Will Athearn "blue box" and Genesis locos run toge

i was just curious if athearn's blue box engines run well with their genesis locomotives and others like the CF-7

I would think not too well but put them both on the track w/o cars, three feet apart & throttle up. If one over takes the other too soon, well that's your answer.
I suspect your blue box may require more voltage since it's not as high tech as the Genesis.
If by chance there's not too much difference I would place the faster unit
as the second loco letting the slower ride along.

From my experience, Genesis and Blue-box locos will run very well together.

When the motor of one engine begins to turn at .XX amps and the motor of the (Blue Box) engine turns at X. amps, running together is out of the question. Unless, you want to tempt fate on the curves!

Bob

When the motor of one engine begins to turn at .XX amps and the motor of the (Blue Box) engine turns at X. amps, running together is out of the question.

Nope! First of all, the current draw doesn't affect the speed as much as the starting voltage. An Atlas, P2K or Genesis engine will probably draw less current than a blue-box, but it may actually run slower due to a higher starting voltage.

Secondly, the current draw isn't all that different between them. A recent, well-maintained blue-box will draw less than 0.5 amps unless stalled.

Thirdly, I have lots of experience running blue-box and Genesis engines together. To test the compatibility, I took a blue-box SD40-2 and a Genesis SD70I and placed them on straight and level track, 3 inches apart. I brought them up to about a scale 30 mph and let them cover about 6 feet of track, then brought them to a halt. They were still 3 inches apart. I have had cases where the engines have uncoupled while running light, and they will cover several dozen feet of track with only a few inches difference appearing between them.