This was originally in Radio Control Car Action magazine. They tested the following engines in a Traxxas T-Maxx using Trinity 20% Racing fuel:

Epic .18 Big Bore:
Top speed - 39.15 mph
Time to reach top speed - 6.94 sec
Time at 132 ft - 3.85 sec
Speed at 132 ft - 33.42 mph

Fantom FR .18:
Top speed - 36.41 mph
Time to reach top speed - 6.62 sec
Time at 132 ft - 3.89 sec
Speed at 132 ft - 33.49 mph

Hot Products .18 Outlaw:
Top speed - 36.65 mph
Time to reach top speed - 7.49 sec
Time at 132 ft - 3.96 sec
Speed at 132 ft - 32.21 mph

HPI Nitro Star .18SS:
Top speed - 36.78 mph
Time to reach top speed - 6.85 sec
Time at 132 ft - 3.91 sec
Speed at 132 ft - 32.42 mph

OS Engines .18:
Top speed - 40.40 mph
Time to reach top speed - 6.27 sec
Time at 132 ft - 3.42 sec
Speed at 132 ft - 38.15 mph

Peak Racing Diablo:
Top speed - 37.05 mph
Time to reach top speed - 7.87 sec
Time at 132 ft - 4.02 sec
Speed at 132 ft - 31.97 mph

Sirio TX-18:
Top speed - 37.31 mph
Time to reach top speed - 6.50 sec
Time at 132 ft - 3.89 sec
Speed at 132 ft - 33.86 mph

Team Orion Wasp .18:
Top speed - 30.18 mph
Time to reach top speed - 6.40 sec
Time at 132 ft - 4.69 sec
Speed at 132 ft - 27.48 mph

XTM .18:
Top speed - 30.56 mph
Time to reach top speed - 6.85 sec
Time at 132 ft - 4.20 sec
Speed at 132 ft - 29.71 mph

From these numbers it is easy to see that the OS was the only enigine to hit 40 mph and was able to get to 132 ft the fastest a full 1/2 second quicker than the next engine.

Engine builders test their engines with their test equipment so the numbers are not apples to apples in comparison. The magazine puts the engines in real world situations to see how they will perform.