Dan called a week or so ago and the part of the conversation was about the stock cruiser fan and the SC fan. It made me curious about how much air the fans actually put out etc. I thought I would throw together a little experiment to test the output. Well, it turned out to be quite a project that degenerated into a test of wills and a week of work later I have something to do some rough calculations.
I loaded a piece of ¾” plate on to a little trailer I built as a base for the electric motor and fan. I got the pulleys from an old drill press and then had to machine up adapters for them and the fan. Looking around I spied one of the spare tire spindles I had purchased from Slee Off Road. I had to do a little modding as the spindles were never intended to spin at any RPM’s. Bet you never thought your spare tire spindle would do 1725 RPM’s eh Christo? Next, I built a wood frame work that has the same size opening as the (97) cruiser front. It was made so I can move it back and forth over the fan to check for different airflow at different fan depths and centering. I used the stock shroud with foam weather strip insulation to seal it.
This post is premature because I won’t have a laser tach till Tuesday or Wednesday to check what RPM’s the measurements are taken at. I thought I would post it now to see if anyone has any suggestions or things they would like tried before I rip it apart or the rain gets to the particle board.
In the one pic there is a round tube I am building to confine the air somewhat for sort of direct test as opposed to the air blowing freely.
I did a quick run with the stock fan and the SC fan; both installed on a new blue fan clutch. I do have my old fan clutch and may try it.
Random thoughts and observations: The stock opening on a 97 has the hood latch support sticking down and I don’t know how that affects the opening size. Same at the bottom. For the test, there is no rad, cooler, or AC stuff to affect the flow. There is very little airflow near the center of either fan. The max airflow seemed to be about 4 inches in from the outside of the blades. The airflow is erratic, not steady. The Spal electric fans seem to direct the airflow toward the center. When I tested the electric 16” fan in the tube the highest air speed was in the upper right, lower right, and center. The tube is approx. 19 ½ inches in dia. and 3 feet long. I took 9 readings around the tube, averaged them, converted them to CFM, and came up with 2393 CFM for the electric. The manufactures rating is 2070 CFM for this fan. Truck was running with jumper cables to electric fans.
The dog came over and whizzed on my tig rod tube holding up the fan for the test. Pretty hazardous work this testing business. Guess I should be glad a cow did not come over.
The blue fan clutch would wind up and throw max. air about 10 seconds after turning the motor on. Then it would drop back and put out about half the amount of air. I went all over the fan clutch with the IR thermometer and the temps ran from 81.8 to 88.3F. Not exactly what I would call getting hot. I let the fans run for about 10 minutes and the fan never kicked back up. Without the tach, I will assume this was at about 1725 RPM’s, as I was running off 1 to 1 pulleys with a 1725 electric motor. FWIW, when I start the motor up and the fan clutch seems to kick back in, the whole setup shakes a good bit as I never balanced anything. It’s a little shaky having my hands (and face) 7” from the blades while this is happening. I did notice my wife thumbing through the life insurance policy. Hmmm. If I run the motor at 50 percent on the variac the fan clutch still seems to engage, but in a much longer time and more gradually. Really need the tach for anything meaningful and I also think I need to run all the fans through the tube. I don’t want to cut the aluminum yet before I run any final tests with the electric fans.
Instruments: Kestrel 4000 to measure airflow in FTM (feet per minute). Variac. IR temp gun.
Pics are Front, Back with tools, and side.
Bill
I loaded a piece of ¾” plate on to a little trailer I built as a base for the electric motor and fan. I got the pulleys from an old drill press and then had to machine up adapters for them and the fan. Looking around I spied one of the spare tire spindles I had purchased from Slee Off Road. I had to do a little modding as the spindles were never intended to spin at any RPM’s. Bet you never thought your spare tire spindle would do 1725 RPM’s eh Christo? Next, I built a wood frame work that has the same size opening as the (97) cruiser front. It was made so I can move it back and forth over the fan to check for different airflow at different fan depths and centering. I used the stock shroud with foam weather strip insulation to seal it.
This post is premature because I won’t have a laser tach till Tuesday or Wednesday to check what RPM’s the measurements are taken at. I thought I would post it now to see if anyone has any suggestions or things they would like tried before I rip it apart or the rain gets to the particle board.
In the one pic there is a round tube I am building to confine the air somewhat for sort of direct test as opposed to the air blowing freely.
I did a quick run with the stock fan and the SC fan; both installed on a new blue fan clutch. I do have my old fan clutch and may try it.
Random thoughts and observations: The stock opening on a 97 has the hood latch support sticking down and I don’t know how that affects the opening size. Same at the bottom. For the test, there is no rad, cooler, or AC stuff to affect the flow. There is very little airflow near the center of either fan. The max airflow seemed to be about 4 inches in from the outside of the blades. The airflow is erratic, not steady. The Spal electric fans seem to direct the airflow toward the center. When I tested the electric 16” fan in the tube the highest air speed was in the upper right, lower right, and center. The tube is approx. 19 ½ inches in dia. and 3 feet long. I took 9 readings around the tube, averaged them, converted them to CFM, and came up with 2393 CFM for the electric. The manufactures rating is 2070 CFM for this fan. Truck was running with jumper cables to electric fans.
The dog came over and whizzed on my tig rod tube holding up the fan for the test. Pretty hazardous work this testing business. Guess I should be glad a cow did not come over.
The blue fan clutch would wind up and throw max. air about 10 seconds after turning the motor on. Then it would drop back and put out about half the amount of air. I went all over the fan clutch with the IR thermometer and the temps ran from 81.8 to 88.3F. Not exactly what I would call getting hot. I let the fans run for about 10 minutes and the fan never kicked back up. Without the tach, I will assume this was at about 1725 RPM’s, as I was running off 1 to 1 pulleys with a 1725 electric motor. FWIW, when I start the motor up and the fan clutch seems to kick back in, the whole setup shakes a good bit as I never balanced anything. It’s a little shaky having my hands (and face) 7” from the blades while this is happening. I did notice my wife thumbing through the life insurance policy. Hmmm. If I run the motor at 50 percent on the variac the fan clutch still seems to engage, but in a much longer time and more gradually. Really need the tach for anything meaningful and I also think I need to run all the fans through the tube. I don’t want to cut the aluminum yet before I run any final tests with the electric fans.
Instruments: Kestrel 4000 to measure airflow in FTM (feet per minute). Variac. IR temp gun.
Pics are Front, Back with tools, and side.
Bill
