Whats the best gearing

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I ran the typhon last Sunday morning and as it was going pretty fast I tried to give it more throttle and it flipped right over,I'm surprised it has soo much power still at high speed. It has a lot of power on bottom still, wonder how much more gear I can give it.
 
I ran the typhon last Sunday morning and as it was going pretty fast I tried to give it more throttle and it flipped right over,I'm surprised it has soo much power still at high speed. It has a lot of power on bottom still, wonder how much more gear I can give it.
More gear is gonna make it flip more.
 
I can't really comment on your motor/ESC combo as I've no experience of that set up.

I use an "RC calculator" to give me a rough idea of possible top speeds of my speed run builds with different KV motors, gearings and batteries. It doesn't take into account all factors (like drag, rolling resistance etc) but as I said it does give a rough idea.
Going off the KV motor you're running on 6S and assuming you're using suitable speed running tyres (GRP - 98mm) then with a 35T pinion/40T spur gear your top speed would be around 103mph.
Link to RC speed calculator: http://www.radiocontrolinfo.com/information/rc-calculators/rc-car-calculator/

FYI your previous set up of a 27T pinion and 46T spur works out to be 69mph odd.
If you want to try it out for yourself on the RC calculator you'll need to add the values for your diff of 13T pinion and 43T spur together with the tyre diameter you're running.
Tyre diameter/weight thread here: https://www.arrmaforum.com/threads/my-tire-weight-list.15771/

If you want to have a look at my Typhon 6S speed runner then just click on my "Build Thread Contributor" banner to see my build thread. (y)
Hi , Not trying to steal this thread but
I tried this rc car calculator and i am not sure i am doing this correct , looks to be a little extreme ???
 

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Hi , Not trying to steal this thread but
I tried this rc car calculator and i am not sure i am doing this correct , looks to be a little extreme ???
2700kv is quite high for 6S. That’s going to over rev that motor at 68k rpm. But, I doubt you even get the motor up that high in reality due to aero holding you back. I would try a lower KV motor with more torque.
 
2700kv is quite high for 6S. That’s going to over rev that motor at 68k rpm. But, I doubt you even get the motor up that high in reality due to aero holding you back. I would try a lower KV motor with more torque.
Hi This is a CM Motor rated for 75 thousand rpm for 6s
I have gearing on my Slash 4X4 with a known MPH and that one as well is incorrect, o well
 
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my 2wd slash cant turn, so idk. but i do know that there are gearing charts for some vechiles, and if u r flippin ur truck then get a wheelie bar
 
my 2wd slash cant turn, so idk. but i do know that there are gearing charts for some vechiles, and if u r flippin ur truck then get a wheelie bar
A wheelie bar isn’t really gonna help going above 70... if the front lifts, the truck lifts... wheelie bar or not.
 
my 2wd slash cant turn, so idk. but i do know that there are gearing charts for some vechiles, and if u r flippin ur truck then get a wheelie bar
2wd Slash with motor at rear behind the axle def needs a WBar as a start. (y) Like @Peeeenuuutt said maybe Wbar is insignicant at thigh speeds. Work on some aero downforce to accomodate?
 
That for sure lol. A brushed 12t would wheelie it.

Lead weight on the front of the truck is the best known solution- if it’s a last resort.
Front end ballast. (y) A cross weight digital scale sets them up best. Body aero. is very important. Don't overlook the obvious.:)
 
I tried this rc car calculator and i am not sure i am doing this correct , looks to be a little extreme ???
Yeah you should always take those calculators with a pinch of salt. ;):LOL:

There are so many variables these calculators don't and can't take into account like; vehicle weight, aero dynamics, rolling resistance etc etc.
 
Yeah you should always take those calculators with a pinch of salt. ;):LOL:

There are so many variables these calculators don't and can't take into account like; vehicle weight, aero dynamics, rolling resistance etc etc.
It is there for a rough guestimate. Real world expectations are always different. Even varying Barometric pressure and ambient temps affect aerodynamics at any given time. (y) Scale racing has proven this.
Simple nuts and bolts placed strategically with Hot glue works. I use scale tire stick on weights. I have a bunch lying around recycled from my truck rims. And a scale weight system gets it precise without "overweighting" your rig. Weight bias and proper aero. is the key to good speed running.
 
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Hi , Not trying to steal this thread but
I tried this rc car calculator and i am not sure i am doing this correct , looks to be a little extreme ???
I like to steal threads :ROFLMAO:

That looks about spot on for what the calculator tells you.
Keep in mind you loose some percentage of wattage to heat, some to efficiency, and consider voltage drop.
Then there is aero drag which is the biggest contributor.
All in all I see ranges of 70-84% of the calculated speed. The faster you are going the lower in that range...

My new theory is take the KV * voltage and multiply by the percentage
2700kv * 21v (after voltage drop) = 56,700 * 72% = 40,8xx rpm

That sounds just about right to me. I have found most speed runs peak around the 36-42k rpm range.

205mph * 72% = 147mph
 
I like to steal threads :ROFLMAO:

That looks about spot on for what the calculator tells you.
Keep in mind you loose some percentage of wattage to heat, some to efficiency, and consider voltage drop.
Then there is aero drag which is the biggest contributor.
All in all I see ranges of 70-84% of the calculated speed. The faster you are going the lower in that range...

My new theory is take the KV * voltage and multiply by the percentage
2700kv * 21v (after voltage drop) = 56,700 * 72% = 40,8xx rpm

That sounds just about right to me. I have found most speed runs peak around the 36-42k rpm range.

205mph * 72% = 147mph
(y) That sounds good and makes sense. Your % numbers are conservative. That comes with much experience as I can see.(y)
 
(y) That sounds good and makes sense. Your % numbers are conservative. That comes with much experience as I can see.(y)
Majorly unknown. Aerodynamics plays a massive part of that equation.
I am anxious to test different motors. We know lower KV has more torque, but if you can gear down to reach the same speed then gearing provides torque back.... All things I'd like to have some solid data on.
#nerd

I have some data on the BLX system in the Typhon 6s

BLX system tests Capture.JPG
 
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I like to steal threads :ROFLMAO:

That looks about spot on for what the calculator tells you.
Keep in mind you loose some percentage of wattage to heat, some to efficiency, and consider voltage drop.
Then there is aero drag which is the biggest contributor.
All in all I see ranges of 70-84% of the calculated speed. The faster you are going the lower in that range...

My new theory is take the KV * voltage and multiply by the percentage
2700kv * 21v (after voltage drop) = 56,700 * 72% = 40,8xx rpm

That sounds just about right to me. I have found most speed runs peak around the 36-42k rpm range.

205mph * 72% = 147mph
Cool Thanks, hopefully soon i will find out ??
 
Back to the original thread, how much lower of a spur gear should I go with the typhon,I'm at 35 pinion and 36 spool and have lots of power all around, but want to drop to a 30 or 32 spool gear and see what it does,anyone else done this setup?
 
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