mtwoolford

When I have overheating problems or breaking in a new engine, I run a restrictor plate; it takes the thermostat completely out of the equation, is just one less thing to worry about, and makes troubleshooting that much easier. Come winter, when everythings sorted out, yeah, the thermostat goes back in.

On a related subject; did you block off or restrict the bypass hole on the pump to the block; some hi performance pumps come with this hole deleted; some put a plug in the block; basically all this hole does is short circuit hot water from the block into the suction side of the pump without sending it through the radiator. It helps warm up rancher john's pickup during those cool North Dakota winter mornings, but may not be needed for your application.

Likewise, restricting or putting a valve in the discharge line from (near) the base of the thermostat housing to the heater core forces that much more hot water through the radiator. I've never seen the logic of having a heater core full of hot water under the dash during the summer.

these are two simple, inexpensive mods that can help a hi performance engine / cooling system.

jfb

I am guilty of not reading every post in this thread! My apologies. BUT, installing a lower temperature thermostat will not do anything to your coolant temperature while stopped IF while stopped your coolant temp remains above the opening temperature of the thermostat you have now. Thermostats can only control the temperature of the coolant when the radiator is capable of removing MORE heat than the engine makes!
214 is a nothing to your engine, it won't harm a thing. With the a/c on and parked, at least see where the coolant temperature settles. GM says to shut the engine off at 260 F and let it cool down. 260 also is not harmful to an engine and GM says this (shut off at 260) because 50% antifreeze at 15 psi boils at 265 F and boiling coolant dramatically has reduced heat transfer abilities and you could have head damage.
My original radiator in my 87 vette became shot and I replaced it with a same size new radiator, then (early summer) we let it idle. Temp went to 238F, the main fan came on, it cooled down to 211 F and the fan turned off and it repeated this cycle. a/c had no gas in it so we didn't try it with a/c on. I rarely use a/c anyway.

GREGGPENN

I know how frustrated (and frequently) you like to jump on the overdone, overheating-thermostat thread. But, you are barking up the wrong tree by pointing that argument at me. That's because you aren't telling me anything I don't know.

I am completely aware that a lower stat won't lower my upper temps. But it will allow lower, low-end temps. I wanted a lower thermostat to lower temps so my fans don't run all the time. I have a rebuilt, modified 383 engine with higher compression. (Maybe you don't have the view signature option enabled?)

You can not assume GM's recommendations for operating temps for an performance rebuild with higher compression. In fact, that would be a mistake.

I want lower temps to be in the 180's w/o a fan. 190-205 would be the ideal range for main fan operation. My replacement aux fan switch kicks on at 208 and would help from there. As it stands, I don't have enough "low-end" room so my temps will dip and let the fan shut off. Oh the other end, I don't have enough room due to compression and aux fan turn-on temp.

I know exactly what I want and why.

87 vette 81 big girl

Its all relative speaking Greg.

I am used to Superflow engine dyno numbers at the flywheel.
Some of my engines in the past I paid to have dynoed this way.

Never had 1 of my cars on a chassis dyno.
Many here on c4 have.

Its 2 different subjects, drivetrain power loss & theoretical & actual thermal efficiency of a gasoline internal combustion engine.

It is actually true,
most of unharnessed BTU energy content of gasoline, alcohol, race fuel, gets dissipated through the radiator & exhaust tailpipes instead of pushing down on the pistons to create rotational torque force to the crankshaft.

The problem raising the thermal efficiency of an internal combustion engine is it would melt down.

Some engineering projects used Solid ceramic pistons in experimental engines.

Smokey Yunick did much research work on lean burn vapor engines in the 1960's, 1970's, 1980's.
Some of his one off prototype engines exist.
He manged to raise the thermal efficiency of 4cylinder iron Duke Poncho engines to 35% to 45% he claimed.
One of those engines lives & runs installed driven in a Pontiac Fiero yet today.
Covered in Hotrod last year for the people that care to read.

Perhaps you only have 500ft/lbs of Superflowed Dyno flywheel torque.
I am a betting man that you have more than that on tap.

GREGGPENN

Can you post/send a link to these "s" fans? At least so I can see what you mean. Does it refer to the shape of the blade?

Who has a recommendation for replacing the front (push) fan vs the rear (pull) fan? I would assume an upgrade to the main, front fan would provide a better upgrade. (I'm asking if the front fan provides less cooling since it's a smaller fan.) OTOH, would any replacement need to be metal (like the OEM unit) to stand up to rocks, etc....

I've seen 1700cfm listed as the OEM capacity...but I think that's both fans together. If I could upgrade ONE of the two fans w/o raising fan noise terribly high, that would be my preference.

GREGGPENN

The only reason I brought it up is because you've mentioned I have 600ft/lbs of torque at the FW (more than once). Since I never measured or claimed it was that high, I didn't want it to seem like I had.

87 vette 81 big girl

I personally know & understand what a true 500 + ft/lbs of flywheel torque can do in a 3,000lb to 3,200lb car.

My 1970 TA weighs around 3,200 lbs with me in it and 1/2 tank of gas( 9 gallons).
Engine has true 550 ft/lbs of flywheel torque.

Anyhow,
Your biggest dilemma if you ever run your car really hard is snapping off the GM wheel studs in the rear.
ARP wheel studs when you can.
You can cut them down with a hacksaw if you do not wish to have the wheel studs hanging out.

You don't drag race I know........
but you enjoy romping on the gas hard often when you can & power shifting the ZF-6 speed.

If you can maintain engine water temps around 170 to 185 steady,
I think you will be A-OK longterm.

BR

jfb

What you do not understand is that with your 180 stat wide open (by your words, "It's never run in the 180's), a lower temp stat will also be wide open and your coolant temp will be the same temp it is now. Your cooling system is radiator limited and you cannot fool the radiator heat transfer equation: Q = 8.3 x GPH x Cp x dT.
If you want lower temps with the radiator you installed, look at the equation, you must increase the GPH (coolant flow rate) or increase Cp. Cp for water is 1, for 50% antifreeze it is .75, dT is the difference temperature between the inlet and outlet liquid of the radiator. Since you want a larger dT, you must increase one or both of GPH or Cp.
Install a 160 stat and find out it didn't do squat!

87 vette 81 big girl

You are correct.
Physics don't lie.
Its been a very long time since I was in college.
After getting my *** in Electronics Technology in 1990,
I kept fooling around with cars day & night.
Chose to become a mechanic.
I had college physics too.
Prerequisite coarse.

You are more versed with mathematics than most of us here on C4 being a veteran electrical engineer.

A list of commen everday formulas practical for the Corvette hobbyist, shade tree mechanic, professional mechanic, and racers COMPILED BY YOU,
I think would be greatly appreciated by all here on C4.

Brian

jfb

I think there is a limit to the size of a thread!

87 vette 81 big girl

I meant start your own thread.

LOL

The formula you provided,

If you increase the total cooling system capacity,
especially the radiator square frontal airflow are & actual liquid holding volume.......

What then?
More BTU heat transfer capability?
I am assuming yes.

2 things also I recall from college physics,
Copper is a better conductor of heat than aluminum.
A different coefficient factor in place.
Copper also dissipates heat faster likewise.

It has been a long time,
But I recall the coefficient check sum difference between the 2 different metals being around 2 : 1.
Copper being the winner.

Thanks for your insight .


Brian

GREGGPENN

Oh, for crying out loud! There are conditions where I'm certain the temp will drop below 195 -- if the thermostat would allow it.

How do I know? Because temps drop when rpms or vehicle speed increases. Air flow (and probably, water pump speed) accelerate "the cooling process" and the temperature drops. Big surprise, huh? They drop until they hit 195. They can't go (back down) any lower than when the thermostat closes to restrict flow, now can it? If I lower my stat temp, my running temps will go lower -- when the car is moving down the road.

I would let the temps drop into the 180's -- while the car is in motion -- and shut my fans off when temps drop below 190. The fans don't have to run all the time.

Bye!

GREGGPENN

Interesting...I wasn't aware of the bypass hole. And, the link to my waterpump doesn't show the backside. I'd have to call and see what PRW knows. Probably won't pull it to find out!!! LOL

I like the idea of having (a manual?) valve to divert flow to the heater core in the summer. But, as long as I retain the factory oil cooler, I don't believe that's an option. After water exits the heater core, it splits off to the oil cooler. I would think the oil cooler would quite functioning w/o flow thru the heater lines.

:



BTW...The factory oil cooler also helps speed the rise of water temp. While coolant works to cool the oil, the oil can also work to heat the coolant (especially during warm-up).

GREGGPENN

For those interested in managing the proper temps for their performance build, use this chart as a guideline.




Instructions:
1) Pick the octane you wish to run.
2) Look across and find where that intersects with your thermostat temp.
3) Look down to find the max DCR you should run with that combination.

Addition consideration from Vizzard's Compression Considerations:
Most stock engines of the post '70s emission era are on the edge of detonation and run with water temperatures in the 200-210 range. While this may be good for lower emissions, it is not good for power or staving off detonation. For a high-performance street machine running service station fuel, water temperatures of 170-180 deliver a couple percent more power and the ability to use about a quarter of a ratio higher for every 10 degrees reduction in water temperature. Your first move toward utilizing higher CRs then is to use a 170-180 degree thermostat.

The real goal we are trying to achieve with reduced water jacket temperatures is to reduce the temperature of the air entering the engine and ultimately the charge temperature just prior to ignition. The starting point on this quest is to route cold air to the carb/throttle body of the induction system. Cold air packages not only deliver a denser charge to the cylinder but also move detonation further away, opening up the door for more compression.

The complete HotRodding article can be found here.

oldalaskaman

I got the best cooling by upgrading the engine side fan , the front fan seemed to make the A/C colder and after a while aided in the cooling , but not much, "S" is in fact the shape of the blade, the dewitts straight blade fan flows 2360cfm but is very noisy, "S" blade fans are by design, alot quieter. I tried the two speed taurus 's' blade that on low flows about 3000cfm and on high flows 4000cfm, which is how I found out about the 's' blade being quieter. bought them used and they didnt last, but for the time they did I never needed the high speed.. Theres a whole lot of research on this in other forums. Currently running a 16" spal "S" blade thats 2300plus cfm and quiet, in a dewitte fan adapter . this isnt scientific, but it works. hope this helps

jfb

Let me point out again that by your own admission, your coolant temp has never been in the 180's with a 180 stat in place, so installing a lower temp stat will not allow lower coolant temps. It will when the outside temp falls, but it won't do it now!!!!

88BlackZ-51

From what I hear Ron Davis rad's are pretty much as good as it gets for our cars.

I need a rad for the 421 for any type of spiriting driving. The question is how much is too much to spend on a hi-po rad.

My friends C4 with a very hi-po motor (585rwhp) has a Ron Davis rad and it stays right about 178. Kinda of incredible imo.

GREGGPENN

Did you mean to say inside fan...You found the most improvement by upgrading the inside (aux) fan? Seems to make the most sense since it's mounted in a shroud and is closer to the radiator.

oldalaskaman

yes gregg, but from everything i've read, the outside fan(in front of radiator) is the aux. and the inside fan(behind the radiator) is the main

engle1147

To stay on top of the best heat exchange, even with the new 3 row radiator installed, I run a H20 with ~ 25% antifreeze (dex cool) mix and 3 quarts of Water Wetter. Keep in mind I live in Florida where the summers are HOT and the winters are MILD....and I run an underdrive crank pulley(H20 pump turns a bit slower than a stock application).

Drive the car for a bit and see how the cooling system performs. Make as many cooling system modifications as you want since "there is more than 1 way to skin a cat". One thing though, from my L98 experince I wouldn't go any lower than a 180 "T" stat for a year round application.

Stay cool