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Why modified racers use shorty lipo?

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Why modified racers use shorty lipo?

Old 01-15-2022, 06:46 PM
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Originally Posted by DirkW View Post
What of it is not true with a low profile shorty? That shorty packs are lighter than stick packs of the same height (which was what he responded to)? That you have to add weight to get the car back to minimum weight? That a flat brass weight mounted directly on the chassis plate (in front and behind the battery) has an even lower CoG than even an LCG / low profile shorty? I don't quite see which of his statements becomes untrue.

The reasons why people use shorties in mod (and stick packs in stock) were already given. Nobody claims you have to do it this way or could not maybe get the same result in a different way. Still doesn't make the answers of why people (even world class pros) do it any less true.
I quoted the wrong post.. honest mistake. My apologies
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Old 01-16-2022, 03:26 AM
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Originally Posted by blanks596 View Post
I have very little understanding of electronics so pardon my ignorance. Does 17.5 pull more on a battery than mod? if you have a shorty 6000 vs a standard 6000 2cell, wouldn't they produce the same amount of power?
No. Mod pulls way more power from the battery. But: in mod, due to the motors being open (want more power? Go even lower in turns!) especially with boost and turbo settings on the ESC, you will end up having (more than) enough power.

In (super) stock classes, you are limited to a certain motor wind - could be 25.5T, 21.5T or 17.5T (or even up to 13.5T or 10.5T in some classes) and also limited to no ESC timing (=blinky mode), which in combination will limit your overall power - with not much you can do to improve that. Bigger motor? Not allowed. More timing / boost / turbo? Not allowed. In that situation, a good battery, i.e. one that can give you the maximum voltage (punch) for the longest and have the least voltage drop during the race can become a real factor. That's why you see people use larger and heavier batteries in the less powerful classes.

Originally Posted by Sortafast View Post
I quoted the wrong post.. honest mistake. My apologies
Ah. I was truly flustered with why you thought he was wrong.
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Old 01-16-2022, 01:45 PM
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Originally Posted by gigaplex View Post
You can do the exact same thing with the really low profile full length packs.
Not exactly, a LCG pack is usually between 20 and 22mm. if you use a shorty (not LCG), the weight used to compensate are about 8mm height, so in the end the mass center is lower. I agree with you that we are talking about millimeters here.
Still the best would be to use lcg shorty and brass or titanium plate under the lipo. But LCG shorties are really near the limit (4000mAh) for a mod motor.
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Old 01-16-2022, 01:49 PM
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Originally Posted by Airwave View Post
Not exactly, a LCG pack is usually between 20 and 22mm. if you use a shorty (not LCG), the weight used to compensate are about 8mm height, so in the end the mass center is lower. I agree with you that we are talking about millimeters here.
Still the best would be to use lcg shorty and brass or titanium plate under the lipo. But LCG shorties are really near the limit (4000mAh) for a mod motor.
I'm guessing you meant tungsten.
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Old 01-18-2022, 12:41 PM
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Originally Posted by WayneKerr View Post
​​​​​​DNot have a photo handy, but basically it's finding the balance on four corners raise the rear axle "x" amount, note the front weight and your wheelbase and then it's math and trig by that point.

I'm sure Google would have it. My work involves motorsports and I've done this everytime my team changes cars I already have an excel sheet built in.
I'm so confused, i would think the noise in the measurement of the change of the projection of the CG on the horizontal plane, when raising one of the axles by a couple of mm, would more than wipeout any of the calculation of the location of the CG on the z-axis... That might work on fulo scale cars but on something which is 250 mm wheelbase with partially sticky suspension that prevents you from measuring anything accurately better than 1%...

Can you share a couple of links that describe the method please?

I'm not saying I'm an non-believer, I just say I want to learn
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Old 01-18-2022, 12:47 PM
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The other bit in the equation is also the fact that the weights to accommodate the LCG shorties are increasing the rotational moment of inertia as they are located outwards ... So that setup is basically trading agility for less traction roll...

What we need is an ultra-dense LCG Shorty, denser on the underside 😁
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Old 01-18-2022, 03:52 PM
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Originally Posted by Lonestar View Post
The other bit in the equation is also the fact that the weights to accommodate the LCG shorties are increasing the rotational moment of inertia as they are located outwards ... So that setup is basically trading agility for less traction roll...

What we need is an ultra-dense LCG Shorty, denser on the underside 😁
Or get a ULCG shorty and put the extra weight under the battery.
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Old 01-18-2022, 04:02 PM
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Originally Posted by Silverbullet555 View Post
I'm guessing you meant tungsten.
Indeed, thanks.

Originally Posted by glennhl View Post
Or get a ULCG shorty and put the extra weight under the battery.
Been there, done that.




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Old 01-18-2022, 07:39 PM
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Originally Posted by Lonestar View Post
I'm so confused, i would think the noise in the measurement of the change of the projection of the CG on the horizontal plane, when raising one of the axles by a couple of mm, would more than wipeout any of the calculation of the location of the CG on the z-axis... That might work on fulo scale cars but on something which is 250 mm wheelbase with partially sticky suspension that prevents you from measuring anything accurately better than 1%...

Can you share a couple of links that describe the method please?

I'm not saying I'm an non-believer, I just say I want to learn
that's why you don't use the spring and damper unit and just rig up solid replacements to take those out of the equation. and since you're comparing only the effects of the battery change, the test can be done on setup wheels so it takes the squish of the tire out as well. Hell machine solid aluminum disc fi you don't like the fact that the setup wheels have rubber rings around it, but i don't think thbat's a low hanging fruit by that point.

you won't raise it by a few mm, due to small angle. I usually go for 2 inches at a minimum.
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Old 01-19-2022, 01:02 AM
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Originally Posted by WayneKerr View Post
that's why you don't use the spring and damper unit and just rig up solid replacements to take those out of the equation. and since you're comparing only the effects of the battery change, the test can be done on setup wheels so it takes the squish of the tire out as well. Hell machine solid aluminum disc fi you don't like the fact that the setup wheels have rubber rings around it, but i don't think thbat's a low hanging fruit by that point.

you won't raise it by a few mm, due to small angle. I usually go for 2 inches at a minimum.
I get it now. Thanks for sharing 😊
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Old 01-19-2022, 06:39 AM
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Originally Posted by Lonestar View Post
The other bit in the equation is also the fact that the weights to accommodate the LCG shorties are increasing the rotational moment of inertia as they are located outwards ... So that setup is basically trading agility for less traction roll...

What we need is an ultra-dense LCG Shorty, denser on the underside 😁
The weights aren't any further outwards than the battery itself. An ultra-dense LCG shorty would just be a shorty with a tungsten weight inside the case.
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Old 01-19-2022, 06:59 AM
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Originally Posted by Lonestar View Post
The other bit in the equation is also the fact that the weights to accommodate the LCG shorties are increasing the rotational moment of inertia as they are located outwards ... So that setup is basically trading agility for less traction roll...

What we need is an ultra-dense LCG Shorty, denser on the underside 😁
You won't increase IZZ using tungsten. If anything it'd lower it because you don't even need the heavy holders. All the mass will be around the footprint of the battery.

That's the beauty of tungsten, you can get pretty creative with size and placement because it's so dense.
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Old 01-19-2022, 01:34 PM
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Originally Posted by WayneKerr View Post
You won't increase IZZ using tungsten. If anything it'd lower it because you don't even need the heavy holders. All the mass will be around the footprint of the battery.
Yes we're saying the same thing. You want the mass low to reduce traction roll chances and centered to reduce polar momwnt and increase agility.
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Old 01-20-2022, 02:51 AM
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Hey, guys what's up?
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Old 01-20-2022, 11:35 AM
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The battery weight does not stick out further than the chassis. The battery does. So battery weights move the weight low to the chassis and further inward than just getting an LCG lipo.
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