In lieu of brushes, brushless motors incorporate a speed controller that generates a magnetic field to make the motor spin. (high output) brush fans, the new brushless models have several advantages over traditional brush motor tech. Although ultimate rated peak flow (depending on specific fan diameter) might not quite match SPAL's best conventional High-Performance series, H.O. Used by the OE's for years, brushless fans are just now becoming available in the aftermarket, with SPAL one of the pioneers. Bottom line: don't skimp on the wiring.īrushless fan technology is more efficient than a traditional brush motor in terms of electrical energy required vs. Unless you have a MIL-SPEC-level crimper, I lean towards soldering, not crimping, any 10-gauge or larger (lower gauge number) terminal or splice. Consider relays with a higher than standard amperage rating. If SPAL specs an AWG 10-gauge wire for the power-side of the motor relay, go to an 8-gauge wire. With a high-output alternator, this calls for a 6-gauge (or even larger) main charge wire for the battery, alternator, and main power distribution hub. Living in Tucson, you might need larger than standard electrical wires to compensate for heat buildup. Electrical resistance also increases along with heat, but most wire size assumptions are based on so-called "normal" outside air temperatures. The longer the wire run from the battery and alternator, the higher the "natural" resistance (and therefore the greater the voltage drop). If electrical output is fine at the alternator, there are no red flags at any of the splices and grounds downstream from the alternator to the fan motors, and yet there's still not enough juice at the motor, increase the wire size. Overdriven alternator pulleys are available as a last resort. Keep the crank-to-water-pump drive-ratio at least at the stock 1:1-GM's stock drive-ratio on most LS stockers. Be sure you're not running an underdrive crank pulley at the crank. Plus, the new breed of alternators is more compatible with modern ECUs and electric fans. Late-model alternators not only have higher peak outputs, they put out more juice at idle than older alternators and take less power to do so. Don't use earlier 10- or 12-SI first gen integrally regulated alternators or (shudder) an old-school, separately regulated alternator. You need to use a high-output, late-model alternator like GM's CS-series, or an aftermarket analogue that makes even more amps at idle than a GM stocker. If you get all the way back to the alternator BAT connection and voltage is still low, there might be a problem in the alternator: insufficient low-speed output, an underdrive pulley, or insufficient charge wires. If voltage at the motor is low either initially or after a full hot-day warm-up, recheck voltage at each of the circuit's junctions, splices, terminals, and grounds all the way back to the alternator to see where the drop occurs. We discussed your situation with the real-world guys at Rollings Automotive, a full-service hot rod and general repair auto-repair shop that we've worked with in the past on "real-world fix-its." But if you must ultimately start over from scratch because none of the incremental patches we'll be recommending below solve your problem, it might be more cost-effective in the long run to jump right to the ultimate solution. You could first try incrementally crutching things along with basic diagnostics and minimal parts replacement and see if they generate sufficient improvement. As I see it, there are several approaches to solve the problem of a LS motor (or any motor, for that matter) that overheats on extremely hot days at low speed. I suppose a cold shower is out of the question? Pusher fans might help at low speed, but on the other hand, they can plug up the works and prove a restriction at higher speeds, so we generally frown upon extra ones. Mike, no doubt when Tucson, Arizona, is in heat it's hard to cool a wild engine down.
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