Conversion to 12V thermo fan?

[*Kiwi]

Well, I drove to the next town west of here for lunch, 145 km each way. It's hilly and lots of passing required with speeds mostly between 80 and 110 kph.

My previous two trips in the stock GV yielded 7.31 and 7.29 L/100km.

With my shiny new free-wheeling hubs I netted 7.04 L/100km, a 3.6% improvement.

The only variable that I can't confirm is the same is that I may have used the AC occasionally in the first two trips, while I did not use it today.

[murcod]

13.44l/ 100km out of my last tank. (17.5mpg)

I tried to avoid too much heavy use of the accelerator, but still was well and truly out the front of the traffic (so not being ridiculous and trying for the best figures possible.) That's outer city driving too with mostly 17km trips to and from work.

Not as much use of the A/C now as the weather is cooling down.

[3stage]

Question:
Why use the voltage control switch on the ECU rather than a simple inline thermostat switch? It doesn't seem that difficult to do, but if someone gets the trigger voltages wrong, that could seriously affect cooling performance.

I am thinking about using a simple 80deg thermostat switch placed in a custom housing in the upper radiator hose for my J20A motor.

Mishimoto 80deg




The above diagram offers a manual bypass for demanding conditions..

btw, does anyone know what the trigger temperature is for the newer J20 Grand Vitaras with electric rad fans?

Thanks

[murcod]

I used the voltage switch so I could set the temp up as close as possible to the "normal" temp with the viscous fan.

You've pretty well summed it up with "does anyone know the temp...." - I didn't know the temp, but I do know the voltage for the H27

It also saved me plumbing in extra sensors into the coolant lines ( I would also have needed two sensors of different temps to do the dual speeds.)

[fordem]

It's interesting that this thread should resurface right now - I'm just about to order a 16" SPAL puller fan and considering whether I should use their PWM controller, or put a thermoswitch in one of the radiator tanks.

Murcod - why did you chose to go with two smaller fans rather than a single large one? I'm looking at a 16" so that I can keep the original shroud - just need to fab some sort of bracket so that the fan is located in the right position.

3Stage - using a variable controller lets you set the switch on/off points precisely where you need them, rather than having to futz about changing your thermoswitch.

Let's take that proposed 80*C thermoswitch as an example - from the SQ420 FSM, the thermostat in the J20A engined Grand Vitara ('98~05) starts to open at 82*C and is fully open at 95*, so you would, at least theoretically, have the fan coming on before the thermostat is fully open, making me think, that depending on the exact location of the thermoswitch, that 80* might be on the low side.

I should have the JB420 FSM somewhere, I'll check see how the electric fans are handled there, and see if they provide temperature details - I seem to recall them being ECU controlled.

[3stage]

I was took some temperature measurements today with an IR thermometer. Need to take some more readings to verify.

The top of my radiator was 93.5°C and the bottom was 55.4°C.

I forgot to ask about the temperature setting on the factory thermostat.

Was speaking to my Honda mech and he said the factory Civic thermostat starts to open at 78°C and is fully open at 88°C. The thermo switch acticates the factory fans somewhere around 92 - 96°C..

[3stage]

2nd test in hot weather..

Top of radiator - 95.3°C
Bottom of radiator - 55.9°C

I think an ideal fan activation temperature would be around 85 - 90°C..

The 80°C Mishimoto thermoswitch is actually a 'performace' oriented unit design to run 15°C cooler than the factory Honda switches.

Personally, I will be using the thermoswitch to operate the fan. I just need to find an ideal location to mount it..

SPAL has some 85 and 90 switches.

85deg
http://www.spalusa.com/store/main.as...il&item=185-TS

90deg
http://www.spalusa.com/store/main.as...ail&item=195TS

[fordem]

The thermostat opening points for the SQ420 are in an earlier post - I dug out the JB420 manual and went through the engine cooling section - there is not that much in terms of specific details.

The thermostat has very similar opening points to the SQ420, there are two fans of unspecified size and air flow capacity, which are independently controlled by the ECU, and there is no information as to the switch points.

Looking the wiring, it appears that the fans can be run in series (reduced speed, air flow & noise) or independently (one or both full on) in pretty much the same manner as Murcod has his set up.

With regards your temperature measurements and the "ideal" fan activation temperature - as you have seen, the temperature at a given location at any point in time is different depending on the location - the most convenient place to put the thermostatic switch may not be at 80* at the time when you want the fan to come on - this is the advantage of an adjustable unit - you get to locate the sensor where you can, and then turn the fan on when you want and off when you want.

The SPAL PWM controller goes one step better - you can turn the fan on at half speed at one switch point, and as the temperature rises, so will the fan speed until a second switch point is reached, where the fan will be at full speed, and an optional second fan can be energized.

Unparalleled flexibility, which I assume comes at a price.

[murcod]

Originally Posted by fordem

Murcod - why did you chose to go with two smaller fans rather than a single large one? I'm looking at a 16" so that I can keep the original shroud - just need to fab some sort of bracket so that the fan is located in the right position.

From memory the dual 11" fans flow more air? They also come with a shroud built in which is almost an exact match for the width of my radiator. It also simplifies the dual speed control (run them in series or parallel). If I sell the XL-7 I can removed the whole kit and refit the old system as I haven't modded any of the stock parts for use in the conversion.

I wanted to "over engineer" this conversion. I've done a previous conversion using thermo switches etc and it was never good enough in hot weather. The current conversion has proven itself in the most extreme temps.

[fordem]

I thought that might been it - I did look at the air flow figures and the twin 11 inchers flow just about double a single 16" incher.

We don't hit the temps that you mention, at least not on the coast where I spend most of my time (and there is very little data for the interior of the country, which is mostly virgin rain forest).

You're running the 2.7V6, I'm running the 2.0I4 - I'm still in the "tape measure" stage - this would be so much easier if there was data available on what the optimum air flow required was.

Thanks.