more cooling

[Lewis Maudlin]

OK, I have a 355 sbc with aluminum heads and headers putting out about 375hp. I had the hood louvered to allow the heat to escape. Lately, on our 100 degree days with the air on, my car has been getting hot. Even tonight at 75 degrees without air, my car was at 185 with a 160 degree thermostat. During the day, it continues to climb. I do not have an aftermarket water pump and I am using the camaro radiator. Do I need one of those high flowing aftermarket water pumps? What about a 1" core radiator? Do I need the 1.25" core radiator since I am running air conditioning? I can buy a new 1" twin core radiator for $135 or a griffin 1.25" for $290. Do I really need the 50% extra capacity that the griffin will give me for more than double the price?

[Guest Anonymous]

I have the howe radiator in mine with 1" tubes and I run a/c on my sbc and have a 180 thermostat and yesterday on the freeway at about 6:30 here in Az, I went to meet Zdreamer who is here on business. It was about 103 with 36% humidity and I was seeing a gauge temp of 205 deg at one point. The thing that makes me a bit nervous is the inaccuracy in the autometer electrical gauges, but even so, it wasn't hot enough to boil over. I'm going to put in a 160 thermo and water wetter and see if I can do better with that.

 

I said before I'd give progress reports on how well it cools here once it heated up pretty good. I think it obviously could be a issue if it ever goes the 122 (but then, what car wouldn't ) that has happened here before. I guess GM (or was it ford?) doesn't have a desert proving ground down here for nothing.

If you can spring for the extra, it might not be a bad idea. I've never felt the camaro unit was a great choice in some areas anyway, it was designed for a 4-6 cyl car and I never understood why it would be desirable in a V8 except for the fact that it fits. Many use it with no problem, but on a hi-po motor I just can't see it, but people run them all the time so what do I know.

I well say that three cars I've first hand witnessed with aluminum heads put quite a bit more stress on the cooling systems that they did with iron heads (better heat transfer to the water passages I guess), could be a factor.

 

Good luck,

 

Lone

[Mike kZ]

I'm running the Camero Rad with a Taurus fan. My 327 made 435hp (engine dyno),and I have aluminum heads. In 96 degree heat with 80%+ humidity with the AC on and a 180 thermostat, I'm running 185 to 190 driving, and a max of 198 at idle in traffic. Now I do have a Weiand water pump, and I'm running Water Wetter.So my car is running cool enough, if it was over 230 or so I'd be worried.

[Guest greimann]

This engine temperature subject seems to heat up during the summer, Har Har.

 

An engine running over its thermostat temperature is not unusual. A thermostat's basic function is to set the LOWER limit of an engines temperature range so the motor does not run too cool. The upper limit is going to be a combination of many factors including ambient temperature and the influence of all of the mechanical devices associated with cooling. A motor that sees 220 degrees or less in the MOST severe conditions is not in jeopardy of overheating or blowing a gasket. If the temperature continues to climb towards the upper end of the gauge, around 260 - 270, then you have a problem.

 

Getting a large motor to stay right at the thermostat temperature in any weather is going to require massive cooling capacity that is, in my opinion, unnecessary. If you have a high compression motor and are trying to control detonation, then lower temperature combined with timing adjustments may be warranted. BTW, I also run about 180 - 200 degrees in the summer with a Griffin 26 x 19 and Black Magic fan.

 

Remember, the system is under pressure and the boiling point of the coolant is going to be above 260 degrees. (maybe someone can calcualte the boiling point of water at sea level + 13psi)

[pparaska]

Dave, thanks for the well informed post. I've been concerned a bit lately since my Z always runs at 210. But that's where the fan switch turns on. It's crept to 215 momentarily in traffic in very hot weather with the A/C cranking, but never above that.

 

I'm fairly convinced that my Camaro radiator is enough, and I run a 195 thermostat to keep the temps up for better effieciency and power.

[pparaska]

O.K. Engineer here - better check my math!:

 

(assuming they meant degrees F, and you're at sea level, and the BP of coolant water is the same as water??)

 

Boiling point = 212F + 16psi * 3 deg/psi

Boiling point = 212F + 48F

Boiling point = 260F

 

So a 16 psi radiator cap gives 260 boiling point?

[Guest greimann]

Glycol raises the normal boiling point of water. From what I could find, A 50/50 mix of water and glycol has a 15 degree F higher boiling point than water alone, so in Pete's example above, you have boil out protection of 275 degrees.

[Phantom]

OK guys - lets talk cooling.

1) Glycol raises your boiling point and lowers the freezing point BUT it is not as good of a heat transfer medium as water. In the case of glycol - more is not better. If you want a way to improve your cooling - that actually can save you money - only run the minimum amount of glycol you need to protect the motor.

2) Heat transfer is a direct function of temperature differential - ie: the difference in temperature between your radiator water and ambient air. As the air temperature goes up the difference decreases and the water temperature goes up proportionally until it again achieve equilibrium. That is why a 160° thermostat controls fine in the winter but once the air temperature goes above about 85-90° the water temperature starts to drift. The only way to affect that is to move more air or move more water with moving more air the more effective way to cool - or increase the exposure time to the air by getting a bigger radiator or having more rows. If the air temperature is 100° and the leaving water is 85° then the radiator has a 85° "approach". If you double the number of existing rows on the radiator you can get that down to about a 45°approach which means that you could run 160° on a day where the ambient is about 115°F.

V-8 conversions have a lot of room in the nose for deep radiators. Adding rows is a standard industry solution. I have no idea why everyone is so hung up on single row or 2-row radiators - Give me a 4-row any day.

[Lewis Maudlin]

Thanks for all of the great info. My car heats up. When I said it gets up to a little over 210, that is only because I find an open road or turn it off. If I did not, it would continue to climb. I already overheated it once. Thermostat didn't open and temperature gauge chose not to work that day. Bad combo. Anyway, what I need to know is whether I will be sorry if I fork out the $139.99 that it is going to cost me for a 1" 2 row aluminum griffin copy. Or should I shell out the $289.99 for the 1.25" now. Also, do I need a high performance water pump. Seems to me that if the water is flowing slower, it would cool just as well because it would spend more time in the radiator. Does that make any sense. Let me know. Thanks. Lewis

[Guest greimann]

Yea, we got a little off track from your original question, but great dialog huh?

 

I have the 1" X 2 row Griffin and have had no temperature related problems with it. Get a good fan. Ford Taurus or Flexalite Black magic. A high flow water pump helps, but may not be necessary. If you NEED to replace the water pump because it is leaking, the get a high flow one. Heat transfer is all about flow; air and water.

 

The urban legend about water cooling better by spending more time in the radiator is just that, a myth. People saw that when they removed their thermostats, the car would boil over. The assumption was that removing the thermostat somehow caused the operating temperature to increase and came up with that dwell time theory.

 

The actual cause of boil over was the redistribution of pressure within the entire system and not temperature related at all. The thermostat is a restriction that creates a higher fluid pressure in the block by resisting the flow of the pump. There is lower pressure in the radiator because the pump suction is drawing from there. Removing the thermostat transfers the the higher pump pressure to the top of the radiator where the pressure relief valve (cap) is poised and ready to vent excess pressure. Really rev the motor and you could probably push coolant past the cap, way below the boiling point of the system.

 

To answer Mr. Phantom's question about why 2 row cores: The aluminum aftermarket radiators use 1" wide tubes in two rows versus 1/2" wide tubes in 4 rows for a copper - brass unit. They are both relatively equivalent in cooling capacity.

[Lewis Maudlin]

So is the consensus that 1" X 2 row aluminum will work? keep the stock water pump until issues arise? Some of the others on the last post said that they wish that they would have gone with a 1.25". How big are the tubes in the Camaro radiator? Thanks

[Lewis Maudlin]

Oh yeah, and you guys who say that 1" works, is that with the air on in traffic or that it works without air while going down the freeway?

[Guest greimann]

I have no AC (or condenser) and the temps are stable in traffic. Maybe you should go with the larger unit. But also get a good fan if you dont have one already. Taurus or Black Magic fans are the most powerful out there.

[BAlford]

My car was running 220 degrees or so, I tried several things here is what worked. I put two heater cores under the front finders ahead of the tires.

 

http://waskomtexas.com/zcar/re_car/engine_cooling.html

 

Not much math just results. It now runs under 190 degrees.

[Guest Anonymous]

My numbers were with the air on in traffic. The reason for not going 4 cores is the last two cores tend to get hotter air passing over them as its already passed by two cores and heated up considerably before it reaches them. Thats at least what I've read. By the number above, you have to really get the stuff hot to boil it over (and thats without getting into more pressure or water wetter or 40 below or any of the additives).

 

Regards,

 

Lone

 

Ps: Also a tip I've read, never paint radiator finned area's especially in a aluminum radiator, bad idea, it screws the heat transfer up. Sounds like a no brainer, but I've seen it done.

[Guest Anonymous]

I'm hardly the mathematician here, but here is a general statement I found on a site about radiator pressures:

 

"For every additional pound of atmospheric pressure, the coolant boiling point increases

3 degrees F. "

 

Also at 10,000 feet the boiling point of water is 90 c.

 

Math majors, have at it, I am not worthy

 

Regards,

 

Lone

[Pop N Wood]

This topic has been dicussed numerous times so there is a lot of info in the archives.

 

My suggestion is to set up the radiator like everyone else has then if you still heat up, see what you might be doing different.

 

I think what everyone is telling you is the Camaro radiator should do the job. The larger Griffin's will do even more, but if you aren't getting the cooling out of the camaro, then going to the Griffin is just going to make up for something else that you may not be doing right.

 

There are quite a few other things you need to check. Z's are very sensitive to air flow. You have to make sure the air is flowing through your radiator and not around it. Thus make sure you have a decent fan shroud and that the radiator is tight against the sheetmetal so no air can flow around the sides. The early Z's also experienced a loss of air flow through the rad due to turbulence under the car. The fix was to install a chin pan that goes between the frame rails from the back of the rad to about the steering rack. MSA sells these. The other option I have heard is to help the air get back out of the engine compartment. Your louvers may do this for you. I have heard of others that installed electric fans in the wheel wells blowing out.

 

But in your case you need to make sure everything in the cooling system is in good shape. Make sure your radiator cap is good, or better yet just replace it. Try flushing out the block and cooling system. You never know how many cans of stop leak may be gunking up the works. Make sure your lower radiator hose is in good shape and has the anti collapse spring in place. At highway speeds it is not uncommon for the water pump suction to collapse this hose. Put in a new 180 or 195 degree thermostat. Check to see if it opening ALL of the way using a pot of boiling water and a kitchen thermometor. Make sure your engine timing is correct (too much advance makes an engine run hotter). Try replacing the coolant with a fresh mix. Tighten up any leaks and make sure your radiator overflow tub is working.

 

Also note what Phantom said about glycol mix: never run pure water. The engine needs the antifreeze to keep the water pump lubricated and to keep the aluminum in the engine from corroding.

 

Another idea is to add an oil cooler.

 

The final issue is fans. Most people don't agree with me on this one, but what I have noticed is most cooling problems are on cars with electric fans. Mechanical fans have a bigger drive motor and can move more air. But obviously electrics get the job done. If you run an electric, make sure you get a good one that you know will work. Follow the advice given above.

[Lewis Maudlin]

First, what I am doing different is Aluminum heads, close to 400 hp, headers, and air. I agree the camaro radiator works great for an iron block with cast exhaust manifolds without air. GREAT, Jim Powers. But that is not my set-up. Since I have air and additional power the Camaro rad does not work. Even JTR says that it will only work with 225 or 250 hp with air. I have about 400. The next question is how big to go. And whether a high flow water pump is necessary.

 

The previous posts discuss many people saying that they wish they had gone to 1.25". Who out there has a car that 1" will not cool? Is it substantially similar to mine? Do I really need to fork out the $150 extra?

[Pop N Wood]

I guess I misunderstood Mike kZ's posting

 

I'm running the Camero Rad with a Taurus fan. My 327 made 435hp (engine dyno),and I have aluminum heads. In 96 degree heat with 80%+ humidity with the AC on and a 180 thermostat, I'm running 185 to 190 driving, and a max of 198 at idle in traffic. Now I do have a Weiand water pump, and I'm running Water Wetter.So my car is running cool enough, if it was over 230 or so I'd be worried.

[timh]

If you're working toward a stable 180-190° without it creaping up, the 1.25" two row may provide that potential. I have a milder setup, about 275-300 hp, big iron heads, A/C with stock condensor mounted in stock location, small B&M 16000 gvw tranny cooler mounted just below the condensor, taurus fan, stock water pump. I just switched from a Camaro to the double 1" and a 1 quart goza recirculating catch can. My initial timing is now 15°. I'm currently experience a rise to about 205-210° on the highway with air on in 98° heat. I haven't had time to readjusted my mechanical advance, vacuum advance or stuffed around the radiator for improved flow. I won't need the extra buffer the 1.25" radiator likely provides, but the company that sold me my Howe seemed to have more experience with typical hot rods, and was pointing me in the 1.25" direction. All setups are not the same, if you can afford it, go big. This is just an opinion from a guy working out the same problems, just a few weeks ahead and a few bucks lighter.