Nostrixoxide

Hi guy's,

I have what may be a strange problem I'm dealing with. I have a NTC3 with a OS.18tz & a MPPA electric supercharger that is powered with a lipo pack. I usually dial it in right around 240*. My problem is that if I full throttle it from a dead stop it breaks the rims.

This is not a joke, it really does just snap the center of the rims right off & the remaining portion of the wheel/tires goes shooting into the air about 10-15ft. It has not happened on any of the front wheels, but I've gone through about 4 sets on rear. I've tried several different kinds of wheels & the one's that tend to hold up the best are the factory 6 spoke rims.

My question is, is this common with NTC3 that are running .18 size motors? Is the torque to much for the chassis to handle & if this is the case am I pretty much stuck having to purchase a set of alloy wheels for it? I've never had the best of luck glueing tires to alloy, they always seem to seperate from the bead even when I rough up the inside lip of the wheel to promote adhesion.

Also, is there a better brand of wheel that I may not know about that has more material in the center to help reduce this issue. Now that I'm thinking about it I could try a solid wheel, but those don't really look to pretty.

Thanks in advance to any info you guy's can provide me...

SpraydbySprague

iTrader: (64)

The .18 isn't too much of an issue. However, the supercharger adds a whole new variable. Alloy wheels won't help IMO. What brand of wheels are you trying? I've had some good luck with the Jaco wheels. Plenty tough and good looking spoke wheel. The dish wheels will be the strongest. I'd sure like to see a video of that car in acton.

Nostrixoxide

Gosh I wish I had the equiptment & know how to make a video for ya but I'm now the best when it comes to this computer stuff. I have a friend that may be able to help with that. I'll ask & see what I can come up with.

As for the wheels I have tried Stock, Venom & a set of HPI wheels I believe. The Venom wheels & tire combo lasted about 4 seconds. I'm sure you can imagine how unhappy I was coming back from the hobby store thinking I found something that might be the cure but with no luck. And those wheels were prettypricey too if I recall.

As for the supercharger, if you ask me it's just as fast if not faster with it off. I do notice it is alot stronger down low with it on. But I did have a buddy of mine make a special pipe for it. He builds racing 2 stroke motors so he was explaining to me how the exhaust wave works to in escence act like a door to allow the air/fuel mixture to remain inside the combustion chamber. And with the supercharger it pretty much forces this mixture right out of the exhaust unless you make a pipe to allow it to work correctly. The pipe he made kinda looks just like a 2 stroke dirt bike pipe but with a huge bubble in the center of it.

Anyways, it's a fun car. But I'm way to scared to make any top speed runs. I've got way to much money in this thing. I think I'm close to $2K in it right now & thats with me doing alot of the polishing myself by hand. Not fun when you see your handy work get airbourne on a nice black top street.

I'd really like to fit some 50mm foams on it similar to what people run on carpet pan cars. Or maybe something similar to a super nitro RS4? not really sure how to make that work though. The RS4 wheels hit the suspension, like the offset of the rim is not enough.

asw7576

It's not the engine nor supercharger putting so much power to the ground. ( Usually the rear differential gearbox break easy during races from what I observed ...... never make it to finish line ).

Check the wheel hex width thickness. Sometimes a poor designed car like NCT3 have their wheelhex are not wide enough to accept today tires rims. Look at the inside rim edges, are they touching the bearing on the rear upright ?

lil-bump

iTrader: (89)

I would try the GQ foam tires

Oasis

iTrader: (38)

The NTC3 was NOT a poorly designed car..it did have its issues but poorly designed was not one of them..in the right hands they are still fast..obviously the people who you have watched did not know how to build a diff..I have never had diff problem.. and to be honest about it..any top racing .12's make the power that an .18 makes..and "supercharging" a 2 stroke motor doesn't work..your buddy can tell you that....It seems to me that maybe you should try some Yokomo rims and tires..maybe some takeoffs..

Nostrixoxide

I've never had a problem with any of the diff's or any other part on my NTC3 other than the rims not holding the power.

As for supercharing 2 strokes not working, well thats not true. I've built several motors in my lifetime & like to think of myself an mechanically inclined. I have seen numerious 2 stroke motors make significant games via the installation of a turbocharger on a $85K dollar engine dyno. GM made several turbocharged 2 stroke diesel motors that can still be found on the roads to this day.

If you do alittle research on turbocharged 2 stroke snow mobiles you will gain alot of knowledge about how to make them function properly when boosted. The trick is all in the pipe. As long as you can control the pressure wave, you can control the combustion process.

Don't get me wrong, I still feel my NTC3 is faster with all the SC equiptment off then installed. But to me most of that has to do with saving the additional weight. By the time you remove the xtra battery pack, SC assembly, speed control for the supercharger, all the adapters & wiring. Your talking atleast 1/4 to 1/2lb of total weight removed. Thats pretty significant when you consider the overall weight & power of these little guy's.

Here is a quote from another forum regarding boosted 2 strokes.

Allison Diesel made a V-8 heavy equipment engine not too long after WWII... It was a direct injection 2 stroke with overhead valves... they have turbo and supercharged those types of engines for the last 65 years...

You guys are getting too hung up on the number of operational cycles...

The valvetrain is what makes or breaks forced induction suitability...

Any large engine will have some sort of positively actuated valve system... those are fine with forced induction applications...

THE PROBLEMS with small engines are the fact that they have NO VALVETRAIN... or they use simple reed/flapper valves that use ambient pressure to open and close them...

I have a gaggle of small model airplane 2 stroke engines... they work similarly to the chainsaw and weedeater engines in your garage...
The mixture is drawn into the crankcase... and then travels outside the cylinder liner to ports cut into the sides of the liner... the positioning of the ports is what determines the timing of the engine operating events.

These small engines CAN BE "SUPERCHARGED" with a tuned exhaust resonator that uses divergent and convergent cones at each end to set up a standing pressure wave... the pipe is tuned to a frequency that places the lowest pressure trough right at the exhaust port the moment it opens to expel gasses... they are very peaky by design... kind of like an organ pipe plays only one note.... the engine will produce AMAZING POWER at only one speed... the tuned pipe note's speed....

asw7576

YES, IT IS. Compare that with MTX3, V1-RR, FW05, 710.

(And the driver was competing in group C ( out of 116 contestants ). I'm sure he knows how to set up the diff. Otherwise he won't make it to the C final ).

Okay,... friends.... have to go for party now . Happy New Year !!!

Roelof

Alu rims is not the way to go. They are expensive and any crash will damage them. Maybe you are not using the right brand rim/tire?

Regarding a turbo. No that will not work, when the cylinder opens his chanels to enter the mixture also the exhaust is open and there is no way to build up more pressure. What will happen is that more pressure at the carb will fill up the crankshaft faster and a bit more which does give a better/directer responding engine.

Seisick

perhaps using gpr 220mm tires?

Nostrixoxide

Thanks for the info about the Aluminum wheels. It's not my goal to every crash this little guy, but I know that some things are not always in my control.

As for the turbo not working, please do alittle more research before you just state that "No, it will not work". It has been proven to work over & over again. Keep in mind that the way a N/A nitro engine normally works is it uses the pulse wave in the exhaust to sustain pressure on the exhaust port to allow the A/F mixture to remain in the combustion chamber long enough to ignite.

Now if you can tune your exhaust so that it will maintain the correct balance meaning the exhaust pressure can be equal to the amount of air entering the cylinder through the carburator then that means in theory boosting a 2 storke is more then humanly possible. Like I've said before I have seen several turbocharged 2 stroke racing engines before. The entire trick to getting them to work properly is the design of the exhaust system.

Don't ask me how you tune a exhaust system properly to work with a turbocharger. That is not my specialty, but I promise you there is alot of mathmatics involved.

Here is some proof for you.

http://www.youtube.com/watch?v=CjFOO...eature=related

http://www.youtube.com/watch?v=zbwuT...eature=related

http://www.youtube.com/watch?v=GGXcM9evUpo

NiTrO BoOsTeR

iTrader: (7)

hey mate, try some Nitro touring Foam Tyres, they might not last as long as the rubber tyres but they are designed in a different way. also you could try those new Capricorn Foam tyres, they have graphite composite to make then even stronger,

just something you might be able to try. or another thing you could adapt your NTC3 to fit the 1/8th onroad tyres these could give the added strength as well

mitchell

Francis M.

iTrader: (2)

Check your wheel Hex to make sure it did not round out on the corners. You can update the wheel hex to aluminum ones and this should help with your wheel breaking issues.

Nostrixoxide

Thanks guy's I really appreciate all the help. I'm glad I was able to find a site that has some top notch enthusiast