Hippie's GTP Project

[rchippie]

I just found there site . They have two new 60mm motors listed . One is 3100kv & the other was around 2200kv. They also had there 70 mm motors listed They went up to 2300kv .

[BrianG]

Oooh, 3100kv! Perfect for me.

IMO, the 2300kv 70mm would be perfect. Otherwise, the 2200kv 60mm would be my next choice. Actually, you might think this is crazy, but the 3100 60mm on 4s geared down would probably work quite well too. Yeah, it would be spinning close to 46k rpm, but that should be just fine. Would be taking a page out of Novaks book (use a smaller motor that revs high instead of a larger lower-revving motor). Might want to check Griffins motor calc to see where the efficiency starts falling.

[lincpimp]

Dang, the 70mm motors sell for under $125... You can't go wrong there.

I would like the 1200kv model to run 10s on, maybe with a pair of 5s rhino lipos... That would be a cheap setup, and pair it with lutach's 10s esc... Under $500 bucks for a hv car system!!!

[rchippie]

I just had my friend dave order me a OFNA ultra GTP . I will be using the medusa 70mm 2300 kv motor on 4s. What size pinion would be good. Im came up with this using a 13t pinion .


Differential Ratio: 3.142857142857143
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 49
Pinion Tooth Count: 13
Total Voltage: 14.8
Motor KV: 2300
Tire Diameter (inches): 4.5
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0
Spur/Pinion Ratio: 3.77 : 1
Total Ratio: 11.84615 : 1
Tire Circumference (inches): 14.14 inches (359.08 mm)
Total Motor Speed: 34040 RPM
Vehicle Speed: 38.47 mph (61.79 km/h)
Estimated Adjusted Speed: 37 mph (59 km/h) - 5% loss
Effective KV Value: 2300
KT constant: 0.59 oz-in/A
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...
Final Power: Amperage not specified...

[BrianG]

Well, the tires on my GTP are closer to 4.25", which will drop the speed to around 35mph. You can use a 14T pinion to get back up to ~37mph. I don't think you'll have any problems with a 15T (~40mph) or maybe even a 16T pinion (~42mph), if the vehicle is kept light. But, a 14T pinion is a good place to start.

[rchippie]

Well i ordered my GTP today. It will be here friday . I plan on using the RC-monster motor mount with a MEDUSA 70mm 2300kv motor on 4s flightpower lipo with a MM esc.

[BrianG]

Changed thread title per OP...

[rchippie]

Originally Posted by BrianG

Changed thread title per OP...

Thank you BRIAN .

[What's_nitro?]

These GTP kits are becoming quite popular. Not surprising since the rollers are pretty cheap.

Post some pics when you can, rchippie.

[rchippie]

I plan on using 5.5 mm plugs . Sinice the motor i will be using has a max amp draw of 100 amps. Does this sound good ?.

[What's_nitro?]

The 5.5mm plugs will work fine. I use them on the 1515/1Y in my GTP. They are rated for 150A constant. You could probably get away with 4mm plugs, but the less resistance the better.

[rchippie]

Originally Posted by What's_nitro?

The 5.5mm plugs will work fine. I use them on the 1515/1Y in my GTP. They are rated for 150A constant. You could probably get away with 4mm plugs, but the less resistance the better.

I knew they would be . I just like confermation on my descions .

[Arct1k]

Hmm I'm running a 1512 1Y 2650kv on 5s with 20/22T pinion.... I think i might be geared for a little more speed...

[rchippie]

Originally Posted by BrianG

The chassis brace connecting all the diffs was custom. I've found that the normal F/R braces that angle down to the chassis still allows flex. With the brace I made, there is MUCH less flex. The stock rear brace on the GTP attaches to the radio box. I imagine some type of custom brace will need to be done so it is on the other side of the driveshaft (otherwise would interfere with the motor). Pic showing the crappy rear brace layout:

Brian i found this upgraded brace .

http://www.nitrohouse.com/catalog/pr...6e0eaa933db736

[BrianG]

Those braces in your link are just upgraded versions of the stock setup - probably lighter. No matter what, you're gonna need to come up with a different rear brace scheme because that is right where the motor goes - unless you find another location for the motor somewhere...