I have holes in the thermostat for more flow since I am using Evans NPG+ coolant. A side effect is that it can reach equilibrium below the 180F thermostat opening temp (though surely, the thermostats have some variability of the opening temp, so that may be part of it, too -- but I am running an otherwise stock Mazda thermostat). I also have the fans programmed to run at lower temps than stock via the PowerFC/Datalogit settings.

The ducting helps to ensure that you are sucking cool air from outside the engine bay through the radiator core, even when you are stopped with the fans running (good for avoiding IC heat soak, too, I imagine, since the air is pulled through all the cores with my ducting setup). That should be better for cooling than sucking hot engine bay air through the radiator core, which is more likely without the ducting.

Even when you aren't moving, hot coolant flowing through the radiator should shed some heat. I recently had an (aftermarket) oil thermostat issue that was causing the oil to skip the coolers. The oil temps were ~210F when cruising and ~195F when sitting still. After fixing the thermostat, the temps are ~140F when cruising and ~165F when sitting still, even though there are no fans pulling air through the oil coolers. The coolers radiate some heat (and do get some air flow, I am sure) even when you aren't moving. I would assume a similar effect for the radiator (though perhaps a bit less effectiveness since the radiator is in the hot engine bay).

I switched back to the stock main pulley (in combination with the larger-than-stock WP and alt pulleys from SR) to increase belt contact on the WP with no air pump and to increase coolant flow (versus the same WP pulley with underdrive main). It does seem like the WP could easily slip with an underdrive main pulley. The anodization had worn off my WP pulley under the belt when I was running the underdrive main pulley, but I am not sure how much it really slipped since the cooling system seemed to work satisfactorily for all but the most gruelling cooling challenges my car has faced.

-Max

 

What max said and:

Burp, burp, burp, then fully duct.

Do NOT run just one fan ... it will mostly loop thru the other in traffic. Use both or none.

FSM shows 12-17 amps per fan motor, so thin spals likely have less gust.

Check coolant in filler neck cold ... should at top or low by 1" max.

 

Absolutely ducting helps when moving, and to some extent helps the fans pull cold air. I'm saying ducting has little effect on equilibrium temperatures maintained when sitting still without the fans running.

Max, I'm curious about your experiences with Evans at the track. I'll PM you about it so I don't drag this thread further off topic.

 

oil temps, i know its not water temps but they play in on eachother. get a bigger or another oil cooler. that should help out alot more than you would think. and honestly (dont want to start an argument on oils) synthetic oils stay colder and are better for the engine/turbo(s).

 

I get about the same temps as Max does. 82C - 89C while driving (freeway and city). Every once in a while they'll get up to read 91 or 92C on the PFC. But I've got it set to turn the fans on at 90.

 

I don't have any hard data, but it is quite conceivable to me that ducting would also keep the "parked" temps lower since it should pull more cool air into the car.

-Max

 

yep. what max said. it's logical that ducting would help pull ambient air through the IC and rad from the front of the nose when the fans are on. same concept as the fan shroud.

 

Please also note that the context of this thread is hotter temps after installing an FMIC and Koyo rad. Most FMIC installations I have seen are very poorly ducted, with the spaces around the radiator core (sides, top) completely open. I recently installed a FMIC, and had custom duct work made because I was pretty sure I would overheat without it.

The stock radiator arrangement is reasonably well ducted, assuming you have all the parts installed properly.

-Max