KevinW

iTrader: (1)

i'm down here in texas and already have an aftermarket rad and the car still runs hot, i'm running pretty much all water wich actually cooled it down from using water and coolent mix. so now i want to try the lowest temp themostat possible. thanks for any info.

dubulup

that won't change anything except...how long it takes for you car to warm up. you need to change the thermo switch. car Ray at Malloy and tell him you want the miata thermo switch for you FD.

7racer

dubulup....

it does change somethings. I have the pettit low temp thermostat (that they don't make anymore). While at cruise, when I had 70/30 I would frequently only get up to 78c (the temp of the thermostat. It will take A LONG time to warm up like you said. Once the engine is hot enough your right both thermostats are wide open and everything is the same. Also, in stop and go traffic when less air is getting to the radiator it should be the same.

However, with my fans set to come on at around 91c it seems I can regulate the temp better. Does that make sense? It seems that for the same temp, more of the thermostat is open allowing more coolant flow and cooling. I was actually running too cold at night (below 78c) that I ended up switching to Evans to bring the temp up a bit.

I'm not saying it will make a difference to a car with cooling problems, I was just surprised that after all of my mods (radiator, dp, ducting, 99 front...etc) that the thermostat changed the temp control the most at the expense of a super long warm up time.

KevinW

iTrader: (1)

i dont have problems at idle in stop and go traffic only when on the highway, when the car heats up i put it in nuetral and let it coast for a a few seconds and it cools it right down it's just getting annoying and not sure what else to do. i do have a front mount but i hate seeing the PFC go over 100 celsius. dont know what else to do? i currently searching through all the threads but i have done everything listed in there, this is really pissing me off because i cant drive the car hard or it shoots up over 100-107 and thats too damn hot.

7racer

well the front mount might be a issue that you can't get around. Did you set the PFC fans to come on lower?

Also, have you done the trick of drilling a couple of holes in the thermostat?

KevinW

iTrader: (1)

i havent drilled the holes yet, i was going to buy a lower thermostat and drill the holes, also i dont have an AST just an overflow bottle could this be an issue as well?

7racer

probably not but there is some thought about the additional cooling capacity that the ast holds.

If your ok in stop and go but bad on the highway, it tells me that your fans are working but the front mount isn't allowing enough air to the radiator. If that is the case, then the thermostat is wide open and probably even a low temp thermostat won't help you. I would try lowering the temps the fans come on high by the PFC.

Julian

iTrader: (14)

maybe the pettit thermostat had better flow openings ?? otherwise a cooler therm should do nothing good. The engine need to be at operating temp to produce most power, colder is not better.

Kevin,

I have been running about 86-88 C measured at PFC oil 195-220F in pan; spirted driving < 120mph (4000-7000 rpm 3rd 4th but not flat out acceleration runs), in the last round of this heat 97-103 f using 70/30 water plus water wetter, ast, large rad with extra detail to sealing rad air leaks during install. Stock but new themo and stock fan settings.

If you are hot I would check other items, air in system, water pump cavitation, timing ...

Julian

iTrader: (14)

107C is still below danger level. I have a warning light set to come on at 225F (107) to remind me to back off, I don't get there now with current mods, will see next month at TWS if air temps are still in 100 range

KevinW

iTrader: (1)

ok, i understand everything except the cavitation for the waterpump, i know what cavitation is but how would i check, also i noticed while using a 000 steel wool to polish my waterpump pully with the car on,(using the motor spinning to do the polishing for me) the pully would actually stop if i apply any pressure, i dont think this should happen but maybe i'm wrong, and i dont think anyone really has tried to dtop their waterpump pully so i'm not sure if anyone will have an answer for me, and no i was not trying to stop it, just apply a little pressure so it would shime up a bit. aany ideas on this? if not i will see if someone in the area will let me try this on their car with a rag or something

Speedworks

maybe you should do the fan mod

http://rx7.voodoobox.net/howto/fanswitch/fanswitch.html


good luck

KevinW

iTrader: (1)

i have my PFC to have the fans come on at 81 celsius

fdeeznutz

If you have a pulley kit and no airpump the resistance on the pulley is greatly reduced(If not......???) The belt doesn't hug the water pump pulley like it was designed to. My WP pulley belt has to be extra tight to ensure proper contact.

KevinW

iTrader: (1)

can the PFC also control the fan speed?

KevinW

iTrader: (1)

yeah, no airpump, maybe i should tighten the belt, it could be slipping at higher RPm i guess

Julian

iTrader: (14)

Cavitation is a common rotary engine problem because the rpm range is so wide, common cooling fix on first gens was to change pulley size to slow it down. Also Mazda's drop of system pressure from 1.3 to 0.9 bars does not help, as cavitation if the forming of vapor bubbles in a liquid due to a pressure drop such as dev elopes over the surface of a propeller/impeller blade. The concept of changing pulley size to increase HP really started with trying to reduce WP and alternator rpms vs higher engine rpms, result is a slight increase in HP with a slower turning alt, but biggest gain is reduced speed of WP improving water flow. Must be careful of poor pumping and thus cooling if car is used in stop and go rush hour driving as slow speed pumping is less.

I have not changed my pulleys, but am using a 1.1 bar after market pressure cap not the 0.9 recall cap ... I would like to go back to the 1.3 bar cap that I had for 10 years, but can not find for Pettit AST tank. FYI a higher pressure system is less susceptible to cavitation as well as raising the boiling point of water.

7racer

you cen tell the PFC what temp for the fans to come on for low/med/high IIRC

dubulup

are you using the stock pulley with no air pump? Get a bigger pulley.

if you are using a big pulley, adjust the alt so you get more tension on the WP pulley.

Pineapple Racing sells a AP elimination kit, you might need one.

dubulup

I don't know what you are talking about?!?! there is only one t-stat and if you get a cooler one, this will do nothing to aid cooling while on the interstate. The only thing it will do is cool your engine coolant before it is at operating temp...

KevinW

iTrader: (1)

maybe i need the fans to turn on high sooner then what they currently are set at, thanks for the advice, i guess i'll leave th t-stat alone for now and try the fans and tighten the belt and maybe get an AST put on

DamonB

Cooler thermostats do not solve over heat problems!

Once the thermostat is open the system has the ability to cool at its maximum rate. If coolant temps continue to rise out of control after the thermostat is open a cooler thermostat can do absolutely zero to help you. It's useless.

You have other problems you need to solve. There is no point in swapping the thermostat.

dubulup

maybe you can try ducting...works wonders!

KevinW

iTrader: (1)

i did the other day just a 15 min cardboard job just to see if it was going to help at all and if it did i was going to do a full job using aluminum or some sort of insulation but it didn't help even 1 degree. Oh well i guess i will just do it the right way and see if it works

7racer

Wasn't there someone on the forum who made a scoop that brought in extra air to the radiator slightly bypassing the frontmount?? I don't recall if that worked all all or not. Kevin, what kind of front mount do you have?

papsmagu

iTrader: (19)

doesn't the FC thermo switch work better. i've heard the plug is exactly the same and there is not splicing required. also, i know that it comes on at a lower temp.