[promptcritical]

Originally Posted by Squidward

Yup. I can still put someone to sleep discussing the different means to achieve critical heat flux. What flavor do you like, departure from nucleate boiling, or dryout?

It's been a couple decades, but every once in a while I still have a dream where I'm doing a fast recovery startup. It's amazing what stuck.

But it's also amazing that I can forget the name of someone I talk to once a week for seven years, like I'm de-evolving into a functional idiot with the changing of the seasons.

Ha! I haear ya. They somehow pounded that nuke school stuff into a permanent part of our brains.

[70GS455]

Whats wrong with using both type of fans? Mechanical AND electric. I use a stock GM mechanical fan with clutch and shroud, and a slimline electric helper fan hidden inside the shroud. Best of both worlds.

Sent from my SM-T817V using Tapatalk

[Squidward]

I see benefit to the electric at idle. My electric setup could cool just fine at idle under the worst conditions. My clutch setup works great in all AZ weather except extended idle with ac running, in 115* summer weather. You know, stuck in a drive thru for 15 minutes. But in the wintertime when Temps are 70's I don't even sweat that.

I'd be OK with a dual as long as the electric unit didn't present an impediment to air flow at cruise. I learned to alter my driving habits, tho. If the drive thru line is long, I just go inside to enjoy somebody else's icy air conditioning.

[AdamIsAdam]

Originally Posted by Squidward

I see benefit to the electric at idle. My electric setup could cool just fine at idle under the worst conditions. My clutch setup works great in all AZ weather except extended idle with ac running, in 115* summer weather. You know, stuck in a drive thru for 15 minutes. But in the wintertime when Temps are 70's I don't even sweat that.

I'd be OK with a dual as long as the electric unit didn't present an impediment to air flow at cruise. I learned to alter my driving habits, tho. If the drive thru line is long, I just go inside to enjoy somebody else's icy air conditioning.

you've talked about this "drive-thru dilemma" before. I'm beginning to think you're altering your behavior incorrectly; rather than going inside the restaurant maybe you should cut down on the fast food!

Just kidding. I couldn't resist because when you were helping me with cooling system suggestions you gave the same drive-thru benchmark test of the cooling system.

Oh, and I second the concern about the electric impeding air flow to the mechanical fan on a dual setup.

[Squidward]

Originally Posted by AdamIsAdam

you've talked about this "drive-thru dilemma" before. I'm beginning to think you're altering your behavior incorrectly; rather than going inside the restaurant maybe you should cut down on the fast food!

Just kidding. I couldn't resist because when you were helping me with cooling system suggestions you gave the same drive-thru benchmark test of the cooling system.

Oh, and I second the concern about the electric impeding air flow to the mechanical fan on a dual setup.

The wife likes her Starbucks, and I like Del Taco. Too late to change direction now!

[pokey1]

Originally Posted by Squidward

I also run a 6"-ish wp pulley to go with previously mentioned shroud/fan/clutch/4 core aluminum rad setup. Fan is inset into the shroud somewhere between 1/2 and 3/4 IIRC. I run a mech gauge out of the water crossover. My heads don't have a bung.

After putting in the 4 core/clutch/shroud setup (still running 69 short nose 11 bolt pump) I left the tstat out to test cooling ability without it. In the winter the temp gauge took a long time to get into the 110-120 range. I was spending the spring/fall months not getting over 150 during any condition. I went with a 180 tstat, and it hasn't seen the high side of the tstat setting except for once: My last trip to the strip had me going through the traps above 5k, and my wp divider plate (was clearanced to a tight spec) somehow ended up sucking into the impeller, and my pump blew out a gasket. I actually UN-clearanced my plate some when I did the repair in the pits, and it still cools great.

I wanted electric fans. I really did. I loved the clearance near the radiator, and I loved not having a whirring sausage slicing deathtrap under the hood. But I wondered why my friend Mike could run his 11 second 455 68 'bird all day long on a factory brass 4 core, and I couldn't come close. I decided to just copy his setup of shroud/fan/clutch, and problem was solved.

Along the way I did flirt with the 1st gen chin spoiler. I started fabricating my own, but then I solved my issues. Also, I installed the air filler plates between the nose and the radiator support. Those probably help some, but I know people without the fillers who don't have cooling issues. All I can say is that I underestimated the air flow need.

What fan are you using with the clutch setup? All fans I see are all say for 6 cyl only. I used to have a clutch fan set up and it seemed to work well until one time I was hammering the throttle hard and a blade from the fan went all the way thru the radiator. Wondering if strength of the blades are questionable..

[Speargun]

UPDATE

I finally got my car back on the road after the transmission fiasco. (See other thread)
I installed a repop factory shroud, 18", 6 blade Derale fan, an extreme duty fan clutch, & a 160* T-stat during the down time. The temps still creep up to as high as 215*-220* in town with the AC on, but once I can get up to highway speeds (and RPMs), the temp comes back down to 165*-175*! The faster I go, the cooler it gets, but it sounds like a Cessna 150 going down the road.

Still needs help at idle or around town, but at least it's getting better.

[Ccass]

Originally Posted by Speargun

UPDATE

I finally got my car back on the road after the transmission fiasco. (See other thread)
I installed a repop factory shroud, 18", 6 blade Derale fan, an extreme duty fan clutch, & a 160* T-stat during the down time. The temps still creep up to as high as 215*-220* in town with the AC on, but once I can get up to highway speeds (and RPMs), the temp comes back down to 165*-175*! The faster I go, the cooler it gets, but it sounds like a Cessna 150 going down the road.

Still needs help at idle or around town, but at least it's getting better.

I speed read the whole topic and didn't see what radiator you settled on with the results above. The results clearly show that you do not have an engine issue. It's definitely air flow at idle but you could solve the stop and go problem with more volume as well. What radiator is in there?

Pics? That might also help us spot something that can improve air flow.

[Speargun]

I ended up with the Cold Case radiator since it gave the best overall performance for my setup.
Heres a link to my review of three different radiators I've tried in my car.

I need to find a fan clutch with a shorter shaft. The one I have pushes the fan a little too far inside the shroud.

My total cooling capacity is only about 2.5 gallons so I'm kicking around the idea of fabricating a container to fit in the open space in the front left fender and plumbing it into the inlet side of the radiator. I think I can get another 2+ gallons of capacity in the system if it works.

[1967Tempest]

Are you set up for the Fitech to control the timing? That might be the last thing you need to adjust, if not.

I have heard good things about the Fitech controlling the timing. It might add a bunch of timing while your at idle with a zero TPS reading and temps creeping up.

[Sirrotica]

Originally Posted by Speargun

I ended up with the Cold Case radiator since it gave the best overall performance for my setup.
Heres a link to my review of three different radiators I've tried in my car.

I need to find a fan clutch with a shorter shaft. The one I have pushes the fan a little too far inside the shroud.

My total cooling capacity is only about 2.5 gallons so I'm kicking around the idea of fabricating a container to fit in the open space in the front left fender and plumbing it into the inlet side of the radiator. I think I can get another 2+ gallons of capacity in the system if it works.

This makes a huge difference for a system that is marginal. I added capacity to my 69 GP 428 dirt car and never had any O/H problems after increasing the cooling system capacity. Even under the worst conditions it never rose over 180 degrees after increasing the cooling system capacity. The suggestion was made by the radiator shop owner I used at the time, and he was right on the money.

I increased my capacity by roughly 1-1 1/2 gallons so your 2 gallons should be plenty.

Taking a lit cigarette and usong the smoke trail to trace the air pattern is also an aid to find out if the air is flowing fast enough and in the right places, that he also showed me. The old timers always have some secrets because they've been there and done that before.

[Bruce Meyer]

Originally Posted by Sirrotica

This makes a huge difference for a system that is marginal. I added capacity to my 69 GP 428 dirt car and never had any O/H problems after increasing the cooling system capacity. Even under the worst conditions it never rose over 180 degrees after increasing the cooling system capacity. The suggestion was made by the radiator shop owner I used at the time, and he was right on the money.

I increased my capacity by roughly 1-1 1/2 gallons so your 2 gallons should be plenty.

Taking a lit cigarette and usong the smoke trail to trace the air pattern is also an aid to find out if the air is flowing fast enough and in the right places, that he also showed me. The old timers always have some secrets because they've been there and done that before.

Sirrotica- Im curious on how you increased the capacity of your cooling system. Any pics? Thanks.

[1967Tempest]

X2.

[Speargun]

Originally Posted by 1967Tempest

Are you set up for the Fitech to control the timing? That might be the last thing you need to adjust, if not.

I have heard good things about the Fitech controlling the timing. It might add a bunch of timing while your at idle with a zero TPS reading and temps creeping up.

I haven't got around to switching over to FiTech timing control yet and I have the vacuum advance disconnected right now so the timing should be pretty steady.


I did a little measuring in the unused area between the driver side fender & radiator and I have room for, up to, a 10"H X 12"L X 7"W tank which would give me an extra 3.5 gallon capacity.

I'm thinking that I could plumb the system to come out of the thermostat housing, go into the tank, then out of the tank, and go into the radiator inlet.

Can anyone think of a reason why this wouldn't work?

[Sirrotica]

Originally Posted by Bruce Meyer

Sirrotica- Im curious on how you increased the capacity of your cooling system. Any pics? Thanks.

Bruce, because I had a GP with all the extra room in front of the engine I used 2, 3 core radiators so I gained the extra capacity through all the extra hoses and the capacity of 2 radiators. This is in 1978 so I have no pictures, plus wouldn't apply to most members cars anyway, (it didn't have to be aesthetically pleasing, just functional)........................

In your basic A or F body, my radiator guy at the time, suggest a tin gas can with nipples soldered in both ends, one in the filler neck and one in the bottom. The can would be spliced into the upper radiator hose. Of course it would need to be properly secured under the hood.

I was going to do just that when I decided with all the extra room in front of the car I would instead use 2 radiators. I placed them with both front sides facing each other so the necks on the front radiator faced forward, and the rear radiator faced in it's normal direction, yes the plumbing was ugly....LOL

The path of the water was, out of the thermostat housing into the upper front radiator, out of the bottom of the front radiator into the top of the rear radiator then out of the bottom of the rear radiator back to the timing cover. It took awhile to get it plumbed with hoses and small diameter exhaust pipe. I was rewarded with a Pontiac that never got above 180, no matter how long the race was, how long it idled, or how hot the ambient air temp was. I had a double pass cooling system before there were double pass cooling systems.......

Pontiacs on an oval track are really tough to keep cool with the standard cooling system, been there and done it enough times to know that you really need more than the engineers designed into the OEM system.

In another 455 Firebird race car we used 2 radiators soldered together because there was no room to have the hoses coming out of the front of the forward radiator. The radiators were stacked and the front radiator nipples were soldered into the tanks of the rear radiator, in effect making a 6 core radiator (2, 3 cores soldered together). The thing is the fan has a problem pulling air through all those fins and tubes (the reason that there are never more than 4 core radiators in cars). In effect we probably hurt the heat transfer from radiator to air by exceeding the 4 core limit, but we more than gained what we lost by the added capacity of coolant. Nether one of these cars ever ran hot after addition of the extra radiator.

One other experiment was in a demo derby 71 Bonneville, 400. We put a 15 gallon barrel under the package shelf with connections on it to plumb it into the heater circuit. Pontiacs used for demo derby usually O/H in short order because when abused they seem to need a lot of cooling, and if the radiator starts leaking the time it takes them to O/H and shut down is usually fairly short.

With 15 gallons of extra water that would buy some time before the engine heat got critical. This was kind of a failed experiment however because the car got knocked out long before the engine ever got hot. But having that extra 15 gallons we felt we could have run it with no radiator at all for quite awhile.

So that is the ways I've added coolant capacity to race/demo cars and none of those 3 engines even hinted of getting warm after adding coolant capacity.

HD trucks have coolant tanks for upping the capacity of the coolant routinely, hauling 80,000 Lbs over mountains, they need the extra coolant capacity. Problem is in a car you usually don't have a bunch of room under the hood to add a tank.

In a Pontiac I would be looking at the rectangular can I described earlier inline in the upper radiator hose, or possibly a tank inline in the heater circuit.

Now I really don't have enough data from the demo car to know if the reduced hose size down to heater hose would offer enough flow to impact the coolant temps on a Pontiac or not. This would be an area someone would need to build the system into the heater circuit to see if there was enough flow to work. I feel that the heater circuit may just be the little extra some Pontiacs need to have enough, just my opinion.....

Adding the tank into the heater circuit opens up being able to mount it other than under the hood. If you mount it further away you'll also gain more capacity in the plumbing needed to have it remote mounted.

I think most people that have been around Pontiacs for any length of time know that the OEM type system has to be spot on for it to hold up to any racing or hard use. Any deficiency will show up quickly. I believe that when designed originally Pontiac engineers had a small percentage of reserve cooling and as soon as any component wasn't operating at 100% there went the reserve cooling. To put it simply, it was right on the edge when new, after some aging we have problems. Add to that someone trying to use a OEM style system to cool a 505 CI engine, your going to run into problems. Time to think outside the OEM box..........

There you have it, my experiments into cooling a dirt track/demo derby Pontiacs. If someone can transfer some of these experiments and success's over to their own cars, that's great, glad I could help out.

[Bruce Meyer]

Good info Sirrotica. I was toying with the idea of using my 69 Lemans parts car as a dirt track car for fun.

[Ccass]

Originally Posted by Speargun

I ended up with the Cold Case radiator since it gave the best overall performance for my setup.
Heres a link to my review of three different radiators I've tried in my car.

I need to find a fan clutch with a shorter shaft. The one I have pushes the fan a little too far inside the shroud.

My total cooling capacity is only about 2.5 gallons so I'm kicking around the idea of fabricating a container to fit in the open space in the front left fender and plumbing it into the inlet side of the radiator. I think I can get another 2+ gallons of capacity in the system if it works.

Automatic or Manual trans radiator? There is a difference in our 1st gen F body AT vs MT cooling capacity.

I hate for you to have to do all that extra work to solve what is now only a stop and go cooling issue.

[Speargun]

I have the AT radiator, but I'm using a separate tranny cooler so all of the tests would be the same.

[70GS455]

Originally Posted by Speargun

UPDATE

I finally got my car back on the road after the transmission fiasco. (See other thread)
I installed a repop factory shroud, 18", 6 blade Derale fan, an extreme duty fan clutch, & a 160* T-stat during the down time. The temps still creep up to as high as 215*-220* in town with the AC on, but once I can get up to highway speeds (and RPMs), the temp comes back down to 165*-175*! The faster I go, the cooler it gets, but it sounds like a Cessna 150 going down the road.

Still needs help at idle or around town, but at least it's getting better.

Find the post on this site regarding adjusting the clutch engagement point on the severe or extreme duty fan clutch. It will drop the temperature at which the clutch engages and help your idle temps

Sent from my SM-T817V using Tapatalk

[Ccass]

Originally Posted by Speargun

I have the AT radiator, but I'm using a separate tranny cooler so all of the tests would be the same.

Cold Case MT radiators are Tri-flow. I'm pretty sure the AT is standard flow. However, that radiator is a very large capacity radiator with 1 1/4" tubes. Air flow is bringing down the temps dramatically at highway speeds. So the key is to figure out a way to mimic air speed through the radiator at idle.

Any way you can show a picture of the fan/shroud setup?