Infraction Infraction V2 to Kraton 8s electronics upgrades Questions

[psychoswat]

Just got the infraction arrived in the mail today, pretty excited for the new project.

Looking to upgrade to the tried and tested K8s power system (firma 160/1250 kv) Not doing any speed runs just drifting and bashing, however would love to have just a little bit more top end speed.

What Sized pinion/spur would suits the best with my application, and diff oil choices?

Do I need the 49series motor plate from Arrma (ara320603) to mount the 1250kv motor to the infraction or does the stock motor plate will fit the motor? I have found this 50 series motor mount plate ( https://www.arrma-rc.com/part/ARA320538 ) from the option parts list for the infraction V2, wanted to know what motor is this one’s for.

Thanks in advance!

 

[SrC]

Its just me.....
Drifting and bashing with 6s is fine. I don't think you have tuned or dialed 6s enough yet for a "little more speed" and feel spending $$$ with 8s is the answer. And the Firma 8s gear is not all that. Perhaps the cheapest 8s way to go if you buy from JennysRC maybe. Are you stuck into the Spektrum Smart Eco "thing"? I think you are wasting time and money for a "little more speed" just to bash and drift. You will just eat more tires. What more do you expect to gain? You clearly wont speed run it! But hey its your wallet.
Use a gear calculator to find a suitable pinion. Have a complete set of pinions on hand to dial 8s. Can't cheap out on this. Its trial and error.
8S gear will make it much heavier. How is that an advantage for bashing and drifting? A little more smoke from the tires?

 

[psychoswat]

Its just me.....
Drifting and bashing with 6s is fine. I don't think you have tuned or dialed 6s enough yet for a "little more speed" and feel spending $$$ with 8s is the answer. And the Firma 8s gear is not all that. Perhaps the cheapest 8s way to go if you buy from JennysRC maybe. Are you stuck into the Spektrum Smart Eco "thing"? I think you are wasting time and money for a "little more speed" just to bash and drift. You will just eat more tires. What more do you expect to gain. You clearly wont speed run it! But hey its your wallet.
Use a gear calculator to find a suitable pinion. Have a complete set of pinions on hand to dial 8s. Can't cheap out on this. Its trial and error.

Yep just played around the gear calculator and had around 16.5k rpm with stock setup, if I want to stay within the ball park I would need a 20T pinion for about 17.5k rpm. Might go a little bit higher, but just worried about temperature issues as I live in a hot area. I have no problem on getting a set of pinions, it’s just that I had bad experiences with Arrma pinions they got extremely tight tolerances, I literally had to hammer it down on my bigrock and I won’t be expecting to get it out soon.

I got a bunch of Spektrum batteries and a DX5R for my Arrma rc’s, I guess I Am stuck into the smart eco thing they got. Not just Arrma, traxxas too

 

[vans5oh]

I currently have a limitless with the Infraction/Felony diff in it and the 8s system from my Kraton 8s. I am running all stock fluids in the diffs and with a 27T pinion I topped out at 79mph on 8s with and the hottest I saw the motor get was about 160F. It's a good setup and so far I am a big fan.

 

[psychoswat]

I currently have a limitless with the Infraction/Felony diff in it and the 8s system from my Kraton 8s. I am running all stock fluids in the diffs and with a 27T pinion I topped out at 79mph on 8s with and the hottest I saw the motor get was about 160F. It's a good setup and so far I am a big fan.

I expected a lot more with the 27T pinion on 8s good to know thank you. I am going to do a stock base run this weekend after the loctite is cured on the set screw and decides what to do with it.

Edit: may I ask were you using the v1 infraction/felony diff or V2, cuz v1 had a 50T spur 43 diff gear and v2’s had a 46 spur 42 diff.

 

[SrC]

Yep just played around the gear calculator and had around 16.5k rpm with stock setup, if I want to stay within the ball park I would need a 20T pinion for about 17.5k rpm. Might go a little bit higher, but just worried about temperature issues as I live in a hot area. I have no problem on getting a set of pinions, it’s just that I had bad experiences with Arrma pinions they got extremely tight tolerances, I literally had to hammer it down on my bigrock and I won’t be expecting to get it out soon.

I got a bunch of Spektrum batteries and a DX5R for my Arrma rc’s, I guess I Am stuck into the smart eco thing they got. Not just Arrma, traxxas too

I got ya. DX5R is no slouch. Smart friendly and all. I get it.
16k-17.5k Rpms should not run hot. You are not even pushing that motor. Barely. If you are not getting your motor to 40k-50k rpms ( any BLX motor), you are doing something wrong. Thats where more speed and torque is. 40-50k rpms.
Rethink your pinions. Arrma pinions are just fine enough for the 6s line of Arrmas. They are not the best. But work for me. Most of my pinion sets are Tekno's however. But they all fit the same. And you want them snug. I wouldn't compare a 4x4 Arrma pinion to any 6s line pinion. Not a fair comparison at all. I would recommend tweaking your current 6s setup better first. I think you can get much more out it as it is.

 

[vans5oh]

I expected a lot more with the 27T pinion on 8s good to know thank you. I am going to do a stock base run this weekend after the loctite is cured on the set screw and decides what to do with it.

I have not trimmed the aero on my limitless so that could still be slowing it down. When I calculate it out 27/46 and assuming the battery sags to about 3.8v per cell that gives me 80mph. I believe the internal gear ratio on the limitless is different than the Infraction so the top speeds will be different. I did try a 25T pinion and that top speed was about 70mph and the motor stayed cool to the touch and it seemed to be the sweet spot for bashing.

 

[psychoswat]

I got ya. DX5R is no slouch. Smart friendly and all. I get it.
16k-17.5k Rpms should not run hot. You are not even pushing that motor. Barely. If you are not getting your motor to 40k-50k rpms ( any BLX motor), you are doing something wrong. Thats where more speed and torque is. 40-50k rpms.
Rethink your pinions. Arrma pinions are just fine enough for the 6s line of Arrmas. They are not the best. But work for me. Most of my pinion sets are Tekno's however. But they all fit the same. And you want them snug. I wouldn't compare a 4x4 Arrma pinion to any 6s line pinion. Not a fair comparison at all. I would recommend tweaking your current 6s setup better first. I think you can get much more out it as it is.

Good to know that the 6s line pinions will be better than 4x4s, I got the ET48 2.0 kit as well waiting to be built, might get the Tekno’s pinion instead thanks for reminding me

50k rpms after spur and pinion, wouldn’t it work out to be 100k plus rpm at the motor?

I have not trimmed the aero on my limitless so that could still be slowing it down. When I calculate it out 27/46 and assuming the battery sags to about 3.8v per cell that gives me 80mph. I believe the internal gear ratio on the limitless is different than the Infraction so the top speeds will be different. I did try a 25T pinion and that top speed was about 70mph and the motor stayed cool to the touch and it seemed to be the sweet spot for bashing.

Thank you. Guess I will start with 23 and work my way up.

Did you need the kraton motor plate to mount it up?

 

[vans5oh]

Good to know that the 6s line pinions will be better than 4x4s, I got the ET48 2.0 kit as well waiting to be built, might get the Tekno’s pinion instead thanks for reminding me

50k rpms after spur and pinion, wouldn’t it work out to be 100k plus rpm at the motor?



Thank you. Guess I will start with 23 and work my way up.

Did you need the kraton motor plate to mount it up?

No. Just used the stock motor plate that came with the limitless.

 

[psychoswat]

No. Just used the stock motor plate that came with the limitless.

Okay cheers

 

[SrC]

I speed run my Lim with 28/34 6s ( 2 6s wired in parallel) I am getting consistently in the mid-high 90's. HW XR8/2250kv Sensored. I need more room distance. Hard to find where I am. But I have larger pinion combos to try. No smooth roads with space to run though.
I also tried 46 diff with 20pin. (500k center diff oil) F/R diffs with 15k. Also in the 90's ( low 90's)
Trim the rear wing Flat for sure. Must do this. Remove the front black Canards or trim them down completely also. It is worth another 3+ mph at least every time. Drag will increase amp draw. Also very important to drop Punch all the way down for speed running. Your ESC and lipos will thank you. You will struggle less to get more top end speed. More consistent passes. Always cool downs between runs. Fans, fans, fans.

Edited.

 

[psychoswat]

I speed run my Lim with 28/34 6s ( 2 6s wired in parallel) I am getting consistently in the mid-high 90's. HW XR8/2250kv Sensored. I need more room distance. Hard to find where I am. But I have larger pinion combos to try. No smooth roads with space to run though.
I also tried 46 diff with 20pin. (500k center diff oil) F/R diffs with 15k. Also in the 90's ( low 90's)
Trim the rear wing Flat for sure. Must do this. Remove the front black Canards or trim them down completely also. It is worth another 3+ mph at least every time. Drag will increase amp draw. Also very important to drop Punch all the way down for speed running. Your ESC and lipos will thank you. You will struggle less to get more top end speed. More consistent passes. Always cool downs between runs. Fans, fans, fans.

Edited.

May I ask where can I find those big server fans that people use in their speed run vehicles who ships to Australia? Might get a limitless for dedicated speed runs I’m tempted..

 

[SrC]

They are all over Ebay. Bangood, Aliexpress, AMZ.

 

[SrC]

I currently have a limitless with the Infraction/Felony diff in it and the 8s system from my Kraton 8s. I am running all stock fluids in the diffs and with a 27T pinion I topped out at 79mph on 8s with and the hottest I saw the motor get was about 160F. It's a good setup and so far I am a big fan.

8s and all you got was 79mph??? Topped out?
160F shoud be its limit for sure.

 

[vans5oh]

8s and all you got was 79mph??? Topped out?
160F shoud be its limit for sure.

If you calculate it out that setup should give a max speed of about 88mph. Its a 1250kv motor with a 27T pinion and 46T spur. That's assuming no voltage sag on the battery. If you assume the voltage sags to about 3.9v (which is fully reasonable) the calculated top speed becomes just under 82mph. Now include the drag from full aero and any friction losses or even just rough driving surface (the surface I ran on was not the best) then 79mph is fully reasonable. If I trimmed the aero, ran on a better surface, or even had some better batteries then I could have hit a higher top speed. Also, I did not have a super long run so it is even possible that the car didn't fully hit top speed. As for the temp 160F is perfectly fine. Most manufacturers recommend staying below 180F. I don't start to worry until I hit 170F. Plus that 160F was read after a few "speed runs" and some general bashing around. If that is as hot as that motor got then I am perfectly happy with that.