Cooling questions... - Team Camaro Tech
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post #1 of 11 (permalink) Old Feb 25th, 12, 12:30 PM Thread Starter
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Question Cooling questions...

Sorry this is so long... boring Saturday afternoon.

Basic 350 with the typical bolt-ons.
Large aluminum radiator without trans cooling (using remote cooler mounted in front of radiator). 2700cfm electric fan\shroud set to come on at 160 degrees which is adjustable. So that means it runs non-stop as long as the engine is up to temp.

I used to have a 190 degree thermostat in it, but on hot summer days I'd be pegging to the point where it would puke a little. If I was on the expressway going 70, it was getting pretty hot. Slow down to 65 or 60 and it got a little better. Sitting at a stop light or creeping along in bumper-to-bumper traffic was scary.
So I swapped for a 160 degree thermostat and it runs a lot cooler. Doesn't make sense that it would help, but it did. I rarely see it go over 190\200 now.

My first question has to do with operating temperature and how the engine responds. I realize the rated temp is what the thermostat opens at.
Is the 160 thermostat hurting me in any way by opening so soon? Would I be better off with a 180 degree? Engines are huge heat pumps and we spend so much time (and engineering!) trying to keep them cool.
If I'm not mistaken, a typical 350 would have come with a 180 degree thermostat in it, right?

Second question..
I just read an article in one of the April car mag issues about radiators and cooling. It got me to thinking about the shroud and fan capacities and how they function at different speeds. High pressure and low pressure zones around the radiator and the shroud.

I don't know how I'd be able to measure that type of thing, but I'd love to know if there are zones of pressure or restrictions from my shroud and fan capacity that I may have an issue with that I could correct. As large and new as my radiator is, and the large capacity of the fan, I would think I wouldn't have any problem with the engine running at whatever temp I want to set it to run at.

I was thinking about the shroud trying to funnel all that air through the one fan and it not being able to pass enough over the radiator to properly cool the water. Would I be shooting myself in the foot if I put 2 or 3 small diameter holes in the shroud to let some air pass through? I'm talking about an inch diameter.

Ideas? Suggestions? Comments?

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post #2 of 11 (permalink) Old Feb 25th, 12, 04:02 PM
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Re: Cooling questions...

Indeed it is a long borig afternoon….so hopefully you won't mind my long boring response…

If the engine temperature is at 190\200 with a thermostat of 160, it tells me that the rad is having a hard time cooling your engine in the environment that you are operating it. However, if you are on the highway on hot summer days, one would expect the engine temperatures to rise above normal. And if this is the worst scenario that you are going to experience than what you are seeing is probably OK. But at the other extreme, the engine under normal or even cool day conditions, should fall and stabilize somewhere between 165 to 180 (with your thermostat). If that's not happening, than I would think your rad/setup cannot disperse heat well enough for your engine.

An engine running too cool (constantly) will not reach a temperature that can burn off moisture in the engine. Oil, water and the pollutants of combustion will mix to form sludge and a acid byproduct. An engine that reaches OPTIMAL operating temperature can burn off these pollutants an prevents the building up of slugde and corrosive byproducts.

When the engine manufacturers specify an optimal operating temperature , they take this into consideration as well as the expansion (rate) factor of the materials that make up the engine. Too much expansion and you have excessive friction wear; insufficient expansion and you run the risk of fuel leaking into the oil (via blow-by), diluting it and you end up with a lubricant that can't do it's job...end result is also wear.

So what's the right thing to do?...Always try to operate the engine at the temperature that the manufacturer recommends. If that means changing your thermostat in winter and then back in the summer…so be it. If however, your rad setup is such that it can cool the engine on the hottest of days on the highway and maintain just above normal temperatures, then chances are you won't have to worry about changing thermostats..and 180 will do just fine all year round. That's the case with most cars...but when we start putting bigger "heat pumps" () in....then we have to increase our cooling capbilities..i.e. bigger rads, more efficient rads, auxillary cooling fans, etc, etc.

Is the electric fan (2700 CFM) the only thing cooling your rad?
I personally use a flex-o-lite fan PLUS a two stage electric cooling system (1200 CFM and then 2400 CFM). The electric system is most useful if you end up in city traffic. I find that the flex-o-lite fan does a tremendous cooling job at normal traveling speeds…BTW..I use a 180 degree thermostat….and never drive the Camaro between late October through May.

BTW, I would be reluctant to start putting holes in the shroud. Oh , and 2700 CFM is really not as much as you think. I tried running my car with just the electric fan running (2400 cfm)...and my stock radiator could barely keep up with the heat that my little 327 was producing. I saw a huge difference when I re-installed the flex-o-lite fan.

Vic Brincat

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Last edited by cadmanof50s; Feb 25th, 12 at 04:37 PM.
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post #3 of 11 (permalink) Old Feb 25th, 12, 04:56 PM Thread Starter
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Re: Cooling questions...

Quote:
Originally Posted by cadmanof50s View Post
But at the other extreme, the engine under normal or even cool day conditions, should fall and stabilize somewhere between 165 to 180 (with your thermostat).
It will but only on cool nights and in the Spring and Fall.
Since I put the 160 in I've been lucky, even during the looooong boiling summer we had. But there were still times I was staring at the gauge in fear of polluting mother nature.

Quote:
Originally Posted by cadmanof50s
... insufficient expansion and you run the risk of fuel leaking into the oil (via blow-by), diluting it and you end up with a lubricant that can't do it's job...end result is also wear.
Fortunately my oil is always clean and free of fuel.

Quote:
Originally Posted by cadmanof50s
Is the electric fan (2700 CFM) the only thing cooling your rad?
Yep... that's all.

Quote:
Originally Posted by cadmanof50s
BTW..I use a 180 degree thermostat….and never drive the Camaro between late October through May.
Neither do I.
I suppose I could put a stock type fan on. The only reason I'm running what I have is because it was readily available from a friend across the street the day I installed the engine. I didn't have a radiator OR patience to go buy one.
I'm going to put the 180 in and see what happens this year. I can always go back to the 160.

Thanks Vic
By the way... your screen name should be CONVmanof50s. You sure have a lot of beautiful convertibles!!

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post #4 of 11 (permalink) Old Feb 25th, 12, 05:27 PM
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Re: Cooling questions...

Joe,

Not to be-labour a point, but are you in the position to install a mechanical cooling fan?

The fan I use litteraly cost $15.00 and has made a world of difference to my cooling set up. (I only have the electric fans for those rare occaisonas where I am stuck in high-way traffic.


My mechanic suggested it over the stock clutch fan. I didn't believe it would make a difference and even avoided putting one in for a month. I could not believe the difference it made once I installed it. It is MUCH lighter than the stock and has an extra blade. Only one down side that I could notice...a whirring noise at high speeds.

Maybe this would work well inconjunction with your existing set up of electrical fans?
I use the Derale low profile cooling fans..they are 3.5" deep and tehre is still a good inch between them and the flex-o-lite fan.

Joe, if I'm not mistaken you are in the Rochester area? I am 100 mile due north across the lake so I think we share the same poor winter weather!

Vic

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post #5 of 11 (permalink) Old Feb 25th, 12, 05:35 PM Thread Starter
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Re: Cooling questions...

I don't know if there's enough room to put my clutch-type fan on AND keep the electric. If need be, I'll just remove the electric fan and figure out a way to fabricate a new shroud.

What winter weather? Hell, it's been Spring since October!

It's snowed a little here and there the last 2 months, but we just started getting cold temps this weekend! It's really strange. "The winter that wasn't!" I was THIS close to driving the Camaro a couple weeks ago... it was that nice out.

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post #6 of 11 (permalink) Old Feb 26th, 12, 06:59 AM
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Re: Cooling questions...

Joe,

I think the holes would probably help a little at higher speeds but hurt at lower speeds. Since you have overheating issues at both high and low speeds I wouldn't suggest putting any holes in the shroud. The problem is most likely that you don't have enough cooling capacity. That could be from many things: fan shroud, fan capacity, voltage at the fan, water pump, trans cooler blocking to much flow through the radiator. If you are confident that the mechanical parts are all good I would suggest measuring the voltage at the fan when the car is idling at temp. If the voltage is low that will cause the fan to not perform well.

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post #7 of 11 (permalink) Old Feb 26th, 12, 07:20 AM Thread Starter
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Re: Cooling questions...

Good idea...
I'm also in the process of spacing the trans cooler further away from the face of the radiator anyway, so that should help.

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post #8 of 11 (permalink) Old Feb 26th, 12, 05:45 PM
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Re: Cooling questions...

I had a 388 stroker motor that ran hot all the time with a electric fan ,so I pulled it off and put the stock fan back on, It made a huge diff !!!!!
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post #9 of 11 (permalink) Old Feb 26th, 12, 06:39 PM
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Re: Cooling questions...

Ditto on the holes. Air is like electricity...takes the path of least resistance. The fan would just pull air through them and blow it back out. Get some foam tape and make sure your shroud is as sealed to the radiator as you can get it.

High speed heat might indicate a pump that's not doing it's fair share. I've also heard of electric fans that don't turn off at speed affecting air flow. Dakota or somebody makes a fan controller that uses a pulse width modulator to ramp up fan speed based on selected low and high temp and also uses a VSS input to turn the fan off at whatever speed you set. Costs more than six or seven clutch fan combos though.

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post #10 of 11 (permalink) Old Feb 26th, 12, 07:39 PM
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Re: Cooling questions...

How is your timing?

I have a big block (4 core) radiator, stock water pump, and flex-o-lite fan. I was having some heat issues for a while with this set-up--to a point where I was running a 160 thermostat, just to keep my motor under 200 degrees (sometimes it would still hit 210).

I had to pull the dizzy when I was doing an auto to manual tranny swap two years ago. Took me a little bit to get the timing dialed back in. Not to mention fixing the idling problems that was giving me fits, adjusting the timing did wonders for my cooling--I was able to put a 180 thermostat back in, and it never ran over 190--all summer long last year!

Just a thought...

Keith
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post #11 of 11 (permalink) Old Feb 27th, 12, 03:33 AM
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Re: Cooling questions...

Quote:
Originally Posted by HwyStarJoe View Post
I don't know if there's enough room to put my clutch-type fan on AND keep the electric.
The clutch could be bad.
If a non-thermal (flat front) or thermal (has a spring), you should hear the fan at first cold start-up, then the thermal will level out, or coast, until needed. Clutch fans are 5-blade configuration.

Non-thermal spin at 60%-80% of engine rpms, but are engaged at idle.
Thermal's spin at 80%-90% when engaged and one would 'feel' the heat pulled on the face and hear the fan when it kicks in.

Some Euro manf's did put holes into the shroud, but they had flaps on them closing at idle. As suggested, I wouldn't put any holes in the shroud either.

You were asking about high/low pressure areas. Front of the radiator is high, engine side is low. One science project you might try is blocking off the radiator support, cardboard on top between the support and header, same for support and valance, and the two holes behind the headlamps. Half round pipe insulation between the radiator and support. All of this ducting will prevent, or slow down, the recirculation of hot air through the radiator.

Water has better surface tension than ethylene glycol/water mix.
Radiators are designed to have a min 20F difference inlet and outlet tanks.

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