OFNA Ultra GTP-2e Build

Me too.  I've got the wing mounted now and it makes the car look more balanced having some carbon fiber look on both ends.
I've learned a lot from this paint job and next time I think my "carbon fiber" will look even better.

I got a Mercedes CLK-GTR body now too.  I plan to add headlights and taillights on that body for some night racing.  I have an idea for a way to make some inexpensive track lights also that I am going to prototype in a week or so.  I need to locate some heavy (weighted) bases maybe 12 inches in diameter or less but they will need some taper to the outer edges so in case a car hits them.  If anyone has some ideas let me know.

Nice paint ... I like a good road racer

Thank You w00d.

The car is complete now. Here are a few photos before I take her out to maiden drive her.

Here is the completed cars insides.

We're off to the middle school on Harbeck. Cowabunga!

Your most welcome GP ...

Help a noob out will ya w/ a few quick questions ... and my apologies if already answered
[list type=decimal]
[*]Would you mind giving me the links for your little beastie, retailer and/or manufacture?
[*]What scale are we talking about here 1:8 maybe, a rough estimate of teh size would be cool? Just in case the links don't help
[*]I'm darn curious to, how did you get that Carbon Fiber (CF) look?
[*]Got any recommendations as to which manufactures I should be looking at?
[/list]This one has me interested in buying. Not your car specifically but one in this scale. However I won't guarantee I'll NOT copy that CF look {LOL}. As I said "I likes a good ROAD racer" especially a GOOD looking ONE

Thanks in Advance
    [glow=blue,2,300]w00d[/glow]

First Driving Impression: OFNA Ultra GTP-2e.  I ran the car for the first time yesterday at the school on Harbeck.  On my first battery after I ran a couple laps with my girl running her E-Maxx Brushless Edition I thought the OFNA Ultra GTP-2e would be faster.  It was pretty fast but compared to her E-Maxx I was expecting more from the car and the Mamba Monster system.  I brought the car in to check out the motor temperature and noticed that the brakes were very aggressive, not proportional much if at all.  I remembered that when I setup the car on the bench and bound the Futaba R603FS receiver to my Futaba 4PK radio that the car ran in reverse so I simply reversed the settings on the transmitter and I thought all was good.  Now on the track it felt that I could be going faster.  So I switched two wires on the brushless motor and reversed the transmitter back to the original position.  Wow, big difference!  The car screams, fast and powerful and now my forward braking is proportional and very nice.  Considering I eyeballed the sub-trim on the steering when I set the end points the car ran perfectly straight, no more trim needed.

I am using Gen Ace 4S 5000 mAh batteries that are 40C rated.  Did I say the car is fast?  The car handles like a dream.  You can stay on the throttle a lot in the curves but punching it a little early in the apex and you will drift.  I can tell that this car will use a lot of tires if you get too crazy on the throttle and brakes.

Around the time my girl finished her first set of batteries in her E-Maxx (twin 7 cell Traxxas 3000 mAh) I decided to come in to check temperatures and verify nothing had worked itself loose.  The motor was quite warm, but not so hot you could not hold your hand on it.  I really need to get a temperature gun.  After checking the car and my wheel nuts I went back out still on the first battery.  I figure I am getting at least 12-15 minutes of run time from these batteries and they perform very well.  At the end they quit pretty abruptly, meaning the warning that the battery was low was subtle before what may be the ESC LiPo cutoff kicking in and the car just stopping.  I wouldn't want that to happen in a race with other cars tearing around with me.  I will run another couple charges and time them to figure out a timer setting for my radio so I can pit before the LiPo cutoff kicks in hard like that.

I used the Futaba BLS157HV brushless servo in this car and it is super fast.  The steering is very quick and precise.  Even on high G-Force turns I could do steering corrections and angle changes easily.  So far I am very happy with this servo.

The car handles extremely well.  Even on hard fast turns I never saw or felt like I would roll.  I can get some suspension lean going into turns but overall I will say that the car keeps level.  Hard braking will dip the nose a bit but breaks applied into turns does not dip the nose much and the car seems to brake front to rear very balanced.

I am very pleased with this car!  I can see it becoming a favorite already.

I wish I had let the paint cure another 24 hours before running the car fast in a parking lot.  I have some small pitting on the inside of the door sills that I feel would have been avoided, but overall the paint still looks great and I am happy my body height and wheel well cutouts were accurate and I did not have any rubbing of the tires or the ground, even on hard turns.

Pile of Toys - I checked the bottom of the chassis at the end of the day and no scrapes of the aluminum chassis pan!  I was concerned that I would be scraping on the ground or stones and debris.  The car is low, but not as low as a on-road car like a X-Ray or Schumacher.
I may still take you up on the number plate background, but so far I can report that rubbing or scraping is not a issue.

This car fully loaded is pretty heavy and it goes really fast.  When I approached turns and got off the throttle I could hear the tires working hard and I can see that tires will be one of the most expensive aspects about running this car a lot. 
One thing I have not mentioned in my build part of this thread is the tire assembly.  These are the most complicated tire and wheel assemblies that I have ever built.  The wheels are one piece, but the tires are three pieces: The actual tire, and two foams that are flat strips, not donuts like we are used to on off-road cars and trucks.  You have to wrap a smaller strip around the wheel in between two vertical fins in the wheel, cut off some excess and glue the foam ends together.  Then you have to take the second larger foam and wrap it around the first foam and wheel and also glue the ends together.  The trickiest part for me was getting the tire over the foams.  The outer foam wants to roll and twist whle stretching the tire over it.  I had to pull and tuck and pull and tuck my fingers all the way around the wheels to get the foams flat.
This is not nearly as complicated as some of the tire work Highlandcrawler has done on his crawler tires, but it was all new to me never having to assemble tires like this.  The final result was a very good tire as the foams can get right into the sidewall of the low profile tires and I feel this attributes to the great cornering, but it is a lot of work getting the tires and foams together and balanced that there are no "lumps" of foam rolled up under the tire.

Overall I feel this is a great car and I can highly recommend it to anyone wanting to get into 1/8 scale on-road.  Even if I am the only one running this car I expect to have a lot of fun with it tearing up the parking lots.

Your most welcome GP ...

Help a noob out will ya w/ a few quick questions ... and my apologies if already answered
[list type=decimal]
[*]Would you mind giving me the links for your little beastie, retailer and/or manufacture?
[*]What scale are we talking about here 1:8 maybe, a rough estimate of teh size would be cool? Just in case the links don't help
[*]I'm darn curious to, how did you get that Carbon Fiber (CF) look?
[*]Got any recommendations as to which manufactures I should be looking at?
[/list]This one has me interested in buying. Not your car specifically but one in this scale. However I won't guarantee I'll NOT copy that CF look {LOL}. As I said "I likes a good ROAD racer" especially a GOOD looking ONE

Thanks in Advance
    [glow=blue,2,300]w00d[/glow]
[/quote]


While you were posting I added my first driving impression of the car.  In that post are all the components I used with links.  Let me know if I missed anything, or if I can help further on my build components.
The car measures approximately 23.5 inches long by 12.5 inches wide with the body mounted.  It is a 1/8 scale size car.  I will post some photos of it soon with other cars and trucks and maybe a helicopter for scale and size comparison.
I like OFNA's stuff a lot.  I also own their OFNA Hyper 10SC short course truck and it handles better that any other short course trucks I have driven.  I am no expert and have not driven them all, but my Hyper 10SC is a great truck and a terror on the dirt.  I can whole heartedly recommend OFNA's cars and trucks.

The way I did the carbon fiber paint job was to first paint a coating of Pactra brand "Window Tint" paint on the masked off hood and front air splitter.  I did this un-evenly so I could get that effect that carbon fiber has naturally in that the lighter weave is not perfectly even across the span of most surfaces.  Next I used some of that rubberized shelf covering laid over the window-tinted area and sprayed Pactra "Indy Silver", again un-evenly.  This gives a checkerboard-ish effect of silver squares.  Last I sprayed a coat of Pactra "Outlaw Black".  This is all done on the inside of the clear body.  I used the Pactra rattle can paints for the entire paint job.

BTW: I robbed the shelf cover from a kitchen drawer and my girl didn't notice yet...shhhhhhhh.

That's great as there's more than enough info in your "First Driving Impression" post ... {LOL} I had thought to myself "WOW what a great price" but then I noticed it does not include the ESC/BEC, motor nor teh battery ... Is 4S typical for this size car or was it something you wanted to do for the horse power and speed?

I think 4S is common for this type of car.  The ESC can go up to 6S and I'm sure 2S or 3S will move the car, maybe 2S would be a little slow, I will try it one time and see for myself.  I suspect 3S would be acceptable and maybe wear the tires less.  With 4S I have a very good performance and I feel I am not stressing the car very much.  The car is heavy and weighs at least as much as my girls Traxxas E-Maxx Brushless Edition (4.36 kg/9.59 lbs) which I think has the exact same motor and ESC.  She is running factory dual 7 cell NIMH 3000mAh batteries which comes to 16.8 volts as they are in series so I think I am operating at a very acceptable level at 4S, 14.8 volts.  I intend to also try 6S to see what that is like, but judging from the performance I have at 4S I think 6S will be too much and seriously wear on the tires.

I think if others had the same car regardless of motor and ESC combo the battery selection would be a good way to establish classes for racing.  This car has a roomy battery tray that will be able to accommodate somewhat physically larger batteries than my 4S Gen Ace batteries.

I just test fitted a ThunderPower 6S 5000 mAh (P/N TP5000-6S45) and width-wise there is still some room in the battery tray but the battery is slightly too long, however there are three velcro straps and I am sure they would hold the battery securely enough for a test run.  You may remember I purchased this battery for my JR Vibe 500e helicopter only to discover it didn't fit so it's brand new and unused on a shelf looking for something to do. 

I was wondering how that would handle,they are heavy.My OFNA nitro GTP has never rolled-never. I hasn't been ran much,and never has been dialed in.It spins out before getting close to rolling, but it is fun to drift an 1/8 scaler.=Good times ahead for you 8)

The handling is simply amazing.  You know what?  Until you said it I hadn't thought about spinning out.  I never spun the car on neither battery of the maiden run tests.  Is your OFNA 4WD?

ya=4wd-it could use some tuning (breaks).The down side to "gas" is the exhaust being sprayed onto the back wheel.I should put an exhaust tip on it too.

Thanks again GP ... As always more info than requested which as always is a GOOD thing and being something I always appreciated ...

Given the info you gave me I must agree - 6S would not only be hard on the rubber but also hard on the rest of the mechanics and not least the motor. Wouldn't be easy keeping her stuck to the road, I mean not without loosing traction ...

... Lots-o-Power is great at the top end no so at the bottom, would need to work on the "gearing" to get the perfect tune

    [glow=maroon,2,300]w00d[/glow]

The guy in this video got 97 MPH out of 4S LiPo, but I don't know what gears he used. I am using a 14 tooth pinion and I think my temperatures and acceleration are good for on-road style racing. For straight line drag racing and high speed runs maybe a 16 tooth pinion or even more would be necessary. On top of that 6S would just make this thing a animal!

Too much power off-the-line could also be an issue with the BAJA 1:5. I've been told on
good authority the clutch that ships with my BAJA is the 8000rpm clutch which could/will smoke
the wheels off-the-line if one is too aggressive on the throttle. Which by the way also looks
great in it's advertising!! For the BAJA that ships with the 6000rpm clutch which is a less
aggressive clutch this is somewhat less of an issue ...

... So again dependant on what the driver needs from his car he would have to look carefully
at what he needs from his car thus clutch. Will he for example be Drifting, Smash'em-Up,
Drag Racing (but not to confused with teh troupe of drag queens at Track'n Field) or just
crapin about his backyard etc etc etc ......

The clutch is a issue with gas/nitro cars and trucks. You don't move until you hit the engage RPM. Our electrics don't have that problem and we get to regulate our output with the throttle finger....now if we could get the run times that gas/nitro cars enjoy there would be no comparison and I bet gas/nitro would cease to exist.

I followed your link and watched the video on that page. I am no Mini Cooper fan but very cool work.

{LOL} I remember riding around in the original Mini Copper (yeah I'm dating myself now) but they sure were a blast until we got next to a SEMI ... Boy-O-Boy DID we feel small then {LMAO}

As for your video, yeah that certainly a cool ride. I wouldn't say no to one if offered one ....

How Big Is It?

A lot of people who have not seen the OFNA GTP-2e in person have asked me how big it is. Here it is on the left with a Traxxas Slash 2wd (middle) and a OFNA Hyper 10SC on the right. In the front is a E-Flite Blade mCX for you helicopter guys.

Tire Autopsy

On my last run of the OFNA GTP2e car one of the front tires came unglued in one spot on the outside sidewall and I could feel a lump in that area inside the tire.  Obviously the foam has bunched up and caused the lump but I could not tell how.  Today I got the tires outside sidewall to separate from the wheel and after folding the tire over inside out to the wheel inside I could now see that the foam had come unglued and bunched up.  While at the race track I had originally thought that the foam had rolled from the inside of the wheel towards the outside but that was not the case.  The foams are strips that need to have the ends glued together and the ends had become unglued and one end of the foam pulled back and got bunched up, probably from the centrifugal force of the wheel spinning.  I was able now to glue the ends back together and re-glue the tire back to the wheel.

I want to try and find a one-piece foam solution so I don't have to glue two different strips of foam together for these tires, but after searching around and looking at some foams from ProLine, AKA and others it could end up costing another $14 per four wheels to the cost of the already costly tires and wheels.

If anyone has some ideas, or knows of sources of good one-piece tire foams that are suitable and low cost, please let me know.

On the other hand I think I figured out a better way to assemble these tires with the stock two piece foams.  If I stretch the tire over the wheel without the foams installed and only glue the inside rim after the glue dries I should be able to fold the tire inside-out, glue the two foam strips, and then fold the tire over the foams.  Theoretically I should be able to do this and not cause the foams to roll as they did when gluing the foams and then stretching the tire over them.  I plan to try this method on my spare tires tonight or tomorrow.  I'll let you know how that works out.

It sounds like the foam separates when the tires balloon.
It stands to reason if you take steps to minimize the ballooning, that could help preserve the foam.


I've become sold on the notion that filament tape can be beneficial in spite of the little bit of added weight. Applying a tape belt to the foams will still allow the tires to balloon. Applying tape to the tire will limit the ballooning and "may help" to keep the foam from expanding too much.