chedda_j

As i said before in my other thread, is it possible to use the auto oil cooler on the bottom of my radiator for my car to get rid of the beehive and make my turbo application easily adapted?

trochoid

iTrader: (6)

NO

End of discussion, again. Been covered at least 3 times since spring.

slashdawg00110

You mean a tranny fluid cooler? I think I'd stick with a real oil cooler.

chedda_j

ok...sorry for asking haha

Just thought because they are both oil coolers...nvm

85rotarypower

if you look at the auto tranny cooler line inlet and outlet, its about half the size of the stock oil cooler lines. Not nearly enough flow and nowhere near enough cooling capacity. There is a reason the air to oil oil coolers are so big.

chedda_j

k, whats the minimum size for the cooler lineS?

jgrewe

iTrader: (1)

-6 or 3/8"

85rotarypower

I'd say the minimum is closer to -8 or 1/2". The stock lines are pretty big, actually about 1/2". I could be wrong though.

RXn407

^ no you're right they are 1/2" or -8 jic. I have an extra T2 oil cooler for sale if you're interested? PM ME!!!
-Erik

trochoid

iTrader: (6)

There is no difference between the FC oil coolers, NA vs TII.

Think of the autocooler this way. Approximately 30% of engine cooling is from the fmoc. The beehive works better than the tranny coolers in terms of heat rejection. also the smaller supply and return lines restrict the flow volume and will reduce overall oil pressure due to that restriction.

chedda_j

K i understand i have a oil cooler i got off my old truck, How hot do oil temps get?

I heard the normal range is from 140-200. Im going to silver sauder fittings on the ends of the OC and use stainless hoses.

trochoid

iTrader: (6)

What do you mean you understand? Sounds like you plan on using a tranny cooler as an oil cooler, that is not understanding. If you need an FC oil cooler, PM midwest7s. I was at his house last week and he has a decent one he could sell you. I should have bought it just to have another spare on hand.

Silver solder, no, it may break down, maybe not from the heat but the vibration. If your cooler doesn't have at least 3/8-7/16" lines, you can severely restrict oil flow and harm the engine. Galled bearings and e-shafts are not a pretty sight.

I don't know why this issue keeps coming up and members keep trying to work around the fmoc which has been proven to work. Auto oil coolers are NOT a better mousetrap, period. Piston oil coolers are not an adequate substitution either due to the much higher oil cooling loads/needs generated by the rotary.

Just so you have some more understanding of why oil cooling is critical, not only is the oil cooled for better lubricity of the bearings, it is also the only way to remove heat from the rotors themselves. The cooling system cannot/does not do that. What do you think happens when the rotors get hot and expand?

chedda_j

its an oil cooler i baught before,, it has 1/2" inlets, i think it will be enough.

85rotarypower

What are the physical size and material of the oil cooler you have? To this day I have not seen one as big as the stock oil cooler, or of aluminum like the stock one.

Rx-7Doctor

iTrader: (13)

Just let him use whatever he desires. I don't know about you or others but I am tired of his constant asking of the same question. He starts a thread, then it is answered by knowledgeable members, then he posts up another thread to ask the same question.

chedda, if you don't believe or like the answers you are getting then stop asking them. Members are trying to keep you from making big mistakes and compromising the longetivity of your motor.

Pele

iTrader: (28)

Even the factory WELDING cracks... Silver solder will not hold up. Too soft.

Also, the oil cooler on the RX-7 is BIGGER than the one on my Ford F350 7.3L Diesel tow truck.

That should tell you something about the specific oil cooling needs of the rotary.



If you're doing it to have something custom, enjoy your custom blown engine down the line as well...

If you're doing it to save money, I hope you can find a cheap rebuild to add on to the costs...

nick812

You should be able to get a good used oil cooler from a 2nd gen.

chedda_j

Yeah in cranbrook, yeah il just ebay one or go to calgary...are you shitting me. Thats prety far. How about this, why cant i just run a seperate oilcooler and pump for my turbo? Just an idea, considering i that i dont have acess to sources around me. Btw, the one i have is 12x8x1.5 1/2 inlet, 1/2 outlet, ALL aluminum. I guess that means i would have to find alum fittings and weld them on, any other ideas.

You know i am going for something custom and i have asked different questions, just because you are trying to save me money by telling me the RIGHT way, i want to know WHY. **** if i dont know whats the difference between right and wrong then il end up ******* up later on anyways because when i look at a problem, il go "um use a bigger one uh...because...yeah i dont know, i just know to use a bigger one." Dont look down on me just because im a noob on this forum, really to tell you the truth, i was expecting more of a family like the last car forum i belonged to. Anyways, enough of my bitching.

Pele

iTrader: (28)

Look at a diagram of a rotary and of a piston engine. Or better yet take one of each apart.

Notice the coolant and oil systems.

In the piston engine, you'll see that the water jacket SURROUNDS the combustion chamber. Coolant is against the outer walls of the cylinder and flows through the head near the valves and spark plug.

In the rotary, you'll see that the coolant only flows through the aluminum housings and the outer edges of the iron plates. The center iron is hollow as well as the rotor. These hollow spaces are filled with oil.

So, more oil is exposed to the combustion chamber... That's number one.



You'll notice that nobody runs a glass pack muffler, and if you attempt to put one on, you'll see that it doesn't last too long. They make special EGT gauges for rotaries and cheap headers and catalytic converters tend to melt pretty quick. You'll also notice that we have pretty beefy radiators and cooling fans, and nobody recommends a small electric radiator fan. All electric fans from from large V6'es, V8's or Rear/Mid engined cars like the MR2 and Fiero...

Why is this? It is because the rotary engine runs HOT. More heat produced... That's number two.



Finally, you'll notice that we use some of the crank case oil to lubricate the seals by way of the Metering Oil Pump... We need the old oil to be just as good as the fresh oil we put in at an oil change.

Take a look at glass for a second. It's smooth and slippery. Now break it up with a hammer. It's now a rough material similar to sand... But it's the same material. This is oil on a molecular level...

Oil is usually composed of long chains of molecules arranged together called a "polymer." To break these polymers apart, you need heat and/or pressure. Once broken apart, they lose the ability to be a proper protective lubricant. It won't stick properly to parts or slide as well. That's number three.


1.) More heat is put into the oil
2.) More heat in general is produced.
3.) Longevity of the oil is harmed, and the oil needs to be in good shape in these engines.

There's three reasons to use the proper oil cooler.


We've already covered why the auto transmission cooler is improper...

It doesn't flow well with small fittings, and is usually integrated with the radiator, meaning it won't shed heat as well, and what it does, it'll just put into the coolant system, which will just heat up the oil system more. This is why people get rid of the beehive, which is barely adequate for a stock engine.

Additionally, the auto tranny cooler is designed to cool off an automatic transmission... There is no compressed air to heat up an auto tranny, nor is there any fuel burning inside it. Automatic transmissions see far lower temperatures than engines.


About your cooler. 12x8x1.5 inches... That may or may not be adequate for the rotary... Remember, most stuff is sold for piston engines which don't shed as much heat through the oiling system.

I'm fairly sure that yours is a bit smaller than the stock units, although I don't have precise measurements on me.

Would anyone care to contribute the size of the stock S1/2, GSL-SE, or FC oil coolers?

trochoid

iTrader: (6)

4-1/2 X 2-1/2 X 22-1/2, FC, but very little difference between all of the different versions. They are also dual pass and have a thermostat.

Chedda j, all you are doing is inventing a square wheel, try the proven round one instead.

85 FB

Here's a simpler way to put it and this is what was told to me by one of the techs at my rotary shop:

"Our oil coolers are the best out there."

He told me this when I asked if I could exhange it out for a bigger badder one on my GSL-SE. That is what he told me, word for word. So, that's another reason to keep it in the rotary family.

Pele, unfortunately I do not know the measurements of my oil cooler off hand, even tho I did measure it a long time ago. It should be about 17" wide, 4-5" tall, and about 4" in depth. Hope that helps for now, tomorrow I can go out and measure if it's still needed.

chedda_j

K thank you thats prety much all i need. Im going to have to look around for a cooler. So on the stock OC in these cars, is there a fan that cools the oil or does it just cool from driving air. Just asking because i want to know if when i have to install one, where should i install it to keep it cool enough.

So the idea of running a seperate cooler for the turbo isnt a good idea? Fair enough.

I suppose a small radiator wouldnt suffice?

Rx-7Doctor

iTrader: (13)

What happened to the factory oil cooler your Sa came with?

The cooler is cooled by air. You can mount it below the radiator like it came from the factory.
That is if you still have the short radiator, otherwise it can be mounted in front of the radiator at the bottom.

85 FB

Radiators are meant for coolant, not oil. Oil coolers are meant for oil, not coolant. And, yes, the oil is cooled via the air that's rushed into it. Also, the 13B oil coolers have a thermostat in them so oil won't circulate through the oil cooler until it reaches a certain temperature.

Another thing to keep in mind, once you install your oil cooler, is to get an Oil Temperature Gauge to monitor everything. While normal oil temperature varies, it's usually between 140 and 200 degrees, according to Racing Beat's website.

bliffle

Oil cooling is ultra important in a rotary (even in a piston engine, too) as you can see. You need good engineering reasons to change it, not just a yen for something 'custom', which you hope to arrive at by Trial and Error. You'll notice that half of that method is Error, and when you make errors your engine crashes. An expensive way to learn.

The first thing you should do is install a simple oil temp gauge. Any car or truck that gets extreme service that may subject it to high operating temps should have an oil temp gauge. In fact, oil temp is more important than oil pressure in a race car. Lacking an oil temp gauge one monitors oil pressure looking for a drop in pressure as a symptom of oil thinning caused by overheating. It's that thinning caused by overheating that causes your engine to blow, not the reduced pressure.

Paradoxically, oil pressure will increase if you run your oil thru the auto transmission cooler under the radiator because of the restrictions. That's because the oil pump is a gear type positive displacement pump: it creates volume per second and pressure is just an artifact of the hydraulic impedance of the oil circuit.

Frankly, I would rather have an improved beehive cooler than replace it with an oil to air cooler because heat transfers more readily and quicker from liquid to liquid than from liquid to air. Thus, sudden increases in oil temp are more speedily reduced by a beehive than a radiator. Of course, on a longer time-scale the heat must be dissipated to the air thru the radiator, but the really important aspect of oil temp fluctuation is reduced when the oil is in intimate proximity to the coolant rather than air. The way an engine accomodates changes in temp is to wear out more stuff, thus speeding demise of the engine.