671 Turbine question

I agree: MTH RealTrax has wider rails and provides more surface for traction. That's why the 671 worked well on your test track.

Wheels ride on top of tubular track. That 671 without Magne-Traction may be light enough and its drivers small enough to impede its pulling power.

Magne-Traction works best on tubular track because the magnetic current flows from the magnet(s) through the rails and metal ties back to the magnet(s) again.

I have heard different opinions about Magne-Traction on GarGraves track. I'll mention that in case someone wants to reply.

I have some "O" left and when I use Gargrave tracks there was no traction, what

I had to do was to wire every couple of feet, join the two outer rails together

like Lionel track does to restore the grounding loop and that improves the

Magne-traction.

I suspect that the biggest difference in pulling power is the amount of oil on the track.  Additional weight in the engine will increase the pulling power. 

The pulling power, before wheel slippage occurs, is the coefficient of friction times the normal force.  The coefficient of friction depends on the material of the wheels and the material of the track and is reduced greatly when there is oil on the track.  The normal force is the weight of the engine on a level surface, thus increasing the weight will increase the tractive force.  The shape of the track, round or flat, has no effect on the tractive force.

Earl

I run a 1948 671 periodically. I have tubular track and on rare occasions I clean the track with a CMX-O car using alcohol. I also scrape and clean all the loco wheels. 

The 671 does have wheel-spinning power. I have never noticed good traction. Six PW cars require care in starting or accelerating. And you won't do either on a 1/4" over 20" grade.

I have used Bullfrog's Snot which helps but wears off quickly. But it is a lot better than nothing. Since it lasts on other locos I think it is worn off by the inevitable wheel-spin occurrences. 

Check to see if the weight is in there - it's a significant chunk of metal that will help with traction.  That said, 671 engines are slippery, and you won't pull a huge train with one.  A 681 seems to be a better puller; my dad had a 671 and 681, and after servicing them the 681 was able to pull more cars without slipping (Gargraves track, Lionel switches on the board).  Definitely wipe down the track and clean off any oliy residue left behind...