My D has an electric fan against the radiator that comes on with the AC and the engine has the standard metal fan with clutch. With AC off - the engine fan has to draw air thru the rad and the electric fan to provide cooling. With AC on - the electric fan seems like it would do most of the work, especially at a traffic light or stop and go traffic. So, when I accelerate from a traffic light and the engine is turning say 2200rpm, how much do you think the metal fan helps when the electric fan is on?

 

Depends on the airflow of the electric fan. If it were to be moving 2000 cfm, I would say the mech. fan wasn't doing much of anything. We pull under 1000 cfm at idle, once the trucks hit 2200 rpm, can calculate we'd be just getting over 2000 cfm at that point.

Otherwise, mech fan is doing most of the work, and I'm assuming the elec. fan is mounted to blow air into the a.c. coil to help it perform.

 

front to back:
AC coil then radiator then electric fan then engine fan.
When the e fan is on it is blowing into the engine fan. So, does the engine fan create suction that increases the flow of the e fan?

 

That is a tricky question, and it probably would depend on the e. fan and what it is actually flowing period. It probably is, but it's kind of a fake boost if the goal of the electric fan was to replace the stocker. In your case, seems the e-fan is more for secondary cooling, primarily to increase the airflow over the a.c. coil for better performance there, so it serves it's purpose (assuming the a.c. kicks out cold air at idle)

 

i cant wait for these results

 

Yeah, Alaskan winters are the main reason I want to go to an e-fan. But in march Im leaving AK, and going wherever Uncle Sam tells me. Hopefully back down to KS or TX so Ill need the cooling side of it then! No rush on figuring this out.....Ive still got almost two months in Kumar's Homeland before I can even start thinking about working on my truck!

 

aahhh, cool....well make it home safe man.

Been thinking more about the custom shroud and think I have an idea on how to fab something up for my testing to simulate different custom shroud depths. Since reading up on the basic design principals on the blades used in these fans, I don't think you can space them more then 1-3 inches off the radiator before they'll really start to drop off in performance.

Once I start doing testing I'll really get a good idea on how much boost you can get from custom building a shroud, specifically with the fans I work with. If you get back and decide you want to work with a different fan, and you have time, send it to me and I'll to some testing and let you know what I come up with. Once I get the chamber built, testing individual fans won't take more then an hour.

I discussed earlier having things delayed on this because of my interest in a home purchase for income property. It's in the state of foreclosure/short sale, which is why I really haven't known for sure what's going on. Decided with the wife today to pull out and wait for the price to drop another 20k before we put another bid in. So unless the bank decides to jump at that offer this week, believe the income property won't be an issue for a month or two. If that's the case, I'm going to build the chamber next weekend, and get started on testing fans shortly after that.

 

Hi I have a 1995 ram 1500 with a 318 auto trans. I have a trans cooler and a oil cooler between the rad and the a.c. coil. I just went out and got a fan from a 1994 Lincoln towncar I dont know haw many cfm I pulls. I was thinking about putting that fan and a fan from a chevrolet cavalier behind the rad and another chevrolet cavalier fan for a pusher fan in front of the a.c. coil. Do you think that would have Enough air.

 

Warning: While I am very familiar with airflow/fan testing, and amp/voltage readings, I am not an expert with alternators/charging systems. If anyone sees any problems in this, yell. Everything I did today was based off research over the weekend, basically off the internet, so obviously it could be flawed.

This seems to be the simplest test I could find to determine alternator operation related to the fan install, or "Can the charging system take it".

Seen it mentioned on here that we have 90 amp alternators. Looking in the 2001 manual I pulled off this site, it rates the alternators as a 117 or 136 sae amps. SAE is an amp reading taken at 80 degrees F, so after the alternator has been running for a few minutes, it's passes that temperature and can't get that rating. Also, in the 2001 owners manual, seen input/test ratings ranging from 90-120 amps for the same alternators, which I assume is what the 'peak' warm operation of the alternators are. This is probably only in a 'new' state, as the alternator will lose it's capability as it ages. An alternator can't run continuously at that rating or you'll kill it quickly.

While I tried taking amp draw ratings for accessories, found a more practical and repeatable test using a voltage meter to be simpler. Keep in mind, an alternator is only capable of doing a percentage of it's charging at idle, so any testing should be done at both idle and 2000 RPM.

The basic premise of the test is this. Hook up a multi tester to the battery leads and take a reading with the truck off. Should be somewhere around 12 volts. Now start the truck, you should see a minimum of a 1 volt jump to show the alternator is working. At idle, start turning on accessories and keep an eye on the voltage. If it holds above 12.8 volts for every accessory, your alternator can handle that amperage load at idle. When you turn on the accessories, do it one at a time, and give the system a minute or two with the voltage test. The battery will take the initial hit of amp draw and won't show a drop in voltage immediately. Repeat the test at 2000 rpm. This tells you what the capabilites of the alternator are at idle and at 'max'. I was able to hook up the leads on the battery and set the tester on the cowl so I could read the readings from the cab, with some craning of the neck. Here's what I got off my truck.

VOLTS/IDLE/2k RPM
Truck off: 12.6/-
Truck on no acc. 14.1/14.3
Truck on-ac/heat on hi 13.9/14.2
Truck on-w.wiper-hi 13.9/14.1
Truck on-headlight hi 13.8/14.1
Truck on-aftermarket stereo 12.5/13.9

Each accessory was turned on in the order of the list, and then left on. By the time I got to my stereo system, it was with everything else on. Obviously, I have an issue with my charging system at lower rpms when my stereo is on and everything else is cranked. I have never seen this before with my driving habits because I rarely drive at night.

For those with aftermarket systems/amps. Do this test with the stereo at the max volume level you will be using. I tested mine at about 65% max volume, but to date I've never turned it up over 50. Turned it up a hair more just in case. Also, how and what you listen too have a huge impact on amp draw. (I have a 5 channel amp, 350 rms@2ohm sub) When I listen to rock/pop/etc, at half volume, my amp was only pulling about 7 amps, and wasn't an issue. Once I got the sub to start hitting, that's when the amps really jumped up. Typically hitting 20. Given that was my worst case scenario, that's where I did all my testing.

What I got from this is the following. Either I have an alternator that is getting to the end of its life cycle, or I need a bigger amp. I'll have it tested at some point, but will wait to replace until I see what type of amp draws the fan will have.

For those without the stereo system, I would believe any electric fan set up with a lower amp draw would not be a problem with our trucks. I expect to have a problem with my set up either way because of the combined issues of aftermarket stereo system, but more importantly, 95% city driving, and a motor that stays around 1200 rpm.

 

Before I answer that let me do some testing on a used fan. My gut feeling is if the Lincoln was a v-8, you should be ok, but I want to measure one first. If the Lincoln was good enough, I wouldn't screw around with the cavalier fans.