The 10 degree fan mod is a very interesting option for more coolant and intercooler loop cooling. I have read complaints about the fan running at high speed and causing much noise though.

10 degree fan mod link

I've done some testing and here is what I know:

I removed the stock thermostat, rated 87 degree C, and stuck it in a pot of hot water.
The thermostat begins to open at 87 C.
The thermostat is full open around approximately 94 C.

I blocked the radiator with cardboard and checked the fan setpoints, monitoring coolant temp via OBDII.
The fan control is variable speed.
The fan starts to rotate at 93 C.
The fan turns off when the coolant drops to 92 C.
At 101 C, the fan gets very loud.

When driving, I've observed coolant temps from 87 C minimum, to low 90s typical, to high 90s on a very hot day.

On a 65 degree F ambient day, I have observed coolant temps of 87-89 C while driving, then the coolant and intake air temps start climbing when I come to a stop until the coolant reaches 93 C and the fan comes on.

At the drag strip, the coolant temp usually sits around 93 C (200 F), which is the fan on setpoint, and may climb a degree or two during the run.

The 10 degree fan mod would have the fan come on at 83 C, 4 degrees before the thermostat opens, and go to loud speed at 91 C, in the middle of the thermostat's operating range. The advantage is that once the car is warmed up, the fan would ALWAYS BE RUNNING. Which means constant airflow for the intercooler heat exchanger. This is great for sitting in the staging lanes waiting to run at the drag strip or sitting at red lights. With the stock settings, the fan will not provide any airflow to the IC HX until the coolant warms up to 93 C.

I think a 5 DEGREE FAN MOD might be a better option. The fan would come on at 88 C, just after the opening of the thermostat. The fan would shut off if the coolant temp gets down to 87 C, which is where the thermostat would close as well. Sitting still, the coolant temperature would be controlled down to 88 C, 5 degrees lower than stock. The thermostat hasn't changed, so temperatures with driving airflow will be unchanged. Cooling for the intercooler heat exchanger while sitting still will be significantly improved, and heat soak at the drag strip will be reduced. The loud speed setpoint for the fan would move to 96 C, which should only be encountered on the hottest of days.

Any thoughts?

 

This is the next area I wanted to work with before it really gets hot here between Sarasota and Ft. Myers. Since I am on the deaf side of hearing the high speed may be something I could tolerate. How are you controlling the temps at which the fan operates? Have you heard of the thermostat having a few holes drilled so coolant passes before the T-stat spring begins to open?
I have noticed the difference when the fan needle(yeah, a lame measurement) stays at 9AM or lower compared to it going past that point. THX

 

I have fan hooked to small toggle switch witch I can control, I turn on when ever I fell like, Intake temps will drop 2c when fan running for 2 mins

 

That fan draws a LOT of amps, I'd be using the "small toggle switch" to drive a honkin big relay.

Just sayin .......

 

I have an appt Thursday at the Mercedes Benz dealer to adjust the fan setpoint. I am going to go with 5 degrees C.

 

i have this option from star diagnostics about a year it helps from overheating water, i have no separate system,engine temp is always on 85

 

I got the 5 degree C fan mod performed at my local Mercedes Benz dealership last week. They charged me for 1 hour of diagnostic time.

It works exactly as I requested. The fan comes on when the coolant gets up to 88 C, and shuts of when the coolant drops to 87 C.

I have only driven in cold temperatures so far. It's too soon to tell how much it is helping intake air temperatures.

 

Damn, I wonder if I can get the MB guys in ATL to do this. I got a "new" car last summer and HATE that it is not done.

Were are you BM?

 

When the fan comes on is like it's in warp speed? Loud?

 

No, when it comes on at 88 C it is very quiet. It still starts at low speed, just 5 degrees earlier. Loud speed should be at 96 C (down from 101). It is not nearly hot enough right now for that to happen.

 

Like I said before I have mine on toggle switch to ground it out, it's like warp speed when it comes on , it drops iat temps by 2'c, plus I can have it running at track with car off. But might do this mod as well to have them both.

 

I actually had the same thing a couple of years ago but removed it because I didn't like the fan running at max speed. The noise was a little obnoxious.

 

I agree I only use it at track or racing, u have ur IC pump running all the time?

 

I think the IC pump runs all the time with the EC tune I have. You know what...I should check that.

 

I also have water mist in front of heatexchanger , I just used the windshield washer hose and out a 3 way valve with on off then ran it through bumber in front of heatexchanger

 

That is pretty cool. Any pics?

 

Morphh, I checked my IC pump: it was not running all the time. After a cold start, revving in neutral would not turn it on. Revving a little in gear while foot braking would sometimes turn it on. Once on, it stayed on. I installed a switch to make the pump run any time the ignition is on. Problem solved. My drag strip cancelled the test n tune tomorrow again because of cold weather. I will have to wait longer to see how well the 5 degree C mod works works.

 

Where u from ? I live in Toronto
I take it u wired it right from pump to fuse box? U run 2 heatexchangers ?

 

I like this. The motor makes much more power when it is on the cold side and living near Fort Myers it gets HOT here to where the fan does not keep up. We get go fast mods and skit some of the obvious. I'll try the 4 small holes in my T-stat and my question is what happens to the computer control of the fan or is it controlled separetly? I don't think I would mind the fan in high speed at all times as then hearing is poor and the car seems so much quicker when it is cooler. maybe 170* would be optimum.

 

Can this be done with the tune as I am thinking I would like a degree of more timing anyways. I would just want the fan on high and come on when the low speed would. Speaking of timing for those who datalog what ism the maximum timing you see? I do run 21psi by the way with 20* timing max. Thanks