Limitless drag gear ratio

[Big Reece]

Hello all,

I am new to the Rc drag scene. Can anyone help me with what a good gear ratio would be for a limitless in the 182 ft world??? I am running a killmode 2900kv motor with an Xlx2 esc. Thanks

 

[Harry infraction]

40/40

 

[Edough13]

For the longer passes you want to gear for right about 80mph I believe. Are you running stock 13/43 diffs and Hoons? Or are you running 15/42 diffs and different tires etc? Also are you running 6s, 8s, if your running 6s and run stock diffs I'd suggest about 20-22t pinion and 46t spur which is right about 80mph on 6s with stock 100mm tires and 13/43 diffs. @jondilly1974 would be more help as he has spent quite a bit of time dialing in his drag setups.

 

[Harry infraction]

40/40 maximum 3s

 

[rotauq]

40/40 maximum 3s

40/40 is an odd proposal. 34/34 is the same and uses standard gears. But like @Edough13 already said, it also depends on the F/R diffs and what tires you use.

Hello all,

I am new to the Rc drag scene. Can anyone help me with what a good gear ratio would be for a limitless in the 182 ft world??? I am running a killmode 2900kv motor with an Xlx2 esc. Thanks

Killmode 2900kv is running 6S i assume?

 

[jondilly1974]

Hello all,

I am new to the Rc drag scene. Can anyone help me with what a good gear ratio would be for a limitless in the 182 ft world??? I am running a killmode 2900kv motor with an Xlx2 esc. Thanks

182ft is new to me. We usually run 132ft or 188ft. But it should be the same setup as a 188ft. You want to get a gear calculator app on your phone and plug in your setup and get it geared for 80-85mph. Then let her rip.

 

[Big Reece]

182ft is new to me. We usually run 132ft or 188ft. But it should be the same setup as a 188ft. You want to get a gear calculator app on your phone and plug in your setup and get it geared for 80-85mph. Then let her rip.

Thank you! I meant to type 132 ft

For the longer passes you want to gear for right about 80mph I believe. Are you running stock 13/43 diffs and Hoons? Or are you running 15/42 diffs and different tires etc? Also are you running 6s, 8s, if your running 6s and run stock diffs I'd suggest about 20-22t pinion and 46t spur which is right about 80mph on 6s with stock 100mm tires and 13/43 diffs. @jondilly1974 would be more help as he has spent quite a bit of time dialing in his drag setups.

I have the stock diff and foam tires

 

[Edough13]

Ok so like I said if your running the 46t center diff I'd start at 20t pinion on 6s

 

[rotauq]

Thank you! I meant to type 132 ft

I have the stock diff and foam tires

With that motor on 6S your rpm would likely hit near 50k.
Hitting 80-85mph would indeed be ~22P/46S with the diff and with a spool you could probably do 17P/34S. As i believe, with or without center diff is distinctive preference whiles dragracing.

 

[jondilly1974]

Ok so like I said if your running the 46t center diff I'd start at 20t pinion on 6s

He’s gonna need a smaller pinion than that for 132ft pulls. Probably between a 13-14T is the sweet spot.

 

[rotauq]

He’s gonna need a smaller pinion than that for 132ft pulls. Probably between a 13-14T is the sweet spot.

13P/46S would be topping out on ~55mph, so thats the aim topspeed for 132ft?

 

[jondilly1974]

13P/46S would be topping out on ~55mph, so thats the aim topspeed for 132ft?

.

 

[rotauq]

View attachment 164016
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Yeah you're probably right. I used my speedrun sheet, predicting more voltage sag and efficiency drop. With such low gearing it acts different

 

[jondilly1974]

Yeah you're probably right. I used my speedrun sheet, predicting more voltage sag and efficiency drop. With such low gearing it acts different

It all depends on whether or not that 2900 will really make 69k RPMs. I know it’s rated for 75k, but reality might be different. I’ve never owned one myself.

 

[rotauq]

It all depends on whether or not that 2900 will really make 69k RPMs. I know it’s rated for 75k, but reality might be different. I’ve never owned one myself.

I own an almost similar TP 2700 (cm) and it never ran above 85% efficiency, even on medium load.
That's why i estimated 50k rpm on 6S. Drag is geared very low, so maybe ~58k max.
69k will only be free spinning.

 

[jondilly1974]

I own an almost similar TP 2700 (cm) and it never ran above 85% efficiency, even on medium load.
That's why i estimated 50k rpm on 6S. Drag is geared very low, so maybe ~58k max.
69k will only be free spinning.

If that’s the case then the 14/46 should work well for 132ft pulls. I try to gear for 80mph on 188ft pulls, so I’m thinking 70mph for 132ft is where I would start.

 

[flynlw]

Was wondering, could one use the tp nokill 2700 for speed runs? What gears would you recommend with the xl2x?

 

[jondilly1974]

Was wondering, could one use the tp nokill 2700 for speed runs? What gears would you recommend with the xl2x?

6S? 8S? What car? Which diffs? What tires? What’s your speed goal?

 

[flynlw]

6S? 8S? What car? Which diffs? What tires? What’s your speed goal?

, so it’s a carbon 3.0 4tec chassis. It’s gonna end up as a drag, but still waiting for pulleys from China. So thought I’d try speed running it for a minute.

 

[Hookedup]

Try 22/42.. i have no idea where these other ratios came from.. seem way off to me