[scott70]

Originally Posted by Formulajones

Well after much debate, parts swapping, and lots of driving in the Arizona heat, we've come to some conclusions on dads GTO. Running a 571 CI that makes 724 hp and 764 tq. He runs a 160 thermostat in it that actually starts to open at 155.
He started out a few years back running his 25 year old 4 core copper and stock shroud/clutch fan. This worked fine but would warm up a bit on the highway at 3000 rpm to about 190 degrees. All other times in slower cruising it would run about 175. This is with 85-90 degree ambient temps.

Fast forward to this year. He wanted to try a Cold Case 2 core radiator with 1 1/4 inch tubes. Along with the Cold Case dual electric fan setup. I noticed the radiator looked like a very nice piece, nearly identical to my Griffin I run in the Chevelle. Nice tight fine count, stamped tanks and good workmanship. I was skeptical of the fan setup however. Pretty boxy and flat, and mounted right up against the core. The flat portion of the shroud is only 1/4 inch from the core. I thought this might pose an issue. Driving the next few months confirmed it. With fans programmed to come on at 185, off at 175, they would never shut off. On the highway this thing would run 190-195 and slowing down on back roads to 30-35 had no affect. If we let the car sit and idle, fans full blast, after about 20 minutes it would finally pull the temps down to just below 190, but not even close to these things shutting off. We tried opening the shroud with rubber flaps, hoping that would help temps while moving but it just wasn't enough.

So as an experiment I decided to reinstall the factory shroud and clutch fan. Left the Cold Case radiator in place. As I suspected the Cold Case radiator is an excellent piece and does the job. Went for a long cruise today, ambient temp was 85 degrees. 3,000 rpm down the highway for 15 miles and the temp only got to 165, then actually settled in at 162-163 and stayed there for the rest of the highway trip. Got off the exit and cruised back roads at 30-35 miles. The first mile the temp dropped to 160, by the second mile it dropped to 155. Pulled in to pick up dinner, shut the car off and let it heat soak for 20 minutes. Mechanical gauge climbed to 175 as you would expect. Fired it back up and within 10 seconds it was back down to 155 degrees. Cruised back roads to the house for another 6-7 miles and temp actually dropped to 150 and stayed there for the rest of the trip.

More driving to follow but as it sits right now I've seen enough to convince me. The Cold Case shroud was just blocking too much radiator. The factory shroud and clutch fan is keeping the engine a solid 30 degrees cooler than before. Now dad shouldn't have to worry about engine temps as Arizona will continue to get hotter as the summer progresses.

The Cold Case fan setup may work well enough on a lesser engine, but it just wasn't cutting it here. Thought it was worth a try though. Nice product for the money. Radiator, as I figured early on, is an excellent piece and does the job nicely.

Off topic but have you run this car at the track?