Thermostats and Thermostat Housings

[Dynomite]

Originally Posted by Hog

Delay the cooling function of the radiator until enough heat has been produced by the engine.

As you suggest the purpose of the Thermostat is to stabilize the engine heat at a target of 180 F deg in all environments. But as experienced when temperatures ambient exceed 90 deg F there are Engine Cooling issues associated with the LT5 especially in Stop and Go Traffic using the Stock (but clean) Radiator.

The cooler Thermostat will set the bottom temperature but does nothing to set the top temperature once both thermostats are fully open.

This is assuming both a 160 deg F Thermostat and 180 deg F Thermostat both allow the same maximum coolant flow which seems to be the case as I observed maximum opening area on both.

A cooler 160 deg F Thermostat does nothing to cool the engine better in the situation described above on a HOT day when both 160 deg F and 180 deg F Thermostats are FULLY OPEN. But.........if one wants to experiment.

If you drill additional holes in the 180 deg F Thermostat around the periphery as Jerry suggested at one time.....you might be able to actually drop the max coolant temperatures in the HOT situation described above while not dropping to the cooling effects associated with a 160 deg F Thermostat on cool days. In other words reach a happy medium. But realize that those additional Thermostat Holes are open from the start so the engine temperature rise will be slower getting to operating temperatures of 180 deg F.

[Hog]

Since a thermostat can either be, closed, open or somewhere in between, once the thermostat is fully open, at that point, it is ordering for as much coolant flow through the rad as possible. It is now up to the rad to do its job. If engine coolant temps continue to rise to the point of overheating, not enough heat is being removed from the system compared to the amount of heat being added.

It would be very interesting to see the GM data from the LT5 car desert testing. Heck if Chev is dishing out info, I'd take a copy of all the Stillwater dyno printouts as well.

[efnfast]

I would think that the thermostat being fully open is rare. If it were common, the temp would exceed 180 frequently. I don't think that is the case. We also need to take into account water flow via pump speed, which is governed by engine speed.

[Dynomite]

Originally Posted by efnfast

I would think that the thermostat being fully open is rare. If it were common, the temp would exceed 180 frequently. I don't think that is the case. We also need to take into account water flow via pump speed, which is governed by engine speed.

I would say not rare at all but actually almost always fully open at temperatures above ambient 90 deg F

[efnfast]

Originally Posted by Dynomite

I would say not rare at all but actually almost always fully open at temperatures above ambient 90 deg F

I repectfully disagree. A fully open thermostat represents the max cooling the system can handle. Disregarding air flow and water flow which are kinda' manually controlled.

[Dynomite]

Originally Posted by efnfast

I repectfully disagree. A fully open thermostat represents the max cooling the system can handle. Disregarding air flow and water flow which are kinda' manually controlled.

I have tested many Thermostats and all the 180 deg F Thermostats start to open around 175 - 180 deg F and are fully open around 190 deg F.

On my digital readout on a 90 deg F day my coolant temperature is running 190 - - 200 deg F. On hotter days my Coolant Temperature is running over 200 deg F and up to 210 deg and a bit higher.

Which of my observations are you disagreeing with

Actually if you disagree with my observations.....End of Discussion

Oh.....Five ZR-1s all running Aluminum After Market Radiators and ALL with 180 deg F New Thermostats installed.

[George Maz]

Originally Posted by Dynomite

Oh.....Five ZR-1s all running Aluminum After Market Radiators and ALL with 180 deg F New Thermostats installed.

Can you list your favorite choices for Aftermarket Aluminum Radiators? ...obviously FLUIDYNE is at the top, but it's no longer made.
Criteria of fitment, cooling, cost, and particulars, etc.

The repair & modification guides you post on the forum are outstanding. Thank you for taking the time to do so.

[Dynomite]

Originally Posted by George Maz

Can you list your favorite choices for Aftermarket Aluminum Radiators? ...obviously FLUIDYNE is at the top, but it's no longer made.
Criteria of fitment, cooling, cost, and particulars, etc.

The repair & modification guides you post on the forum are outstanding. Thank you for taking the time to do so.

Interesting question....I just had to buy Hib's Fluidyne for my 95' couple weeks ago as it was stored in the original box for probably years....it was mint and is a great radiator. I cannot tell for sure how well the Fluidyne does in heat as I also replaced a Thermostat that was opening at 195 deg F rather than 180 deg F.

Marc suggests that old Thermostats creep up in opening Temperatures as well as creep down in Opening Area.



Blocking TB Coolant and Fluidyne Radiator

The Fluidyne has a thicker core than stock and comes within 1/8 - 1/16 inch of the internal fan baffles but does not require any baffle trimming.

I use Ron Davis in two ZR-1s which has a thicker core and requires removing 3/8 inch of the internal fan baffles on the 90' and 91'.

One 90' ZR-1 came with a Dewitt and another 90' came with a nice aluminum of unknown brand. Both function super but am not sure in HOT climates as have not run those in ambient temperatures over 90 deg F. I actually switched those two Radiators between ZR-1s as I wanted the Dewitt in the 90' with Headers

Also.....having removed several stock radiators I have found the crimped plastic type end caps usually are found leaking or have leaked.

I always make sure the radiator is super clean and I install a Debree screen on all. I also clean the AC coils and the Oil Cooler coils. Lastly I always install a NEW 180 Deg Thermostat.

Costs for the Ron Davis, Fluidyne and other good quality aluminum radiators are in the neighborhood of $500-$600.
You want the Aluminum Radiator WITHOUT automatic transmission cooling and all of the Aluminum Radiators I have installed went in easily with the only issue being trimming of the internal fan baffles for the Ron Davis.

Oh....the trick on removing the Radiator Housing/Cover.

1. Remove all bolts holding the Radiator Housing.
2. Remove the Oil Cooler Flange Adapter (and two oil cooler hoses) from the Oil Cooler.
3. Remove the Air Cleaner housing and Corrugated Connector.
4. Disconnect ALL Fan Shroud screws top and bottom including the two screws holding the AC Dryer.

5. Now....the trick.....Lift up the Housing on the Drivers side clearing the hood hinge which will take some pressure but nothing will crack or break. Lift that Housing on the Drivers side as high as you can.
6. Now....the trickiest......Lift up the Housing on the Passenger side bending the Housing Tab inside the AC lines (you can bend them a lot with no damage).

7. The Housing will then be free.

Now the BIG TRICK....Disconnect the Thermostat Housing two bolts to the frame and the single bolt holding the Thermostat Housing pipe pointing to the Drivers side. The Thermostat Housing can then be moved so you can disconnect that lower radiator hose. You can then split the Thermostat housing (I had a frozen bolt on the last one which is another story).

Use a flat scraper blade to hold the New Thermostat in place tight (as it wants to spring outward as the main spring is compressed when installed) as you install the two Thermostat Housing halves (yes....I use a bit of Permatex on the faces of the Thermostat Housing and on the rubber seal of the Thermostat)

You do NOT want to pinch that Thermostat rubber seal on the flat surfaces of the two Thermostat Halves (the rubber seal resides in a groove of the Thermostat Housing Half containing the Thermostat).

See Item #6 Blocking TB Coolant, Fluidyne Radiator, and Thermostats

[Hog]

Any closeup pics pf the fin design of some of these aftermarket radiators? Its amazing how the more modern OEM designs are able to have fewer cores/less thickness and are still able to cool better than older designs.
In an effort to reduce the amount of materials, therefore make a radiator that does the job for the least amount of money, there have been some impressive advances in radiator design.


I used to think that a radiator fin was a radiator fin, not so much anymore.
Here is one pic that shows some of the design going on.






I remember as a kid on road trips with my Dad, I would read the owners manuals of whatever vehicle we were driving and it was suggested that if in a situation of overheating, to shift into Park/Neutral and hold engine rpm at 1500-1800rpm until temperature came down. Of course this is relying on increased coolant and airflow circulation through the radiator to bring coolant temps down.

Obviously doing so with an LT5 would only increase coolant flow as the fans are already working at full duty cycle.

[George Maz]

Originally Posted by Dynomite

....I just had to buy Hib's Fluidyne for my 95' couple weeks ago as it was stored in the original box for probably years....it was mint and is a great radiator. Costs for the Ron Davis, Fluidyne and other good quality aluminum radiators are in the neighborhood of $500-$600.
You want the Aluminum Radiator WITHOUT automatic transmission cooling and all of the Aluminum Radiators I have installed went in easily with the only issue being trimming of the internal fan baffles for the Ron Davis.

Last year I purchased a C4 FLUIDYNE new in the box, but it's the automatic transmission version. Are there any special considerations to installing it? Plug the unused ports and it's the same as the manual transmission version?...or I'd have a separate cooler/warmer section if needed for something else.