PhotoVette1

... sense air temperature like a thermal fan clutch?

Seems to me just sensing the radiator inlet coolant temperature doesn't take into account air velocity, water pump impeller speed (coolant flow rate), or air temperature entering the radiator. I.E. radiator effiency per given conditions.

A thermal fan clutch does this automatically. And, they do a great job of controlling temperature.

So, I thought about getting the SPAL dual fans. By putting a buffle in between the 2 fans, I make them into to two separate independant cooling areas. Then I use two air temperature variable speed controllers to control each one separately.

So, the fans act like two small thermal fan clutch systems.

The Flex-A-Lite Variable Speed Controller would work if I substituted a bead sensor for their contact sensor.

This would always give me the minimal fan speed required to achieve the correct engine coolant outlet temperature. Thus making the electric fans extremely effienct.

Any thoughts?

SanDiegoPaul

Arruh?

WhichVette?

You said it, Scooby Doo...

mrvette

Sounds like a good engineering project to me, I would love to find a reasonable priced (CHEAP) flow controll valve that can be easily controlled from a servo, in place of the t-stat, and combined with your idea there, it would be a neat high tech cooling system....for all kinds of weather....

GENE

Twin_Turbo

How does an electric fanse sense anything? The thermal clutch fan does what..it operates by the air around it that heats it up, does that relate directly to engine cooling needs? Not really, it also depends on air speed and other variables. What you want is something to give you additional flow when needed so the best way to go about it is to switch the fans off a sensor in the cylinder head, that's where the temperature is most critical. Plugging a sensor in the thermsotat or rad tank will work but I feel putting it inside the head is a better method. For the same reason the sensor for the gauge is also threaded into the head.

So the question is, what do you want to be the parameter to switch the fan with? Air temperature or cylinder head coolant temperature??

PhotoVette1

Great point. Maybe there needs to be two different setups.

A super cooling program to decrease head temps to prevent pre-ignition--for performance. This setup would attempt to decrease radiator outlet tempereatures as much as possible.

Then a program for steady state cruising--for economy.

neoh77

THey already make one... here.. I found a picture of it! Sorry it was just too good to pass up



I'm going cylinder head sender PLUS manual on switch. Keep the fan running in the staging lanes all the time to minimize temps and auto for the drive home...something like that!

jbs75

Seems to me the thermostat takes care of the engine, as long as the coolant coming from the radiator is cool enough. So having temp sensors in the radiator to control the fans makes the most sense. What you may want are two sensors(one for each fan, if you have two); one set for maybe 160 degrees, and the other at 190 degrees or thereabouts. If you have one fan, you can control the speed; needs a little more electric(relay plus resistor, mount resistor in fan air stream) but will work.

Jim

Boofers

Agreed. I am making a variable speed control for my fan. The input will come off a stock temp sender in my passenger side head. I also have a manual switch to drive the fan full power as a safety feature.

82Vette'ster

While you're at it you could add an air pressure driven switch to turn the fans off at higher speeds when the air flow through the rad is plenty without it.

Boofers

You would probably save $ and keep things simpler by using only one controller for both fans.

an81shark

clearly this is a sign of over analyizing.

just put a manual switch in the cockpit or a temp switch in the head and be done with it.

why make something more complicated then it needs to be (see vacuum controlled everything)

Z-man

I brought this up once and was booed off the stage. Everyone said that at high speeds the temperature would be cool enough so the fan would be off anyway...

CGGorman

Seems moot. If the engine temps are within the specified range, the electric fans won't run...regardless of exterior conditions. What's the point of a separate mechanism/program to force the fans off if air flow is sufficient? The coolant sender already knows and has already done that...unless it sees high operating temps because of excessive load or timing or something...

Seems like we are inventing a solution for a problem that doesn't exist...

PhotoVette1

Because of the thermostat, water coming into the radiator always exceeds 180F. So, everytime the t-stat opens, the fans come on. Unless it's set to come on much higher than 180F.

The fan temperature sensor--most being mounted on the radiator inlet--don't care if it's winter or you're traveling at highway speeds--they will come on irregardless.

My thought is, by monitoring radiator effiency, it may be possible to considerably reduce fan run time thereby increasing the benifits of having the electric fan in the first place.

Twin_Turbo

Why would you want the fan to be on w/ the stat closed?? The fan doesn't have to run everytime the stat opens, it depends on what temp. your switch engages, the fans are needed to force air through the rad in case of lack of airflow, which results in higher coolant temps and therefore a higher coolant temp at the head, where it's most critical and where the sensor should be. This system is bullet proof and doesn't need some kind of fancy setup, if with this setup the fans run they should be running because of cyl. head coolant temp and if your system is in fine condition, coolant is circulating and no trapped air pockets exist (since steam gets much hotter than coolant and when the steam hits the switch it will turn the fan on) when the fans aren't running the coolant temp is below the switching temperature... so how can the fans run for even less time than this??? I'm really not getting it.

82Vette'ster

Maybe it's not needed. I was assuming that the fan was also cooling an a/c condenser. And with electric fans, don't they kick on when the a/c compressor kicks on, Or maybe there's a trinary pressure switch in the a/c so its not necessary.

Z-man

It sounds like this setup has a sensor located on the inlet to the radiator. I think your sensor is located in the wrong spot. I think the sensor should measure something on the engine - preferably the heads because that is where the fire is and that is what needs to be cooled. I will be using a sensor which measures the head/water temp at the heads in the normal spot. If the temp at that location gets too hot, then the fans will cut in. If the temp is OK (hopefully at speed), then no need for fans.

Boofers

Hypothetical situation - compare two electric fans.

Fan1 is efficient and only uses 250W to keep the engine cool. Fan2 is inefficient and uses 500W to do the same job.

1 horsepower = 746 watts.

Fan1 consumes 250/746 = 0.34 horsepower
Fan2 consumes 500/746 = 0.67 horsepower

You won't feel a 0.33HP difference when you are driving.

PhotoVette1

Probably true. I just like things to work smartly I guess.