Originally Posted by TGGodfrey

What your going to need to do at this point is to get a temp reading on the coolant as it enters the radiator and as it exits to see if your radiator is reducing the coolant temp.

do you have a fluke or another type of meter that has an electronic thermocouple?

Something like this would work, you need to be able to get a reading of both inlet and outlet at the same time.
H-B Instrument Durac Electronic Thermometer, with Alarm and Timer, with 152mm Probe and 1.5m Stainless Steel Cable, -50 to 300 degree C: Amazon.com: Office Products

Take your hose off and clamp the thermocouple into the hose. This will leak a little during testing but your not too concerned about that as long as the hose clamps are tight and hoses are not blowing off.

Compare your incoming temp on the radiator to your outgoing temps..... Obviously if the coolant entering the motor is not cool, then the radiator and/or fans are not able to keep up. There is also the possability that the water pump is pushing coolant through the radiator too fast and not allowing the radiator a chance to dissipate heat. An Aluminum radiator might be required. This test will at least put you on the right track as far as what is causing the temps to keep increasing.

Like mentioned before, verify the pump is still running when your fans kick on from low to hi. You can do this without running the car, just jumper the relays on low, verify water pump is getting power, jumper the fans to hi and recheck the pump feed.

Here is a shot in the dark.....I didnt see where you mentioned any type of ECU tuning. Did anyone retune the timing maps in your ECU and perhaps maybe they advanced them too far causing this? Pull your plugs and read them for timing.

Originally Posted by Thirim

no idea on the stock fans' cfm rating but they both only come on with the AC or above a certain temp... like 220/230 or something... Granted you don't have a stock motor either..
Idling ok? No vacuum leaks? I know leaving the brake booster off the intake makes red headers quicker than you can find the problem lol.... whoops!

Originally Posted by Injuneer

Late 94 on up both fans come on, low speed at 226-degF, or with AC; both switch to high speed at 235-degF. My stock fans/Griffin radiator setup has no problem handling the engine with the 300-shot of nitrous.

The fact that the problem lessens at idle when he turns the fans off seems to point to the fans. The other possibility is that somehow the power source for the electric water pump is interupted when the fans turn on.

Originally Posted by gaedbo

As an observer reading the threads, it sounds like the fans are blowing the air into the radiator, instead of pulling the air through the radiator towards the engine.

Originally Posted by Injuneer

I think some forced induction guys stand the radiator upright for more room for fans.

Use a clamp on ammeter to verify the water pump does not shut off when the fan relays kick in.

Originally Posted by TGGodfrey

Looking back through some of the posts to determine what you have changed with the motor/SC setup.......... You added a few cubes and upgraded you SC trim.

You have checked flow direction, Alum or factory radiator still does it, Pump is operating with fans on, twin 850 CFM fans (should be enough at idle).

Have you checked what your timing is doing at idle when your dealing with this? If you timing is advanced more than normal, thats going to contribute to overheating as well.

Another thing that sticks out like Fred mentioned is with the fans off the issue seems to lessen. Do this for a simple test. Run the pump direct to the battery and see if it still does it. Depending on where your power is coming from on the pump you could be starving the pump for voltage (not amp) when the fans kick on. At that point it appears the pump is drawing enough amps but its not getting enough voltage to operate at the correct speed.

You didnt mention where the pump is getting its power and I wonder if the shop tapped into the main feed for the fans. This could lead to a line loss issue on the wire due to the current draw on undersized wiring. Aftermarket higher CFM fans are only going to make that worse.

edit: Remember Amperage and Voltage are inversely related. Meaning if your voltage sags, the amperage draw will increase. Motor will still spin slower.

Terry

Originally Posted by bw_hunter

I just went out and checked mine. The pump draws 6.5 amps and 8 seems a little high. Mine is the wp118hd

I have mine wired with a relay directly to the battery (circuit breaker in line, of course, with a trigger coming off the a hot wire on key on or acc. I had 14.2 volts at the pump pigtail and the engine running...essentially alternator output.

I hope this helps...