[Firebob]

I just installed a new elect fan and now I notice that when the temp hits 192 I notice a little bit of detonation when I take off after stopping. It's a 4sp car. I never noticed it doing this before. I'm not sure what changed. I may have to back down the timing just a bit at around 1200-1500rpms( about the niche where I let the clutch out). I have not tried at any temps higher. It may be the point where the temps transition between the low and high speed fan operation. I'm wondering it the first xtra elect draw from the high sp fan would have some sort of effect on detonation.
Any suggestions?

[shaker455]

Hi Robert ,
Today's gas boils @ 190 F
I am not a fan of any electric fan and some of the shrouds they come with.

I have found best results with a Summit mech flex fan & Champion alum 4-core rad

https://www.summitracing.com/parts/sum-g4917

Also 160 thermostat & proper clearance on divider plate.

I've had many PY forum members & local classic cars here and most need heat to be addressed
Jeff

[Formulajones]

Agree with Shaker.
From my experience, if it's an engine that is somewhat marginally fine on pump gas, it's likely going to be temperature sensitive. High ambient temps outside combined with an engine running 190+ degrees is probably going to be fussy.

[Squidward]

You have a Sniper, so you should be able to monitor your AFR during these ping conditions. Watch or datalog your target afr and readback afr, and see if it is going lean. Maybe try adjusting your afr target down by .1 in steps, and see if going a tiny bit richer helps. See if you are going lean on acceleration.

If your ignition curve hasn't changed, then I would look at fuel. Too much advance or timing coming in too early can cause ping. Lean conditions can also cause pings.

[steve25]

If I am reading you right with what you posted then I would have to say that your swap from a belt drivin fan to a electric, and the electric is moving less air at idle.

[Cliff R]

I probably have the perfect engine combination to use an electric fan w/o a belt driven one and tried that deal a couple of years ago. My engine runs as cool as any I've ever seen, takes nearly FOREVER to get up to 180 degrees (I don't use or recommend 160 degree stat's as they hurt thermal efficiency and the oil doesn't get hot enough in some applications which results in "froth" under the valve covers from excessive moisture in the oil, etc). Anyhow, to each his own on that deal but my engine just doesn't put much heat into the coolant so I figured I'd save some power by not running a belt driven clutch fan.

The install went perfectly and it worked just like one is supposed to. The temp probe cycled the fan and it never ran hot, or overheated, etc. During the very hottest months of the year at the track I even used the electric fan to pull some heat out of the engine and cool it down on test & tune nights so I could makes runs closer together, etc.

Anyhow, I ended up removing the electric fan and going back to a HD clutch fan, which was and still is flawless for cooling my engine. The problem I was having is that using an electric fan pulled the battery down too much and the alternator was working it's butt off to keep it fully charged up. I have a high output alternator and the heavy load placed on it was spinning the belt around on the pulleys on drag strip runs. This had never happened one single time until I went with that system. It was also throwing off ET/MPH some even when it didn't "toss" or flip the belt as the battery charge condition was rarely the same run to run so varying alternator load effected the results.

I ran that set-up for a while then ended up going back to a belt driven fan and all those problems went away. Just providing another way of looking at this conversion that can cause issues..........Cliff

[Half-Inch Stud]

CLIFF's 1st para nails my experiences. 180 stat, elec fan, no mech fan, takes long while to warm up. and i'm 3/4 second slower and 7 mph slower.

Difference; My GM elec fan (is pulling air) is rarely on & when on it doesn't tax the 63 Amp alt.

[ponjohn]

All current draw issues can be resolved with a PWM fan controller. Several solutions on the market. This improves efficiency and thermostatic control of the fan.

The fact that the fan was using more current than available simply states you need a larger alternator OR the fan was not large enough and ran continuous.

I ran one Lincoln Mark 8 fan with a fan controller - worked way better than the belt driven fan.

[Firebob]

Well I changed out the alt to a power master 140a unit awhile back so I'm assuming the alt is big enough but maybe it's the extra draw on the alt that is making the difference. The setup is running on the edge as far as CR and pump gas but this seemed to be a new thing. I don't think I had the issue with the flex fan that was on before. I'll try adjusting the AFR to richened things up at the point of ping and see if I can tune it out.

[LeoP]

Are you running ported vacuum to the dist or full manifold vacuum?

[lust4speed]

Might be something simple like winning the lottery on bad gas. While it's hard to visualize, it is still possible to fill up with even worse gas than what we are normally subjected to. Before getting too far into fixes, maybe drain out the current tank and use it for your lawn mower/daily driver and fill up from another station. THEN if the pinging is still there, take appropriate action.

[ponjohn]

Is it possible you just didn't hear it over the belt driven fan?

[HWYSTR455]

Yeah, wiring needs to be up to snuff if you plan on using an electric fan, and it's best to use a PWM controller. The on/off hits on an alt when using a high output fan, like a 50a dual fan, can cook an internal regulator in short order. Oddly, a car stereo capacitor can help that.

Newer EFI ECUs can control OE PWM controllers, like the '06-up Vette one, or the Ford Fusion one. If they go bad, auto parts store and done.

With a good, programmable PWM controller, the fan 'ramps' up as temp increases, and is managed by '%' values. You do have to run a variable speed type fan though, so have to be careful the fan you choose.

If the fan kicks on, and your wiring is not up to par, it's possible your ignition might not get enough voltage, and can screw with timing. That would be more common to happen at idle, like at a light.

One thing I would suggest is to do the 'Power-Up!' mod by MAD. That would help in a number of situations.

http://www.madelectrical.com/electri...evymain1.shtml

I know I had somewhat of a steep learning curve when I went to electric fan(s), a well as other voltage-robbing mods. But I can say, once I got everything ironed out, I will never go back to a mechanical fan. Especially on an A/C car, or one that does considerable stop & go traffic stuff.


.

[68lemans462]

I just a 7 blade OEM fan with an OEM heavy duty clutch designed for use with AC. I'm NOT a fan of the flex fans, they will cut the crap out of your hands under almost ANY conditions.

[Lee]

Another supporter of PWM control for electric fans. Only uses enough current to keep the temp at your set point. Use PWM for fan AND an electric waterpump, and you don't even need a thermostat,

[ponjohn]

Originally Posted by HWYSTR455

Yeah, wiring needs to be up to snuff if you plan on using an electric fan, and it's best to use a PWM controller. The on/off hits on an alt when using a high output fan, like a 50a dual fan, can cook an internal regulator in short order. Oddly, a car stereo capacitor can help that.

Newer EFI ECUs can control OE PWM controllers, like the '06-up Vette one, or the Ford Fusion one. If they go bad, auto parts store and done.

With a good, programmable PWM controller, the fan 'ramps' up as temp increases, and is managed by '%' values. You do have to run a variable speed type fan though, so have to be careful the fan you choose.

If the fan kicks on, and your wiring is not up to par, it's possible your ignition might not get enough voltage, and can screw with timing. That would be more common to happen at idle, like at a light.

One thing I would suggest is to do the 'Power-Up!' mod by MAD. That would help in a number of situations.

http://www.madelectrical.com/electri...evymain1.shtml

I know I had somewhat of a steep learning curve when I went to electric fan(s), a well as other voltage-robbing mods. But I can say, once I got everything ironed out, I will never go back to a mechanical fan. Especially on an A/C car, or one that does considerable stop & go traffic stuff.


.

I disagree that certain fans are needed.



The fan does not know the difference. The controller pulses the DC creating an average this is why the efficiency is very high. It closes the pulses to increase the speed in a very controlled manner.



The capacitor acts like a DC voltage storage device. So it can aid in starting the fan and not tax the alternator. Not the best solution.

[JSPONT]

Well, did a bunch of research on electric fans. My good friends car always runs real cool. He has a duel speed Ford Taurus fan, same as an older Volvo.
In the Volvo's the have a very nice relay fan controller. BMW has a 2 speen coolant fan switch, low speed kicks on at 180, shuts off 170, high speed kicks at 195.
There are a ton of guys running this set up with no issues. Bunch of street race cars I know use them. I am just about done with mine, plenty of info on you tube on this.
I got the volvo fan and cut the shroud down to fit with the water pump. I have had electric, flex and clutch fan on my car.
The worst was the flex, and had the worst belt squeel.
The clutch worked well, but the explosive power and rpm of my car broke it.
My 1st electric fan worked well but went bad, so I tried the others. I am back to electric.
There are pros and cons to both

[HWYSTR455]

It's been a while since I've looked into it, but can tell you there was or is an issue with PWM controllers and brushed fans. For one, brushed fans require a min voltage to even start spinning, for example like 7-9 volts, and the speed of the fans are not linear to voltage. Sure, they work kind of with varying voltage, but not like with a brushless fan, which are designed to be 'variable speed'.

Most OE and aftermarket fans are brushless these days, so maybe it's less of a problem. But there are still brushed fans out there. Usually, brushless fans are denoted as 'variable speed'.

The capacitor in my car was originally installed due to my stereo, but it does provide similar results to any spike load, like a fan. I used to EAT alts, and it wasn't until someone at a stereo shop schooled me as to why, and since I've added a cap, I no longer eat alts. You can go back and search some of the threads I posted here on the subject if interested.

If a cap is not the 'best' solution, what would a better solution be? I'm interested.

EDIT: There are also fans that operate at different frequencies, and can be outside the frequency of what a PWM controller outputs.

.

[ponjohn]

Originally Posted by HWYSTR455

It's been a while since I've looked into it, but can tell you there was or is an issue with PWM controllers and brushed fans. For one, brushed fans require a min voltage to even start spinning, for example like 7-9 volts, and the speed of the fans are not linear to voltage. Sure, they work kind of with varying voltage, but not like with a brushless fan, which are designed to be 'variable speed'.

Most OE and aftermarket fans are brushless these days, so maybe it's less of a problem. But there are still brushed fans out there. Usually, brushless fans are denoted as 'variable speed'.

The capacitor in my car was originally installed due to my stereo, but it does provide similar results to any spike load, like a fan. I used to EAT alts, and it wasn't until someone at a stereo shop schooled me as to why, and since I've added a cap, I no longer eat alts. You can go back and search some of the threads I posted here on the subject if interested.

If a cap is not the 'best' solution, what would a better solution be? I'm interested.

EDIT: There are also fans that operate at different frequencies, and can be outside the frequency of what a PWM controller outputs.

.

A controller.

[HWYSTR455]

Originally Posted by HWYSTR455

....it's best to use a PWM controller. The on/off hits on an alt when using a high output fan, like a 50a dual fan, can cook an internal regulator in short order. Oddly, a car stereo capacitor can HELP that.

.

That's pretty much what I originally said, a PWM controller is best for controlling fans. My comments were basically just that, a comment, the cap(s) were installed when the amps were hammering the alt. But I see where I wasn't clear, my bad. I originally had relays doing on/off on my fans, guess that's why I mentioned it.

.