Water Cooled Question, Fan sequencing / works great! Options

[andys]

I would turn the two speed on first at low speed and then when the temp increased switch it to high speed with the second fan.
On my car I turn on both fans at half speed at 190 degrees and if the temp gets to 200 degrees both fans go to full speed.
This is easy to do using 3 relays. Slow speed is the fans wired in series and then put them in parallel for full speed.

Bob,

I've got three different schematics of this setup, but this is the best I've seen. Yeah, I love the low/high speed function, but oddly enough, it stopped working. My manual fan low/high over ride switches work, so the PCM signal is somehow not getting sent. Time to do some troubleshooting! I'm thinking GM coolant temp sensor failure? I'd like to test it; would you happen to know the resistance values to look for? (slight hijack)

Thanks,

Andys

[BIGKAT_83]

I would turn the two speed on first at low speed and then when the temp increased switch it to high speed with the second fan.
On my car I turn on both fans at half speed at 190 degrees and if the temp gets to 200 degrees both fans go to full speed.
This is easy to do using 3 relays. Slow speed is the fans wired in series and then put them in parallel for full speed.

Bob,

I've got three different schematics of this setup, but this is the best I've seen. Yeah, I love the low/high speed function, but oddly enough, it stopped working. My manual fan low/high over ride switches work, so the PCM signal is somehow not getting sent. Time to do some troubleshooting! I'm thinking GM coolant temp sensor failure? I'd like to test it; would you happen to know the resistance values to look for? (slight hijack)

Thanks,

Andys

The GM LS1 sensor (thermistor) is 29k ohms at -20 degress C and 180 ohms at 100 degress C.

[CptTripps]

I'm having one hell of a time locating a radiator anything close to the one you have. I started thinking about a compact sized radiator, and that took me to looking at two smaller radiators. I think the Boxster does something like that too.

What do people think about using two smaller motorcycle or quad radiators.

I could mount two of these, and put the Intercooler radiator in between them...all up front without taking up too much room.

[76-914]

Mike & Tom, Thanks for explaining things to me. Now I get it. Bob tried to tell me but I was too damn stupid to get it. (IMG:style_emoticons/default/slap.gif) He must think that I know what I'm doing. (IMG:style_emoticons/default/av-943.gif) Bob, if your still following, were those MegaSquirt pin numbers that you show in that print?

[BIGKAT_83]

Mike & Tom, Thanks for explaining things to me. Now I get it. Bob tried to tell me but I was too damn stupid to get it. (IMG:style_emoticons/default/slap.gif) He must think that I know what I'm doing. (IMG:style_emoticons/default/av-943.gif) Bob, if your still following, were those MegaSquirt pin numbers that you show in that print?

Didn't mean to confuse you those are LS1 ecu pin numbers. I have two radiators set up like this one in the subaru car. Using two outputs out of the megasquirt to control the fans. The other one is the LS1 car and they are controlled with the stock ECU.

(IMG:style_emoticons/default/chair.gif) Bob

[76-914]

Spoke too soon. I see relay 2 powering Fan #1 @ high speed. I don't understand the "path" it takes to run Fan #2 on high. (IMG:style_emoticons/default/chair.gif) Sorry I'm so thick about this.

EDIT: Nevermind. I went back and read where Tom confirmed that both circuits are energized at the same time. God I hope I remember this tomorrow after I've slept.

[Mike Bellis]

I'm having one hell of a time locating a radiator anything close to the one you have. I started thinking about a compact sized radiator, and that took me to looking at two smaller radiators. I think the Boxster does something like that too.

What do people think about using two smaller motorcycle or quad radiators.

I could mount two of these, and put the Intercooler radiator in between them...all up front without taking up too much room.

Horse Power equals heat. You need to be able to dissipate the heat. Most motorcycles make less than 100hp, so you would in theory need 4 radiators rated for 100hp to cool 400hp. It doesn't really work that way since it's not a linear equation.

Things to consider:

1) Surface area - larger surface area will have better heat transfer. Small radiators look cool but may not be cool.

2) Water flow - too much or too little water flow will reduce heat transfer.

3) Air flow - radiator must be sealed with a shroud to prevent air flow around the radiator. Air will follow the path of least resistance.

4) Confection - To create a low pressure area behind the radiator to promote air flow. Most of us accomplish this by having a larger outlet for air and a smaller inlet in the bumper. This creates a high pressure zone in front of the radiator.

5) Fans - fans must pull air through the radiator. Never push through.

6) Surface tension - Increasing the surface tension of the water can promote better heat transfer. This is accomplished by using a product like "Water Wetter" or "Purple Ice"

7) Tuning - an improperly tuned engine can create additional heat.

[BIGKAT_83]

I'm having one hell of a time locating a radiator anything close to the one you have. I started thinking about a compact sized radiator, and that took me to looking at two smaller radiators. I think the Boxster does something like that too.

What do people think about using two smaller motorcycle or quad radiators.

I could mount two of these, and put the Intercooler radiator in between them...all up front without taking up too much room.

Here's a couple for you. These are used on a 993 LS1 conversion.



Bob

[CptTripps]

That got me thinking...what about the front radiator for a Boxster instead of the side radiators? (It has 3, right?)

something like this one.

http://www.pelicanparts.com/cgi-bin/smart/...7-106-037-02-M6

Looks like it's small enough to fit down low. With 2 fans exhausting out the wheel-wells in a fiberglass/aluminium tunnel?

[Mike Bellis]

That got me thinking...what about the front radiator for a Boxster instead of the side radiators? (It has 3, right?)

something like this one.

http://www.pelicanparts.com/cgi-bin/smart/...7-106-037-02-M6

Looks like it's small enough to fit down low. With 2 fans exhausting out the wheel-wells in a fiberglass/aluminium tunnel?

The center radiator was added to supplement the side radiators. I doubt if it has enough Delta T to be used by itself.

[CptTripps]

YeH, that's what I'm thinking too. Looks a little small for what I'd need it for.

Back to the drawing board.

[skeates]

I'm having one hell of a time locating a radiator anything close to the one you have. I started thinking about a compact sized radiator, and that took me to looking at two smaller radiators. I think the Boxster does something like that too.

What do people think about using two smaller motorcycle or quad radiators.

I could mount two of these, and put the Intercooler radiator in between them...all up front without taking up too much room.

Horse Power equals heat. You need to be able to dissipate the heat. Most motorcycles make less than 100hp, so you would in theory need 4 radiators rated for 100hp to cool 400hp. It doesn't really work that way since it's not a linear equation.

Things to consider:

1) Surface area - larger surface area will have better heat transfer. Small radiators look cool but may not be cool.

2) Water flow - too much or too little water flow will reduce heat transfer.

3) Air flow - radiator must be sealed with a shroud to prevent air flow around the radiator. Air will follow the path of least resistance.

4) Confection - To create a low pressure area behind the radiator to promote air flow. Most of us accomplish this by having a larger outlet for air and a smaller inlet in the bumper. This creates a high pressure zone in front of the radiator.

5) Fans - fans must pull air through the radiator. Never push through.

6) Surface tension - Increasing the surface tension of the water can promote better heat transfer. This is accomplished by using a product like "Water Wetter" or "Purple Ice"

7) Tuning - an improperly tuned engine can create additional heat.

A little "confection" goes a long way in many baking recipes, but I'm pretty sure that it's "convection" that facilitates the heat transfer between the radiator and the air (IMG:style_emoticons/default/poke.gif)

As long as you are matching HP figures on the radiators you will be safe (and in my opinion fairly conservative). One thing to keep in mind is that in our radiator set-ups we don't have a massive mass of metal inches behind the radiators. In fact, we have fairly un-obstructed paths for the air flow (particularly if you are ducting or venting through the hood) which dramatically increases the air flow rates and therefore capacity of the radiators.

[Mike Bellis]

A little "confection" goes a long way in many baking recipes, but I'm pretty sure that it's "convection" that facilitates the heat transfer between the radiator and the air (IMG:style_emoticons/default/poke.gif)

Stupid spell check... (IMG:style_emoticons/default/dry.gif)

[76-914]

Got my fans & relays wired in tonite (IMG:style_emoticons/default/piratenanner.gif) I'm happier than a 3 petered Billy Goat. It works great (IMG:style_emoticons/default/biggrin.gif) Thanks for all the help from everyone and thanks for that most excellent schematic, Bob.

[Chris H.]

Gotta bump this great thread...Just a quick question...

Just ordered my 5 pin relays (the SVX stock ones are 4 pin), just trying to understand this diagram. I decided not to use the SVX fans since they are huge and when I started my car and let it run for 10 minutes and it didn't even come up to temp so I'm thinking that's overkill.

My new fans only have two wires (stock ones had 4). Assuming one is power and one is ground. On the diagram it's showing that I only ground ONE of the fans directly and then ground relay 3, which the second fan is connected to. Is that correct?

reposting the diagram:

[76-914]

Es verdad, Christo. Looks funny but think of stacking 2 D cell batts. 6v or 12v depending upon whether the are in series or parallel.

[Chris H.]

Cool thanks Kent! Just seemed weird not grounding the second fan directly.

[76-914]

Thought I'd add this bit of info re: this style system. Last week I noticed that my fans were working on low but when switched to high (yeah, I was chasing a cooling issue) it dropped to Fan #2, only. Following the chart I was able to determine that relay F, in my case, (relay 3 in the diagram) was at fault. I was quite proud of my diagnostic abilities and proceeded to remove said relay to bench test and verify what I knew to be the problem. But the relay tested good. (IMG:style_emoticons/default/WTF.gif) If it had been a snake it would have bitten me. And it's not like I didn't know it was there; I built the damned thing. I just forgot they were there. The fuses are now labeled for my benefit in case I blow another one. So if this one blows I get the above described scenario, however if the other one blew I think none of the fans would operate but you might want to double check me on that one. (IMG:style_emoticons/default/biggrin.gif)

[messix]

Thought I'd add this bit of info re: this style system. Last week I noticed that my fans were working on low but when switched to high (yeah, I was chasing a cooling issue) it dropped to Fan #2, only. Following the chart I was able to determine that relay F, in my case, (relay 3 in the diagram) was at fault. I was quite proud of my diagnostic abilities and proceeded to remove said relay to bench test and verify what I knew to be the problem. But the relay tested good. (IMG:style_emoticons/default/WTF.gif) If it had been a snake it would have bitten me. And it's not like I didn't know it was there; I built the damned thing. I just forgot they were there. The fuses are now labeled for my benefit in case I blow another one. So if this one blows I get the above described scenario, however if the other one blew I think none of the fans would operate but you might want to double check me on that one. (IMG:style_emoticons/default/biggrin.gif)

you are correct.

I think if I built that circuit I would have activated the high speed on relay #2 from the 87 pole on relay #3. if the relay switching speed is not the same it would "buck" power.

so to do so you would run 2 wires off the 87 pole on relay #3, one to the fan and the other to the relay#2 at pole #85. only one high speed wire from the harness.