Does the flywheel protrude thru the chassis or come close to protruding? It might be stalling when the chassis slaps the ground? What diameter flywheel are you using and what typa of car? Some cars, like Xrays and Team Magics use smaller flywheels than others...

I've had this problem with some of my car and a smaller flywheel has solved it!

Correct method to shut the engine down
 

Houston,

I have a question for you. Some of the local racers here just returned from the Hank Perry Race in Spokane and they were informed from more than one Pro racer to not touch the flywheel to shut the engine off. They were told that method is hard on the rod. I'm not trying to start anything here, but that doesn't sound logical about the rod IMO. These guys were told to cover the exhaust pipe stinger to shut the engine off is a better method. I know that can cause a hydraulic lock in the cylinder and dissagree with this method. Am I wrong?

What is your opinion and reasons? Thank you for your time.

when the idle is all the way down i touch the flywheel and its dead , i then bottom out the piston every time i shut down within a second .

engines :)

reverse nitro flow
 

hi guys,
what could've caused the nitro in the tubing to 'back flow' when i crank it on the starterbox?

it's was fine 10mins ago but after it stalls and when i tried restarting, it just wouldnt start anymore and i notice the nitro would 'back flow' and my nitro line will be empty of nitro... :weird:

even if i tried covering the exhaust and managed to pump nitro into the carb, the nitro would 'back flow' again when i crank it on the box! :cry:

Check your temps :nod:

This is just a little bit of trivia, but it's not the sleeve that wears, it's the piston. Nickel plating is supposed to be much harder and more abrasive than chrome, so it wears the piston more quickly than with a chrome sleeve. the result is the same, but I thought you might find that interesting.

That's nonsense. Plugging the exhaust is the worst way to shut down the engine. It causes pressure to build up in the exhaust system, which then increases the pressure in the fuel tank via the pressure line, then it floods the engine. If the engine is tuned well and idles down properly, a light touch on the flywheel WHILE WEARING A GLOVE or with a screwdriver handle is the best way to stop the engine. My second choice is to pinch the fuel line. There's NO harm that will come to the engine (you might hear that from a couple internet engineers) and it keeps excess fuel from entering into the engine. I'd be interested to know which "pro" is suggesting plugging the exhaust because it's the least desirable way to stop the engine. It doesn't cause any harm, but it makes the engine hard to start and, if you shut the engine down at the end of the day using that method, it will leave excess fuel in the crankcase, which may lead to corrosion.

i like this guy , intellegent answers that people can understand :nod:

bravo stevep:cool:

correct
 

The nickle plating is softer, and with thinner wall thickness,than chrome plated liners. In most cases nickle plated liners DO wear quicker than the piston. I see it very often. Hope this helps you guys. RayA

Actually, the nickel sleeve is much harder than the piston. It's the piston that wears. The full name for the coating is nickel silicon carbide and it's hard and more abrasive than chrome. It's applied with an electroplating process that's cheaper and has less environmental impact that chrome plating. It was an easier and less expensive alternative than chrome, but as we gained more experience with this coating, it became apparent that it was too hard on the piston. It's OK for engines that run rings because most of the friction and wear is absorbed by the rings, which can be made of ceramic or other incredibly hard materials. RC car engines obviously have no ring, so it's aluminum vs. the cylinder coating, and nickel silicone carbide is too hard on the piston. Here's a little chart to show you the hardness of the typical cylinder surface treatments.

http://www.eci.aero/IMAGES/nic_chart.gif

abn verses abc construction
 

You are correct with all said above, except actual wear factor of nickle plated liner is greater than piston wear.the nickle plating is,as everyone understands,very thin + not at all as resiliant as chrome plated car truck buggy + truggy engine model sleeve liners.I agree although nickle plating is harder than piston,it is not as resiliant.I have seen thousands of both ABN + ABC piston and sleeve sets. Never seen a chrome plated liner worn through, and have seen many nickle plated worn behond acceptability.in addition, every set I receive I look over inspecting surface finish conditions + wear factors, documenting both.just what I do in my work process and am always pleased to share with the racers.hope this helped.RayA

I know a little bit about this. I've been running nitro engines for 30 years and have been in the business for 25 of those 30, but the point isn't relevant to the topic so I'll just agree to disagree with you. This is the reason I avoid posting on forums too often - there's always an internet expert that wants to challenge the most benign statements. Back to our regularly scheduled topic of engine tuning.

BTW, I grew up and worked back in that neck of the woods for a long time. You and I have probably raced together on occasion.

i have also seen many times the nickel plated sleeves worn through to the brass . os cv engines in 10th scale truck . :)

Ok, let me give you a little background on this, because like many other urban legends, this is one that a lot of people have never tested or researched. It’s easy enough to see a worn coating and, combined with the complaints on the internet about how nickel-based engines don’t last as long, assume that one has something to do with the other. I made the same mistake myself, so I;m one of those people that made an incorrect assumption, but more on that later.

I started running nitro cars in the late 70’s. I started with ringed engines cast in molds that were hand machined, and using parts that were hand machined. There was no CNC back then. Slide carbs didn’t really exist and some engines even used exhaust throttles. The point is, it was pretty Flintstones. A few years later I started Car Action magazine with Chris Chianelli and the owners of Air Age Media. I served in just about every position over the years and finished up as Executive Editor during my tenure, and I also started and ran RC Nitro Magazine. I’ve been running nitro cars ever since. I have a particular interest in nitro, so I did many of the nitro-related tests in the magazines. During my time in the business, I’ve had access to the most experienced nitro people in the world. I picked everyone’s brain, shared observations and, suffice it to say, I think I picked up a fair bit of knowledge and experience over the last 30 years – it’s hard to avoid it. I don’t call myself an expert, but I’ve amassed a lot of information and experience on the subject over the years. So I don’t make these statements based on assumptions – it comes from experience and testing.

Having said the aforementioned, I also shared the same belief many years ago that the nickel silicon carbide coating was too soft and wears too quickly, but I was told otherwise by a good friend that’s a lot smarter than me and a legend in the RC engine business – it’s not the cylinder wearing, it’s the piston. Not willing to accept this at face value, I pulled out a couple of engines with nickel sleeves. I measured both the piston and the cylinder for each, then ran them for a roughly a gallon each and compared the measurements with the original numbers. The results were exactly what he told me to expect. That’s not to say that nickel silicon carbide coating doesn’t wear, but it wears a lot less than chrome – roughly half as much. But, it kills the piston much quicker and that’s what we see in our engines. If you don’t want to take my word for it, the same information is contained in an SAE publication (Society of Automotive Engineers) that I read about 13 years ago, which chronicles a battery of tests performed by a research engineering who worked for Mahle, the company that invented NSC coating. It directly compares Nikasil (Mahle’s brand name) with hard chrome plating in small two-stroke engines and confirms the same result. In every test, the engine exhibited twice as much wear of mating components, such as piston and ring (where applicable), and half the wear on the sleeve in the NSC vs. hard chrome comparison.

Why do some sleeves exhibit wear in some areas? Nikasil or other varieties of the same coating are applied much thinner than chrome. It’s much more ductile than chrome, so combined with the better wear characteristics; it can be applied really thin. Some manufacturers may take this to an extreme with a very thin coat, but the piston will be gone well before you wear out the sleeve. In either case, it has less to do with wear characteristics and more to do with the thickness of the plating.

I don’t want to turn this into a “My Cousin Vinny” moment, but a suspension of the laws of physics would be necessary in order for the sleeve to wear more quickly than the piston in a NSC-based engine. Either that or someone was duped by the plating company and they got gunmetal anodizing and not NSC. ;-) But I digress; the end result is the same – the engine just plain wears out more quickly, so we’re on the same page there, but it’s a fact that NSC is harder, more wear resistant and unfortunately more abrasive and twice as hard on the piston when compared to hard chrome.

Sorry about the blather. I know half of you were probably reading this as “blah, blah, blah” after the first sentence.

Well written! And a history lesson thrown in for free :D

Hahaha, not me :D
I already knew, but still nice to read a good explanation. ;)

From what I'm reading, it sounds like the nickel plating does wear because its a much thinner material than the chrome. But the wear rate on the chrome is much faster so a greater percentage of the chrome has worn if the nickel plating has worn. So if the nickel sleeve is worn, than the piston is really worn. Are the chrome liners thicker?

This is great info! I enjoy reading topics were people can have a discussion and even disagree and not have it turn into an argument. A LOT of people read this including myself and take everything in, look at both sides, do their own research and form an opinion. I wish we had more discussions like this. Everyone learns and the hobby/sport benefits.

You have it mostly correct. It's not really wearing because it's thin. Both coatings will wear, but the nickel wears half as much as the chrome. Lets say for example that the NSC sleeve wears 3µm, then the hard chrome would wear about 6µm under the same conditions. The piston however, is where there's a big difference. In an engine with a hard chrome sleeve, this piston may wear 20µm, but the same piston under the same conditions with a NSC sleeve will probably wear 60-70µm. So, it's easy to see why the performance degrades more quickly in engines with NSC sleeves - it kills the piston.

If the NSC coating is applied via chemical process instead of electrochemical, it can be as thin as .3µm, whereas chrome starts about 2 to 3 times thicker, and gets multiple passes. So, the opportunity for the coating to wear through a NSC sleeve is greater if it's not applied thick enough. but the RATE of wear is still much lower when all other factors remain the same.

you're funny steve :nod:


i think we would get along very well



hows samms doing ? still a busy boy ? :D

monty

I think I'm decidedly un-funny, but I make a lame attempt every once in while. Sams is coming down to So Cal next week, so I'll get a chance to abuse him then. I'm sure he's as busy as ever.

Cylinder
 

Some great info here! It's got me wishing the engine companies would sell just the pistons.

The piston and sleeve are usually sold as matched set. The tolerances are fairly critical, so they usually match one to the other, at least in racing engines.

Hi everyone ! I have a quick question ............ocassionally my engine will go way rich and flame out after refuling during a pit stop . What causes this and how can I tune my motor differently or what do I need to do to prevent it ! Thanks Dave .

Generally you will have the tune go off after a pit stop because the tank was over filled! It usually only lasts for half a lap... Don't over fill the tank and problem solved... some fuel guns are set up in a way that they can't over fill due to the positioning of the vents....

thanks for the info

I should add that the reason the tune goes off when you over-fill the tank is because when you fill to the top orf the tank neck and shut the lid, the extra fuel in the neck is forced up the exhaust pressure line. This means that the exhaust doesn't have the same effect on the tank pressure till you burn off the excess fuel and the motor will go off tune quite quickly.

Hi there.

What a great forum you have :).
Ron Paris was a hero when it comes to glow engines. Many years ago at a EC or WC he looked at a plug for 30 minutes... Just to be sure to get the right diagnosis for his driver.. What a champ :)

Well.

A tank in a car should ALWAYS be filled up to the top - in a race that's quit nessesary to fill the tank 100%.

I would suggest you to lean the LSN a little. If the engine runs too lean on that setting, you could try a little hotter plug. How much nitro do you use? Hotter plugs instead of a RB#6 is RB#5 or even better a SH#7. Increase the idle speed a little. All too often drivers sets their idle speed too low. That's critical with a full tank of fuel, where the mixture gets a little rich = lower idle speed.

put a pressure chamber in the line between exhaust and fuel tank

http://www.abc-rc-shop.nl/catalog/images/B0116.jpg

Hi M7H.

How does the pressure champer work? Do you have a link where to buy them?

Thanks :)

How it works?
After refueling with a full tank, the pressure puls from the exhaust pipe might overload your engine, this pressure chamber then works as a booster chamber to add some volume in the system.
Sometimes the lid of a tank might have this booster volume, but this just might not be enough....

Where you can buy it?
It is from Mugen, part B0116

Thanks M7H ;)

Whoever suggested that they might be overfilling the tank is likely correct. Most off-road tanks are sealed with an O-ring, and depending on the brand, the O-ring may be positioned partly into the filler neck of the tank. If you fill the tank to the absolute top including the filler neck, then snap the lid shut once you're finished refueling, the "plunger" effect of the O-ring forces enough fuel into the carb that it makes the engine run rich until you can clean it out. This is quite common and, as already mentioned, most fuel guns position the vent tubes about half way into the filler neck to stop filling the tank before it reaches the absolute top of the filler neck. I've never needed a pressure chamber on the exhaust pressure line because it's not an issue when you don't overfill the tank.

Hi Steve.

I see your point. When I drove buggies back I the early ´90, we didn’t had that problem. But there was no O-ring putted into the neck like today. We used to fill the tank 100% and then a little bit more when we removed the filler tube – just to be sure ;)
I hope dead1dave can use your replies.

Well said... That was what i was trying to say earlier :)

:) not a problem with kyosho and 8" of fuel line and 8" of pressure line :nod:

learning how to tune properly will alleviate 99% of the flame out problems , listening to the engine and understanding what needs to be done to correct any problems . i know some very very fast guys ;) that have no idea how to do this , that is what a very very good pit guy does :)

hi houston,
just wondering why offroad .21engines usually use a much hotter plug than onroad .21engines?

i've seen people using os p3 for their offroad engines but when it comes to onroad engines they'll use a much colder plug like nova#7. both using 25% nitro, air temp about 77F and humidity about 70%.

also, which is more damaging? over lean HSN or over lean LSN?

the only thing i can really think of about the onroad plug thing is the way the throttle is applied , the weight of the car and the fact that they are always towards the upper revs of the engine . off road cars are definitely easier to tune with the hotter plug , our offroad engines IMO have a much higher torque load that they transfer to the engine so they like to use a hotter plug to give an advanced timing to the engine .



over lean hsn because thats where your engine is revving and needs more oil :nod:

not saying that a lean bog off the bottom is a good thing but its not just caused from a lean lsn . usually high temps or wrong pipe ;)

thankyou for yr reply houston. :D

however, what i'm trying to ask about the engine lean issue is that; what damages will happen to the engine if:

you're running it too lean on the
1) LSN, 2) HSN

by the way, how will the tune be affected if there's a change of plug? example from #6 to #5 or from #5 to #6?

what are perfect running temps for a OS V-spec?

There's no such thing as the perfect temp for any engine? Throw your temp gun into the bottom of your pit box and only use it for running in!... Learn to tune by power, sound and smoke. It's a much more accurate way of getting the best perfomance and longevity out of your engines.

google RON PARIS and you'll find the best tips for tuning nitro engines!