Effects of Lowering fan turn on/off temps
Thread Starter
Teching In
Joined: May 2003
Posts: 33
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Effects of Lowering fan turn on/off temps I've read that if you lower you fan turn on/off temps much lower than stock, you have to adjust your WOT hot and Cold tables, because the PCM will think the engine is still cold. Sounds like crap to me, but I could be wrong. What do you all think?
Re: Effects of Lowering fan turn on/off temps If you lower the FAN1 on/off below 190F (stock
'stat), all that happens is that your radiator
tank will be full-time cooled and your thermostat
will be in charge. It will hold you at about 195F
and life will be good. Further, the cooler tank
will provide an instantaneous "thermal surge"
capacity, that is, if the thermostat sees hot from
sudden high-power-output activity, it has some
"cold reserve" to let in, not just more 210F hot
water.
If you have a 160F 'stat and go this way, the
setpoint might be below some closed-loop ECT
threshold (maybe) and at any rate would be well
away from where the stock PCM data "expects"
operation to be. So there the need for tweaking
might apply. Perhaps more generally than WOT alone
if you want to idealize mixtures & spark for the
cooler temps.
'stat), all that happens is that your radiator
tank will be full-time cooled and your thermostat
will be in charge. It will hold you at about 195F
and life will be good. Further, the cooler tank
will provide an instantaneous "thermal surge"
capacity, that is, if the thermostat sees hot from
sudden high-power-output activity, it has some
"cold reserve" to let in, not just more 210F hot
water.
If you have a 160F 'stat and go this way, the
setpoint might be below some closed-loop ECT
threshold (maybe) and at any rate would be well
away from where the stock PCM data "expects"
operation to be. So there the need for tweaking
might apply. Perhaps more generally than WOT alone
if you want to idealize mixtures & spark for the
cooler temps.
Re: Effects of Lowering fan turn on/off temps what if you have the HPPIII ? Will that correct the charts? Or does it just turn the fans on and off? I have the 160 thermostat and the programmer set to 160. Would that hurt my fuel milage?
Re: Effects of Lowering fan turn on/off temps The only thing I can think of is to buy a dang good radiator that will cool the car down to those temps. But as I said earlier, I do not know if the HPPIII changes the map settings to the cooler temps. I will call them and ask and I will post what they say here.
Re: Effects of Lowering fan turn on/off temps The LS1 radiator (stock) is actually VERY good. All of our race applications (except one) use the stock radiator, and it works great.
Lowering the fan temps to kick on earlier isn't always a good thing. Your fan temps should coincide with the type of Thermostat that you have. The Radiator auxiliary fans are there to facillitate the thermostat.
By lowering your fan temps lower than what the thermostat can provide, then you will be forcing your fans to stay on all the time. This increases both front end lift, front end drag, and shortens the life of your fan.
Fan temps should be set around the thermostat.
Stock Thermo:
First Stage On/Off: 229/222
Second Stage On/Off: 237/230
160 Thermo:
First Stage On/Off: 184/175
Second Stage On/Off: 194/185
Good Luck
Lowering the fan temps to kick on earlier isn't always a good thing. Your fan temps should coincide with the type of Thermostat that you have. The Radiator auxiliary fans are there to facillitate the thermostat.
By lowering your fan temps lower than what the thermostat can provide, then you will be forcing your fans to stay on all the time. This increases both front end lift, front end drag, and shortens the life of your fan.
Fan temps should be set around the thermostat.
Stock Thermo:
First Stage On/Off: 229/222
Second Stage On/Off: 237/230
160 Thermo:
First Stage On/Off: 184/175
Second Stage On/Off: 194/185
Good Luck
Re: Effects of Lowering fan turn on/off temps If you let the fans go like that, you will see
30F coolant temp swings depending on driving
pattern. That's going to be tough to get any
tuning consistency with. How much spark do you
"leave on the table" to accommodate a 225F ECT?
30F coolant temp swings depending on driving
pattern. That's going to be tough to get any
tuning consistency with. How much spark do you
"leave on the table" to accommodate a 225F ECT?
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Re: Effects of Lowering fan turn on/off temps The only time that you are going to get an increase in engine temperature or "swing" is when the vehicle comes to a stop, or slows in traffic and sits at an idle or low RPM for an extended period. Who is interested in tuning performance at this time???
99% of the people out there are going to want to obtain peak performance while the car is moving. While the car is moving forward, the fans should be OFF (to reduce drag) and all coolant control should be done by the thermostat. There is a reason that race cars wire the fans to a manual switch.
I don't have to mess with spark in regards to engine temperature. Your car already does this for you. Our cars already have adjusters and modifiers to deal with changes in engine temp, air temp, etc...
99% of the people out there are going to want to obtain peak performance while the car is moving. While the car is moving forward, the fans should be OFF (to reduce drag) and all coolant control should be done by the thermostat. There is a reason that race cars wire the fans to a manual switch.
I don't have to mess with spark in regards to engine temperature. Your car already does this for you. Our cars already have adjusters and modifiers to deal with changes in engine temp, air temp, etc...
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Verdad Gallardo Re: Effects of Lowering fan turn on/off temps I have the 160' stat in my car and I have the HPPIII set the temps on off for the 160' thermostat. But I do not see a drop on my temp gauge even when I am running down the highway. I don't know why but my car just doesn't seem to get any cooler then factory. And my fans run most all the time now. I read the state before I put it in and it was the 160' stat. I do not know.
Re: Effects of Lowering fan turn on/off temps The factory temp gauge is a dummy gauge. It basically only indicates Cold, Warm, Operating Cold, Operating, Operating Hot, and Overheat.
If you hook up an aftermarket gauge or watch your actually engine coolant temperature on a scantool, you will see it shifting all over the place.
If you hook up an aftermarket gauge or watch your actually engine coolant temperature on a scantool, you will see it shifting all over the place.
Re: Effects of Lowering fan turn on/off temps Exactly. Only it doesn't shift much, if the 'stat
is in charge. My ECT stays between 194 and 197,
solid, per Predator real-time.
As for who wants performance after 2 minutes of
zero airflow? Maybe you like to go KR-slow from
the stoplight. I'll take a little low-speed fan
noise. Fan switch is all well and good for a
track racer. Gonna remember to hit it every time
you coast to the intersection and wait? Not me.
I'd just leave it on. Oh, wait, I did. Sorta.
Drag? Yeh. Lift? Uh, huh. If the fan is on, it's
pulling you forward, man. Woo-hoo! Thing can't
even lift itself off the floor. What's it really
gonna do with 1800lb of nose weight?
is in charge. My ECT stays between 194 and 197,
solid, per Predator real-time.
As for who wants performance after 2 minutes of
zero airflow? Maybe you like to go KR-slow from
the stoplight. I'll take a little low-speed fan
noise. Fan switch is all well and good for a
track racer. Gonna remember to hit it every time
you coast to the intersection and wait? Not me.
I'd just leave it on. Oh, wait, I did. Sorta.
Drag? Yeh. Lift? Uh, huh. If the fan is on, it's
pulling you forward, man. Woo-hoo! Thing can't
even lift itself off the floor. What's it really
gonna do with 1800lb of nose weight?
Re: Effects of Lowering fan turn on/off temps
Exactly. Only it doesn't shift much, if the 'stat
is in charge. My ECT stays between 194 and 197,
solid, per Predator real-time.
As for who wants performance after 2 minutes of
zero airflow? Maybe you like to go KR-slow from
the stoplight. I'll take a little low-speed fan
noise. Fan switch is all well and good for a
track racer. Gonna remember to hit it every time
you coast to the intersection and wait? Not me.
I'd just leave it on. Oh, wait, I did. Sorta.
Drag? Yeh. Lift? Uh, huh. If the fan is on, it's
pulling you forward, man. Woo-hoo! Thing can't
even lift itself off the floor. What's it really
gonna do with 1800lb of nose weight?
is in charge. My ECT stays between 194 and 197,
solid, per Predator real-time.
As for who wants performance after 2 minutes of
zero airflow? Maybe you like to go KR-slow from
the stoplight. I'll take a little low-speed fan
noise. Fan switch is all well and good for a
track racer. Gonna remember to hit it every time
you coast to the intersection and wait? Not me.
I'd just leave it on. Oh, wait, I did. Sorta.
Drag? Yeh. Lift? Uh, huh. If the fan is on, it's
pulling you forward, man. Woo-hoo! Thing can't
even lift itself off the floor. What's it really
gonna do with 1800lb of nose weight?
Re: Effects of Lowering fan turn on/off temps Jimmyblue has been posting solid info on cooling temps for a while and i think he hits the nail on the head. Im not setting my fans at 229 and 237 on temps as nogo suggested thats crazy
Re: Effects of Lowering fan turn on/off temps Stange how GM's multibillion dollar development team uses those settings for ALL of its LS1's. I didn't invent those numbers, those are the stock fan settings for your thermostat.
If you guys feel the burning desire to change your fan temps to something lower, knock yourself out.
Is it going to dramatically effect the performance of your car and make it easier to tune? NO it will not, and inferring to people that they need to do this is just plain WRONG.
There are too many people that think GM's engineering department is just a ship of fools. If you have a stock thermostat, then you should be using the stock settings, bottom line.
If you guys feel the burning desire to change your fan temps to something lower, knock yourself out.
Is it going to dramatically effect the performance of your car and make it easier to tune? NO it will not, and inferring to people that they need to do this is just plain WRONG.
There are too many people that think GM's engineering department is just a ship of fools. If you have a stock thermostat, then you should be using the stock settings, bottom line.
Re: Effects of Lowering fan turn on/off temps Stock settings specified by GM's engineers are so high because the hotter the operating temp the better it is for emmissions. If you are performance minded lower your fan temps, if you are concerned with emmmissions leave them at the stock settings.
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Joined: Jan 2002
Posts: 531
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From: Helendale, Ca (SilverLakes)
Re: Effects of Lowering fan turn on/off temps I decided not to mess with the PCM settings and just got a fan switch. Also, my replacement Thermostat was OEM specified at 186 degrees. When my temp gauge gets up to the 195 range; I just turn on the fans. Works like a charm. No muss. No fuss.
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Re: Effects of Lowering fan turn on/off temps
The LS1 radiator (stock) is actually VERY good. All of our race applications (except one) use the stock radiator, and it works great.
Lowering the fan temps to kick on earlier isn't always a good thing. Your fan temps should coincide with the type of Thermostat that you have. The Radiator auxiliary fans are there to facillitate the thermostat.
By lowering your fan temps lower than what the thermostat can provide, then you will be forcing your fans to stay on all the time. This increases both front end lift, front end drag, and shortens the life of your fan.
Fan temps should be set around the thermostat.
Stock Thermo:
First Stage On/Off: 229/222
Second Stage On/Off: 237/230
160 Thermo:
First Stage On/Off: 184/175
Second Stage On/Off: 194/185
Good Luck
Lowering the fan temps to kick on earlier isn't always a good thing. Your fan temps should coincide with the type of Thermostat that you have. The Radiator auxiliary fans are there to facillitate the thermostat.
By lowering your fan temps lower than what the thermostat can provide, then you will be forcing your fans to stay on all the time. This increases both front end lift, front end drag, and shortens the life of your fan.
Fan temps should be set around the thermostat.
Stock Thermo:
First Stage On/Off: 229/222
Second Stage On/Off: 237/230
160 Thermo:
First Stage On/Off: 184/175
Second Stage On/Off: 194/185
Good Luck
What would you suggest for a 180 thermostat?
Re: Effects of Lowering fan turn on/off temps
If you let the fans go like that, you will see
30F coolant temp swings depending on driving
pattern. That's going to be tough to get any
tuning consistency with. How much spark do you
"leave on the table" to accommodate a 225F ECT?
30F coolant temp swings depending on driving
pattern. That's going to be tough to get any
tuning consistency with. How much spark do you
"leave on the table" to accommodate a 225F ECT?
Re: Effects of Lowering fan turn on/off temps A 180 thermo should keep your car temperatures right around 195 to 200 deg F.
I would set the fan settings to reign in your temperature at around 205.
Fan 1 On/Off: 213/206
Fan 2 On/Off: 222/214
Your fan temps should be somewhere in this area IMO.
Good Luck
I would set the fan settings to reign in your temperature at around 205.
Fan 1 On/Off: 213/206
Fan 2 On/Off: 222/214
Your fan temps should be somewhere in this area IMO.
Good Luck
Thread Starter
Teching In
Joined: May 2003
Posts: 33
Likes: 0
Re: Effects of Lowering fan turn on/off temps 1. Am I going to be losing or gaining any extra timing by lowering my fan temps around a 160 stat?
2. Am I going to lose any performance if the PCM thinks the engine is still cold?
2. Am I going to lose any performance if the PCM thinks the engine is still cold?
