Wednesday, February 21, 2007

Spirit S3X Motor

Here is what the Spirit website says about the new S3X long can motor which is in their newest cars:

"REF.00104 MOTOR SPIRIT S 3X Faster. Better Braking.
Stronger magnet effect
Specifications: 24.000RPM. / 12v
13,10 g.-cm magnetic force"

Ok, what does this mean? I assume the 13,10 "g.-cm" is an error, and they meant to say the motor produces 13.1 grams of magnetic downforce when placed at Spirit chassis height over Scalextric or other rails. This does not appear to be a torque rating, which would be in units of g-cm (a European decimal point is a comma, and a comma is a decimal point, in English). Several tests of other maker's long can motors with a Magnet Marshal show downforce readings of about 13 grams.

So that leaves us with the claim of 24k at 12 volts for the RPM rating.

Slot Car News tested two sample S3X motors; one had the colorful wrapper proclaiming "S3X", while the other is in the photo above; plain metal finish with a white label, reading "FK-180" and "D/V 15.0", among other things. My hunch was the motor was rated 24k at 15 volts, not 12v as claimed.

Under the light of the tachometer, both motors spun up at 12 volts, no load, to nearly the same RPM: 19,725 RPM for one, and 19,814 RPM for the other. I adjusted the voltage upward to 15 for the faster motor, and measured 26,163 RPM.

By extrapolating the numbers, 19.8k RPM (15v/12v)=24.8k RPM estimated at 15 volts; right on the claimed rating for RPM, but at 15 volts. This agrees with both the label on the motor and approximate performance of the motor.

Therefore, the Spirit S3X is correctly represented as a 24k (up to 26k) motor at 15 volts, and correctly rated at some 19.8k at 12 volts. The torque is unknown. The label on the motor is correct; the info on the Spirit website is incorrect.

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