Mazda2ndgen

What is the actual reason for when your say at the track and people always have their cars turned off to cool them down... is it just so that the intake manifold will be cooled down? or is ther more to it than that?

on that note would it be benifical for one to take out the thermostat and replace the radiator with a nice big large griffin radiator so that the water temps will stay reeeaal low? would that help at all with detonation if the motor was running real cool? I used to own an rx7 were heat kills everything so I kninda like the idea of running as cool as possible . Is there a minimum temp that must be reached for everything to run proporly or not realy.

also if the big radiator is a good idea then what about the stupid sensor for the ecu that tells the ecu to be in warm up mode. Would grounding out the sensor make it think it warmed up and therefor not run in warm up mode?
btw this is all on a 90gst

Thanks again!
Jordon

MitsuBucci

4G63s have a cast iron block that holds a lot of heat for a long time. I have to cool my car almost completely between runs or I see knock on my logger.

Of course its a combonation of the intake cooling the intercooler cooling etc etc...

PiercedJD

additionally there is no benefit to removing the thermostat as the ecu on a 4G63 likes to see temps between 170-210...... John Conroy argues that the engine seems to run the most efficient around 210 however I like to keep mine around 180-190 to keep a buffer zone between my engine temp and 240 where the head begins to warp.

I ran my car without the thermostat for a week while comabtinng other issues and it only made it run worse until it warmed up whihc took forever with it pulled. I was seeing temps of 156 or so for about the first 45 minutes to and hour. ecu was overly compensating rich thinking the car was still warming up. was very lumpy hesistating and bucking on acceleration.

on a standalone you wont have the fuel compensation problems however at a certain temperature you will find the engines sweet spot where the pistons and block are heated and expand just right and the oil viscosity is just right and everything is meshing well. too cold can be just as bad as too hot.

highoctane

An engine does have an optimum tempreture for burning fuel which is like 212 degree or so combustion is more complete and emissions are lower.

However as it seems whats good for gas mileage & emissions never seems to work well for producing the most power running cooler in the 190-200 degree range makes a huge difference in reducing the chance of pre ignition.

Icing intakes helps to cool down the topend of the engine drastically(intake & heads) the effect it can have on the intake air is minimal though the air volume flowing through the intake at WOT is too fast to gain any effective cooling effect of the air itself.

Icing intercoolers is a different story ICs are heat transfer units to begin with they have a very effective means to transfer heat from the charge air with their internal core and fin design. Cooling an IC core below ambient tempreture can give a noticable boost in air cooling.

Big radiators are nice if you need one long duration load situations like autocross or lugging require them more than drag racing most drag cars merely have enough radiator capacity to keep the engine cool for a fairly short duration.

As far as an optimum tempreture different ECUs have different factory set minimum temps to function properly for day to day driving some prefer cold some warm some hot just depends on the application.