timer starts counting down, the second timer starts counting up.

Hook the second (fan) timer to the special wire so that when the turbo timer starts, the wire is grounded. Then when the 2 minutes are up, the car switches off. 30 seconds later the fan timer also switches off, and un-grounds the wire. Hey presto! Automatic "fan mod" Provided you set the fan timer to 30 seconds more than the turbo timer this should work sweet as.