Brushless/Lipo vs Brushed/ NiCd

[racerjohnbf]

Ok, so first off I know these are like apples to oranges, but....

I just started working on rebuilding a JRX-T runner and I'm already think of what to power it with. I want to go with modern electronics, but keep the truck a similar speed to what it was back in the day.

So what I'm asking is... What properly geared brushless/lipo combo would be "relatively" the same speed as a good 27t stock motor (think Pocket Rocket or Monster Horsepower) with 1400scr's from the early 90's?

I know a direct comparison is not possible just a ballpark. I'm guessing with the lighter weight of the Lipo, maybe a 25.5?

Thanks,

John

[JosephS]

Ok, so first off I know these are like apples to oranges, but....

I just started working on rebuilding a JRX-T runner and I'm already think of what to power it with. I want to go with modern electronics, but keep the truck a similar speed to what it was back in the day.

So what I'm asking is... What properly geared brushless/lipo combo would be "relatively" the same speed as a good 27t stock motor (think Pocket Rocket or Monster Horsepower) with 1400scr's from the early 90's?

I know a direct comparison is not possible just a ballpark. I'm guessing with the lighter weight of the Lipo, maybe a 25.5?

Thanks,

John

I think what you are going for is about right.
From what I have seen it's going to be a range, but it seems to be that generic 17-21 turn brushless will be about a high quality well tuned 27 turned brushed. The 2s Lipo is about the same as a 7cell pack going from 21-25 should get you back towards 6 cell range.

[racerjohnbf]

Ok, so first off I know these are like apples to oranges, but....

I just started working on rebuilding a JRX-T runner and I'm already think of what to power it with. I want to go with modern electronics, but keep the truck a similar speed to what it was back in the day.

So what I'm asking is... What properly geared brushless/lipo combo would be "relatively" the same speed as a good 27t stock motor (think Pocket Rocket or Monster Horsepower) with 1400scr's from the early 90's?

I know a direct comparison is not possible just a ballpark. I'm guessing with the lighter weight of the Lipo, maybe a 25.5?

Thanks,

John

I think what you are going for is about right.
From what I have seen it's going to be a range, but it seems to be that generic 17-21 turn brushless will be about a high quality well tuned 27 turned brushed. The 2s Lipo is about the same as a 7cell pack going from 21-25 should get you back towards 6 cell range.

Thanks, that's exactly what I was looking for! Any idea on a good final drive ratio for a 25.5? And a FDR for 21.5 in case I want to give it just a little speed boost?

[JosephS]

Ok, so first off I know these are like apples to oranges, but....

I just started working on rebuilding a JRX-T runner and I'm already think of what to power it with. I want to go with modern electronics, but keep the truck a similar speed to what it was back in the day.

So what I'm asking is... What properly geared brushless/lipo combo would be "relatively" the same speed as a good 27t stock motor (think Pocket Rocket or Monster Horsepower) with 1400scr's from the early 90's?

I know a direct comparison is not possible just a ballpark. I'm guessing with the lighter weight of the Lipo, maybe a 25.5?

Thanks,

John

I think what you are going for is about right.
From what I have seen it's going to be a range, but it seems to be that generic 17-21 turn brushless will be about a high quality well tuned 27 turned brushed. The 2s Lipo is about the same as a 7cell pack going from 21-25 should get you back towards 6 cell range.

Thanks, that's exactly what I was looking for! Any idea on a good final drive ratio for a 25.5? And a FDR for 21.5 in case I want to give it just a little speed boost?

Sorry I don't know the gear box for that car. I run an older 17.5 brushless in my rc10t with a 2s lipo and it runs fine gearing it as the manual states for a 27t brushed. Not to fast or too hot for just bashing around.

[racerjohnbf]

Ok, so first off I know these are like apples to oranges, but....

I just started working on rebuilding a JRX-T runner and I'm already think of what to power it with. I want to go with modern electronics, but keep the truck a similar speed to what it was back in the day.

So what I'm asking is... What properly geared brushless/lipo combo would be "relatively" the same speed as a good 27t stock motor (think Pocket Rocket or Monster Horsepower) with 1400scr's from the early 90's?

I know a direct comparison is not possible just a ballpark. I'm guessing with the lighter weight of the Lipo, maybe a 25.5?

Thanks,

John

I think what you are going for is about right.
From what I have seen it's going to be a range, but it seems to be that generic 17-21 turn brushless will be about a high quality well tuned 27 turned brushed. The 2s Lipo is about the same as a 7cell pack going from 21-25 should get you back towards 6 cell range.

Thanks, that's exactly what I was looking for! Any idea on a good final drive ratio for a 25.5? And a FDR for 21.5 in case I want to give it just a little speed boost?

Sorry I don't know the gear box for that car. I run an older 17.5 brushless in my rc10t with a 2s lipo and it runs fine gearing it as the manual states for a 27t brushed. Not to fast or too hot for just bashing around.

All good. Thanks now I know I'm on the right track.

[racerjohnbf]

Sorry, double post

[JosephS]

Ok, so first off I know these are like apples to oranges, but....

I just started working on rebuilding a JRX-T runner and I'm already think of what to power it with. I want to go with modern electronics, but keep the truck a similar speed to what it was back in the day.

So what I'm asking is... What properly geared brushless/lipo combo would be "relatively" the same speed as a good 27t stock motor (think Pocket Rocket or Monster Horsepower) with 1400scr's from the early 90's?

I know a direct comparison is not possible just a ballpark. I'm guessing with the lighter weight of the Lipo, maybe a 25.5?

Thanks,

John

I think what you are going for is about right.
From what I have seen it's going to be a range, but it seems to be that generic 17-21 turn brushless will be about a high quality well tuned 27 turned brushed. The 2s Lipo is about the same as a 7cell pack going from 21-25 should get you back towards 6 cell range.

Thanks, that's exactly what I was looking for! Any idea on a good final drive ratio for a 25.5? And a FDR for 21.5 in case I want to give it just a little speed boost?

Sorry I don't know the gear box for that car. I run an older 17.5 brushless in my rc10t with a 2s lipo and it runs fine gearing it as the manual states for a 27t brushed. Not to fast or too hot for just bashing around.

All good. Thanks now I know I'm on the right track.

Your welcome. Just be sure to post up pics of how project is going.

[R6cowboy]

Like JosephS mentioned, it'll be a range. But that range will more likely be 17.5 to 21.5 as far as comparison rpm wise to a quality 27T brushed.

[BattleTrak]

To help with your gear calculations.. The Losi LRM gear box is 2.18:1. The JRXT came with an 86 tooth spur and the manual recommended a 19 tooth pinion for a stock motor. That would give you a FDR of 9.87:1

[racerjohnbf]

Thanks everyone! I'll probably end up using a 21.5 and playing with gearing to get the speed about right.

And pics will be in this thread......

https://www.rc10talk.com/viewtopic.php?f=27&t=47027