Thanks for the input. Are you saying that the stock radiator & fan setup works better than the FFDynamics setup? Just want to make sure I don't spend extra money to get a less efficient system.
The FFD website doesn't show how the controller works, but do you think that 3 relays wired directly to the battery, each with their own fuse (10A?) wired to the control module would give the fans all the power they want?
I will have to put a call into FFDynamics tomorrow and see what they have to say about the relay situation.
Dave, how long did it take to heat soak the radiator and what were you doing?
~Alex
To answer this and echo some of what Goatman and Jeeper John already said:
I think the FF Dynamics is a better radiator than the stock unit by far. I like the quality, and the support I received from their folks. The fans look to be robust, and the thinnest of any I've researched, and the shrouds are nicely made. The one weak link was the fan controller. I wasn't crazy about the "jam in the fins" temp probe, though I had no issues with it rattling out.
A lot of things conspired against me. Heavy vehicle, small amount of combustion gases (though overheating persisted after head work), originally bad alternator, Death Valley in the summer (not only temp, but low humidity reduces air's cooling capability).
Changing out the fans to the stock '97+ fan, factory shroud, ZJ fan clutch and factory electric aux fan made the Heep drivable in the summer. It still didn't run as cool as I'd like under load. It would get to 240 under load, whereas before we crack 260. However, I now get mistaken for a 767 on takeoff. Since this isn't a daily driver, it's not a big deal, but I do miss the extreme quietness of the FF Dynamics fans.
As far as heat soaking, in the summer, at idle, I could idle for hours and never go past 200 degrees. But, a 5 mile run from 2000 foot elevation to 4000 foot, 25 mph, twisty paved road (PSR to Father Crowley) would take it to 250 degrees. So, the heat soaking didn't take long.
At the risk of boring you, here were some measurements I took with the fans and radiator:
State of Vehicle / Action Taken IR Temp @ Therm IR Temp @ Rad inlet IR Temp @ Rad Outlet IR Temp betw pass & center fan IR Temp betw center & drvr fan Indicated Water Temp Ambient air temp inside Jeep
Baseline warmed up - at rest - no changes 192 186 142 180 170 195 105
Add shrouds, replace alternator - warmed up - at rest 190 180 123 can't reach any more can't reach any more 195 107
Add shrouds, replace alternator - mid way up Pleasant Canyon 238 230 198 can't reach any more can't reach any more 240 110
Flush system, straight water - warmed up - at rest 194 182 135 can't reach any more can't reach any more 195 105 Got up to 230 from Panamint Rd. to PSR
Sorry for the formatting, but the point to see, and reinforce Jeeper John's observation, is that the radiator was dropping the temperatures significantly more when the fan shrouds were installed. Also notice that once I exceeded the temp of the thermostat (195), the temp difference across the radiator was reduced.
Goatman is right - there really is no aftermarket fan setup that will cool better than the factory. Like I mentioned, I think the FF Dynamics radiator itself is better than stock, and if they had a 2000 CFM each fan instead of 1100 CFM, I'd probably still have them in the Jeep. And their prices are very competitive with some of the other options out there.
In summary, I believe that for my application, in my environment, with my rig, the FF Dynamics fans simply didn't pull enough CFM to cool the engine. You simply can't replace a 5200 CFM combo (factory mechanical plus electric) fan with 3300 CFM in the harsh conditions of the desert and expect it to cool the same.
However, I see you live in CT. When I had the Heep in upstate NY, albeit in April, the radiator was so efficient, the fans never came on, not even if idling for an hour, and not under any condition running down the road. So, it is quite likely, given the extra humidity in the summer in CT, that you would have no problem with the setup.
Hope this helps some.
David Bricker / SYR
