***__ The 1/8 Onroad Think-tank __***

Originally Posted by Patrick

That's pretty damn quick. Have you gotten to see how it compares to some of those noisy cars?

Not yet. I hope to race it at our club against other 1/8 racers next Saturday. I will be sure to post the results.

I just need to work out when I will send my MGM 16018 back to have the latest software put on it. Now that I have the car up and running it's going to feel like an eternity while it's away.
I'm sure it will be worth the wait. At the moment if you mash the throttle going onto the back straight sometimes the speedy goes into reduce RPM mode, I hope the new software fixes this and the other little niggleing problems associated with these speed controls.

Here are a couple of pics under the hood. It's a bit agricultural (as I like to call it) but for testing purposes that is all I needed. The next stage will see a CNC'd engine mount with integrated heat-sink fins, and the aluminum battery tray will be replaced with a carbon fibre. The wiring is very messy atm and as you can see I have an Eagle tree data logger in there to monitor the current draw, engine RPM and temps while testing. The ducting over the speed control was due to help the speed control keep cool (I was testing in 35-38 Deg. C ambient) It also looks agricultural but did its job well.

[Sammus]

Wow that thing rips! nice work mate!

[pipeous]

sounds like a friggin jet coming down the front little straight. dam that's impressive. a few of us have been talking about building some 8th scale brushless on roads. now that looks like something that'll scare the pilot (can't call it driver at those speeds ;) )

[mwry13]

Originally Posted by squeeforever

Only reason I would use a 6S setup would be shear power in combination with high efficiency. With the high speeds needed, your gonna need alot of power. 6S setup will yeild more power as far as the batteries go.

Not necissarily...

Using higher voltage doesnt mean the car can go faster or produce more power... it just means its much easyer on amperage...

using a similar 4s setup you would buy a motor that is comparable to say a nitro cars RPM's

Using a 6s setup you would (assuming you want to "compete with Nitros") get a motor similar to RPM in nitro cars

The only difference is amperage difference and hence the price difference on speed controls... More voltage = less amps pulled ^_^

Both Setups are competative... a 6s setup would run a bit cooler but cost a bit more for the speed control

[Sammus]

Originally Posted by mwry13

Not necissarily...

Using higher voltage doesnt mean the car can go faster or produce more power... it just means its much easyer on amperage...

using a similar 4s setup you would buy a motor that is comparable to say a nitro cars RPM's

Using a 6s setup you would (assuming you want to "compete with Nitros") get a motor similar to RPM in nitro cars

The only difference is amperage difference and hence the price difference on speed controls... More voltage = less amps pulled ^_^

Both Setups are competative... a 6s setup would run a bit cooler but cost a bit more for the speed control

Don't forget about the batteries.. if you need say 2kw peak, then at 6s you will be drawing 90A and 4s 135A. So you need much bigger or higher quality batteries to get that peak. Then also there is run time issues, if you run 4s you will need bigger packs again to get the same runtime as the 6s.

[mwry13]

I hope he bought batteries better than say 15c ^_^

on that type car ide go Neu 30c Batteries

Originally Posted by mwry13

I hope he bought batteries better than say 15c ^_^

on that type car ide go Neu 30c Batteries

Yeah I'm using 3 X NEU 2s 25C 5000Mah packs. I brought THESE because I also use them in my 1/10 touring car.
I'm looking at down sizing the Mah to reduce the overall weight of the setup. I think I would be able to get away with something 6s and around 2500 Mah in 30C of course. Down side will be the reduced runtime upside is the car will be around 400g lighter.

[Sammus]

If these are just for the serpent then maybe http://www.hobbycity.com/hobbycity/s...idProduct=6421 would be nice. Some people don't like them because theyre cheaper and chinese made, but for around $100 for a 2500 6s pack you probably can't do much better. The seem to fit your size constraints stated earlier, it could mean making up a different mount though as you'd only need two. or do go a 3 pack setup they make them in 2s too, thin as well for lower cg.

[ziggy12345]

Originally Posted by Countryhick

I was using the available space under the top plate, extending out toward the body. Do you have a photo of your 835 with the cells in it?

I just want to reiterate that I need to be able to RACE continuously for 15 mins (10 mins. minimum) I'm not interested in just doing speed runs.

I have also found out that a high performance nitro engine out of a 1/8 can produce nearly 3HP. Is 2237.0996 Watts out of the question? Of course this would not be continuous.

A .21 circuit engine produces around 1.8 HP regardless of what it says on the box and thats at a very limited rev range. The torque f the motor is almost non existant. It would be comparable to a 1hp electric motor.

Cheers

[ziggy12345]

Originally Posted by mwry13

Not necissarily...

Using higher voltage doesnt mean the car can go faster or produce more power... it just means its much easyer on amperage...

using a similar 4s setup you would buy a motor that is comparable to say a nitro cars RPM's

Using a 6s setup you would (assuming you want to "compete with Nitros") get a motor similar to RPM in nitro cars

The only difference is amperage difference and hence the price difference on speed controls... More voltage = less amps pulled ^_^

Both Setups are competative... a 6s setup would run a bit cooler but cost a bit more for the speed control

Errr. Double the voltage means double the power. 14V x 100 amps is 1.4 Kwatts where 28v x 100 amps is 2.8 Kwatts.

I am getting the stuff together to convert my Evolva into electric. Like you i need the run time to be able to run 15 mins and have batteries that can be changed in 30 seconds. I can then compete against IC 1/8th cars

Cheers

Originally Posted by ziggy12345

Errr. Double the voltage means double the power. 14V x 100 amps is 1.4 Kwatts where 28v x 100 amps is 2.8 Kwatts.

I am getting the stuff together to convert my Evolva into electric. Like you i need the run time to be able to run 15 mins and have batteries that can be changed in 30 seconds. I can then compete against IC 1/8th cars

Cheers

Keep us updated with your progress. Got any pics or links?

[captain harlock]

Wow!

This thing is a rocket!

I just got my MRX-4X from Serum a few days ago.

I'm doing some tweakings here and there and I'm also waiting to get a nice highend motor with a good esc.

I haven't made much progress on the project, I have only just received my speed control back from MGM after having the latest firmware installed.
Attached are a couple of 3D drawings of my motor mount I want to have machined up. There are a couple of minor details missing from the drawings but they are the first drawings before revision.

Cheers Andrew

[ziggy12345]

Originally Posted by Countryhick

Keep us updated with your progress. Got any pics or links?

No not yet. I am concentrating on the speed event in September. I am looking for somebody to run a similar event in Australia. Interested?

Here is the link

http://lincit.myzen.co.uk/rcspeedfreaks/forum/