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Old 12-05-2008, 04:32 AM   #556
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Originally Posted by hanulec View Post
did you run with a receiver pack or voltage booster? if so, which one?
what speedo?
what 13.5T motor?

i'm about to kick off some 1c SMC testing today in both 1/12th and WorldGT trying receiver packs and voltage boosters (my LVBoost from dimensionengineering just showed up).
It was a Novak speedo/motor but, I didnt look to see if he was runing a rx pack or booster.

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Old 12-05-2008, 08:30 PM   #557
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Originally Posted by InspGadgt View Post
The new version of the BMI has a slotted chassis for the servo mount to fit more sizes
That is correct. It will now fit all available 1/12th servos.
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Old 12-09-2008, 02:35 AM   #558
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What setup would be equal to 4,8v NiMH and 4,5 - 5,5 turn? (=Mod like we run it, we don't run stock)

-3,7v or 7,4v LiPo?
-voltage booster?
-motor size/wind?
-gearing/rollout?
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Old 12-09-2008, 03:47 AM   #559
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At our local track, we also have just mod. A 7.4V Lipo with min. 2000mAh will work good. I think a 10.5 or 13.5t Motor will have approx. the same power as 4.8V and 5.5t.
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Old 12-09-2008, 05:46 AM   #560
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I hope you guys have a BIG track.
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Old 12-09-2008, 06:10 AM   #561
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Thx! Anyone else with suggestions? Anyone done actual back-to-back tests or driven together with a NiMH car?
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Old 12-09-2008, 10:34 AM   #562
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Originally Posted by John St.Amant View Post
I hope you guys have a BIG track.
I don't know, how big the tracks in the USA or Asia are. I still can't believe how you can drive Pro10 cars with 4.8V and 13.5 motor, or 12th scalers with 17.5 motors an 4 cell.
At our last clubrace (indoor, carpet), a 2s-lipo-guy was as fast as the 4.8V modified drivers.

Here is a list about the real differences between 1s and 2S Lipo...

1. 1s 4000mAh has as much energy as a 2S 2000mAh pack
(3.7V x 4000mAh = 7.4V x 2000mAh)

2. average battery power of a 1s 4000 is the same as 2S 2000
3.7V x 4Ah x 60min /8min = 111W
7.4V x 2Ah x 60min /8min = 111W

but

3. Cause of the higher average current, 1s Lipo generates more heat (cables, ESC, etc).
Power, that goes away through heat = I x I x R
So, twice current generates quadruple heat.


4. 1s needs a reciever pack or voltage booster
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Old 12-09-2008, 10:56 AM   #563
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Locally, mod 12th with 4 cell NiMh is out of reach except for a handfull of fast or factory racers. Even the speed of stock/17.5 is too fast to get new novice racers started in 12th.

Single cell is a way to slow all of the classes down without having to go to all new electronics to do it. A slower stock class will help nudge some of the stock guys that don't belong there up into a faster class.

Currently in the US many tracks are lucky to have one or two heats of 12th cars on race day. Blame the economy all you want but there's a local indoor dirt track pulling in over 100 entries per week even with the "recession". What's the difference? New racers. Lots of new racers. They get new racers because the cars are at a speed that novice racers can actually control. Not because the slowest class is "fast".

By the way, I'm using about 3000 mAh in 12th with a single cell LiPo and a 13.5 motor. Any more and it would get the motor hot. I could use the entire 2000 mAh of a 7.4v pack in 8 minutes so a comparison based on total cell capacity is flawed.
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Old 12-09-2008, 11:11 AM   #564
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Der Dicke,

It is not the same speed just to halve the voltage and doulble the amps, or vice versa and run double the voltage and half the amps. Higher voltage will almost always have higher top speed.

The amps that motors can pull is limited to the turns of the motor and the resistance of the wire. Just because the voltage is half does not mean the motor can withstand a constant amperage double that of a 7.4V setup. At some point too many amps are pulled and the stator core will magnetically saturate and overheat. The same with the windings as the resistance heats the wires.

On top of that, artifical limits of MAH by using a small battery pack is only adding confusion to the real speeds of the setups.

This is what we all know. 21.5 with 2S is faster than 13.5 on 4-cell. So where is a class of speeds eqaul to 17.5 4-cell with a 2S lipo?

The 3.7v and 4.8V option prodvides speeds for all levels of racers from stock to modified and the 7.4V option does not
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Old 12-09-2008, 11:36 AM   #565
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Hmmm... this is strange, we've always run Mod here in Norway, never stock. We even ran 7,2v and 5 minute heats for some years, with 12 turn motors... and we charged 2400 NiCads at 9,6 Amps! Boy that was fast! Those tyres took a real beating!

Now the class is very big with 30+ entries in the Nats rounds (we're only 4,6 billlion inhabitants). And most guys run 4,5 or 5,5 b/l motors. Even beginners seem to get the hang of it quite quickly, as long as they keep their chassis in good trim they seem to handle the speeds well.

And you want the stock class to become slower? I have to run a 5,5 to last 8 minutes. With better batteries I would have loved to run a 4,5 and floor it! I've never had a race car that's too fast!
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Old 12-09-2008, 12:07 PM   #566
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Where I live, most on-road tracks are indoor carpet and the total lenght of a lap is shorter than most of the long straights that people claim there is no car fast enough.

I've only raced on one large track before and I felt that 3.5 in my sedan was not fast enough. I put my 13.5 sedan on the track and the time it took my car to clear the 250' straight at full tilt and running start was longer than it took for the same car to complete a whole lap at my home track. Yes I geared up!

Not every track is 1000 meters of perfectly smooth asphalt. The option for a slower setup is needed for the rest of the world that races in hobby shop parking lots or indoor sheet metal buildings. IMO the 3.7V is needed so smaller race tracks can have a replacement for 4.8V nimh batteries to help attract more racers into lower cost racing. Larger tracks, don't have needs for stock racing, so why concern yourself with stock speeds?
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Old 12-09-2008, 01:08 PM   #567
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Sorry, no offence! Just curious!

Btw we normally practise on a very small carpet track with high grip, one lap is 7.0 secs.
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Old 12-09-2008, 01:22 PM   #568
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Trailranger, are you still testing the LIFE cells? I had the firat opportunity to try them out this past wwekend and was very impressed with them.
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Old 12-09-2008, 01:51 PM   #569
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Carefull Fred , Do you have permission to correct them? I have to say no matter which way it goes I intend to be ready soon. So far its 17.5 and 4 round ones. Atleast where I'm at that is.
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Old 12-09-2008, 02:04 PM   #570
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How small is small?

At Cleveland this year on a fairly open track Cyrul and Blackstock did 8.7 second laps in the main (fast lap) and normal laps for them were around 9.0 seconds or so.

Most tracks here run laptimes around 9 seconds or more depending on the layout. Lanes are often as narrow as 7 feet at the club tracks.
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