Doug Works On The Cooling System
My priority with using a rear mounted radiator was to provide the coolest air and maximum air flow to the radiator. To reduce air flow restrictions and not add heat into the air flow, the AC condenser was mounted on the rear end with is own fans. The attached picture is of the first generation with a single fan. It was upgraded with a larger condenser and dual fans which are controlled by the exit temperature side of the condenser.
I have a total of eight fans, two for the radiator, two for the engine compartment, two for the AC condenser, one for the AC/heater and one to boost airflow when the AC is used.
I have a total of eight fans, two for the radiator, two for the engine compartment, two for the AC condenser, one for the AC/heater and one to boost airflow when the AC is used.
Some of my findings from my installations:
1) No natural air flow for radiator.
2) All air flow must be supplied by high quality, high power radiator fan(s).
3) Need for a high current 100+ amp alternator (radiator fans can require 50+ amps).
In my quest to say “no” to the question - "Do you have any engine heating problems?" I believe this will be my ultimate rear radiator solution, overkill, OK, but first some history.
My first radiator was a 2 row, 1 inch tube unit measuring 27”x 19” (core size). This worked in town with no problems but did limit continuous* highway speeds to 50 when ambient temperatures were above 75. The next upgrade was increasing the radiator size and air flow. The new radiator size was a 2 row, 1-1/4 inch tube unit measuring 31”x 19” (core size) and increasing the radiator air flow CFM, one pusher fan from a Taurus and one puller fan from a Thunderbird. This worked well on the highway until ambient temperatures went 85+ limiting continuous* speeds to 60 MPH. Coming back from the 2013 Palm Springs Fan Belt Toss at temperatures under 75 on the Nevada roads cruising at 85+++MPH was no problem. Tests later proved that the maximum CFM would have been better with just the puller fan, about 10%. The fans I chose were not of the same CFM which was a mistake on my part. Having two fans of the same CFM may have made a difference in the air CFM.
Now for “my” ultimate solution, a diesel radiator from a Ford, 3 row 1 inch tubes measuring 33-3/4” x 29-3/4” (core size) and a pair of Derale high output fans rated at 4000 CFM. These fans are rated at 100% duty cycle with a life expectancy of 10,000 hours. I took 5 different location CFM measurements over the top of the radiator, averaged the readings for a calculated flow of 3994 CFM. To reduce the overall width of the new radiator I removed the side mounts so it would fit between the frame rails and relocated the water return. The AC condenser is mounted right behind the transaxle assembly with it’s own pair of fans limiting the angle for mounting the radiator. All air is pulled from the grill which limits the air flow to about 65% of maximum. To increase the air flow I raise the front of the deck lid about 1-1/2” reducing the restriction to about 90% of max. Further reducing inlet air flow restriction may be one of my future challenges, large “Yenko” style panels that open automatically as needed? To reduce continuous fan power requirements, I designed a 4 stage fan speed controller. Fan speed can be adjusted at 4 different set point temperatures. This reduces alternator load until full fan speed is required. Final testing will be this summer in ambient temperatures of 100+ to see if I can finally say “no”, I have no engine temperature issues.
* 20 minutes or more
1) No natural air flow for radiator.
2) All air flow must be supplied by high quality, high power radiator fan(s).
3) Need for a high current 100+ amp alternator (radiator fans can require 50+ amps).
In my quest to say “no” to the question - "Do you have any engine heating problems?" I believe this will be my ultimate rear radiator solution, overkill, OK, but first some history.
My first radiator was a 2 row, 1 inch tube unit measuring 27”x 19” (core size). This worked in town with no problems but did limit continuous* highway speeds to 50 when ambient temperatures were above 75. The next upgrade was increasing the radiator size and air flow. The new radiator size was a 2 row, 1-1/4 inch tube unit measuring 31”x 19” (core size) and increasing the radiator air flow CFM, one pusher fan from a Taurus and one puller fan from a Thunderbird. This worked well on the highway until ambient temperatures went 85+ limiting continuous* speeds to 60 MPH. Coming back from the 2013 Palm Springs Fan Belt Toss at temperatures under 75 on the Nevada roads cruising at 85+++MPH was no problem. Tests later proved that the maximum CFM would have been better with just the puller fan, about 10%. The fans I chose were not of the same CFM which was a mistake on my part. Having two fans of the same CFM may have made a difference in the air CFM.
Now for “my” ultimate solution, a diesel radiator from a Ford, 3 row 1 inch tubes measuring 33-3/4” x 29-3/4” (core size) and a pair of Derale high output fans rated at 4000 CFM. These fans are rated at 100% duty cycle with a life expectancy of 10,000 hours. I took 5 different location CFM measurements over the top of the radiator, averaged the readings for a calculated flow of 3994 CFM. To reduce the overall width of the new radiator I removed the side mounts so it would fit between the frame rails and relocated the water return. The AC condenser is mounted right behind the transaxle assembly with it’s own pair of fans limiting the angle for mounting the radiator. All air is pulled from the grill which limits the air flow to about 65% of maximum. To increase the air flow I raise the front of the deck lid about 1-1/2” reducing the restriction to about 90% of max. Further reducing inlet air flow restriction may be one of my future challenges, large “Yenko” style panels that open automatically as needed? To reduce continuous fan power requirements, I designed a 4 stage fan speed controller. Fan speed can be adjusted at 4 different set point temperatures. This reduces alternator load until full fan speed is required. Final testing will be this summer in ambient temperatures of 100+ to see if I can finally say “no”, I have no engine temperature issues.
* 20 minutes or more
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Air flow for the engine compartment comes from under the car (bottom) around the gap between the engine and floor panel. An air dam was installed on the subframe to assist in moving air into the engine area. The two engine compartment fans are temperature controlled. If the temperature in the compartment rises to 135 degree the fans are turned on low speed exiting the air rearward . If the temperature continues to increase to 165 degree the fans are turned on high speed. The fans can also be turned on manually if desired (great when working on a running engine). I have indicator on the control panel that indicate if the fans are running and I have never seen the indicator indicate the fans are running while I was driving (moving).
The radiator fans are also controlled by temperature and can draw 50 amps on high speed. High speed is not needed driving on the freeway (70+) in 95+ degree weather. |
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