Long and Nerdy SC Fan BTDT
As a SC owner with intimate familiarity with the fan blade issue and stock fan modification, I'll put a couple .02 into this thread, and the other link referenced. I had the exact problem the OP mentioned with both the SC ringed fan, and the stock 1FEFZ 8-blader (in both trimmed and untrimmed form). I posted the clearance measures a couple years ago, and came to the same conclusion as Christo, it's the combination of shroud interference (SC vs 80 stocker) and engine>chassis flex that creates the radiator>fan munching. To that end, I explored several options to the stock 80 8-blade fan, including converting to dual electrics. IMO and research, the SC ringed fan is the desired alternative to the stock 80 fan. And I also believe it was (/is) chosen specifically by Toyota for the SC application because the blades are much better at maintaining a fixed-pitch than either the non ringed -65020 (V6 app), or the stock 80 application. (BTW side note: The Fan Blade specification is not mentioned nor required for CARB approval of the SC kit)
First off, the difference between 65010 (ring) and 65020 (non ring) is only the 'ring', the ringed (-65010) will be significantly more efficient fan at moving air. To Dan's comments in the other thread, the tests mentioned are not really relevant to draw the conclusions he did. Putting one's hand in the center of a fan blade is not where the pressure is generated, it's at the tips (ringed or non). Further, a ringed fan (often called a vortex fan ring - specifically for it's anti-vortex design properties) will create less, not more "vortex". A ringed fan will be significantly quieter (almost double actually), since the blade flex and 'eddy' at the tips of a non-ring fan are what creates fan noise. A 'louder' fan doesn't mean it's moving more air, and compared to a ringed fan, the opposite is exactly true.
A ringed fan is also better at preventing 'reverse flow' since the ring eliminates the reverse flow caused by the tips of the fan blades (called 'eddy reverse flow').
To the 'idle overheat' it's quite possible (and my observation/conclusion) that the real cause of SC overheat is the draft resistance at the engine side of the fan. The supercharger and/or dual battery setup causes excessively high draft resistance on the downstream side of the fan blades. Increasing low pressure zones on the downstream side of the fan blades is a better approach to address this problem (read: hood vents). As is increasing the upstream negative pressure before the radiator (aux pusher fan).
To the comment in the linked thread that the airflow 'hit's' the ring and stalls is not true, the design of the Mr. T -65010 ringed fan is a reverse venturi type, which is quite efficient at outflow properties of ring-fan air.
I do believe (and btdt) that the ringed fan will interfere with the lower shroud, especially if the motor/trans mounts are worn. I also know that the non ringed stocker will interfere with the lower shroud, and will flex enough to draw the blades quite far forward (2+inches on a stock 80 fan IIRC). Christo's 1.5in protection ring on the radiator to prevent injestion of the fan blades is good, but the tips of the fan blades will eventually fail, btdt. I see no practical way to use the 8 blade stocker, as it's flex is significant enough that 'major' trimming to the leading blade tips is required. Trimmed to the point that the ringed fan likely moves more air. BTTT with 2 stock 80 fan blades.
My conclusion? Mr. T specs that -65010 fan in the SC kit for good reason, it's the best 17in application fan Toyota makes. I think it's a tight fit on a new 80, and can be an shroud>interference fit on a high mileage 80. The trick is to modify the lower shroud, and/or replace the engine/trans mounts to reduce engine flex, then address the downstream low pressure zones to allow more radiator airflow out of the hood.
HTH and my .02
Scott J
94 FZJ80 Supercharged
16361-065010 equipped
