Your heater is acting like a radiator, so I would say yes, that would lead me to think the radiator isnt working like it should.

 

Back in the day I raced a little rwd Toy Corolla in SCCA ITC. We were limited on what mods we could legally make. The stock radiator wasn't able to keep up with thermal load of the little motor doing all it could do for 1-2 hours at a time racing near coastal TX in 100F heat with high levels of humidity. I always ran the heater on high to help out the rad. Without the htr it would overheat. With the heater it would stay right at 220F. I would typically lose 7-8 lbs. during a 2 hour enduro.

 

great idea!

Cheapest way for weight reduction

 

Too bad most of it was water! I bet he drank plenty after the race!

 

If it had orange (DexCool) coolant in it before, and you've shifted to green, my understanding is that is bad joo-joo.

 

The coolant I used was a "Universal" style coolant and is allowed to be mixed with any, but yeah it is bad to mix red/green

 

seriously, have you tried filling the block though the water pump outlet? It works.

I never had problems burping cooling systems until I bought a bmw and now I'm cursed.

 

You have enough radiator area but in Houston in 100 degree temps your radiator is not up to the task as evidenced by the use of the heater to bring down temps to 190. That proves that your coolant flow is adequate to cool the motor, your old radiator just is not efficient enough, I figure clogged. You also have a turbocharger adding under hood heat , an intercooler and condenser blocking airflow to the radiator. Put in a new, best you can buy, quality radiator and you should be in business.
Jarhead

 

On your water pump, did you loop the heater connections or cap them? If you have them capped it will cause this problem. They make a $10 loop if your not running a heater core.

 

.....and LOTS of people cap them with no problems at all, fwiw.

 

I didn't read the rest of the thread.....

But you have a couple problems. First, no radiator will work, no matter how large it is or how many rows it has or how well it flows......UNLESS the HOT coolant that just left the engine after the t-stat opened has enough time to "SIT" in the radiator until the t-stat opens again.

Once an engine starts getting HOTTER and HOTTER the t-stat NEVER closes all the way. They begin to partially close little by little because the coolant is getting hotter and hotter and each time the HOT coolant in the engine/heads and the COOLER coolant sitting in the radiator swap positions, the HOT coolant gets less and less "SIT" time in the radiator, therefore you have started the beginning of the end......OVERHEAT is coming. Because there will be a point where your T-stat never closes fully again, and at some point when all the coolant is too hot it will stay WIDE OPEN forever. Thats the point at which you see the temp really high, then BAM....the needle just keeps moving to the right.

You need to get a t-stat that allows longer "SIT" time for the HOT coolant that just entered the radiator. The 160*F tstat is very bad. Try a 180......then go to a 195.

BUT.....you really need a fully closed shroud on the rear of the radiator. So ALL of the air that the fans are pulling through the radiator goes through the entire surface of the front and exits the entire surface of the rear. It must have flaps on the back that will open when the fans are off and you are cruising on the highway, to support the openings where the actual fans are for exit airflow. The flaps will also aid in more air flowing over more of the front surface area.

Absolutely nothing wrong with a factory LS1 radiator, for any heat at all.

I work in Dubai 6 months a year......120*F days are common......110*F-115*F is normal for 4 months. The guys I know with Trans Ams, Camaros and Vettes all use the factory radiators.....They just need to be part of an entirely properly set up and healthy operating system. Same with Kuwait where its hotter than Dubai....worked there too, every FBody ownewr I've met use the factory cooling system.

And...on a side note.....if I lived in a real HOT area.....((I live in South Florida and its pretty hot sometimes, but I mean desert hot areas)......I would install a mister system. I actually have the parts for that system sitting in my storage unit waiting for boost set up to get installed. Very simple. You drill a hole in the bottom of your factory windshield washer fluid container.....install an identical windshield fluid pump thats already in there but used to spray the washer fluid on your windshield.....the second pump is for the mister system. Then simply run a line out in front of your radiator snaking it around the entire surface with 15 little mister heads.
If you fill the factory container with water it will run for 4 hours. You hook up a switch to start the mister any time you want to. DROPS temps 30*F in one minute starting from 225*F sitting still with the A/C blasting. Just from the fans pulling air through. At cruise speeds it will aid the ram air in cooling, but we didn't test that.

Get yourself a 1 gallon container, find a windshield pump at the junk yard and run a simple switch.....DONE.

.

 

To anyone who thinks this is true -- can you explain to us why the water pump is designed to turn faster and faster with increasing engine rpm/load? It's coolant FLOW through the radiator that provides more heat transfer. If you get the coolant in there, and there's enough air flow, heat transfer will be achieved. As thermal load increases, the water pump pushes more and more coolant through the radiator by increasing the velocity of the coolant. The faster the engine rpm, the faster the pump turns, the faster the coolant's velocity is, the LESS sit time the coolant has in the radiator. That's because "sit time" in the radiator is a non-issue. As long as it passes through, the air will take the heat out of it. The whole "not enough sit time" in the radiator is an old wive's tale --- no merit to this whatsoever.

Opinions vary. There's mine on "sit time".

On the other hand, I applaud the comment about lower temp t'stats. Whatever the nature of the overheating problem is, if the thermal systems won't remove enough heat to keep the temp at 190F (keeps rising to 200F, 220F, etc.), how can the same system remove enough EXTRA heat to get the temp down to 160F? I believe the factory t'stat on the inlet of my LS3 is a 187F unit (it began to open at 184F and was fully open by 188F). When there's enough heat removed to keep the around that set point, the driver's side head temp where coolant leaves to go back to the radiator (where my ecu coolant temp sensor is) stays at about 196F-197F. When my fan controller has control of the temps, it sits around 202F-203F. A higher temp t'stat means the cooling system will have LESS work to do.

 

 

And there's another data point on the lack of need for "sit time". Sans t'stat, coolant being pushed through engine and radiator as fast as the pump can push it, engines over cool. Because of the high flow rate of the coolant through the system.

 

I THINK what he is trying to get across is that the coolant should not flow thru the radiator too quickly. It can never really "sit"; it's always moving as long as there is flow when any thermostat is open even a bit.. If the coolant goes thru slowly enough, it has a chance to lose the contained heat. Removing the thermostat would prevent this by letting the coolant go thru too quickly to shed the heat. And a too-cool thermostat would only start the process too early to allow the engine to get warm enough.

 

 

What you say is true to a point. Coolant can run thru a radiator TOO quickly to shed a sufficient amount of heat. It needs a certain amount of exposure time in the radiator to do this. This is one reason it needs to be of enough capacity to cool sufficiently. Too small a radiator lets coolant go thru too quickly to cool correctly. A large enough one slows the flow enough to get it done right. In other words, a radiator might be able to handle the flow gallons-per-minute-wise, BUT without letting the coolant be there long enough to cool sufficiently.

 

I've shared my perspective....I'll let it stand.

 

 

I also thought this was the issue, I'm running a vintage air system - which uses a valve to block off coolant flow to the radiator. I opened the valve manually, and the car still over heated (unless I turned the heater on)

I did read a lot of people with the vintage air systems are not over heating with that valve installed, but there were a couple situations where I saw the valve was the problem. Sort of odd