'79rx7

Thanks for the info guys, I really do appriciate it

Racer X

Thats what we're here for.

Hereonout

just for info.....Pontiac Fiero (4 cyl) works excellent and can be found in a junkyard for pretty cheap.

Racer X

What size is the fiero's fan?How can you hook it up??Is it the same thing as hooking up a aftermarket fan?

zebrenoir

Hey, here is a tip I picked up studying PORSCHE RACING CARS OF THE 70s by Paul Frère: When Porsche wanted a little extra downforce on their 935 race cars, (which the RX7 resembles more than most cars, I might add) They reversed the engine fan (air-cooled flat-6 cylinders) so it would suck air from under the car, through the engine, then out the fan at the top of the motor, instead of taking cool air from outside and putting it through the fan then into the motor and out the bottom of the car



They blew the motor from overheating. Same size fan, same fan RPM, etc, but less cooling. Why?



Because, air that has been heated by a hot motor takes up more space. With the fan rotating the same speed, the hotter the air got, the less actual air was getting through the engine, because it was hot and expanded before it got to the fan. The hotter the air got, the thinner it got. So, the fan was pulling less and less air as the motor got hotter and hotter, and finally blew.



So, if you want maximum cooling effect from those electric fans, put them in FRONT of the radiator, not behind.



Supposing you are in 105 degree weather, and the engine is heating the radiator airflow up to about 160. Let's say that decreases the actual air molecules that the 900cfm fan is pulling through the radiator by 20 percent. So, your engine gets hotter, which reduces the number of molecules of air by more, so it gets hotter, thinner, hotter, thinner, hotter, etc.



Now, same engine, same day, but fan in front of the radiator. No matter HOW hot the radiator gets, the fan is still pushing air in that is at a constant and far-cooler 105 degrees, so you get that same 900cfm at all engine temperatures, not just when the engine is cold. The air exiting the back of the radiator will be hotter, and take up more space than the air being pushed in the front of it by the fan. In fact the P51 Mustang plane of World War II used a belly-mounted cowl-enclosed radiator that used the heat from the engine coolant to provide net thrust to the plane, since the air volume was greater exiting the radiator due to heat added by it.



So, having the fan(s) behind the radiator is an installation where you either have to have too much fan all the time to make sure you have enough during the worst case scenario, or you run the risk of overheating.



With the fan in front of the radiator, there is no change in engine temperature that will make any significant difference to the fan's flow capacity. So, front mounted fans are the best. They are usually on the back because it is easier to drive them off the engine, and it is cheaper to install. But, it is the worst place for them.

Hereonout

Damn, teach me all mighty know it all....no pun intended.

zebrenoir

Oh, and another thing: The fantastic Propylene Glycol coolant. I read about this in 1983, and had to wait about 15 years before anyone started selling it.



What is it? Propylene Glycol is FAR less toxic than Ethylene Glycol. It is marketed as "low tox" by Prestone, only place I've ever found it is in Wal-Mart, in the white plastic jug with the cute puppies on it. But, that is Wal Mart anywhere, so that is cool.



What is so great about it?



A) you don't need to use water with it

B) unlike Ethylene Glycol and water, which need to be pressurized so they won't boil off at about 220 degrees, Low-Tox boils at 360 degrees, with NO PRESSURE NEEDED.

C) Since you don't need water with it, it has NO CORROSIVE EFFECT ON YOUR COOLING SYSTEM OR ENGINE



I have run both my 1976 Dodge Power Wagons and my 1985 RX7 on 100% Low Tox by Prestone, with the radiator cap either wired open all the time, or flipped open and broken off for NO cooling system pressure for the past 6 YEARS. When my truck radiator blew a huge seam open, (I sealed a garden hose to it to flush it out, whoops, way too much PSI) I repaired it by crimping the seam back shut with silicone blue sealant, and never had another problem.



IGNORE THE INSTRUCTIONS ON THE LABEL. DO NOT ADD WATER TO THIS STUFF AT ALL. They want you to keep needing the corrision inhibitors in the coolant, so they tell you to add water. But, with no water added, this stuff lasts forever. It turns a darker color over time, but not due to rust or corrosion or such.



Of course, ALL corrosion and rust in my cooling system immediately halted as soon as I switched to Propylene Glycol. It flips people out to see me open my radiator after just pulling up with a nice, hot engine. NO geyser, no coolant splash, just me making sure the level is all the way up to the top. Remember, this is on a radiator cap that has been wired open underneath, to allow free flow of coolant in and out of the overflow jug, or a lever-type cap that has been levered open then broken off to prevent accidental pressurization of the cooling system.



Propylene glycol is the king. It doesn't take away as much heat as water and Ethylene Glycol, but it does something that the old school coolant can't match: when the engine gets nice and hot, it remains a liquid everywhere in the system. This means, less pump cavitation, no blanket of ultra-hot steam over the hottest spots on the engine while the liquid coolant is kept away by the steam bubbles. (this is called BLANKET BOILING, you see this when you boil a pot of water, and the steam bubbles are on the bottom of the pot) Propylene Glycol is the stuff. It exhibits what is known as "nucleate boiling" and won't form a steam blanket over your hottest engine parts. You can run your engine hotter, and not damage it with Propylene Glycol.



I run my 1985 RX7 up and down the mountain where I work every day with NO OIL COOLER! And this is in Hawaii, folks, not Alaska. Why? How? For the last year or so, I have been doing this. Why has my engine not grenaded? Simple: Propylene Glycol and synthetic oil. I am finally getting my oil cooler converted to A/N male -10 fittings to go with the Mazdatrix -10 braided stainless hoses, because the crackmeister idiot bungs on the original cooler seem designed to fail, but until I did, I relied on my Propylene glycol's nucleate boiling and synthetic oil's higher tolerance for heat to carry me through.



When you run Propylene glycol, the hottest spots on the engine are cooler, and the coolest spots on the engine are hotter. Result? LESS THERMAL STRESS due to unevenly-expanding engine parts!



So, your engine temp can be up in the 3/4 up the scale zone, every day, for a year, and no problem, because that propylene glycol is staying liquid, and still cooling your hottest engine zones, where inferior water and ethylene glycol would be busy putting a fat insulating blanket of steam bubbles between the life-saving coolant and the motor parts.



Now, if you had an engine that is hotter than stock, get a bigger radiator. Since propylene glycol carries less heat away per unit of volume than water, it just needs more surface area. But, the benefits far outweigh the disadvantages, especially over the long haul.



But, I can tell you from experience, Low Tox is the absolute stuff to use. Your engine will run warmer, but it will be better off, because the hottest spots will be cooler.



Only seen it at Wal-Mart