56 replies to this topic

[TSR]

I would agree with Gary on this, the "26D" (Champion 607, Dyna or other Mura) were fastest. But the "16D" made the car handle better, so it was a close call between the two... then, the Mura and Champion American-made motors came in and that was it for the Japanese motors.

[Ron Hershman]

I would agree with Gary on this, the "26D" (Champion 607, Dyna or other Mura) were fastest. But the "16D" made the car handle better, so it was a close call between the two... then, the Mura and Champion American-made motors came in and that was it for the Japanese motors.

Bigger and thicker magnets along with a bigger diameter arm..........makes better "horsepower" that the smaller mags and smaller diameter arms in the 16-d's.

I also remember a old guy telling me about using 26-D blanks in 16-D motors back in the day and how much power they made.

When I sat down back in 2004 or so and thought about how I could make the 16-D arms faster, I thought about designing a bigger diameter blank similar to a 26-D. If I remember correctly the 26-D arms are about .600" dia. Too big for a current 16-D set-up.

The first thought I had was to make a bigger arm to fill up the huge air gap in the current 16-D motors. A .513" arm in a .575" air gap is huge....... with the USRA minimum of .575" air gap....a .560" diameter arm was perfect. There was other huge advantages a bigger dia arm offers that I will not go into detail about right now.

The best part is when I and RJR came out with them....how all of the other arm MFG's said they would never work... too big...too heavy and would be slower...... then to sit back and watch all of them copy my technology within a short time and now swear by the bigger diameter arms. My blank design was lighter that a small dia blank and there were other reasons the arms were lighter.

But then again, the big arms have dominated 16-D racing since they came out.

Then I was the first to apply this technology to C-can motors.... I took the big 16-D blank and ground them to .540" for the other USRA C-Can classes..... the results were outstanding and while we made these on a custom basis for a few customers back then......... I was getting ready to submit them to USRA for approval then RJR was sold and then I convinced P-S to make them as I knew they were a winner.

Again...my .540" technology now dominates the scale C-Can classes.

[TSR]

I also remember a old guy telling me about using 26-D blanks in 16-D motors back in the day and how much power they made.
When I sat down back in 2004 or so and thought about how I could make the 16-D arms faster, I thought about designing a bigger diameter blank similar to a 26-D. If I remember correctly the 26-D arms are about .600" dia. Too big for a current 16-D set-up...The best part is when I and RJR came out with them....how all of the other arm MFG's said they would never work... too big...too heavy and would be slower...... then to sit back and watch all of them copy my technology within a short time and now swear by the bigger diameter arms.

Actually, Mura produced in 1970, a large amount of such motors using 26D-size arms and thinner magnets in a standard "D" can. They were the standard "Group 12" motors sold in Cobra, Dynamic and Riggen RTR models until 1972.

One little-known fact is that Bill Steube was intrigued by the idea of running a bigger 26d-size arm in a C-can, no less, using D-size magnets shaved to fit inside the C can. He built 4 of these motors, wound with 24-1/2 wire on the Mura blanks that were pretty thick compared to the standard 7-thou blanks. Bill asked me to try it and see what would happen. I tested it and it sounded like it could do the job, so I drove one in an actual USRA race in mid 1972 at the former Bill Pretzman's BP raceway on his American Red track and on my very first qualifying lap, set a new track record at 3.75" in what was the first race for my Diamond racing chassis. I backed it with a 3.78" and pulled the car from the track. The second fastest qualifier was Earl Campbell with a Bob Green built Mura C-can in one of my conventional chassis at... 4.01". I do not know if these big-arm motors were faster than anything else but they sure were not slower. it sure was not the flywheel that we expected it to be. Why did Bill not pursue the matter? Too much work to make one and the magnets were not quite as good as Champion's. I still have one that Bill gave me.

You can find those D-size, Group-12 Mura motors on eBay quite often, albeit not always in decent condition. They are easily recognizable because they do not have the fully enclosing magnet shim visible through the can holes. They also made them in their one-hole version in 1968, here is one next to a standard 2-hole version as sold to Phaze III for their RTR models.

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[Lou Pirro]

Bigger and thicker magnets along with a bigger diameter arm..........makes better "horsepower" that the smaller mags and smaller diameter arms in the 16-d's.

I also remember a old guy telling me about using 26-D blanks in 16-D motors back in the day and how much power they made.

When I sat down back in 2004 or so and thought about how I could make the 16-D arms faster, I thought about designing a bigger diameter blank similar to a 26-D. If I remember correctly the 26-D arms are about .600" dia. Too big for a current 16-D set-up.

The first thought I had was to make a bigger arm to fill up the huge air gap in the current 16-D motors. A .513" arm in a .575" air gap is huge....... with the USRA minimum of .575" air gap....a .560" diameter arm was perfect. There was other huge advantages a bigger dia arm offers that I will not go into detail about right now.

The best part is when I and RJR came out with them....how all of the other arm MFG's said they would never work... too big...too heavy and would be slower...... then to sit back and watch all of them copy my technology within a short time and now swear by the bigger diameter arms. My blank design was lighter that a small dia blank and there were other reasons the arms were lighter.

But then again, the big arms have dominated 16-D racing since they came out.

Then I was the first to apply this technology to C-can motors.... I took the big 16-D blank and ground them to .540" for the other USRA C-Can classes..... the results were outstanding and while we made these on a custom basis for a few customers back then......... I was getting ready to submit them to USRA for approval then RJR was sold and then I convinced P-S to make them as I knew they were a winner.

Again...my .540" technology now dominates the scale C-Can classes.

Ron,
I am with you up to the part about being the first to apply your .560 technology to C-can motors. This is the way I remember it:
Skeeter Lengyl who owned SMF and was partners in Front Line had about 500 pair of c-can magnets made in hope of makeing his own C-can motor. The engineer got the dimensions wrong and the magnets came out to thin. .550 air gap in most c-cans. Skeet was looking to build a motor for glue GP-12, the magnets did not work. He gave me some sets to try in scale classes. With a .513 dia arm they worked great for flat track racing, but lacked brakes and punch on high speed tracks. When you and Robert cam out with the .560 blank for 16ds I called Robert and asked if he would make some X-12 arms for me with that lam ground to .540. He did but the quality was.... lets just say only a few were usable. The few that ran and had good balance were fast! Heres where you come in. You had just moved your shop in with Robert and I new if I had you make the arms the problem with the Quality and bad balance would be gone.It was. Then Robert went and sold out to Viper which put us both out of the .540 dia. arm business until I got Viper to wind them for me and you got Pro Slot to make them. To bad you could not get Pro Slot to reproduce the narrow crown, its faster.Maybe I'm wrong but that the way I remember it.

[Ron Hershman]

Ron,
I am with you up to the part about being the first to apply your .560 technology to C-can motors. This is the way I remember it:
Skeeter Lengyl who owned SMF and was partners in Front Line had about 500 pair of c-can magnets made in hope of makeing his own C-can motor. The engineer got the dimensions wrong and the magnets came out to thin. .550 air gap in most c-cans. Skeet was looking to build a motor for glue GP-12, the magnets did not work. He gave me some sets to try in scale classes. With a .513 dia arm they worked great for flat track racing, but lacked brakes and punch on high speed tracks. When you and Robert cam out with the .560 blank for 16ds I called Robert and asked if he would make some X-12 arms for me with that lam ground to .540. He did but the quality was.... lets just say only a few were usable. The few that ran and had good balance were fast! Heres where you come in. You had just moved your shop in with Robert and I new if I had you make the arms the problem with the Quality and bad balance would be gone.It was. Then Robert went and sold out to Viper which put us both out of the .540 dia. arm business until I got Viper to wind them for me and you got Pro Slot to make them. To bad you could not get Pro Slot to reproduce the narrow crown, its faster.Maybe I'm wrong but that the way I remember it.

Lou your are correct..... I had already been testing/racing .540" X-12 arms at the local track and they were pretty fast. You had Robert make you some stuff that wasn't so good. I only had Robert wind and grind for me and I did all the other work up of the arms. You called me and asked about .540" stuff being made to fit your set-ups with the SMF magnets that would work...... we did that and the rest as they say is.............. History.

[idare2bdul]

So we morphed from fastest motors to fastest 12's.

Hmmmm,how about fastest 16D? Game on!

[Ron Hershman]

So we morphed from fastest motors to fastest 12's.

Hmmmm,how about fastest 16D? Game on!

Depends on if it's a USRA spec 16-D 70 T of 30 Ga or a unlimited wound 16-D of years past.

Today's 16-D's aren't your father's 16-D's.

[Victor Poulin]

So we morphed from fastest motors to fastest 12's.

Hmmmm,how about fastest 16D? Game on!

Ok Ron,
You started it, lets hear it. Id be interested to get your take on this being that I,ve been getting into motor building. I feel that you are da man and who better to learn from. Could you feel that pat on the back?

Vic

[Ron Hershman]

Ok Ron,
You started it, lets hear it. Id be interested to get your take on this being that I,ve been getting into motor building. I feel that you are da man and who better to learn from. Could you feel that pat on the back?

Vic

Vic...... do you want my opinion/suggestion on building a current USRA Spec 16-D motor?

[Victor Poulin]

Vic...... do you want my opinion/suggestion on building a current USRA Spec 16-D motor?

Sure Ron, I need all the tips I can get. lol

[Ron Hershman]

Any of the 16-D cans are useable, depends on how light you want to go. If you want to be as light as possible, the Kelly Can or the Kamen can. I still get good horsepower out of a P-S can.

I prefer the P-S or Parma magnets....air gap set to .575"

Pro-Slot .560" arms.... timed 42 to 44 degrees.

Gold Dust Brushes and Red Champion springs.

[Victor Poulin]

Any of the 16-D cans are useable, depends on how light you want to go. If you want to be as light as possible, the Kelly Can or the Kamen can. I still get good horsepower out of a P-S can.

I prefer the P-S or Parma magnets....air gap set to .575"

Pro-Slot .560" arms.... timed 42 to 44 degrees.

Gold Dust Brushes and Red Champion springs.

Thank you Ron,

Im going to build one up this comming week. I,ll let you know how it goes.
Sorry guys, I didnt mean to get off topic

Vic

[Prof. Fate]

Hi

As it happens, the locals are all over me because of their own limited classes using 16ds and supers. They are clueless, but keep insisting someone is cheating based on what the SEE as endbell color or color of the plating on the hardware.

I keep explaining that the S16d arm is BIGGER and the magnets thinner, but they are convinced that some people are "cheating".

But then these are the guys who believed that the Ninco motors were un-modifiable because of the wrapper.

Another aside. I remember that Mura had some odd name for their 26d arms in a 16d set ups, but I cannot recall it. Most of my stock survivors are these as I preferred the 513 arms in these set ups at the time. Local conditions.

Fate

[TSR]

Another aside. I remember that Mura had some odd name for their 26d arms in a 16d set ups, but I cannot recall it.

Rocky, it was "Group 12". It is written on the motor...

You must be thinking of something else, like the obsolete Mabuchi clones, American built "617" motors, renamed "Charlie Brown" in 1970 and bombarded legal for Group-12.

[Horsepower]

If I remember correctly, the 26D arm in the 16D can was a flop because of overheating due to the larger arm and poorer quality steel used in them.

[Hworth08]

I can't give the reasons but the Mura NCC-12 motor was pretty doggy. A stock Mabuchi oval hole motor was quite a bit faster on our 240 foot track and a couple bucks cheaper. The Mura 12 did have a good endbell though.

[Prof. Fate]

Hi

The name was something like "mini-brute". I should go look.

Group 12
Before they were tagged, the rule was just that the arm not be balenced.

The Mura 12 was a 65t/30s wind as was the 1970 Mabuchi BB and the Champion 5001. The mura waa a short stack and should have revved higher than the other two, so I am unsure why it was "doggy" for you. For the next 20 some years, Mura made zillions of the motor. After "tags" they were called "The Mura Wasp". The standard medium stack was called "contender". And Champion sold its own versions of these two arms from the 70s thorough about 2000. Often popular in limited motor flexi based classes.

Fate

[TSR]

Rocky,
The Mini-Brute was just that, "mini". It was a shortened MURA 16D motor designed for 1/32 scale racing. But it was also plastered with an NCC sticker just in case...



The regular Group-12 motors are the standard length:

[vsrn]

It's been 15 years or so, but I had also heard 200,000+RPM and 200 amp inrush current draw
for "modern" drag motors !

vsrn

[Prof. Fate]

Hi

How about "Maxi-brute" then? I am sure there was some silly name for them!

Fate

[retro]

It's been 15 years or so, but I had also heard 200,000+RPM and 200 amp inrush current draw
for "modern" drag motors !

vsrn

Interesting - just exactly what wiring is used to conduct this
figuring 12 volts thats 200x12=2400watts
figuring the load exists for say one second---that's a pretty good load. a 40 volt electric moto poweing a a large model airplane and pulling 60 amps would be the same load
the wiring typically used is 13 guage
if the voltage were reduced to 12 volts the watts could be the same but the wires required would be far larger
so just wondering whre these figures originate?

[TSR]

How about "Maxi-brute" then? I am sure there was some silly name for them!

Rocky,
I will review the Mura catalogs (I have them all from beginning to 1972 now that Ron Mura has donated his archive to the museum), but I do not believe so... Maybe later in the mid-1970s?
I will let you know.

[Prof. Fate]

Hi

It is one of those stray memories, I can SEE the ad in my head, but not well enough to read.

Fate

[retro]

Are there any documentations on "drag race" motors
So far the only info I have seen, smacks of whimsey.
having been absent from th slotcar scene for a couple of generations (human generations), I see some excellent,equipment and the power used seems to be much as it was in the 60's
When I sarted asking about track power and voltages - I received some interesting replies - not entirely consistant with what I know about power and power distribution.
Shirley, somebody has some recorded data

Rookie?
Rocky?

[idare2bdul]

Not sure what you want for documentation but I cut a .401 light and ran 119MPH and got beat by Beuf a couple years ago. The motor was getting a little soft after too many runs without a re-cut com. I think the faster guys that day were in the mid to high 120's and most of us were in the mid to high .4's if my memory is correct. This wasn't close to the national record.

The funny thing is it would probably be easy to make more power but trying to get it to hook up would be the hard part.