[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.

[Goatracer1]

Thanks for the post. I bought the same type setup and have similar problems. I have a 421 with AC and while it cools down at speed the temp climbs at low speed and idle. The 2 fans never shut off. The shroud seems too tight to the radiator and appears to block air flow through about half the radiator. I'll try re-installing the original clutch fan and shroud.

[4zpeed]

You can actually envision how the electric fan setup would be obstructing the air flow, especially looking at the original.

Thanks for the post, I have a Cold Case (with no shrould) that's not installed yet, very nice to know.


Frank

[64speed]

I special ordered the HO radiator for my 64 without the fans cause I am running my shroud and clutch fan. Never had any luck with electric fans

[lust4speed]

Have a member in our car club that paid close to $1,200 for a custom assembly that included the radiator, shroud, and fans. His custom assembly looks very close to the Cold Case, and his results exactly match your temperature results with the tight fitting aluminum shroud.

[HWYSTR455]

Went thru this years ago with electric fans, only 2 setups actually worked well for me, the Flex-a-lite 4600 dual setup and the Derale dual powerpacks, both with shroud reliefs.

https://derale.com/product-footer/el...ual-powerpacks

It's not just the fan selection, or just the shroud selection, it's both.

So many advantages to running an electric fan, if you're not after an original look or build, there's no reason not to run electric fans. Just choose wisely.

.

[Formulajones]

This was a package deal situation so it was worth a shot.

Keeping in mind it never overheated, but it just ran warmer than comfortable and would never pull the temps back down. Once up there, it seemed stuck up there. Being an engine that's on the edge of pump gas we really don't like to see temps approaching 200 degrees.

Nothing about the drivetrain in this car is original, just the outside appearance. The whole reason dad wanted electric fans was for the HP advantage as he's become a HP junkie, lol. It just about killed him to put the clutch fan back on for the test but I had to know.
Personally for me, as rock solid as his cooling temps are now, I'd have no problem giving up 20-25HP driving that clutch fan for reliability and piece of mind. he can afford to sacrifice a little. But most likely dad will try another electric fan setup in the future. I've already been talking to a couple of members about it and have decided the dual Flex-a-lite 295 would be a good choice. It pulls 4600 cfm from 2 13.5" fans vs the 2400 cfm and 12" fans from Cold Case. But for now he's going to drive it for a few weeks and continue to monitor. Hopefully everything on the car will be the way he wants before the Pontiac drags in November, as there are a few other things he wants to change as well (driveshaft, gears, converter) But reliability is more important as this car is 95% driver and 5% fun track car. So right now I'm liking the clutch fan.

The good news is the radiator is an excellent piece and has no trouble at all cooling this engine.

[dataway]

A good compromise might be a factory shroud with a good direct driven flex fan. Should move plenty of air at low rpms and rob less HP at high rpms.

[HWYSTR455]

That's the Flex-a-lite I ran prior to the Derale setup I have now. That thing would suck a beer can out of your hand if they were on and you walked to close to the front of the car. It can draw 63 amps on a full startup, so either run a PWM controller, or a ramp-up controller. Also, if you plan to go more than 75% on the fans, you need to update wiring & alt. Probably should do that anyway, but guess you already know!

The Derale PWM controller has been hashed out, and they are great. Nice the shroud actually has a mount built into it, makes it nice. I will be doing one of those on my 'bird project.

..

[GTO JONES]

I think I'll stay with the clutch fan, more reliable , keeps it cooler and more constant temperature in the Arizona heat. I will say the Cold Case radiator is an excellent piece.

[torqhead]

All I'm going to say is anyone that takes a good look at that setup and thinks about it should realize the concept of cooling water through a radiator is airflow. When you block airflow over roughly almost half of the radiator undoubtedly you will lose cooling capacity.

Although the fans don't move as much as other options, I bet if you cut big ol holes in the metal areas of that shroud so air could pass through it would probably keep it a lot cooler. I'm sure that wasn't cheap, but sure looks to me like it was designed for looks versus proper cooling.

[RocktimusPryme]

Thanks for the post. I went on my first long 120 mile round trip this weekend. Mine runs hotter than I was comfortable with. Ambient temps around 85, thermostat is a 180*. Ran between 200 and 212 at highway cruise. More like 195* at lower speeds. But since it runs that warm at cruise I suspect if I ever got caught in hard traffic I would be in trouble. If I knew it would never get over 215 I would be fine. I just don't trust it. This is with a factory type shroud, and 19" clutch fan.

It actually dropped like 8-10* on the way home, but I got caught in the rain. Probably lowered ambient or the water splash on the radiator lowered temps.

I have a Chinese knockoff aluminum unit from Ebay. It works, but since it runs warmer than I want I wish I had spent the extra $100 and bought a cold case. Now I think Im going to go ahead and do just that. Your results make me feel better about the expenditure. I think that aluminum one I have would be just fine for a smaller engine. It almost keeps up with mine.

Ill probably wait for the next big show, in my experience Cold Case has pretty good in person show deals. Plus the Cold Case should actually have the provisions to mount the shroud which the Ebay unit doesn't.

[torqhead]

Originally Posted by RocktimusPryme

Thanks for the post. I went on my first long 120 mile round trip this weekend. Mine runs hotter than I was comfortable with. Ambient temps around 85, thermostat is a 180*. Ran between 200 and 212 at highway cruise. More like 195* at lower speeds. But since it runs that warm at cruise I suspect if I ever got caught in hard traffic I would be in trouble. If I knew it would never get over 215 I would be fine. I just don't trust it. This is with a factory type shroud, and 19" clutch fan.

It actually dropped like 8-10* on the way home, but I got caught in the rain. Probably lowered ambient or the water splash on the radiator lowered temps.

I have a Chinese knockoff aluminum unit from Ebay. It works, but since it runs warmer than I want I wish I had spent the extra $100 and bought a cold case. Now I think Im going to go ahead and do just that. Your results make me feel better about the expenditure. I think that aluminum one I have would be just fine for a smaller engine. It almost keeps up with mine.

Ill probably wait for the next big show, in my experience Cold Case has pretty good in person show deals. Plus the Cold Case should actually have the provisions to mount the shroud which the Ebay unit doesn't.

Check out the Champion radiators, they're pretty good and stand behind their product. Had a warranty issue 2 years later and they took care of it immediately.

[Hooter]

A little off topic, but what brand thermostat are you running. I've been trying to find a decent 160 unit and they all seem junk(and I've tried several).

[HWYSTR455]

Shrouds for electric fans need to have one way reliefs, so when there's a vacuum from the fans created in the shroud area, it pulls thru the whole core, not just the diameter of the fan(s).

You also need to be sure to have all the baffles in the core support, and around the radiator. I've seen too many times where folks remove the OE shroud, and don't seal the area between the core and the radiator. So the radiator sucks hot air from the engine compartment, and when folks go back to the original setup, they blame the electric setup.

A radiator is a heat exchanger, and the area only cools X number of degrees as dependent to the flow of water and air. If the air is a higher temp, the drop is less than desirable.

Nice thing about electric fans is, regardless of vehicle speed, the amount of air they draw thru the core can be varied, hence, the amount of cooling can also be varied.

.

[Bruce Meyer]

Originally Posted by Hooter

A little off topic, but what brand thermostat are you running. I've been trying to find a decent 160 unit and they all seem junk(and I've tried several).

Contact board member Schurkey. He has a supply of the good ones that he is selling off. Very good price too. I bought a couple.

[GTO JONES]

Originally Posted by Hooter

A little off topic, but what brand thermostat are you running. I've been trying to find a decent 160 unit and they all seem junk(and I've tried several).

Its a Stant brand.

[Formulajones]

Originally Posted by dataway

A good compromise might be a factory shroud with a good direct driven flex fan. Should move plenty of air at low rpms and rob less HP at high rpms.

Here ya go Dataway, an old fan test. The heavy duty thermal clutch fan (which we run) was only 20 HP shy of no fan at all, and bettered all the high performance flex fans they tested. Pretty interesting, only one performance flex fan matched the HP of the heavy duty thermal clutch fan.

Clutch fans are hard to beat.

[Formulajones]

Originally Posted by torqhead

All I'm going to say is anyone that takes a good look at that setup and thinks about it should realize the concept of cooling water through a radiator is airflow. When you block airflow over roughly almost half of the radiator undoubtedly you will lose cooling capacity.

Although the fans don't move as much as other options, I bet if you cut big ol holes in the metal areas of that shroud so air could pass through it would probably keep it a lot cooler. I'm sure that wasn't cheap, but sure looks to me like it was designed for looks versus proper cooling.

Yep, and if you notice in the pictures of the first post with the Cold Case fans sitting on the floor. They were already removed previously and dad cut an opening across the entire bottom of that shroud and installed a long piece of rubber. It didn't come like that originally. When I talked to Ccass he was gracious enough to send out small 4" long pieces of rubber free of charge to try and correct the airflow problem. But after looking at it, we decided to make a bigger change and put the long piece in that spans about 28" across.

Unfortunately after all that, it had no affect on cooling at idle or at speed. As you can tell, there is still a good 40-50% of that radiator blocked with that shroud.

[Formulajones]

Originally Posted by Hooter

A little off topic, but what brand thermostat are you running. I've been trying to find a decent 160 unit and they all seem junk(and I've tried several).

It's a stant, but I see now dad answered that already, lol

I also modify them and drill a pair of holes in them. Usually no bigger than 3/16.

I always test these things on the stove top with a temp probe. These in particular start opening at 155 and are pretty much fully open by 165. But I find in most cases, if the radiator and fan/shroud setup is sufficient, the engine will run cool enough to barely have that thermostat open at all, as was the case with the test drive yesterday.