56 replies to this topic

[Lars Bertelsen]

Hi all! I'm another one of those who are rediscovering slot racing after many, many years of sad neglect.
One of the things that struck me right off the bat was these new motors out there... They are so SMALL! They look like something out of a very cheap toy, and I really, really hated them at first! :-)
Must admit there are nice motors out there, though and at very low prices too.
But it got me thinking about the motors I used to dream about as a kid, and led to the question:

Which was the fastest slot car motor ever built?

I seem to remember hearing of motors doing close to 100.000 rpm, but I may be wrong.
Of course, "fastest" is not only a question of rpm but of torque and rpm, so I guess I may be opening a can of worms here. I kind of hope so!

So how about it? Anybody have an opinion on the fastest motor ever built?

[don.siegel]

Welcome aboard Lars!

You might have to define the question a bit more: the fastest motor ever, up to now, just in the classic period, for all types of slot cars, or ?

I assume the fastest motor available would be one of the current strap motors for unlimited 1/24 Group 7, unless one of the specialized drag motors is any faster. I have heard figures of 150,000 to 200,000 rpm, but I'm sure somebody like Ron H. would know the facts.

Some of the motors from 67 or 68 also claimed RPMs of over 100,000 rpm, and that may have been true, at least free running, but they would have nowhere near the torque of a modern motor with cobalt type magnets.

The Globe SS91 was already turning out a legitimate 40k in 1964 (I've checked this on my current stock of NOS motors and it's even a bit conservative!), and a 26D was around this same figure in 1966-67 - but for 1/5 the price! And I saw a figure of 50k for a Pittman DC19-65X (6 volt arm) in about 1965.

[Victor Poulin]

Don,

I think your right. To the best of my knowledge the open group 7 would be one of the fastest out there. At least for the current motors. There could even be something faster out there. Im not sure what the euro guys are running . Maybe someone will chime in.
This is probley a better question for Ron .

[Guy Spaulding]

Welcome aboard, Lars!

One more question to refine your answer is whether you are looking a free-wheeling RPM or actual RPM seen on the track.

In 1984, I got up enough curiosity to come up with some figures. I'm sure they differ now, because cars are faster:

European Blue King @ 155 ft
Grp7 Slot car
lap time 2.5 sec
gear ratio 8:43
tire diameter 0.760"

Yield:

96,000 RPM Average
42 true MPH Average
1008 scale MPH Average (if you believe there is such a thing)

[Lars Bertelsen]

Define my question better indeed! Now I have to make an EFFORT too?!? :-)

What I was thinking of was the motors back in the late sixties to mid seventies, and yes I was thinking in terms of RPM, and that would probably mean free running RPM.

But I do realize that this is a question with many answers. So let's make it:

- Fastest motor in terms of raw RPM back in the Good Old Days
- Overall best performing (Yeah, yeah, I know: "Refine your question" :-) ) G.O.D. motor . Opinions and subjective views are fine!
- Same two categories for current motors

I'm hopefull; it seems there are some really knowledgable guys around here. :-)

[TSR]

Lars, welcome.
In your days, the motors were Mura and/or Champion C-cans with ceramic magnets. The fastest were also near un-drivable and were single-23AWG wire, like 18 turns of the stuff, and I do not think that anyone DARED to rev them freely at 12 volts unless they wore a Bell Star with the visor down.

I am pretty sure that those exceeded 125 thousand RPM then... but RPMs are not what is important here, TORQUE and where the torque curve is. are more important factors. Remember the Audi R8s revved at 14000RPM at le Mans, and the R10 diesel revs at... 5500RPM but has TWICE the torque, and so is faster.

So if you want to know which motors were the FASTEST, I think that you have 3 top candidates in the old days: Camen (Joel Montague), Checkpoint (Bill Steube) and a bit later, Trinity (Tony P and club). All used both the Mura and Champion C-cans and rarely used the beasts that "23s" were, mostly 24, 241/2 and even 25s. There were others but these 3 kind of dominated until the end of the 1970s.

For the more modern stuff, I don't know but I am sure that the younger generation will fill you in.

[Victor Poulin]

For the more modern stuff, I don't know but I am sure that the younger generation will fill you in.

Dokk, Might you be implying that your in the old farts club like a select few of us here??

[Phil Irvin]

Dokk, Might you be implying that your in the old farts club like a select few of us here??

OUR BOAT IS UNSINKABLE AND POWERFULL Just ask us...We will tell you!

OLPHRT
PHIL I.

[TSR]

I have been told that I am older than Noah after he got out of his boat.
It sure feels like it too, especially in traffic.

[Foamy]

The fastest Modern motors are in Drag Racing. 135 MPH AA/FC motors are going at a rate of 280,000 RPM thru the lights.

[TSR]

That's all?

Just kidding, thanks Dennis!

[Bob Campbell]

The fastest were also near un-drivable and were single-23AWG wire, like 18 turns of the stuff, and I do not think that anyone DARED to rev them freely at 12 volts unless they wore a Bell Star with the visor down.

Hey Dokk,

Right now I'm looking at my old Checkpoint 16T 23.5 arm and also a Stuebe 17T 24. Both of these are in old Trinity 4 hole set up's. I think I need to get

hold of John Havlicek and see what can be done! I also have some (built by me) steel center, open class chassis from the same period. Might have to build up some old pro cars that I used to run in "back the day".

Bob C.

[TSR]

Those are scary motors... if they are in Trinity setups, does that mean that they are post Bill Steube arms?

[idare2bdul]

Sounds like a Big Jim Checkpoint motor. Not as collectible as a Steube motor but faster. If it is one of the X Magnet motors they were nice runners. If it is a full cobalt magnet it's one of ten made. My full cobalt motor ran with a double 25, somewhat hotter than your 231/2

[don.siegel]

Double 25??? Very scary Mike...

Did anybody ever actually put a tach on these motors? I know that RPM doesn't mean it's the fastest on the track, but I'm kind of a hick, and I just want to hear the big numbers...

Don

[idare2bdul]

The amazing thing about the double 25 was that it actually ran well geared 9-43. On the Engleman in the Texas Nat's it actually kept accelerating through the bank.

[Ron Hershman]

Welcome aboard, Lars!

One more question to refine your answer is whether you are looking a free-wheeling RPM or actual RPM seen on the track.

In 1984, I got up enough curiosity to come up with some figures. I'm sure they differ now, because cars are faster:

European Blue King @ 155 ft
Grp7 Slot car
lap time 2.5 sec
gear ratio 8:43
tire diameter 0.760"

Yield:

96,000 RPM Average
42 true MPH Average
1008 scale MPH Average (if you believe there is such a thing)

Do that math with 155 ft track...... 1.50 lap time, gear ratio of 8/39 and .750" tires. And you will get a modern open motor RPM range.

The fastest "racing" slot motors would be today's open motors in either Gr 7 or Open Drag racing classes. Next month they could be faster depending on technology or track conditions.

[don.siegel]

But did you ever actually tach one of these free-running on 12V Ron? Or is that motor suicide?

Just curious...

Don

[Prof. Fate]

Hi

I don't remember ever actually measuring RPM.

Modern motor RPM ratings are mostly fiction and it amazes me how many clubs out there have rules specifying the fictional RPM limits in various classes!

Anyway, in the day, each generation of better magnets slowed the motor down, but increased the efficiency and horsepower. I did build several 24s for other people, and ONE 22 just to do it. Personally, I didn't have a local track with enough traction or straight for ME to drive something like that. I ran some 25s, but mostly 26s for the local tracks. I have a couple 24s in a box somewhere from the day with only a few minutes on them. They are Endbell drive era curiosities rather than a serious racing motor.

Fate

[Ron Hershman]

But did you ever actually tach one of these free-running on 12V Ron? Or is that motor suicide?

Just curious...

Don

I know of no actual accurate way of measuring a motor's rpm's with a tach of any kind.

Motor suicide???? Well I would want to be anywhere near a current open motor free reving at 12 volts..... maybe 6 feet away with a scatter shield between me and the motor.

That's why I feel dyno's are a joke...... you don't run the motors at the correct operating voltage nor can you simulate the actual "load" on the motor based on car weight/ traction / track voltage and the variables in track voltage.

When someone says they dyno tested a motor.... my first question is at what voltage? Some say 5 volts.... OK Fine...do we race on 5 volts? Nope.

The only way to know how a motor it going to run.... is to put it into a car and test it on the track. If you have 5 motors, then you have to put all 5 motors in the same car, the same day to know how they will run in that particular car. If you have three cars and five motors, your going to be a the track quite awhile doing some serious testing.

[idare2bdul]

I haven't seen anybody dyno testing motors at 5 volts. Using the Trinity motor tester at 5 volts gives a ball park idea of what the RPM and Amp draw differences are between different motors. I developed this method for testing Falcon type motors at a voltage to avoid any kid of brush bounce or potential damage to the motor. So far it's been an accurate indicator with both the FK style motors and the ProSlot mini motors. Track testing can take the variables out if you are willing and able to do it. I can't as a 180 mile round trip commute(if I bring Foamy) and limited time and money keep me from much on track testing. Life is hard.

[Hworth08]

Do that math with 155 ft track...... 1.50 lap time, gear ratio of 8/39 and .750" tires.

The car averages 70.4545454541 actual MPH.

Considering no wheel spin or tire growth the motor averages 136,830.484 RPM.

The armature makes 3420.76 rotations per lap.

[Ron Hershman]

The car averages 70.4545454541 actual MPH.

Considering no wheel spin or tire growth the motor averages 136,830.484 RPM.

The armature makes 3420.76 rotations per lap.

Ok good stuff..... I remember back in the mid 90's being somewhere where they had a speed gun set-up in the bank and the cars then were hitting 90 actual MPH in the bank.... I have no idea what the speed is now days......... so the RPM's would be higher in the bank and that would be max RPM.

They could also go faster and have higher RPM's in the bank if we took the air contol off the bodies.

[Hworth08]

Ron,

This will apply to any car with .750 tires and 8/39 gears. The motor is turning 1,942.11 RPM for EACH MPH.

I believe it will be two years this summer at the Wing Nats that only one car was over 100 MPH in the bank.

At any rate a car travelling 97 MPH is turning 188,384.67 RPM or 97 X 1942.11.

A good reason not to hook your thumbs on the wall if you're marshalling the deadman!

[Gary Bluestone]

In the good old days( G.O.D.) we used to spin the motors full blast , unbridled, to see which way they turned fastest. This turned out to be motor suicide, and a good way to throw a winding. Recently I had the opportunity to dissassemble a K&F dynomometer and inspect it's innards. What I found inside was a shocking joke. The roller on which you were to put your rear wheels to spin, was attached to one of those grey can Mabuchi 35R as used in the early AMT 1/24 kits. The 35R was wired to a meter, so the faster your wheels turned the roller , the more power was gererated in the 35R , sent to the meter, marked in RPM. So accuracy was suspect, though it would tell you comparitively ,which was faster.
In terms of the fastest motors from the 60's ( since I don't get too involved with modern stuff) I try to focus on what was commonly available to the average guy, not the stuff made of unobtainium. Around here , the 26D was tops and the Dyna rewind version came out on top of these.