Thermostat

[Keoke]

Hey you guys lets think in terms of volume of coolant flowing . Initially the Healey thermostat reduces the volume of water flowing through the radiator.
If the volume of water is less then the time it takes that volume to flow through the radiator is less than the time it takes to flow the larger volume when all the coolant flows through the radiator.-Maybe---Keoke- :frown:

 

[John Turney]

Hi Ray,

....
I maintain that is why Geoff added a louvered hood in the 100Ms (to get the hot air out) and a hood scoop on the 6 cylinder cars. ....

Tim

The general wisdom is that hood scoop is there so that the hood will clear the radiator.

 

[Cottontop]

Hey John,

I have not had a Healey radiator in my car for a couple of years, but as I rememeber, the hood vent is well above the radiator cap.

You've got one. How about going out and measure the distance from the ground to the top of the radiator cap. Then close the hood and see where that distance hits the bonnet.

You may be right, but Geoff also had the option of just putting a closed bump in the bonnet instead of the additional expense of making a hole and covering it with a chrome grille.

Hmmmmm.......

Tim

 

[Keoke]

Yep John BN4, you are right had a conversation with Geoffin Breckenridge Have also read it in other places too..As a matter of fact if you do not set the stock radiator in correctly it will bump the bottom of the hood.--Fwiw--Keoke

 

[RAC68]

Hi Tim,

I learn quite a bit from these discussions.

I am interested in knowing what body inner structure reengineering you had to do to install that large 24” radiator? I expect you were hampered by the steering boxes and much more.

Also, how did the 45 degree angled fins perform under the transmission?

I had installed a panel covering the center portion between the front shroud and the radiator to better capture and direct air through the radiator. Although I did leave about 2” in front of the radiator lower tank to allow some air to escape, I found that the front end became a little light at speed. Although the panel did provide further cooling improvement at speed, this simple addition is becoming too complex to retain as I think an air dam will be needed to recapture handling.

As far as any benefit from slowing coolant flow is concerned, I have long been under this impression and have only now heard contrary comments. I expect that the flow rate, the radiator’s capacity for heat exchange, and air flow & temperature differential will have a lot to do with it. In short, I will probably be keeping my thermostat.

All the best,
Ray (64BJ8P1)

 

[Bob_Spidell]

I've tried a lot of different things to keep engine temp reasonable on my BJ8. Currently, I have an aftermarket ("Excel" or equivalent) radiator core and a Texas Cooler fan. Cooling is adequate; I've even made it through Death Valley on a 115degF day when lesser cars were on the side of the road steaming (I did have to turn the heater on when we got close to 212--good for 4deg).

By far the biggest impact was when I put in a Hayden 7-bladed stainless steel flex fan from BCS, along with their partial shroud. Note this isn't the same SS fan they currently sell, this one had rectangular, highly curved blades and made a howling noise and blew dust and leaves out from under the car sitting at idle. But, my temps almost never got over 180 on the road and not much more than that at idle. The TC fan, however, is not as effective at highway speeds. I attribute this to the flex fan flattening out at higher engine speeds, allowing more air to flow through the radiator. IOW, above a certain speed a fixed-blade fan cannot pull the air through as fast as the forced flow through the radiator, so it becomes an impediment to airflow.

Unfortunately, I had to pull the SS fan cause the howling noise got to me.

 

[Cottontop]

Bob,

On my Healey, because of the narrow width of the stock Healey radiator, I had the best luck with a Texas Cooler with the blades 1/2 way into a full shroud.

On my 66 Mustang GT Fastback, I did not have good results with any flex fan. As you pointed out, they tend to flatten out at RPMs and become a solid disc and iimpede the airflow.

I had the best results with a stock Ford 17", 5 fixed blade, fan with a hydraulic clutch.

My current Healey mod is a work-in-progress, but it looks good on paper.

Tim

 

[Cottontop]

I am interested in knowing what body inner structure reengineering you had to do to install that large 24” radiator?

Ray,

Shoot me an Email address and I'll send you a report.

Tim = tim@ntahc.org

 

[Bob_Spidell]

Bob,
...
As you pointed out, they tend to flatten out at RPMs and become a solid disc and iimpede the airflow.
...
Tim

Twas the other way around--the flex fan flattened and worked better at highway speeds. Not sure about the aerodynamics here--gotta think about it. I know when you 'fine pitch' an airplane prop--firewall the blue knob--it does act like a disk and slow the plane down.

I think the flex fan and the clutch fan have the same idea: at high speed the fan doesn't need to pull so much air so they 'disengage' to save power and fuel.

 

[Patrick67BJ8]

Bob,
...
As you pointed out, they tend to flatten out at RPMs and become a solid disc and iimpede the airflow.
...
Tim

Twas the other way around--the flex fan flattened and worked better at highway speeds. Not sure about the aerodynamics here--gotta think about it. I know when you 'fine pitch' an airplane prop--firewall the blue knob--it does act like a disk and slow the plane down.

I think the flex fan and the clutch fan have the same idea: at high speed the fan doesn't need to pull so much air so they 'disengage' to save power and fuel.

Food for thought:
I have AC in my BJ8. I use a TC and also had the radiator redone with a core increase of about 30%. A thermostatic fan is in front of the condensor and radiator. Temp during Texas heat wave is about 190 max unless I'm really at a long standstill in traffic.

The TC is "fixed" with no clutch to freewheel when temp drops so it would be the type that would be of little use at highway speeds. Most fans on cars I've had had a thermo clutch on them like the one in my 12cylinder XJS I used to own. It would seem a better better set-up to completly remove the fixed fan from the water punp and only go to an electric fan in front of the radiator??

Thermostats: Race car engines I've seen had a restrictor plate in them where the thermostat was to slow down the water flow through them. This was explained to me by the race car engine builder.

 

[Cottontop]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] Thermostats: Race car engines I've seen had a restrictor plate in them where the thermostat was to slow down the water flow through them. This was explained to me by the race car engine builder. [/QUOTE]

Did they explain to you WHY they were slowing down the water flow?

Tim

 

[Patrick67BJ8]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] Thermostats: Race car engines I've seen had a restrictor plate in them where the thermostat was to slow down the water flow through them. This was explained to me by the race car engine builder.

Did they explain to you WHY they were slowing down the water flow?

Tim [/QUOTE]Something like, water too fast through the radiator wouldn't be cooled enough by the time it got back to the engine.

 

[Bob_Spidell]

Hi Ray,
...
Now... We need to work on your incorrect notion that slow moving coolant is more efficient than fast moving coolant.

Tim

My thermodynamics fu is very weak, but wouldn't the flip side to that slower moving coolant theory also mean the coolant moves more slowly through the engine, thereby getting hotter?

 

[Randy Forbes]

I know this to be a fact: MGBs in Southern Louisiana overheat when you remove the thermostat. Put the thermostat back in, and they stay within operating range.

Most of the MGBs I had when living there, were running with a *gutted* thermostat; basically a wide open thermostat, or <span style="font-style: italic">restrictor plate...</span>

 

[Cottontop]

wouldn't the flip side...mean the coolant moves more slowly through the engine, thereby getting hotter?

<span style="font-weight: bold">Precisely!</span> That is one of the BIG take-aways from the Stewart Components Tech Tip #3 (https://www.stewartcomponents.com/tech_tips/Tech_Tips_3.htm)

Also... Read this statement about Smiley's Water Restrictors. Smiley's Racing is the Summit Racing of dirt and circle track racers.

Note that Smileys does NOT say that the restrictors let you control the amount of heat released by the radiator.

Thermostats and restrictors are about the ENGINE, NOT the radiator.

Tim

 

[Patrick67BJ8]

wouldn't the flip side...mean the coolant moves more slowly through the engine, thereby getting hotter?

<span style="font-weight: bold">Precisely!</span> That is one of the BIG take-aways from the Stewart Components Tech Tip #3 (https://www.stewartcomponents.com/tech_tips/Tech_Tips_3.htm)

Also... Read this statement about Smiley's Water Restrictors. Smiley's Racing is the Summit Racing of dirt and circle track racers.

Note that Smileys does NOT say that the restrictors let you control the amount of heat released by the radiator.

Thermostats and restrictors are about the ENGINE, NOT the radiator.

Tim

I would say that you need a good balance of your cooling system components to make everything work to maintain proper engine temp. I will not run without a thermostat. Done it both ways in my Healey.

 

[Rob Glasgow]

With reference to the bulge on the bonnet of the 100/6-3000, I understood it was to allow the extra length of the six cylider engine. I'm sure they added the open scoop so it wouldn't look like an MGC which came along later.....

 

[steveg]

Years ago Bill Fisher of HP Books said: "Parts left off a car cost nothing and cause no maintenance problems. Therefore you can assume it's there for a reason."

I follow that philosophy in the thermostat issue.