A 1/10 nitro car that runs like a bullet
Nov 07, 2006
 

The completed chassis with the Mugen/Novarossi MT12 and an RB pipe. This chassis is so similar with the new Kyosho Mk3 that I think that there must be some kind of joint venture between the two manufacturers.

I went on a business trip to the US (S.Diego) and I know that South California is some sort of RC paradise. This Mugen and the Serpent Impulse were racing in my head against each other for some time. None of them was winning and I had to find a solution for the dilemma.

Some time ago, RC Car Action had a special number about nitro cars, and the Mugen was on top of the ranking. The Impulse won the Nitro car of the year and this was not helping. However the few drawbacks of the Serpent were enough for me to go with this car. I bought it from Ace Hardware Hobbies, and I have to say that their service is 1st class. They sent me the car to the hotel in 2 days, with all the spares I asked. BTW the spares are so cheap that I couldn't believe it.

Here I am ready to burn asphalt with this screamer. Let's see how it goes.

Building

The car comes equipped, among other top features, with threaded shocks, pivot ball suspension, 3 shoe clutch and 2 speed gearbox.

The chassis is very thick, with recessed screw holes. The edges of the chassis is sharp, but I didn't cut myself building it. 

The top deck is molded fiber reinforced plastic of a very high standard. All the other plastic items are of the same material and they seem to withstand punishment due to their sturdy appearance. All the screws, pins and shafts go very smoothly on their places. This car can be built by anyone. The instructions could be a little bit better (like Kyosho or HPI) but the pages are very explanatory with the indication of the parts in 1:1 and clear drawings.

All the fluids come in the box. 30000 diff oil for the front diff, 5000 for the back diff and a bottle of 600 oil for the shocks. A thing that I like a lot is the fact that many of the screws are Allen screws. They look much better than regular Philips screws and the chances of ruining the head with a good wrench, is very remote.
The foam bumper and a set of threaded tires, inserts and rims are also included in the kit.  The manifold coupler straps and the fuel line is also included. You only need the pipe, radio and that's it.

I bought the kit version with the Mugen / Novarossi engine. It's a little beauty with rear exhaust and a slide carburetor. The carb intake is huge, and it is consistent with the claimed performance of the engine - 36.500 rpm. Ace Hobbies sold the RB X15 pipe, and as you can see is a beautiful aluminum polished work of art.

Here you can see the belt tensioner. It uses two bushings inside a plastic cylinder and a steel wire that acts as a spring. To adjust tension, there's a grub screw on the mount at the left of the fuel line. 

One of the issues pointed by RC Car Action was the possibility of the middle belt rubbing against the exhaust manifold and the fact that the car didn't include a belt tensioner. I made sure that would not happen by buying the tensioner by an unbelievably low price (the prices of spares for this car really surprised me). It's the same unit that equips the 1/10 on road competition Mugen car. It lacks instructions but a couple of minutes looking at it, and I knew how it should be installed. Very simple and effective design.

The car looks sturdy. The gearbox uses the same method of shifting that Kyosho uses, but instead of plastic it's all metal. The forces involved with this little engine are far bigger than the ones with the Kyosho GS11 motor. Just put a more powerful motor on the Kyosho and you'll break gearbox shafts like straws.

Bodies

What do you think about the choice of bodies?
I didn't want another Stratus (in spite of believing now that they are the best bodies around (see Body tests on the RS4 Pro 2 page).

I called the helpful guys at Apex Models in the UK and explained my inner struggle. The answer was fast and concise. The Accord and the Vectra show the same characteristics of the Stratus with a different (thank God) look. That's good, because after seeing the real Stratus I wonder how they did such a nice body. It's a really ugly car (of course this is an European point of view).

I had a Vectra (sold in Portugal by Opel) and I really liked the car. That front view is almost unbeatable.  The Accord will be painted like the one you see in the photo and with the Vectra I guess I'll apply some Thunder Designs decals.

The car will look cool and it will go fast. I'm sure I'll love it.

Racing

Well, not exactly racing...

Before the end of the year 2000 there was a proposal for rules in this class to be adopted in order to level the field and provide a common ground for competition.

The rules allowed only .12 engines no matter what type of exhaust they have.

Portugal, with a very deep wisdom, decided not to follow that proposal because the rear exhaust engines are much more powerful than the side exhaust versions and this would cause big differences between cars.
However, it decided to allow .15 engines to compete against .12 because some people already have them and they don't want to change. One of the excuses has to do with the fact that some of the cars already come with the .15 engines.

With this "small" move I still can't race with my MT12 motor in sanctioned races around here. The Brits do it, the Americans do it (and I guess that more countries do it also) but the Portuguese decided (in a enlightened way) that we won't. So, to have the cars leveled, we race .12 and .15 on the same race, but no .12 with rear exhaust. Does this make sense to anyone?

Solution? Buy a side exhaust engine in order to race the car...until some persons with voting power decide they want a rear ex. .12 and change the rules (or make them) again the next year.

In spite of liking the RC cars a lot, this type of attitude regarding the protection of investments is causing these stupid contradictions around here, and it is making me wonder what kind of mind processes are behind these stupid decisions. The same goes for the 12 turn limit on electric cars. Portugal didn't adopt it to protect the investments of the guys that have hot motors with 8, 9 or 10 turns. On top of that they are sponsored. They probably have the motors for free or for half the price.

What will happen is a guaranteed humiliation when our drivers go to ANY competition with their European counterparts. EVERYBODY in Europe has this 12 turn limit. The Brits had this rule last year and they had several drivers at the World Champs in Japan.

The only good drivers that we have, Matias 3rd in the World 1/8 TT and another guy in 1/5 scale are running under World/European rules.

Only these classes in which we have nobody that can drive to achieve a place in the top half of any event, have this sort of approach. And you know why? I guess it's because they like to be the Champions of their street. If they leave the shell there might be better drivers out there and they just are blown away by 12 year old kids. It's got to hurt.

Finally I tested it (11/1/2001)

I took the car to the track. I now have the needed starter box and all the gadgets to race this car.

As expected a few things got loose (1st gear pinion) and I couldn't seem to adjust the gearbox correctly. The motor was run in with a tank running at idle and another one running very rich and very slowly around the track. The day came to an end before I could start to lean the engine a little bit.

But the next day I was prepared to make it fly. I started to progressively lean the engine and the car was getting faster and faster. I had installed TRC foams that I had and I could see that this setup has real potential.

Even with the engine very rich the car is a blast. At the end of the day the carburetor has the correct  setting, and boy, does it fly!!! The thing is a bullet. I had a short ratio for our LONG track but the speed of the thing is absolutely scary!!

I was plagued by radio problems (again, and it seems that never ends) so I had to be very careful with the car. I don't want to scratch it at all.

This car is a potential winner. The motor revs so much and so fast that's incredible to observe. A soft throttle finger is a must. Probably a negative EXP on the radio may help. I'll try that.

I got tired of all the radio problems that I have since I started, so I went to a Hobby Shop and got myself a SANWA M8. No more problems for me. It's over. And that Multiplex radio goes to the factory for repair.

I've broken so much parts due to these radio problems that I can't recall the last time I had a race without glitches. Probably I never did.

Racing it, finally!!!

I decided to enter a race with the car. not before a few modifications because I just can't stand the look of all the racers saying - "Look ! Box stock! the poor guys has a car just like the ones we buy on the shop!" LOL, nahh not really.

I decided to give it a try with an Orion .12 Wasp engine. It's basically a Picco made for Orion and it's very powerful. 1.5 hp and something like 38.000 rpm.

The track is very twisty and with a small straight. No one ways in there because brakes are really a major necessity.

On the first qualifying run I made 18 laps with a time well below my expectations and everyone else's. This run put me in the half finals with ease.  It was a relief because the air temperature way very high and on the 2nd the engine refused to start and the 3rd was a little worse still with 18 laps.

My half final was run under 35ºC and a lot of pilots eager to get into the final. Luckily I was one of the drivers that went to the final 10. The car was behaving strangely letting the rear go and inconsistent on the turns. The engine was not tuned as it should and the car was lacking some top speed. However on that track speed is not a major consideration, but acceleration and good driving are the tickets to success.

On the final I was able to jump from 10th to 6th on the start (I always get behind to avoid the first pile of cars) with my usual strategy and when I was running in 5th, just 7 laps after start a guy hit me when entering a turn, and another T Boned my car on the exhaust pipe. The pipe was flat after that incident and I had to abandon.

I must say that I didn't care that much because getting to the final on the first race in the middle of very seasoned drivers is already half a victory.

The experience I gained with the car was crucial for the tuning I did after that.

A few more hop ups and we're ready to go...

I had already installed a Centax clutch on the Orion Wasp but a few things were troubling me. The brake plate is not up to the standards, and the upper deck flexes enough to be visible.

So I changed the upper deck for one made by Kawahara and the brake plate is also by Kawahara.

This new upper deck has a different distribution of servos and battery pack, with the later behind the throttle servo. This pack has to be hump style and can be installed from the top of the deck.

The servo moves forward and it's very close to the steering servo.

Kawahara provides the new linkages and all the hardware needed to make the change. The carbon plate is first quality and the car flexes a lot less and handles like a charm.

A word of commendation to SpeedTech RC for their excellent service and response time. A big A+ on service and quality.

The brake plate is a much better option than the one included on the kit. That kit plate is sloppy, soft and the brake eccentric axle moved around a lot.

Instead the new one has BB for the eccentric and is a very well machined piece of aluminum. Not only improves the looks but also a very good addition, performance wise.

You can also see the Mugen reinforcement brace that replaces the plastic original with great results. Again, the flex in here just disappears. The chassis is now stiff and responsive.

I've been running this combination on a fairly big track and the car moves like running over rails.

With rear 30 mm foams from UFRA and a front one way the car is very difficult to beat. As my driving and tuning skills progress, a place in the top 10 at other races seems a very reasonable expectation.

After the incident with the pipe (flat...) I changed to a Picco inline exhaust and although the sound is a bit higher, the response in acceleration and the top speed improved with the change. This system allows the engine to rev so fast that almost seems like an electric car. The Centax clutch is also a must if you need the best in terms of tuning.

A small front belt tensioner from Kawahara was also installed and it's very important because the belt distends a little with running and the pulley is very very close to the chassis. After a while the belt starts to rub the chassis.
This little and ingenious piece takes the slop out and the belt doesn't rub anymore.

To top everything I decided to get the gorgeous BMW body from HPI. It is SO NICE that I'm afraid to scratch it.

And here are the links to Kawahara site and SpeedTech

Specs