its really not that complicated, the picture I made apparantly shows the correct routing scheme for the coolant reroute and basically you block the front thermostat and put one in the back that pipes around to the top of the radiator.

 

Because there is zero clearance behind the engine? I can't see anything back there. I don't feel safe randomly unscrewing things without a plan of what I will put in their place.

 

Hmm, I guess the NB's have more clearance back there. Can you see what's there if you use a mirror? All you need to do is swap the front and rear t-stat covers.

 

You could probably get by pulling the coils and CAS to gain more access. Remember to reset your timing.

 

I've installed mechanical coolant temp sensors at the rear of the head on both NA and NBs. You just need to clear out all the parts up top on the back of the head.

 

You can take a look at my picture thread from my build, it should have alot of related pictures in it. I'm pretty sure I posted back of the head pictures with and without my reroute stuff. I also have later pictures of my reroute piping, its not exactly the same as the majority would run (engine bay stuff is a big different), but I believe its all done properly.

 

O RLY? I thought i needed special custom parts to make this work. If it is just a straight swap of the existing parts, I suppose I can do it when I get back from atlanta next week.

Well besides hoses and stuff. I remember you used copper pipes for your and ran it over the turbo manifold, correct?

Man it is hilarious how the temps jump from low 90C to nearly 110 just by turning on the AC (no boost or anything).

 

Dude, you're in Atlanta?

 

No, I'm driving there on tuesday for an interview with a law firm. I'm in tally.

 

I can't understand how the thermostat fits behind the engine. It pokes straight out like half a foot in the front. Is there something I'm missing?

Also I assume you have to remove the cam gears for this mod as well, correct?

 

I dont really remember exactly what people did but I looked into it a bit about a year ago and there were certain years of miatas that had the correct front thermostat thingie to go back there ... but not sure if it was a 90-91.5, 92-93, 94-97 or what.

 

I'm not upgrading the radiator unless I can figure out the coolant reroute thing.

Also, I like the idea of dumping the heater core outlet into the post-thermostat line back to the radiator. Or would this make the water from the front of the engine too cold?

Do you have to remove the timing belt to get the thermostat housing out? I'm just wondering how many hours I need to set aside for this adventure. It is beginning to look like a weekend long job.

 

The 1.6 thermostat cover fits back there and can throw the flow exactly left or right.

 

beer, you only need to swap the t-stat covers. No timing belt removal.

The concept is very simple. The water pump sucks coolant from the radiator and the heater, and pushes it into the front of the block. Water goes up into the head.

You want the coolant to come out the back of the head (because it entered the front of the engine block), before going to the radiator, instead of out the front. So you swap the covers and move the t-stat to the back, and extend the rad hose. Doing this, the heater inlet moves from the back to the front too, so you extend that 5/8" hose too. No biggie. The coil pack will probably have to be relocated to make room. The EGR tube may need to be bent a little. Some have suggested t-stat covers from other cars which improve the way the hose points.

As for the heater. The heater's outlet goes into the water pump inlet. Good for cooling if the heater is on, bad for cooling if the heater is on, because coolant coming out of it is hot and re-enters engine. The effect of this on engine temps is noticeable in my measurements, but not huge. Maybe 4°C at idle IIRC. (Effect is greater at idle).

If you simply tee this into the radiator's inlet (a) the heater will not see much of a pressure differential across it, so the heater will be weak and (b) hot coolant will flow through the radiator despite the t-stat being closed during warmup, slowing down warmup, which increases engine wear and fuel consumption.

The optimal solution is to place a valve on the heater outlet. Close this valve in the summer, and open it in the winter.

Or you can do what I suggested to Shaikh @ FatCat. Make said valve automatic - place an oil t-stat in there, configured to close above its temperature setpoint - typically 80°C. (config'd to flow less the hotter it gets above 80°C, and is completely open below 80°C). This way, if you turn the heater on to either heat the cockpit in the winter, or to help cool the engine in an overheating situation, it will flow because the heater is cooling the coolant flowing through it. If the heater is off and the engine is hot, t-stat is closed, which is what you want.

 

Oh wait, I'm a retard. Just remove the highlighted part and exchange with a similar part on the back of the engine? I stupidly thought I had to replace the whole stalk coming out the front.

 

Correct.

 

On these re-routes, cant you run a small hose (1/4") from the rear of the head to the upper radiator hose (at the radiator) just to let air out and run the upper radiator hose anywhere you want?

 

hmmmm im new and dont mean to be a bit funny but mazda desgined it the way it is because it works and works well!!!!!!

 

lol mazda used that design because it worked "well enough" to fit into their economic, engeneering, ergonomic, etc pricetag. This same motor has the coolant flow going front to back on the fwd cars that use it anyways. BTW did someone make a new profile so they could post that as a really retarded joke?

 

Actually, mazda designed it the rerouted way originally and then broke the design when they converted the engine from FWD to RWD. All the FWD cars still flow the water in one side and out the other.