NEW Dart 331 Temps acting up.

[vtecwho]

hey everyone,

i just finished a build of a supercharged Dart 331 with afr 185 heads and a comp cams nx274hr. everything on this motor is new and i have been experiencing some funny temp readings lately.

first, i have been running after market gauges for a long time including AFR, boost, oil pressure and water temp.

im VERY sure all gauges are working properly.

with that being said....

everything seems fine during warm up, the car reaches 180* and stays there.

however, during high revs ill let off the gas and allow the rpm to slow the car down. this is where the weird temperature readings start

druing decelleration the water temp cool down to about 150-160 degrees!!

i have a flex-a-light fan- if that matters.

i was thinking that during decelleration the fuel is cutoff (as we all know) and the high rpms allow the fan to pull in massive amounts of air, cooling the motor off while there is not much additional heat being created by bc of the fuel cut.

just wanted to know your opinions. none of my cars have ever done this before and thought it was worth mentioning. other than that car runs VERY well.

thanks
Eric

 

[HISSIN50]

What t-stat do you run? It should be the limiting factor.

Periods of engine braking from high revs do not take very long. Or are you coasting down a mountain or something?

 

[lincoln+ford]

What t-stat do you run? It should be the limiting factor.

Periods of engine braking from high revs do not take very long. Or are you coasting down a mountain or something?

thats what i was thinking.Whats your fan set to come on at and off?

 

[vtecwho]

I happens dramatically when engine braking from a slope.

However, it does not take long for the engine temp to drop if im, lets say, in third at 3000rpm and see traffic ahead and let off. then it may drop to about 175* or a bit lower. I see this on my tuning software (tweecer) in a numeric value as well as gauge drop.

I think Im using a "maxflow" t-stat or something. it is a brand from autozone that sticks open when/if overheating ever occurs.... thats the only difference that I noticed, but the car is not over heating.

I know there are two types of "flex fans", ones that flex and high revs and ones that do not. could this be a result of a non flexing fan at high rpms drawing in too much air?

 

[HISSIN50]

It could simply be that there is a lot of hysteresis in the stat. It doesnt fully close till 150-160*F. I run a balanced 180 and it doesn't fully close till 172*F for instance.

The fan is not real important in the scenario. E.g., if you ran an E-fan that was on all the time, the fan would run but the stat would close to allow engine temps to remain the desired range. The same is true for mechanical fans (clutched or flex).

Did you drill any extra bypass holes (in the rim of the stat, adjacent the jiggle valve)?