Cooling systems and operating temps

Need some help here, trying to get an idea of Regal cooling efficiency:

What do you run for a cooling system (fan/rad/trans cooler) and what are your operating temps? If you can post some about the engine combo too that'll help.

I'm debugging the new engine and it's pretty warm on first run. They dyno numbers were good and clean so I know the machine work was spot on.

I currently have a 26" 4 core triple pass rad with electric fans and it's not cooling well at speed or at idle (shut down when temps reach 210 oil 220 water). Never had this problem before with less rad and the mech fan...

...going back to a mechanical fan and 160* thermostat this weekend...

Any ideas are appreciated!

 

I'm not sure if mine is where its supposed to be or too high but here's what I got...

70 350 stock bore

4 core radiator with dual electric fans, no trans cooler yet.

I run between 205* to 210*

 

i have an 84 regal with a 455. i use a summit 31x19 2 core
aluminium rad with a 7 blade clutch fan and a 160 therm.
i use an external tranny cooler. it runs so cool i somtimes have trouble
getting it up to operating temp. hope this helps.

 

my 82 regal has a .030 over 430, TA Stage1 SE aluminum heads, SP1 intake
aluminum radiator, large electric fan (from '96 T bird) 180* T stat, painless #30103 electric fan control
185*on, 170*off

 

Do you have a high-flow thermostat or regular t-stat?

 

...all good info so far guys, keep it coming.

I only put in a 180* standard flow thermostat so that is on the suspect list.

I'm diagnosing it in this order:

1. Drive it around again at 50 MPH to rule out an airbubble. If I see high oil/water temps at this speed then there is not enough rad or flow through the rad.

2. Change the thermostat to a 160* high flow unit, repeat #1.

3. If we've still got a problem at speed - buy a new 28" summit aluminum rad. and repeat #1.

4. If no cooling issue shows up at speed then we move onto whether or not the fan is too low... I'll drive it in stop and go and see if it starts to creep up.

5. Change back to a mechanical fan, repeat steps 1 & 4.

 

I take it these are good factory salvage fans or quality aftermarket fans not cheap weak supplemental fans that they have in the partstores. Does your fans and shroud pretty much cover and seal the back of the radiator. Might be something else entirely blocked cooling passage timeing etc.

 

I have a high flow 180* T stat

 

The 455 is best cooled by, in this order,:


proper ignition timing
7 blade 18 inch stock metal blade fan
known good high quality thermostatic fan clutch
correct BBB shroud
aluminum radiator
known good stock water pump
either 160* or 180* t-stat
external trans cooler, bypassing radiator

 

Timing was dialed in at the dyno, no problems there :TU:

The fan is an electric 15" 9 bladed unit from Cadillac Norstar v-8. It is very well sealed to the rad - better than the mechanical fan shroud in fact. I can run the electric fan with the engine off and feel it suck air in through the front grille.

...however...

Even if the fan was crap, at 50-60 MPH the system should run around 180-200* with a 180* thermostat. Until i get the at-speed resolved, the fan is off the table.

 

my regal has the stock 307 radiator and shroud, a flex fan, external tranny cooler, 160 regular tstat. motor is 71 455, stage 1 heads, 290-08h cam, sp1, stock water pump. sitting at idle its right at 185-190 deg

 

Normally 180-190 for mine. 160 stat, F-Body radiator (Autozone $109 out the door), single GN/fiero fan, no shroud or air deflector under car. After a romp and then sitting in traffic at BG it got as high as 212; I switched on my aux pusher fan in that case. Combo is same as below, but with Edelbrock heads now.

Ditch the 4 row.

That Fbody rad looks way to small to do any good, but it actually works. I bet with your fan set-up, and being in Canada, it'd be a perfect solution.

 

Ramin that setup is pretty close to mine so maybe I'm not too far out. I suspect the 180* thermostat at this stage. The 3 pass 4-core needs a high flow rate and I tend to think that the thermostat is not fully open until 190-195. It neatly explains the high-speed problems (I have an air deflector). It looks like I'll have some time to tackle this on Saturday - I'll be sure to post the results.

 

I tried My electric fan thermostat yesterday, it came on at 185*,and went off at 170*,as it was supposed to. I have a 180*stat also, I'm very happy with my setup

 

My therostatic fan comes on, but never goes off.

I might just try a cut-up thermostat to use as a restrictor orfice and see how that works. I'd love for the temps to be closer to 160 for drag racing.

 

Well, some results just not good ones...

-Eliminated all air bubbles - no change.
-I tried it without a thermostat (can't get a 160 high flow just now) - no change.
-Something nobody mentioned yet, but I changed to a larger drive pulley and smaller waterpump pulley. I have not tested it at speed but it did not help the idle condition.

...it goes like this:

Water temp goes to 190 then drops to 180 (thermostat opening)
Holds at 180 until...
Oil temps come up to 180...
Water temp starts to build to 200
Oil Temps follow 5-10 degrees behind water temp.
Shutdown at 210-220 water temp.

...next up: the pulley tested at speed, back to the mechanical fan and changing out to a remote transmission cooler...

Anybody think i should try the oil cooler?

 

I would try this first, it's quick and cheap. Take the guts (spring, copper pellet, supports, etc.) out of a standard thermostat and use that. It will act as a restricter.

I'm not hopeful that this will work, but it's so easy that it's worth a try. If you had a single-pass core I would guess that it's possible for you to have too much flow. But a 3-pass acts like a restriction anyway, so it might be that it's already too restrictive and that you need more pump flow.

Other thought:
Does your water pump have the cast impeller or stamped (like the fins on an alternator)? Do you recall how many fins on the impeller and how far did they extend towards the outer edge?

 

Interesting idea Scott, I was thinking the same thing about the 3 pass. It actually looks to be flowing kind of slow with the rad cap off. (didn't check this after the pulley swap though).

I ran it initially with no thermostat and it was overheating so i tend to discount that. I picked up a high flow 160* and a bottle of water wetter yesterday. I'll try them one at a time and see what happens.

Water pump is one of those brand new units. I don't recall the exact number of blades but it was less than the full-blown impellers I've seen pics of.

 

From stewart components site:

"Double pass radiators require 16x more pressure to flow the same volume of coolant through them, as compared to a single pass radiator. Triple pass radiators require 64x more pressure to maintain the same volume. Automotive water pumps are a centrifugal design, not positive displacement, so with a double pass radiator, the pressure is doubled and flow is reduced by approximately 33%. Modern radiator designs, using wide/thin cross sections tubes, seldom benefit from multiple pass configurations. The decrease in flow caused by multiple passes offsets any benefits of a high-flow water pump."

 

Glad you posted that Scott... this is a rant I've been wanting to do for a while, hope this get5s some fuel on the fire...

Full article can be found here:

http://www.stewartcomponents.com/tech_tips/Tech_Tips_5.htm

I read that before I bought this rad :TU: their analysis has got a number of problems.

First, pressure losses (or head losses) for turbulent flow in pipes is proportional to the length of the pipe, not the square of the length. Check out the Darcy-Weisbach Equation for this. The length increase is added, not geometrically multiplied. Making 2 or 3 passes is NOT a geometric loss as they postulate. That 16X 64X is pure fiction.

Don't take my word for it:
http://www.pipeflowcalculations.com/pressuredrop/index.htm using calculator number one, enter an L (length) value of 1000 and you get a pressure drop of 548.35. Now increase the length by a factor of 3 for the triple pass and you get 1324.83...looks linear to me!!!

Second, their reduction in flow rate is meaningless unless you calculate out the COOLING capacity. If you work this out in detail for an actual fin-tube cross flow heat exchanger (facy terms for a radiator) you find that tripling the distance of the cross flow rad amounts to a pressure loss of about 35%, but more importantly a cooling capacity increase of about 28%!!! This translates to about a 10% reduction in outlet -vs- inlet temps assuming you run at 180-200* Who cares about the flow losses if the cooling is increased??

Third, (and if Ken is reading this post he'll agree) arguing the theory is pointless in a complex car situation. You have to do tests and see what works. The test should back up the theory if the theory is correct...

These guys tested it: http://www.usradiator.com/testing.htm

...and found a 15% reduction in outlet temp:

http://www.usradiator.com/options.htm

...just what the correct theory predicted.

OK. How about a home test. If you have a heat gun, shoot the rad at the top of the inlet tank and the bottom of the inlet tank. If the temp drops then you can prove that the tank is not circulating the coolant through all the tubes evenly. I tried this with a typical rad on my 1978 Century and found a difference.

So far I can't fault the radiator. It might be what is wrong due to losses at the critical airflow/coolant flow point. It may be junk, but nobody has proven that to me yet.

...any thoughts?