Use your Power Cabs amp meter and check the current draw of the F7 compared to the F45. Press program, 6, enter and select amp meter. Run each engine alone and note the readings.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
Your welcome.
This shows that those lighted passenger cars really tax the power out of the Power Cab. Removing the lighted cars and running just the F7 will probably increase top speed but probably not by much. You may have to read what the value of CV25. It should either be 0, 1 or 2. This would eliminate any speed curves and give you a constant acceleration. Also add just a tiny amount of momentum in CV3 and CV4. 2 or 3 should be enough.
Here is a list of supported CVs and the defaults.
http://www.soundtraxx.com/factory/OEM%20pages/walthers/walthers_ho_e8.pdf
This is probably more the gearing than anything. If no adjustments haev been made to the decoder (no speed tables, no top speed (CV5) adjustment, etc., then the top speed witht he throttle turned up all the way is pretty much as fast as it will go. There's no magic bullet to make a loco go faster than the top speed setting. You can slow down faster ones, but you can't make a slow one faster - hence the mention of adjusting speed tbles or CV5 - these can REDUCE the top speed of a loco, but when left at their default settings, the do nothign to the speed - the loco will go as fast as it goes.
ABout the only thing that MIGHT have some effect is BEMF, you could try turnign it off (at the expense of some of the slow speed performance) and see if that gets a little more at the top end - sometimes it does.
If you actually time the F7, it's probably moving at a fairly reasonable speed for the designed purpose of the loco - haulign freight trains. The F45 is probably too fast. Even though the loco might be geared for an 89mph top speed (prototype - although that's more a passenger speed then a freight drag loco speed), the didn;t usually run that fast anyway. SO it probably goes fast enough. You could adjust CV5 to slow down the F45 to more closely match the F7.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Proto engines are known for having different gear ratios, hence different top speeds for different models. Hopefully someone else here has an F7A and can chime in here.
Jay
C-415 Build: https://imageshack.com/a/tShC/1
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A couple years ago Walthers decided to use 14:1 gears in all their Proto-2000 units regardless of the prototypical use. So an E8 will only make the same speed as a GP7 (basically about 69 smph). I was very disappointed with the Empire Builder F units and Hiawatha Es. Recently I've heard they have backed off from the policy (possibly due to my and others like me bellyaching about a 1950s passenger train that can only due 70 smph.) I can't even imaging the El Capitan limping along like that. As a child my grandparents had a farm on the SF mainline race track. The trains regularly flew through at 100+.
It would be a very rare high geared F7 that would do 115. Typical freight geared F7s were WELL under 100mph top speed - even downhill, as overspeed could damage the traction motors. 65 is about right for common freight gearing.
Once upon a time, it was very easy to buy model engines that went 100 scale MPH or higher (I recall reviews of some early N-scale engines where the top speed was in the 170-220 sMPH range). Model manufacturers listed to model railroaders, and thru the years made changes to allow trains to run at "prototypical speeds" meaning much slower than the old slot-car-speed engines. It seems now the trend is going the other way, folks are frustrated by getting engines with great slow-speed capability but that can't go as fast as they want. Interesting how things change!!
BTW it never hurts to check all the speed-related CV's (Decoder Pro is a great help!) to make sure somewhere along the line one of CV's affecting top speed or a speed curve didn't accidently get changed while programming the engine.
Newer passenger locos in particular are overall geared/motored to run too slowly. Not just the Protos. It's more evident now that more are using DCC vs higher voltage DC. And the decoder is parasitic.
Richard
I don't understand all the fuss about wanting an engine run at such speed on our generally smallish layouts. Even at the quite large club layout where there are places of 60' straight runs, anything faster than 60-70 scale mph seems nuts and dangerous to expensive equipment..
I thought the days of "Drag racing" those old pancakes were long gone.
Modeling B&O- Chessie Bob K. www.ssmrc.org
I hear ya.
"But the real <insert famous name passenger train here> went 90mph!"
Not on the equivalent of 30 degree curves it didn't. (about 26" radius in HO)
Table of curve in degrees vs HO radius here: http://www.trainweb.org/freemoslo/Modules/Tips-and-Techniques/degrees_of_curve_to_radius.htm