Hippie's GTP Project - RC-Monster Forums

rchippie · 09:27 PM

Im thinking about converting a 1/8 buggy based car. I have a couple of ?'s for those that have done it . What would be the best for racing single or 2 speed ?. Also what is the better car for racing . The ofna gtp or kyosho gt ?. I can get a used kyosho gt ( in very good shape) from my friend dave for $150.00 as a roller & it comes with a 2 speed . Then there is the ofna gtp with a single speed new for about the same price. There is also the ofne dm-1 spec a little pricy at $300.00 my cost . Im thinking i would use a MEDUSA motor on 4s. Which one would be the best choice ?.

lincpimp · 10.13.2008, 09:54 PM

I would go with the single speed if racing. My yusa with the 2 speed gets sideways when shifting under power. Fun when playing but i can see it being a big issue when racing.

By dm-1 do you mean the 1/7th scale car or the newer, shorter one with the std rear shocks and the pushrod front shocks?

rchippie · 10.13.2008, 10:06 PM

Quote:

Originally Posted by lincpimp

I would go with the single speed if racing. My yusa with the 2 speed gets sideways when shifting under power. Fun when playing but i can see it being a big issue when racing.

By dm-1 do you mean the 1/7th scale car or the newer, shorter one with the std rear shocks and the pushrod front shocks?

The newer shorter one. What medusa on 4s would be goog for this project ?. I cant afford another neu

.

Arct1k · 10:14 PM

60 - 2000kv should be good...

I'd love the DM-1 but not sure how easy to convert - the kyosho gt I thought was no longer made - A GTP2 would be easiest and parts are pretty easy as a lot is shared with the new LX1/MBX...

lincpimp · 10.13.2008, 10:17 PM

Quote:

Originally Posted by Arct1k

60 - 2000kv should be good...

I'd love the DM-1 but not sure how easy to convert - the kyosho gt I thought was no longer made - A GTP2 would be easiest and parts are pretty easy as a lot is shared with the new LX1/MBX...

I agree with the motor choice, that would be the best bet. Only thing I do not like about the gtp are the k-sereis diffs. Not the best bet. Wish they had an upgraded jammin version with hyper diffs...

rchippie · 10:24 PM

Quote:

Originally Posted by Arct1k

60 - 2000kv should be good...

I'd love the DM-1 but not sure how easy to convert - the kyosho gt I thought was no longer made - A GTP2 would be easiest and parts are pretty easy as a lot is shared with the new LX1/MBX...

They now make the gt2 . But my friend has a gt in real good shape . Do you agree with linc that the single speed would be better for racing, than the two speed ?. The only way i can get the gt2 is to buy a rtr kar . whick i would rather not do .

Arct1k · 10.13.2008, 10:25 PM

Well I have the single speed pretty good - To be honest I have no issue with torque because of the brushless (1512 1Y). The only thing I wanted a two speed for was more top end speed. 60-70+...

But then I'd have all the pain of pinions etc so for me single speed I think is fine... I just need to get my but into gear to paint my new 350z body...

rchippie · 10.13.2008, 10:46 PM

Quote:

Originally Posted by Arct1k

Well I have the single speed pretty good - To be honest I have no issue with torque because of the brushless (1512 1Y). The only thing I wanted a two speed for was more top end speed. 60-70+...

But then I'd have all the pain of pinions etc so for me single speed I think is fine... I just need to get my but into gear to paint my new 350z body...

Would the motor you recomended still be good with a single speed ?.

BrianG · 10.13.2008, 11:06 PM

I ran my GTP the other day on 4s (set up for 10s, but the cells aren't in yet), and even though it wouldn't get fast enough to shift, it was really hard to keep from spinning those tires. Then, this evening (in between bouts of rain), I made up a quick-n-dirty harness to tie 4 2s packs together just to see. Well, I got it to shift all right, and what people say about on power shifting is correct; all 4 tires broke loose and started to fishtail. Was able to get it under control, but barely. Man, this thing was FAST (no GPS or radar to verify)!!! I'm sure the damp road conditions didn't help.

If you go with the 2 speed, make sure you have really sticky tires. It might help to keep the difference in ratio closer together so there isn't such a drastic change in rpm/torque when it shifts.

rchippie · 10.13.2008, 11:16 PM

Quote:

Originally Posted by BrianG

I ran my GTP the other day on 4s (set up for 10s, but the cells aren't in yet), and even though it wouldn't get fast enough to shift, it was really hard to keep from spinning those tires. Then, this evening (in between bouts of rain), I made up a quick-n-dirty harness to tie 4 2s packs together just to see. Well, I got it to shift all right, and what people say about on power shifting is correct; all 4 tires broke loose and started to fishtail. Was able to get it under control, but barely. Man, this thing was FAST (no GPS or radar to verify)!!! I'm sure the damp road conditions didn't help.

If you go with the 2 speed, make sure you have really sticky tires. It might help to keep the difference in ratio closer together so there isn't such a drastic change in rpm/torque when it shifts.

Thank's for chiming in brian . If thats the case maybe i'll just get a single speed car. It's looking like the ofna gtp is the leading canadit . since my friends kyosho has a 2 speed that i would have to lock in gear . I can get a really good price on the gtp . Do you agree with the MEDUSA motor recomended eairler in this thread . This would be run on 4s .

60 - 2000kv should be good...

BrianG · 10.13.2008, 11:23 PM

People say the 60mm will be fine, but I personally would go with the 70mm version when it comes out. The GTP is a fairly heavy vehicle (at least mine is) and geared tall enough to hit higher speeds with one gear will put a decent load on it.

Again, for something that will be going fast, I would probably mate a 2000 kv motor with 5s. For 4s, I would run a kv of ~2500. I like higher rpms when geared tall, because the ESC may have trouble getting rotor position on take-off, which may cause cogging. A faster motor geared right should take off smoothly and have decent top end. The Medusas are rated upwards of 60k rpm, so 40k+ should still be well into the efficiency range.

rchippie · 12:08 AM

Quote:

Originally Posted by BrianG

People say the 60mm will be fine, but I personally would go with the 70mm version when it comes out. The GTP is a fairly heavy vehicle (at least mine is) and geared tall enough to hit higher speeds with one gear will put a decent load on it.

Again, for something that will be going fast, I would probably mate a 2000 kv motor with 5s. For 4s, I would run a kv of ~2500. I like higher rpms when geared tall, because the ESC may have trouble getting rotor position on take-off, which may cause cogging. A faster motor geared right should take off smoothly and have decent top end. The Medusas are rated upwards of 60k rpm, so 40k+ should still be well into the efficiency range.

I only have a 4s pack & would rather not buy a new pack . My buggy uses a 2550 kv motor on 4s & runs great . Do you know when the 70mm medusa's are going to be avalible ?. Also i noticed your gtp2 has a chassis brace connected to the diff's not the chassis . The gtp car has a rear chassis brace connected to the chassis that looks a little different than normal bracs. Will this cause a problem wtih mounting a motor ?.

BrianG · 10.14.2008, 12:03 AM

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:

rchippie · 12:13 AM

Brian i just looked at the medusa motor on your calculator . The 60mm motor only goes up tp 2000 kv. Do you know if they make a larger kv motor ?.

BrianG · 10.14.2008, 12:13 AM

Not that I know of. That's one of the odd things about Medusa; their kv ratings don't go high enough for each range of motors IMO. For instance, I'd like a 60mm one for my Slash running on 3s, but the kv as you see only goes to 2000. I have to step down to a 50mm to get the kv I want. I'm sure it'll be fine but...

I would wait to see what others say though. I've never run a Medusa, but the little I saw the wires seem kinda thin compared to Neu or even Feigao. They seem to run ok though. For $100, I suppose you could run the 60mm 2000kv on 4s and see how it goes. If their present models are any guide, their 70mm motors will probably only go up to 1200-1500kv.