Keeping with the "originality" goal, I wanted to run the stock radiator. Well, stock tanks, anyway, as this radiator has a three-row core. It should be enough to keep a non-turbo SR cool, especially as the all-aluminum construction of the SR will radiate more heat than the iron KA. I installed a Griffin all-aluminum radiator in my KA510 and during some months of the year, even in SoCal, it overcooled the engine and left me with 150° coolant on the freeway and next to no heating action. I don't want to undercool the SR, especially as it is all aluminum and a bad overheat may well warp the entire engine, so I came up with the following cooling accessories.
The stock 510 fan shroud isn't made to mount a fan, and the opening was much larger than necessary. It must be oblong because at its widest it was over 14", yet the core of the radiator isn't more than 11" tall. In searching for electric fans, I came across the Perma-Cool HP line. These fans drew more CFM than their lesser brothers (Perma-Cool has a few different lines of fans) with only a small additional cost. I purchased the 10" fan, P/N 19010 which is 13" x 10.5" x 2.5", and pulls 1250 CFM at 6.8 amps. I looked at the 12" fan, but at 3.75" depth, I didn't have room to mount it between the radiator and the engine. It would have pulled an even more useful 1650 CFM. I could have fit this fan if I used a thinner VW-esque radiator.
In any case, as the fan arrived via Summit Racing last night, I set about making a fan shround and mount in one. The fan came with the through-radiator cable ties, but the fan's effectiveness would be largely diminished without a shroud. Some 20ga sheet metal later:
The shroud looks a little restrictive and it remains to be seen if it is. If it is I plan to cut large holes along the sides and bolt on rubber flaps, as is common on VW stuff. This allows enhanced flow through the shroud when the car is moving (moving air will push the flaps open) yet will still provide a mostly-sealed area for the fan to draw through when the car is stopped in traffic and the fan's on.
The assembly mounts nicely to the stock radiator:
I purchased a Painless fan wiring kit, mostly because it came with a GM metric temp sender. This sender screws right in to the sensor bung in the SR, so I don't have to splice in an adapter to the main coolant hoses.