hyujmn

iTrader: (27)

I think D3.5s came with a 12.3mm powerband rotor. Usually purple, I think?

John Wallace2

That's the rotor that came with my RPM Kill shots too. The Maxzilla version of the D3.5 and Kill shot spec motors come with the 12.5mm high torque rotor (TEP1112) installed.

John Wallace2

I have two 21.5 RPM Kill shots, one with the pink 12.5mm high RPM rotor and one with the turquoise 12.5mm High Torque rotor. I'm down to a 3.4 FDR on both motors and they are both fast but still not getting warm (used the 3 second rule and didn't bother with the IR temp gun). Running on a long straight and very open turns. The High Torque version does has some cogging on start but other than that it runs great. Hi RPM rotor version is running 60* timing and the Hi torque rotor version is at 55* timing. Am I lucky or do I have a problem? Most posts are talking about 3.6 FDR and higher. Thinking that on the big outdoor asphalt track I run on the FDR of 3.2 or so might be where these motors come to life. I ran 3.4 FDR last weekend and had the same top end as the winner but he came off the track at 180F and I was about 140F with the 12.3mm broad power band rotor that came with the RPM Kill Shot. Does the 12.5mm rotors make that much difference? Only thing I did when I swapped out the original rotors was to shim the new ones so there was a little more end play on the shaft, just seem too tight to me.

wiringnatzi

iTrader: (6)

Running a 17.5 high torque motor with stock rotor 12.3mm broad powerband rotor (purple)….

What would the difference be between the 12.5mm broad powerband rotor (silver) and the 12.5mm high torque rotor (turquoise)? What will you gain with the 12.5mm broad powerband rotor over the existing? Gains with the 12.5mm high torque over the existing.

Currently the car seems as fast or faster than any car on the track at club races. Just looking for a little more for the big races.

Its geared at 72/27 with ~55* timing and comes off the track right between 140-150 depending on ambients.

Running off road dirt, stock truck. Track size?, see attached:
https://www.youtube.com/watch?v=IUugbzB7Onc

John Wallace2

We had a test and tune day at our track and I had a chance to experiment with the FDR on the High Torque version (12.5mm rotor) of my 21.5 RPM KS motor. As I kept increasing the FDR from 3.2, the car got faster and faster. Must say that at 3.6 FDR the car was awesome, turning in consistent laps at or near the fastest lap times from the previous weekend USGT race on the same track layout. Coming off the track at less than 130 degrees after a 5 minute run. Some of the 17.5 guys even came over to see what I was running in my USGT car as they were barely able to pass me in the straightaway. May try 3.8 FDR next, just to see what happens to the lap times. With races, testing, and practice; I have probably the equivalent of 15 races on my KS motor and so far no problems. Hopefully the RPM stator doesn't have the smoking issues others have experienced with the HI torque stator version of the KILL Shot.

Also I have my Fantom FACTS MACHINE II dyno almost up and running so I can check the timing and amp draw of the motor and how different rotors affect the motor in terms of power (watts), acceleration, torque, amp draw, and RPM. This should provide valuable information on how to gear the motor and how to tune the motor.

And as a transplanted former Seattle Sonics fan now living in San Antonio: GO SPURS GO!!!!

dizope

iTrader: (5)

Add me to the burned up motor club. Have yet to check if the ESC survived.

17.5 HT/HT, 71-72* timing, 3.93 FDR, lasted 4-6 race days.

Going to get another one.

goots

iTrader: (20)

Too much timing try backing it down allot more

John Wallace2

+1 on too much timing. Just surprised the motor doesn't cog really bad and/or run really hot with that much timing.

I have my Fantom dyno going now and have been conversing with Ron Mick on brushless motors at "The RC Conference" (Deccosoftware.com), especially about timing and AMP draw. He contends that after 35 or 45 degrees of timing, the amp draw increases dramatically and motor efficiency drops dramatically too. I must say I've seen that on some motors I've dyno'd. One motor pulled well over 20 amps throughout the entire dyno test when timed at ~50 degrees. But at 30 degrees, the amp draw was less than 10. However, with my two Kill Shot 21.5 motors even timed at 55 and 60 degrees the amp draw is less than 5 amps. Not sure why I'm not seeing huge amp draws with these motors, but I'm not and I can tell it by how little charge it takes to recharge a battery after a 5 minute race.

Before I got my dyno running I was thinking the KS with the High torque rotor was the better motor of the two (the other has the RPM rotor); however, after seeing both the HT and the RPM rotors in the RPM stator on the dyno, the RPM rotor now appears to be the better of the two. It has more power (measured in watts), it accelerates faster, has more RPM (~1600), and most surprising it has slightly more torque than the high torque rotor. It would have taken me many hours if not weeks or months to find that out with track testing particularly here in San Antonio when we only have a track set up two days a month. It took only a few minutes to see it with the dyno. Come visit us on the RC Conference. I set up a thread Fantom Fun to discuss using the Fantom dyno to test brushless motors. I know from my oval racing days there are a lot of Fantom dynos out there, many probably like mine in an attic somewhere collecting dust, when with a few simple changes (e.g., connecting a brushless ESC between the motor and the dyno) the Fantom dyno can give you the same info on brushless motors as it does for brushed motors. The RC Conference is Free; however, you do have to register just like you do here at RCTECH.

oeoeo327

iTrader: (75)

+2 - WAY too much timing. You really shouldn't need more than 55 degrees under any circumstance, maybe a smidgeon more if manufacturing tolerances are a little off.

dizope

iTrader: (5)

But it's sooo much faster with the extra timing.

b20btec

iTrader: (11)

The KS 17.5 RPM Stator and HT rotor is faster than the KS 17.5 HT/HT, I have both and ran tested them at the track, too much fading off of with the HT/HT. Lap time may appear to be slightly faster with the HT/HT but overall race time the RPM/HT is faster.

John,

It'll be fun to run asphalt on the 20th of July up in Austin, hope to see you there at eos and I'm anticipating a huge USGT turnout! the 12 min A main USGT is something I'm not used to, FDR was key in conserving battery life. Also my experience is somewhat lacking on asphalt so I hope to do well.

dizope

iTrader: (5)

I need to order a new motor and am planning on getting the Fantom labeled 17.5 RPM/HT Pro Select. What do you guys think for the track below? The back straight is roughly 100 feet and it's ran clockwise.

For a 17.5 geared at 3.93 with 71-72* of timing, RPM's reach around 18k in the straight. Temps were around 190* with a R1 fan after a 7 min main. Lap times in the mid 13's.

Fantom Rotor Chart: https://www.fantomracing.com/Rotor_G...ec_4-11-14.pdf

b20btec

iTrader: (11)

Adjust fdr for infield and 3/4 of straights and check temps. I would start at 3.6-3.7 on a track that size. I run 3.5 on a large outdoor track.

John Tag

iTrader: (42)

You should NEVER run above 59* MAX...Unless you got a shot at winning a National A Main then plan on 1 run and done on motor. We did that in Vegas A TC Main with a HT/HT 3.50 65* as a hail mary..finished top 4 but motor went weak after..go figure..LOL But 57* at 3.56 should be all you need.

goots

iTrader: (20)

I agree with Tag and have a very similar fantom motor layout. 3.7 fdr 55 timing, with a 120ft straight. Plenty fast outdoors.