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We tested with one fan. Actually between Jim and I we tested about 8 different configurations (maybe more.. lost count). The problem with 1 fan and no shroud is that sitting in traffic or at low speeds the fan simply isn't cooling enough fin surface area of the radiator. This would not be a problem if the NSX had a radiator configuration which the end tanks on the sides (instead of on the top and bottom). We actually thought of doing this but the mounting and coolant tube layout made it a pain in the ass for the gain. If it's at the top and bottom, placing one fan leaves too many tubes whereby the coolant tubes that does not cross the path of the fan simply doesn't get cooled at all and recirculates back into the system hot. The best one fan configuration i've tried is mounting a Spal fan using the OEM shroud (which still leaves some fins exposed to free air on the sides). Ideally, I'd like to build a shroud with lightweight flaps. This way when the fan is on the flaps close thru vacuum but when the air flow is high (as in high speed driving) the flaps open and let the hot air escape. Obviously, this takes a lot more testing but both Nick (@ Applied) seems to like this idea. I haven't gone down this path because it seems the OEM fan configuration seems to work well in my car. We'll have to see how it works when it's ridiculous hot out. I'm almost tempted just to put two fans in there and call it day and go tracking! However, I was hoping to keep the ABS, even if upgraded to a 00+ newer unit whereby you have to use a slim fan on the driver's side because the ABS unit leaves little room for a full size paddle or turbine style fan due to the ABS unit and the "cage" around it.

<blockquote data-quote="RYU" data-source="post: 1747431" data-attributes="member: 20915"><p>We tested with one fan.&nbsp; Actually between Jim and I we tested about 8 different configurations (maybe more.. lost count). The problem with 1 fan and no shroud is that sitting in traffic or at low speeds the fan simply isn&#039;t cooling enough fin surface area of the radiator.&nbsp; This would not be a problem if the NSX had a radiator configuration which the end tanks on the sides (instead of on the top and bottom).&nbsp; We actually thought of doing this but the mounting and coolant tube layout made it a pain in the ass for the gain.&nbsp; If it&#039;s at the top and bottom, placing one fan leaves too many tubes whereby the coolant tubes that does not cross the path of the fan simply doesn&#039;t get cooled at all and recirculates back into the system hot.&nbsp; The best one fan configuration i&#039;ve tried is mounting a Spal fan using the OEM shroud (which still leaves some fins exposed to free air on the sides).&nbsp; Ideally, I&#039;d like to build a shroud with lightweight flaps.&nbsp; This way when the fan is on the flaps close thru vacuum but when the air flow is high (as in high speed driving) the flaps open and let the hot air escape.&nbsp; Obviously, this takes a lot more testing but both Nick (@ Applied) seems to like this idea.&nbsp; I haven&#039;t gone down this path because it seems the OEM fan configuration seems to work well in my car.&nbsp; We&#039;ll have to see how it works when it&#039;s ridiculous hot out.&nbsp; I&#039;m almost tempted just to put two fans in there and call it day and go tracking!&nbsp; However, I was hoping to keep the ABS, even if upgraded to a 00+ newer unit whereby you have to use a slim fan on the driver&#039;s side because the ABS unit leaves little room for a full size paddle or turbine style fan due to the ABS unit and the &quot;cage&quot; around it.</p></blockquote><p></p>

[QUOTE="RYU, post: 1747431, member: 20915"] We tested with one fan. Actually between Jim and I we tested about 8 different configurations (maybe more.. lost count). The problem with 1 fan and no shroud is that sitting in traffic or at low speeds the fan simply isn't cooling enough fin surface area of the radiator. This would not be a problem if the NSX had a radiator configuration which the end tanks on the sides (instead of on the top and bottom). We actually thought of doing this but the mounting and coolant tube layout made it a pain in the ass for the gain. If it's at the top and bottom, placing one fan leaves too many tubes whereby the coolant tubes that does not cross the path of the fan simply doesn't get cooled at all and recirculates back into the system hot. The best one fan configuration i've tried is mounting a Spal fan using the OEM shroud (which still leaves some fins exposed to free air on the sides). Ideally, I'd like to build a shroud with lightweight flaps. This way when the fan is on the flaps close thru vacuum but when the air flow is high (as in high speed driving) the flaps open and let the hot air escape. Obviously, this takes a lot more testing but both Nick (@ Applied) seems to like this idea. I haven't gone down this path because it seems the OEM fan configuration seems to work well in my car. We'll have to see how it works when it's ridiculous hot out. I'm almost tempted just to put two fans in there and call it day and go tracking! However, I was hoping to keep the ABS, even if upgraded to a 00+ newer unit whereby you have to use a slim fan on the driver's side because the ABS unit leaves little room for a full size paddle or turbine style fan due to the ABS unit and the "cage" around it. [/QUOTE]

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