Category Archives: Facts in evidence

List of engines tested with data, revised 5-9-16

The various engines that are examined in these tests will be listed in this post. Because of the number of tests, it is unlikely that each test will be documented per say. Clearly the unique ones will see some sort of post, but less will be more in most cases.

This list is anticipated to grow large. Ten is the minimum number for a statistical sample size. Since these engines will have a variable age, the list could have as many as twenty-five of a given model. In this case, a Stewart F3, F7 or F9 are all essentially the same model. There are a number of examples like this and they will be grouped together.

There is a summary of each engine. At minimum this will include the traditional values that represent engine performance. Additional values are expected to be included, some of these will evolve as time goes on.

With this listing, the engines have been organized by manufacturer and the road or model. Classic engines from before 1965 have been grouped in a separate listing. Some in the larger list may also fit that catagory, but for now it is better to have them where they are. Finally, the steam engines tested are listed separately. At this point, it is a small family, but more are in the wings and will be added as appropriate.

As indicated this list and the post itself will evolve as time and information requires. Check back often and feel free to ask questions. The number of engines tested has reached 263. See below:

Athearn RTR SW1500 switcher

Athearn Genesis SP F7A engines

Athearn Genesis GN F7A engines

Athearn RTR SP daylight F7A engine

Athearn RTR Rio Grande RS-3 engine

athearn SP RTR SD40R DCC sound engine







Atlas S2 switcher engine

Atlas BNSF dash8 engine



Kato Locomotive

Kato electric engine

Kato Amtrak P42 engine



Bachmann Locomotive











Rivarossi Virginian 2-6-6-6 steam engine

BLI BnO 4-6-2 steam engine

Bachmann 2-8-4 steam engine

MTH 2-8-8-4 steam engine

Athearn Genesis UP 4-6-6-4 engine



The car pull data is based on the Higgins testing. I have not defined the car resistance as of this writing.

The grayed out cells are either data that was not taken or has been misplaced. The stall current was mistakenly not part of the original test data list I was using. It is now.

The engines with the green shade in the number and condition are part of my collection and will likely show up again after some additional tuning activities.

Three voltage/ level data for stall current and draw bar pull have been added. Stall current data is now taken at 8, 12 and 16 volts. The draw bar pull is measured at 12 and 16 and the maximum pull. In the chart, the maximum pull and 12 volt pull are listed.

This adds relevance to DCC as well as DC applications. The simple fixed resistance current varies with voltage at stall has not shown to be true in the measurements. In some cases, it has been difficult to get an actual stall to occur. For those there will be a dash where there should be a number. Generally The stall current is measured at 8, 12 and 16 volts. If everything was perfect they would all satisfy Olhms law, V=IR. However, a few motors have been fried attempting to get this measurement. A fourth column has been added. This number is the highest voltage at 12 volts implied by the measurements. This number has also been increased by 5 percent for a further margin. This should be the minimum decoder capability required for the engine in DCC or other control module system.

The draw bar force is a critical measurement. Again knowing the maximum and the value at 12 volts are both important. It is interesting that engines designed during the DCC era tend to max out in draw bar force at or below 12 volts. Those designed before the acceptance of DCC tend to max out above 12 volts. Some at 16.

Additionally the Nickel Silver wheels are a significant detriment to maximum draw bar pull. Literature indicates a friction coefficient loss of twenty percent with polished wheels. These tests have been showing at least that impact.

The critical performance criteria calculation has been added. Engines with a value over 40 are very good. Those with a value less than 5 are poor or sick. For more information on this parameter see the Performance Criteria post.