Electric fans

[ComicArtist]

I installed two 10" electric fans on my recent turbo build, and she appears to be overheating. My temp gauge doesn't work as of right now, and I'm trying to get that fixed, but after running her a short time, she's really hot. Abnormally so. I replaced the thermostat which helped a little, but it still seems to be hot.

 

I'm running out of the downpipe right now, so the exhaust is coming up my engine bay. That should heat things up a little, but I wouldn't think it would have this drastic of a difference.

 

The only thing I can think of is inefficient cooling from my fans. I didn't think that would happen, as I was told on zcar.com that if anything, they should OVERcool. It doesn't look like that's happening though.

 

Any suggestions?

[RTz]

Any suggestions?

 

Yes... fix your temp. gauge before doing anything else. Guessing is overrated.

[Zmanco]

+1 what Ron said.

 

When does it overheat? If only when in stop/go traffic, then it might be the fans. But if it's on the highway, then it's not them as the airflow from the car moving at speed dominates over any flow from the fans themselves.

 

How are the fans mounted? Is there any shroud? And what type are they? Are they the typical ones sold on ebay, MSA etc? If so, then it's likely they don't have enough air flow for low speed driving. I started with 2 10"s when I was NA and they were on almost all the time in stop/go traffic. I run with 2 12" and turbo without a shroud and they're adequate, but not much more than that, on hot days (90+).

Edited May 6, 2010 by Zmanco

[FubarI33t]

Temp gauge is a must thing to fix. I don't run elec fans, but i have been running the stock fan without any shrouds, and i have no problems

[MikeBZ]

Also make sure the fans are setup up correctly, I once had a fan on the engine side of the radiator thinking it came setup as a "puller". When in fact it was setup as a pusher. The fan was fighting the natural air flow when the car was moving,..

[m1ghtymaxXx]

Hmm, I was about to install a 14" electric fan and build an aluminum shroud, in order to gain clearance for I/C pipes (free up a little bit of power). Do you guys think that would be adequate for a turbo L?

[Mylesofsmyles]

Wondering what most are doing to trigger their electric fans. If going from a clutch type fan to an electric, you'd need some fan switch...are most using an aftermarket kit? If so, what do you set them to turn on at?

[hoov100]

General rule of thumb is to have it controlled by a switch on the dash, or if you are running an aftermarket EMS, most can control electric fans now days. I don't trust those little black fan controller boxes, I went through 7 of them over a 3 month period and will never go back.

[Mylesofsmyles]

General rule of thumb is to have it controlled by a switch on the dash, or if you are running an aftermarket EMS, most can control electric fans now days. I don't trust those little black fan controller boxes, I went through 7 of them over a 3 month period and will never go back.

 

 

for what it's worth, i swapped in an electric fan to my Volvo 240. Grabbed a fan and relay from a Volvo 850, trimmed the shroud to fit the radiator, one lead went to the battery, another to ground and one lead to my fan switch, which fits right into the radiator...setup from Volvo 740...when the coolant gets to a certain temp, I believe 87* celcius, it kicks the fan on and shuts it off when it gets below X*. It works flawlessly and got me to Colorado and home without the slightest problem. For the Z car, I have an in-line fan switch housing from a Saab, which is to be mounted in line with the lower radiator hose...just interested on what temp fan switch to get.

[Tony D]

Two 10" Hayden fans on a three core radiator without shroud was more than enough to maintain my 350HP Turbo 240Z.

 

The largest issue I saw was running a 160 F thermostat, and having the cut-in temperature set properly. If you wait for the switches to turn on at the preset 180 or 185 F, you are too late, and the spot boiling will happen after long highway runs when you pull off into traffic on surface streets.

 

My car runs at X degrees at 30 mph in 5th gear, my fan is set to turn on at X+10F.

 

Using this setting scenario, and a 160F thermostat, I have never had an issue with the engine overheating with a three core radiator. The fans will not run if I'm going 30mph or faster. It's as predictable as the sun rising and setting.

 

I described this to KTM, and he reset his switches accordingly, and his 'overheating in traffic' stopped. Remember whatever temperature you show at the outlet neck of the thermostat---it will be 20F higher at the back of the head. Once a small steam pocket forms from no / stagnant flow at the back of the head due to low NPSH on the pump, youre through!

 

If you want, put a 24# cap on the radiator to see if it helps, but generally a set 180F switch is FAR too high a temperature to work reliably in SoCal desert temperatures when coming off the freeway into stop and go surface streets. This is well documented in the archives.

[z-ya]

I run a single 12" fan on both my turbo Z and NA track car. Both cars use a standard 192F thermostat. The ECUs control the fans, and are set to come on at 198F with a hystersis of 5F. So when the temp drops to 195F, the fan will shut off. Both will idle all day in 93F temperatures without exceeding 198F. The turbo car is using a stock 280Z radiator, and the track car is using a 4 core 240Z radiator.

 

Running a 160F thermostat is really not a good idea. First of all, these engines were designed to run in the ~190F range. Second, if you cooling system does not have the capacity to maintain a 160F or less operating temperature, then the thermostat will never close. Having the thermostat close actually makes your cooling system perform better because on average the coolant stays in the radiator longer. I've run L6s with 160F thermostats, and they never actually ran at 160F. They were always running hotter.

 

Ran the track car in the autocross and lapping events in Nashville at the convention last week. Zero overheating problems in 95F+ heat.