If the straight was long enough, and the scalextric car was standard with an 18,000rpm motor, 1 to 3 gear ratio (a 9 tooth pinion and 27 tooth contrate gear) and the car had 19x10 wheels , ie 10mm diameter. How long would it take to accerate and what top speed in real speed and scale speed would it reach?

30mph but you'd have to give it a little push at the start. ..sorry but your question was so in depth and the '25mph' was so short and to the point with no reason why the person had came to this conclusion. Hope you get a serious answer real soon, cos i wanna know to now!

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Scalextric Speed Calculations I came up with a result of 13.35 mph, based on a tyre diameter of 19mm (not 10mm) for a 19x10 tyre. Calculations below : ROTATION SPEED OF WHEEL, PER HOUR 18 000 (motor rpm) / 3 (gearing) = 6000 x 60 (minutes in 1 hour) =360 000 revs per hour DISTANCE PER HOUR, IN INCHES Circumference of tyre is 19mm x 3.14 = 59.66mm. as there are 25.4 mm in one inch that's 2.35 inches. (59.66/25.4 = 2.35). This is the distance travelled in each turn of the wheels. Therefore speed is 2.35 inches x 360 000 = 846 000 inches per hour. REAL SPEED To convert to mph divide by 63 360 (12 inches per foot, 5280 feet per mile = 63 360). 846 000 / 63360 = 13.35 mph. 2005 OFFICIAL SPEED TRIALS In 2005 scalextric ran speed trials with 50 competitors. They were filmed for a BBC TV show called 'Toy Stories'. It looks like they used there Sportworld technology to measure the results accurately. All the cars were scalextric body/chassis but could have replacement motors, gears etc to increase speed. They ran over a 1/32 scale Measured Mile (flying start given?). Aside from a few real duds the results ranged from 342 to 697 mph scale speed, which convert to 10.7 to 21.78 mph real speed. See the forum at scalextricsportworld.com for the details. SCALEXTRIC SCALE 124 Many years ago scalextric made a 1/24 scale range with the above name. It ran on a wider 3 slot track. The cars were well-engineered and very fast. They tested their Jaguar 'E' Type on a little rolling road and got around 40 mph real speed, which is 960 mph at 1/24 scale. You may still be able to find some around, at a price. Carrera make 1/24 scale cars now.

Where I race anything between 2.9-3.2 seconds around a 110 tri oval is consider "competitive lap times"..Anything slower then those times is a "also race.