Counted Out

So I have a couple questions-

1. I have manual fan switches, and for the most part I always leave both of them running, is that bad?

2. Is getting a low-temp Thermostat worth getting if I already have the manual switch?

3. The past owner did alot of the low cost mods, how can I tell if the thero has already been changed?

1997whitez28

same questions, any answers?

shoebox

1. IMHO, not necessary or needed. Wasteful. It's just more wear and tear on the fans and causes more drag from the alternator to make the power.

2. Yes. The fans won't nearly have to run as much.

3. If you have a 160° thermostat, your cruising temp will normally be less and the needle will stay more toward the low end of the gauge. The thermostat also has a stamp on it with the temp rating.

Counted Out

But couldn't I just turn the fans on anytime I saw it start to get hot? I'm just a little confused.

shoebox

You can turn the fans on any time you want. With the lower temp thermostat, you won't need them as often. People seem to get obsessed with keeping the engine cooler than it needs to be.

kylersaulsbury

Just curious what would you do, if you had a motor w/o any emissions? Im just wondering b/c I do know the adverse affects of lowering the engine running temp and also how the emissions also help lower combustion temps. So basically which one out ways the other?

Injuneer

Lower coolant temps reduce the thermal efficiency of the engine = less power output. In the LT1, there appears to be an offset of this loss through gains from reduced inlet air charge temperature, and the ability to crank in a few degrees extra advance. If you aren't tweeking the tune, you probably aren't gaining much by super-cooling the engine. It's not all about emissions, although that plays a part. The only proven power producer in the over-rated Hypertech Power Programmer was the low temp stat + their tune to lower the fan temps and play with the timing.

95ltbird

so your saying with us cooling down the overly hot running engines of our cars it makes them slower? if it makes them slower...why the HELL do we put these things in?

shoebox

I don't think that was said at all. I suggest you re-read.

Injuneer

As I already posted, you have three things working in different directions:

1) Reduced coolant temp lowers engine thermal efficiency = lost HP

2) Reduced inlet air charge temp increases air density = increased HP

3) More aggressive timing may increase HP (depends on stock vs. modified)

The "net" is the combination of 1 + 2 + 3. If you don't do "3", you are leaving something on the table, and possible gaining nothing at all.

And.... why do you say the engines are "overly hot running"? They were designed to run at the stock fan on/off temps. There is no harm in running them at that temperature. Yes, it lowers emissions, but it also improves fuel economy. Yes, if you do it correctly, you may gain some power with lower coolant temperature. But there seems to be way too much fascination with lowering engine operating temperatures, without a basic understanding of what is happening.

caldercay

I'll take a stab at why - the fascination is probably due to folks
feeling threatened by engine overheating. When I first got my Z,
the average temp hovered around the first tic (which I think relates
to somewhere around 180*). Now, she seems to hover more closely
to the 1/2 tick mark (210*?). But I dont sweat it - I just flip the A/C
on and that will bring it down.

However, during the summer months down here in south Texas,
the temps can average 95-100*, so the cooling system has to work
harder - during the summer months, the gauge sits on the 1/2 tick
mark.

The point is, I think folks worry about the danger of the engine overheating.

Counted Out

Sorry, another question.

Do you have to get the PCM tuned for a new thermostat?

And how much will it effect emissions? Would I be able to change back to the stock one before I had to go to emissions, or would that require tuning the PCM back?

shoebox

No, you don't have to do anything to the PCM. I sometimes swap between the 180 and 160 in winter/summer.

Counted Out

I noticed the "have" was in italics, what to emphasize?

shoebox

Some people like to adjust the fans ON temps to go along with the thermostat change, but you don't have to.